graduate student symposiump. 2 paschalis alexandridis sriram neelamegham nae member • faculty...

Friday, October 1, 2010

1:00-5:00

The Center for the Arts, University at Buffalo North Campus

GRADUATE STUDENT SYMPOSIUM on Research in Chemical and Biological Engineering

Siirola is a member of the Board of Directors of ABET. He is also a trustee and past president of

CACHE (Computer Aids for Chemical Engineering Education), and a member of the American Chemical Society, the Association for the Advancement of Artificial Intelligence, and the American Society for

Engineering Education. He has served on numerous National Research Council, National Science

Foundation, and Department of Energy panels, and on the advisory boards of several journals and

chemical engineering departments.

Siirola is a member of the National Academy of Engineering and was the 2005 President of the American

Institute of Chemical Engineers.

Featuring Jeffrey J. Siirola of Eastman Chemical Company

Sustainability and Carbon Management in the Chemical and Energy Industries

Jeff Siirola is a Technology Fellow in the Eastman Research Division of

Eastman Chemical Company in Kingsport Tennessee where he has been

for 38 years. He received a BS in chemical engineering from the University of Utah in 1967 and a PhD in chemical engineering from the

University of Wisconsin-Madison in 1970. His areas of interest include

chemical process synthesis, computer-aided conceptual process engineering, design theory and methodology, chemical process

development and technology assessment, resource conservation and

recovery, sustainable development and growth, carbon management, and

chemical engineering education.

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Faculty Paschalis Alexandridis • self-assembly, complex fluids, soft materials, nanomaterials, amphiphilic polymers, biopolymers

Stelios T. Andreadis • stem cells, cardiovascular and skin tissue engineering, wound healing, controlled protein and gene delivery

Chong Cheng • polymer-drug conjugates, nanomaterials by mini/microemulsion, biodegradable polymers and nanostructures

Jeffrey R. Errington • molecular simulation, statistical thermodynamics, interfacial phenomena

Mattheos Koffas • metabolic engineering, bioinformatics, natural products

David A. Kofke • molecular modeling and simulation

Michael Lockett • NAE member • multi-phase flow and mass transfer in process equipment, distillation, air separation

Carl R. F. Lund • heterogeneous catalysis, chemical kinetics, reaction engineering

Sriram Neelamegham • biomedical engineering, cell and molecular biomechanics, systems biology

Johannes M. Nitsche • transport phenomena, dermal absorption, biological pore and membrane permeability

Sheldon Park • protein engineering, directed evolution, structural bioinformatics, and simulations

Eli Ruckenstein • NAE member • surface phenomena, thermodynamics of large molecule solutions, interaction forces in

nanosystems, protein folding and defolding, hydrophobic bonding

Michael E. Ryan • polymer and ceramics processing, rheology, non-Newtonian fluid mechanics

Harvey G. Stenger, Jr. • environmental applications of catalysis, hydrogen production, fuel cells

Mark T. Swihart • nanoparticle synthesis and applications, chemical kinetics, modeling reacting flows

Esther S. Takeuchi • NAE member • energy storage, novel materials, reactivity at interfaces

Marina Tsianou • molecularly engineered materials, self-assembly, interfacial phenomena, controlled crystallization, biomimetics

E. (Manolis) S. Tzanakakis • stem cells, pancreatic tissue engineering, cardiac tissue engineering, biochemical engineering

Chemical and Biological Engineering faculty participate in many interdisciplinary centers and initiatives including The Center of

Excellence in Bioinformatics and Life Sciences, The Center for Computational Research, The Institute for Lasers, Photonics, and Biophotonics, The Center for Spin Effects and Quantum Information in Nanostructures, The Center for Advanced Molecular

Biology and Immunology, and The Center for Advanced Technology for Biomedical Devices.

http://www.cbe.buffalo.edu

All Ph.D. students are fully supported as research or teaching assistants. Additional fellowships sponsored by the State University of New York,

the National Science Foundation, Praxair, Inc., and other organizations are available to exceptionally well-qualified applicants.

For more information and an application, go to http://www.cbe.buffalo.edu, e-mail [email protected], or write to Director

of Graduate Studies, Chemical and Biological Engineering, University at Buffalo (SUNY), Buffalo, New York, 14260-4200

Department of Chemical and Biological Engineering

Integrative Research at the Leading Edge of

Chemical and Biological

Engineering

Genetically Modified Skin

Silicon Nanocrystal Simulation of Ordering

of Water Molecules

Genetically Modified SkinGenetically Modified Skin

Silicon Nanocrystal Simulation of Ordering

of Water Molecules

Silicon NanocrystalSilicon Nanocrystal Simulation of Ordering

of Water Molecules

Simulation of Ordering

of Water Molecules

Biochemical & Biomedical

Biomedical Engineering

Nanoscale Science &

Engineering

Computational Science &

Engineering

Chemical Engineering Science

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1:00 - 3:00, Presentations in the Center for the Arts Screening Room, first floor

3:00 - 5:00, Poster session and reception in the Center for the Arts Atrium, first floor

Presentations

1:00 – First graduate student lecture

Gaurav N. Vajani

Doctoral Candidate in Professor Carl Lund‟s group

Deactivation of Gold-Ferrochrome Very Low Temperature Water-Gas Shift Catalysts

1:25 – Second graduate student lecture

Eric Hao-Fan Peng

Doctoral Candidate in Professor Stelios Andreadis‟ group

Engineering Arterial Substitute from Hair Follicle Stem Cells and Small Intestine Submucosa

1:50 – Break

2:00 – Keynote Lecture

Dr. Jeffrey Siirola

Eastman Chemical Company

Sustainability and Carbon Management in the Chemical and Energy Industries

There is much interest in environmental protection, greener chemistry, and the general notion

of sustainability within both the chemical processing and energy industries. In this

presentation, sustainability will be examined in the context of long term raw material and

energy availability, the desire for strong economic growth, and climate change threats.

Population and economic trends, material and energy resource availability data, and

elementary engineering principles are applied to help frame sustainability issues for the

chemical and energy industries, the satisfaction of expected energy needs, and environmental

impacts. Simple concepts from chemical structure and carbon oxidation state, stoichiometry,

and thermodynamics are useful for understanding and screening among raw material and

energy alternatives at present and going forward. Such analyses suggest that a sustainable

future path may be feasible, although carbon capture and sequestration innovation will be

essential. Carbon dioxide management will likely include schemes to decrease generation

rates, schemes to offset emissions with carbon removal from the environment, schemes to

capture generated carbon before it can be emitted to the environment, and schemes to

permanently store captured carbon. Although the magnitude of the carbon to be managed

and the costs and technical challenges for doing so are very large, a roadmap of feasible steps

that might be taken on a global scale is suggested.

Symposium Schedule

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Biological Engineering

1. Triple Promoter Lentiviral RNAi Vector for Vascular Smooth Muscle Cell Differentiation

Stella Alimperti, Jun Tian, Pedro Lei, Stelios Andreadis 8

2. Induced Pluripotent Stem Cells Derived Functional Smooth Muscle Cells for Cardiovascular

Tissue Engineering

Vivek K. Bajpai, Stelios Andreadis 9

3. Mesenchymal Stem Cell for Vascular Tissue Engineering: Effects of Nanog or Oct4 Overexpression

on Proliferation and Myogenic Differentiation

Juhee Han, Sindhu Row, Daniel D. Swartz, Stelios Andreadis 9

4. Covalent Conjugation of Transforming Growth Factor-beta1 to Fibrin Hydrogel for

Tissue Engineering Maoshih Liang, Stelios Andreadis 10

5. Characterization of the Multi-lineage Differentiation Potential of Human Hair Follicle Derived

Stem Cells

Panagiotis Mistriotis, Vivek Bajpai, Stelios Andreadis 10

6. Live Cell Array for Monitoring Real-Time Gene Expression in Mesenchymal Stem Cell Differentiation

Janhavi Moharil, Pedro Lei, Jun Tian, Stelios Andreadis 11

7. Cell-controlled and Spatially Localized Gene Delivery with Fibrin-conjugated VSV-g

Pseudotyped Lentivirus: Implications for Lentiviral Microarrays Roshan M Padmashali, Stelios Andreadis 11

8. α-catenin is involved in Adherens unction formation and cell proliferation in 3-dimensional

skin constructs Aishwarya Ranganathan, Meng Horng Lee, Hui You, Stelios Andreadis 12

9. Effect of Nanog on young and aged bone-marrow derived mesenchymal stem cells using scaffolds

for tissue-engineering Sindhu Row, Juhee Han, Hao Fan Peng, Stelios Andreadis 12

10. Directed evolution of Stilbene Synthase to improve Resveratrol production Namita Bhan, Zachary L. Fowler, Mattheos A. G. Koffas 13

11. Strategies for Improved Anthocyanin Biosynthesis in Recombinant E. coli

Hila Dvora, Chin-Giaw Lim, Sridhar Ranganathan, Lynn Wong, Costas D. Maranas, Mattheos A.G. Koffas14

12. High-yield resveratrol production in Engineered Escherichia coli

Chin Giaw Lim, Zachary L. Fowler, Thomas Hueller, Steffen Schaffer, Mattheos A.G. Koffas 15

13. Biosynthesis of Anthocyanins in Metabolically Engineered Escherichia coli Lynn Wong, Chin-Giaw Lim, Mattheos A. G. Koffas 16

14. Biosynthesis of stereo-selective flavonoids using bioreactor: Targeting pathogens with non –

natural flavonones and catechins

Sriram Ramamoorthy, Karan Shah, Joseph Chemler, John C. Panepinto, Amy Jacobs, Mattheos A.G Koffas17

Table of Contents

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15. Systematic optimization of Escherichia coli metabolic pathway to increase flavanone yields and

productivity based on genome-scale metabolic simulation Peng Xu, Mattheos A. G. Koffas 18

16. Identification of Important α1,3 Fucosyltransferases in Regulating Human Selectin

Mediated Adhesion: Cooperation of either FT-IV or FT-IX with FT-VII Alexander Buffone, Jr., Kyle P. McHugh, Nandini Mondal, Sriram Neelamegham 19

17. FRET and flow cytometry based assays to measure plasma protease activity Shobhit Gogia, K. M. Dayananda, Gian Paolo Visentin, Sriram Neelamegham 19

18. Quantifying Site Specific O-Glycosylation using Flow Cytometry: The case of leukocyte PSGL-1 Chi Lo, Sriram Neelamegham 20

19. The VWF Propeptide Binds and Inhibits The Function Of Multimeric VWF In Blood

Sri R. Madabhushi, Chengwei Shang, K. M. Dayananda, Thomas E. Ryan, Sriram Neelamegham 20

20. Design, testing and analysis of a novel microfluidic flow device that assays the mechanism

and dynamics of platelet adhesion and aggregation Nandini Mondal, Nicholis Geile, Kwang W. Oh, Sriram Neelamegham 21

21. Decreasing the size and increasing the throughput of glycosyltransferase activity assays

Shilpa A. Patil, E. V. Chandrasekaran, Khushi L. Matta, Sriram Neelamegham 21

22. Developing Tools to Study the P-selectin Glycoprotein Ligand-1 Binding Interaction with Selectins

Han-Wen Yang, Alexander Buffone Jr., Sriram Neelamegham 22

23. Construction and analysis of novel domain swapped streptavidin dimer Cheng-Kuo Hsu, Kok Hong Lim, Sheldon Park 23

24. Engineering High-Affinity Monomeric Streptavidin Kok Hong Lim, Sheldon Park 24

25. Stable streptavidin heterodimer containing complementary interfacial mutations

Jasdeep Mann, Sheldon Park 25

26. Application of population balance models to the bioreactor cultivation of stem cells

Diana Cadavid Olaya, Manolis Tzanakakis 26

27. Expansion of human stem cells in a microcarrier bioreactor and their directed differentiation

toward pancreatic islet cells

Lye T. Lock, Manolis Tzanakakis 26

28. Engineering Pluripotent Stem Cells for Cardiac Cell Therapy

Abhirath S. Parikh, Donghui Jing, Manolis Tzanakakis 27

29. Genomic analysis to identify and manipulate important signaling pathways in glial progenitor

cell fate determination

Suyog Pol, Melanie O‟Bara, Gregory Conway, Fraser Sim 28

30. Roles of cell division and gene expression on stem cell population heterogeneity

J. Wu, Manolis Tzanakakis 29

mailto:[email protected]

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Molecular and Multiscale Modeling

31. Monte Carlo Simulations to study effect of roughness on wetting

Vaibhaw Kumar, Jeffrey R. Errington 30

32. Using molecular simulations to study wetting behavior of ionic systems

Kaustubh Sunil Rane, Jeffrey R. Errington 30

33. Wetting of Alkanes on nanorough surfaces using Monte Carlo Simulation

Shyam Sridhar, Jeffrey R. Errington 31

34. Statistical thermodynamics of hard-sphere fluids inside small pores: A virial approach

Jung Ho Yang, Andrew J. Schultz, Jeffrey R. Errington, David A. Kofke 31

35. A New Method for Calculating Free Energy of Solids Nancy Cribbin, David A. Kofke, Andrew J. Schultz 32

36. Signature for Structural Transitions: VEOS for Square Shoulder Potential model fluids Venkata SM Josyula, David A. Kofke 32

37. Molecular Based Modeling of Associating Fluids via Calculation of Wertheim Cluster integrals

Hye Min Kim, Andrew J. Schultz, David A. Kofke 33

38. Efficient computation of virial coefficients for effective screening of quantum-mechanical models

Katherine R. S. Shaul, Andrew J. Schultz, David A. Kofke 34

39. Efficient, precise and accurate methods of calculating solid-phase free energies by molecular simulation

Tai Boon Tan, Andrew J. Schultz, David A. Kofke 35

40. Solubility in Supercritical Fluids from Virial Equation of State Shu Yang, Andrew J. Schultz, Katherine R.S. Shaul, David A. Kofke 35

Nanoscale Materials Science and Engineering

41. Block copolymer - silica nanohybrids

Biswajit Sarkar, Vinithra Venugopal, Paschalis Alexandridis 36

42. Self-Assembly of Block Copolymers in Ionic Liquids Aikaterini Tsoutsoura, Paschalis Alexandridis 36

43. Efficient Synthesis of Well-Defined Functional Polylactide-Based Nanoparticles and Nanocapsules

by Thiol-Ene Reaction via Miniemulsion Chih Kuang Chen, Jiong Zou, Lu Yu, Efrosyni Themistou, Paschalis Alexandridis, Chong Cheng 37

44. Synthesis and Self-Assembly of Janus Double-Brush Copolymers

Yukun Li, Jiong Zou, Efrosyni Themistou, Chong Cheng 38

45. Synthesis, Characterization, and Biomedical Assessment of pH-Sensitive Brush Polymer-Drug

Conjugates for Cancer Therapy

Yun Yu, Jiong Zou, Goran Jafr, Zachary A. P. Wintrob, Efrosyni Themistou, Paschalis Alexandridis, Alice C. Ceacareanu, Chong Cheng 39

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46. Kinetic Study of Glucose hydrolysis and Characterization of Humins formed during this process

Sushil K. R. Patil, Carl R. F. Lund 40

47. Deactivation of Gold-Ferrochrome Very Low Temperature Water-Gas Shift Catalysts

Gaurav N. Vajani, Dongxia Liu, Carl R. F. Lund 40

48. Near Infrared High Quantum-Yield Luminescent Silicon Quantum Dots Coupled With

Gadolinium Ions for Biological Applications

ChingWen Chang, Folarin Erogbogbo, Mark T. Swihart 41

49. Controllable Synthesis of ZnO nanocrsytals

Xin Liu, Mark.T.Swihart 41

50. Combustion-Driven Synthesis of Non-Oxide Nanoparticles in a High Temperature Reducing Jet

William J. Scharmach, Vasilis Papavassiliou, Perry Pacouloute, Ray Buchner, Mark T. Swihart 42

51. Electrochemical Reduction of Ag2VO2PO4: Analysis of Discharge Products

Po-Jen Cheng, Esther Takeuchi 43

52. AgxVOPO4: a demonstration of the dependence of battery-related electrochemical properties of

silver vanadium phosphorous oxides on Ag/V ratios

Young Jin Kim, Esther Takeuchi 44

53. Characterization and electrochemical reduction of a new silver vanadium phosphorous

oxide Ag2VP2O8: In situ formation of silver nanoparticles

Chia-Ying Lee, Esther Takeuchi 45

54. A Novel Silver–Polymer–Carbon Composite Electrode for Nonaqueous Oxygen Reduction

Shu Han Lee, Amy Marschilok, Esther Takeuchi 46

55. Carbon Nanotube Sheets as Substrate for Lithium Vanadium Oxide Cathode Active Material Corey Schaffer, Esther Takeuchi 47

56. Thermodynamics and Temperature Effects of Lithium Silver Vanadium Phosphorous Oxide cells Munish Kumar Sharma, Esther Takeuchi 48

57. Layer-by-Layer Assembly of Clay with Strong and Weak Polyelectrolytes Biswa Das, Marina Tsianou 49

58. Effect of pH on Layer-by-Layer Film Growth

Adam Batchellor, Biswa Das, Marina Tsianou 50

59. Competitive Interactions in Surfactant Solutions: A Neutron Scattering Investigation

Ankitkumar Fajalia, Marina Tsianou 50

60. Synthesis of Hollow and Porous Zinc Sulfide Spheres by Spray Pyrolysis

Sha Liu, Mark Kaus, Mark T. Swihart 51

Acknowledgements 52


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BIOLOGICAL ENGINEERING

1. Triple Promoter Lentiviral RNAi Vector for Vascular Smooth Muscle Cell Differentiation

Stella Alimperti, Jun Tian, Pedro Lei, Stelios Andreadis

Department of Chemical and Biological Engineering, State University of New York at Buffalo, NY 14260 Email: [email protected]

High throughput technologies based on loss-gene function (RNAi library) is a valuable tool for screening genes

for cellular processes e.g. embryonic development or cancer. To this end, a lentiviral smooth muscle

differentiation RNAi library can be a valuable tool for identifying signaling pathways regulated during differentiation.

To achieve this goal, our lab has designed a triple-promoter lentiviral RNAi vector. This vector expresses

three different genes independently. More specifically, this vector contains a constitutive promoter (e.g hPGK) that drives DsRed expression determining the transduction efficiency; a second tissue specific promoter (e.g. α-

actin) drives the expression of second marker (ZsGreen) and H1 promoter expressing the knocking down gene

(Figure 1). The major advantage of this vector is that the promoter activity is independent of the gene transfer

efficiency reflecting the real biological activity of the promoter affecting by the gene silencing. To demonstrate a proof-of-concept, we cloned shRNA sequences from genes regulated by TGFβ1 included in RhoA (e.g RhoA,

KLF4) or SMAD pathway (SMAD2, SMAD6). Our results show that knocking down of SMAD2, RhoA,

repressed the α- actin promoter activity in response to TGFβ treatement. On the other hand,silencing of KLF4, SMAD6 upregulated the α-actin promoter activity under the same conditions. Therefore, the effect of gene

silencing into smooth muscle differentiation can be monitored with the triple promoter lentiviral RNAi vector.

Notably, high-throughput application of the vector like RNAi lentiviral library will be an important tool for identifying new genes and novel pathways related to smooth muscle cell differentiation.

Key Words: lentiviral vector, promoter activity, gene silencing, RNAi, smooth muscle cell differentiation

Figure 1: Schematic of smooth muscle cell lentiviral vector carrying shRNAs

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2. Induced Pluripotent Stem Cells derived Functional Smooth Muscle Cells for

Cardiovascular Tissue Engineering

Vivek K. Bajpai, Stelios Andreadis

Department of Chemical and Biological Engineering, State University of New York at Buffalo, Buffalo, NY 14260

Email: [email protected], [email protected]

Tissue engineered blood vessels represents attractive alternative to the shortage of autologus vascular grafts for coronary artery disease which is the prominent cause of mortality and morbidity in the United States. In

this light, induced pluripotent stem cell (iPSC) technology bears great promise for cardiovascular tissue

engineering as it may provide a potential inexhaustible source for autologous cells. Here we report that mature contractile smooth muscle cells (SMCs) can be selectively obtained from the iPSC cultures using tissue specific

promoter. Specifically, we allowed iPSCs to differentiate on matrigel coated dishes in presence of human

embryonic stem cell media conditioned with mouse embryonic fibroblasts after transducing them with dual promoter lentiviral construct containing smooth muscle alpha actin promoter driven reporter. Next, we

selectively enriched iPSC derived SMC (iPS-SMC) population by treating them with media M231 plus smooth

muscle growth supplement as confirmed by flowcytometry. Additional treatment with media M231 plus smooth

muscle differentiation supplement for five days resulted in mature SMC phenotype as evidenced by immunocytochemistry for a-SMA, calponin and myosin heavy chain (MHC). In reactivity analysis, cylindrical

vascular media equivalents fabricated from iPS-SMCs displayed significant contractility in response to

vasoagonists like KCl, U46619 (Thromboxane A2 agonist) and endothelin-1 suggestive of well developed receptor mediated and non-receptor mediated pathways of contractility. Our results suggest that iPSCs can serve

as an untapped autologous cell source of functional SMCs which has tremendous potential for cardiovascular

tissue engineering and regenerative medicine.

Key Words: iPS cells, smooth muscle cell differentiation, contractility, cardiovascular tissue engineering

3. Mesenchymal Stem Cell for Vascular Tissue Engineering: Effects of Nanog or Oct4

Overexpression on Proliferation and Myogenic Differentiation

Juhee Han1, Sindhu Row

1, Daniel D. Swartz

2, Stelios Andreadis

1

1Department of Chemical and Biological Engineering, State University of New York at Buffalo, Buffalo, NY 14260 2 Women and Children‟s Hospital of Buffalo, State University of New York at Buffalo, Buffalo, NY 14260

We demonstrated that bone marrow derived smooth muscle cells (BM-SMC) have high potential as an

autologous cell source for vascular tissue engineering. However, recently we examined the effect of organismal aging on the properties of BM-SMC. We found that the proliferation potential and contractile function of BM-

SMC declined with donor age. Recent studies suggested that overexpression of embryonic pluripotency

transcription factors improved the quality of adult stem cells. Therefore, we proposed that overexpression of these

transpcription factors such as Nanog or Oct4 may be used to increase proliferation and differentiation potential of adult bone marrow derived mesenchymal stem cell (BM-MSC). To this end we used lentiviral vectors to

overexpress Nanog or Oct4 in neonatal and adult BM-MSC and examined the effects on the properties of stem

cells and tissue engineering vascular constructs (TEVs). Our results showed that Nanog or Oct4 overexpression significantly enhanced proliferation and clonogenic capacity of BM-MSC. In addition, TEVs constructed from

Nanog+ adult BM-MSC demonstrated significantly higher level of vascular contractility as well as mechanical

strength compared to counterparts from control adult BM-MSC. On the other hand, Oct4 overexpression in

neonatal or adult BM-MSC displayed mediocre effect on vasoreactive contractility and resulted in lower mechanical strength of TEVs. These results are extended to obtain a gene expression profile of control or Nanog+

BM-MSC using DNA microarray and determine potential targets to reverse aging effects in adult BM-MSC.

Key Words: Ageing, Bone marrow derived mesenchymal stem cell, Nanog, Oct4, Smooth muscle, Vascular tissue

engineering

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4. Covalent Conjugation of Transforming Growth Factor-beta1 to Fibrin Hydrogel for

Tissue Engineering

Maoshih Liang, Stelios Andreadis



Transforming Growth Factor-beta1 (TGF-beta1) is a multifunctional cytokine that participates in various

physiological processes. Previous work showed that covalent conjugation of TGF-beta1 onto cell seeded tissue

engineered scaffolds increased extracellular matrix (ECM) protein deposition and improved the mechanical

properties of tissue constructs. Our present work aimed at covalent conjugation of TGF-beta1 to fibrin hydrogels during polymerization. To this end, we engineered fusion TGF-beta1 to contain the Factor XIII recognition

peptide for binding to fibrin. We started from optimizing the position in the TGF-beta1 sequence where the

peptide could be inserted without affecting TGF-beta1 expression. The results suggested that the sequences should be introduced at N-terminus of mature TGF-beta1, right after the latency associated peptide (LAP). The

fusion proteins were expressed in CHO cells and purified by affinity and size exclusion chromatography.

Proliferation of lung epithelial cells and promoter-driven luciferase assays showed that fusion TGF-beta1 had similar biological activity as the native protein. Using immunoprecipitation assays we showed that fusion TGF-

beta1 bound to fibrinogen in a Factor XIII dose dependent manner. When smooth muscle cells (SMCs) were

embedded in hydrogels with immobilized TGF-beta1, they compacted the gel more significantly suggesting that

TGF-beta1 improved the force generating ability of cells in a 3D context. Furthermore, these constructs showed enhanced strength and vaso-reactivity in response to different restriction agonists. Collectively, our data

demonstrated that this technique to conjugate TGF-beta1 to fibrin has potential for vascular tissue engineering.

Key Words: transforming growth factor-beta1, fusion protein, fibrin, controlled release, tissue engineering

5. Characterization of the multi-lineage differentiation potential of human hair follicle

derived stem cells

Panagiotis Mistriotis#, Vivek Bajpai

#, Stelios Andreadis

Department of Chemical and Biological Engineering, State University of New York at Buffalo, Buffalo, NY 14260 # These authors contributed equally to the work

Adult stem cells have been shown to reside in different tissues and play an important role in homeostasis.

Hair follicle harbors a rich stem cell pool with multipotent characteristics. In the present work total population of

human hair follicle cells (HFCs) were induced to differentiate into osteogenic, chondrogenic, adipogenic and

myogenic lineages. Gene expression kinetics was studied to confirm up-regulation of lineage specific early and late genes at the transcriptional level. Functional assays signifying lineage maturation were performed to observe

matrix mineralization, proteoglycans deposition, lipid droplets accumulation for osteogenic, chondrogenic and

adipogenic lineages respectively. In addition to that myogenic differentiation was assessed by gel compaction assay. We further studied the effect of long term in-vitro expansion on the multilineage differentiation potential of

human HFCs. Differentiation potential is heavily decreased after six passages of culturing as evidenced by

functional assays for respective lineages. To confirm the true stemness of human HFCs, single cells were isolated, expanded and successfully induced to differentiate towards ostegenic, chondrogenic and adipogenic lineages.

Taken together our results suggest that human hair follicle total cell population contains mesenchymal stem cells

that can effectively be used as a cell source for tissue engineering applications

Key Words: human hair follicle, stem cell, multipotent, differentiation, tissue engineering

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6. Live Cell Array for Monitoring Real-Time Gene Expression in Mesenchymal Stem Cell

Differentiation

Janhavi Moharil, Pedro Lei, Jun Tian, Stelios Andreadis


Stem cells are very promising in regenerative medicine therapies owing to their ability of self-renewal and differentiating into various cell types. However, the challenge still remains to understand regulatory

mechanism of differentiation of adult or embryonic stem cells. Using a novel dual-promoter lentiviral vector

engineered in our lab, we developed scalable live-cell microarrays to quantitatively measure gene expression dynamics in real-time as human Bone Marrow derived Mesenchymal Stem Cells (BM-MSC) differentiate along

the myogenic lineage. To do this, we generated a library of lentiviral vectors encoding promoters or transcription

response elements of genes that are potentially involved in myogenic differentiation. Subsequently, we arrayed

the lentivirus and used automated fluorescence microscopy to monitor real time gene expression as BM-MSCs differentiate toward smooth muscle cells. After identifying the optimal conditions that maintain BM-MSCs in the

undifferentiated versus differentiated state the kinetics of gene expression was interrogated in real time under

differentiation promoting conditions. Our experiment identified temporal patterns of gene expression of various proliferation and differentiation markers as BM-MSCs undergo differentiation. In contrast to standard methods,

our studies provide rich dynamic information of gene expression over a period of several days, thereby providing

real-time data that maybe useful in deciphering gene regulatory networks in stem cell differentiation.

7. Cell-controlled and spatially localized gene delivery with fibrin-conjugated VSV-g

pseudotyped lentivirus: implications for lentiviral microarrays

Roshan M. Padmashali, Stelios Andreadis


Email: [email protected]

We have previously reported that fibrin hydrogels can be used for effective plasmid DNA and lentivirus

encapsulation and gene delivery. Here we report our recent efforts to generate cell-controlled and spatially arranged live cell arrays with fibrin immobilized lentiviruses for enhanced gene delivery and high throughput

applications. Gene transfer in fibrin gels was strongly dependent on matrix degradation by target cells however a

significant fraction of lentiviral particles diffused out of these gels over time. To eliminate viral diffusion we engineered lentiviral particles that can bind covalently to fibrin during polymerization. Briefly, we generated

fusion proteins between the viral envelope glycoprotein (VSV-G), peptide domains that are recognized by factor

XIII and protease cleavage sites that are recognized by plasmin. All modified variants exhibited high transduction efficiencies relative to wild type enveloped viruses and bound to fibrin hydrogels in a factor XIII dose dependent

manner. As a result diffusion of virus from the gels decreased dramatically even for fibrin gels with low

fibrinogen concentration. When the modified lentivirus preparations were spotted in an array format, gene transfer

was strictly confined to virus-containing fibrin spots with no cross-contamination between neighboring sites. Our results suggest this transduction system with a high signal/noise ratio may be ideal for generation of lentiviral

microarrays for high throughput studies. We demonstrate this by patterning multiple fibrin conjugated lineage

specific vectors on glass slides. Cell type specific expression is localized to corresponding vector coordinates thereby revealing a high degree of spatial control.

Key Words: lentivirus, factor XIII, fibrin gel, microarray

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8. α-catenin is involved in adherens junction formation and cell proliferation in 3-

dimensional skin constructs

Aishwarya Ranganathan, Meng Horng Lee, Hui You, Stelios Andreadis


Adherens junctions (AJ) formation and dissociation is a phenomenon that can be observed during cell growth, migration and proliferation. Previous studies showed that α-catenin links β-catenin/E-cadherin complex

to the actin cytoskeleton, and hence it plays an important role in AJ formation in cells. Recently our laboratory

demonstrated that α-catenin is involved in JNK- mediated AJ formation in cell monolayers. To see if the same mechanism is involved in AJ formation in 3-dimensional setting, tissue engineered skin equivalents were

constructed from wild-type ME 180 cells that lack a-catenin and those that were genetically modified to

overexpress a-catenin. This is compared to the human foreskin and skin equivalents made from keratinocytes (which have α-catenin inherently). The skin equivalents made from all these cells show a similar organization of

cells as seen in the normal skin which could suggest that there is a possible difference in the mechanism of AJ

formation in 2- and 3-dimensional settings. We also observe that cells that lack α-catenin continue to proliferate in

all layers while those with α-catenin stop proliferating in the upper layers and show normal growth. These indicate the possible involvement of α-catenin in cell proliferation and AJ formation in 3-D.

Key Words: α-catenin, adherens junction, skin equivalents, proliferation

9. Effect of Nanog on young and aged bone-marrow derived mesenchymal stem cells using

scaffolds for tissue-engineering

Sindhu Row, Juhee Han, Hao Fan Peng, Stelios Andreadis


Organismal ageing is associated with impaired growth, function and differentiation of stem cells.

Previous work in the group on young and aged Ovine bone-marrow-derived mesenchymal stem cells by Han et al showed the effect of ageing on proliferation, clonogenicity as well as differences in functionality in tissue

engineered grafts made from these cells. Work by Liu et al implemented contractile hair-follicles in tissue

engineered grafts for vascular tissue engineering. This method used a bio-compatible scaffold, namely SIS (Small Intestinal Sub-mucosa), which provided mechanical strength, alignment and allowed cells to migrate into the

matrix.

It is necessary to develop vascular tissue constructs for elderly patients as most incidences of cardiovascular diseases are amongst older people. Moreover, autologous sources are important in regenerative

medicine as they do not invoke any immune response. Nanog is a known transcription factor present in embryonic

stem cells, which enhances properties of aged stem cells. The aim of this study is to use SIS to evaluate the effects

of Nanog on young and aged stem cells. SIS can also be subjected to strain (constant, ramping or periodic), shear and other mechanical conditions which give us important information about the robustness of the grafts. The

methods used here will test the functionality of the stem cells by investigating various properties such as

vasoconstriction, contractile function through receptor and non-receptor mediated pathways. It is necessary for vascular tissue constructs to be functionally characterized before further implementation. This study will enable

us to make implantable tissue engineered vessels for the elderly patients with cardiovascular problems using

autologous stem cell sources.

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10. Directed evolution of Stilbene Synthase to improve Resveratrol production

Namita Bhan, Zachary L. Fowler, and Mattheos A. G. Koffas



Stilbenes are small molecular weight naturally occurring plant secondary metabolites synthesized by the

enzyme stilbene synthase (STS). Resveratrol, a 3, 5,4‟-trihydroxy-trans-stilbene, is reported to have anti-cancer

and anti-inflammatory effects, anti-oxidant properties and slows the progress of cardiovascular diseases.STS has independently evolved in a few diverse plants (such as grapevine, pine, and peanut) via the duplication and

divergence of chalcone synthase (CHS) genes, the latter of which are ubiquitous in higher plants. STS enzymes

from different plant sources show varied catalytic conversion rates, so the idea is to evolve the STS (Vitis vinifera) by creating a random mutagenesis library using error-prone PCR. Higher yielding mutants will be

isolated by screening using a medium throughput colorimetric assay. The assay is based on the activity of laccase

enzyme (a phenoloxidase) to oxidize 2,2'-azino-bis(3-ethylbenzthiazoline-6-sulphonic acid) (ABTS) to produce a

blue coloration. Laccase takes up 3‟, 4‟-dihyroxylated compounds as substrates, leading to no oxidation of ABTS and thus, lesser coloration in the presence of resveratrol. Hyperactive mutants obtained from the first round of

random mutagenesis will be isolated and subjected to a second round of random mutagenesis. Finally

characterization of the mutants will be done to find their catalytic conversion rates and compare it to the wild type. Presently, the first round of mutagenesis has been carried out, and the screening is in progress.

Key Words: resveratrol, laccase, directed evolution

Figure 1: Arachis hypogaea STS with resveratrol (PDB ID 1Z1F)

p. 14

11. Strategies for Improved Anthocyanin Biosynthesis in Recombinant E. coli

Hila Dvora1, Chin-Giaw Lim

1, Sridhar Ranganathan

2, Lynn Wong

1, Costas D. Maranas

2,

Mattheos A.G. Koffas1

1Department of Chemical and Biological Engineering, State University of New York at Buffalo, Buffalo, NY 14260 2Department of Chemical Engineering, Pennsylvania State University, University Park, PA

Polyphenols in general and anthocyanins in particular have recently drawn vast interest due to their associated health benefits. Recent studies suggest that anthocyanins could have a preventative effect on diabetes,

obesity, cancer, and cardiovascular disease. However, significant research into these health benefits is limited by

the difficulty and high cost of obtaining pure compounds or well-defined mixtures from plants. An attractive alternative is production in recombinant microorganisms such as Escherichia coli. As a production platform, E.

coli has been extensively engineered for various non-native products. In addition, the growth characteristics of E.

coli allows for efficient production of non-natural analogues. Here, we demonstrate strategies to optimize

anthocyanin biosynthesis in recombinant E. coli. One strategy involved directing carbon-flow towards the biosynthesis reactions based on predictions from the recent OptForce model. Based on flux measurements

available for the wild-type strain of E. coli (BL21Star), OptForce identified the fluxes that must be modified in

order to ensure that the metabolic network produces anthocyanin at the target yield. The predicted interventions guaranteed a yield of 75% of theoretical maximum yield for anthocyanin while supporting the production of

biomass. Another strategy was designed to improve transport of anthocyanins to the culture media after synthesis

to simplify product recovery after fermentation. Here, the expression of the bacterial transport proteins was manipulated to increase anthocyanin titers in culture media. Finally, we took a closer look at improving

expression levels of anthocyanin biosynthesis genes through translational studies.

Key Words: flavonoids, anthocyanins, E. coli, metabolic engineering, computational predictions

p. 15

12. High-yield resveratrol production in Engineered Escherichia coli

Chin Giaw Lim1, Zachary L. Fowler

1, Thomas Hueller

2, Steffen Schaffer

2, Mattheos A.G. Koffas

1

1Department of Chemical and Biological Engineering, State University of New York at Buffalo, Buffalo, NY 14260 2Evonik Degussa GmbH, Creavis Technologies & Innovation, Paul-Baumann-Strasse 1, D-45772 Marl, Germany

Plant polyphenols have been the subject of several recent scientific investigations as many of the molecules in this class have been found to be highly active in the human body with a plethora of health-promoting

activities towards a variety of diseases including heart disease, diabetes, cancer and even the potential to prevent

aging. Further development of these potent natural therapeutics hinges on the formation of robust industrial production platforms designed by using selected as well as engineered protein sources along with the construction

of optimal expression platforms. In this work, we investigated the recombinant expression of stilbene synthases

under the control of different promoter constructs to create an Escherichia coli strain capable of producing

superior resveratrol titers sufficient for commercial usage. Further improvement of metabolic capabilities of the recombinant strain aimed at improving the intracellular malonyl-CoA pool, a major limiting factor for resveratrol

biosynthesis, resulted in a final improved titer of 2.3 g resveratrol/L. Additionally, we report the investigation of

various stilbene synthases from an array of plant species considering structure-activity relationships as well as expression efficiency in microorganisms and their relationship to resveratrol production.

Key Words: resveratrol, stilbene, protein expression, Escherichia coli

p. 16

13. Biosynthesis of Anthocyanins in Metabolically Engineered Escherichia coli

Lynn Wong, Chin-Giaw Lim, Mattheos A. G. Koffas



Anthocyanins are water-soluble colored pigments found in terrestrial plants. They are responsible for the

red, blue and purple coloration of many flowers, fruits and other plant parts. Anthocyanins have been known to

possess various health benefits such as cardioprotective, anti-inflammatory, antioxidant, and anti-aging properties. However, minute quantities of these polyphenols produced in plants complicate the effort to assess their full

potential. Thus, the overall goal of our project is to engineer a recombinant E. coli strain capable of high

anthocyanin production. The capacity of synthesizing anthocyanin from the recombinant E. coli was initially low. First, to accelerate the in vivo reaction rate, fluxes toward the UPD-glucose backbone were increased via gene

deletions and overexpressions. Second, we altered various E. coli transporter genes to improve substrate uptake

and product excretion. However, high-level synthesis was only achieved through altering the expression system. Overall, through these strategies, an extracellular anthocyanin titer of 230 mg/L was achieved. This result

demonstrates the feasibility of E. coli as a host for anthocyanin production for pharmaceutical applications.

Key Words: anthocyanin, UDP-glucose, transporters, E. coli


p. 17

14. Biosynthesis of stereo-selective flavonoids using bioreactor: Targeting pathogens with non

– natural flavonones and catechins

Sriram Ramamoorthy1,3

, Karan Shah1, Joseph Chemler

1, John C. Panepinto

2, Amy Jacobs

2,

Mattheos A.G Koffas1,3

1Department of Chemical and Biological Engineering, State University of New York at Buffalo, Buffalo, NY 14260

Email: [email protected] 2Department of Microbiology and Immunology, State University of New York at Buffalo, Buffalo, NY 14214

http://www.smbs.buffalo.edu/microb 3NYS Centre of Excellence in Bioinformatics & Life Sciences, State University of New York at Buffalo, Buffalo, NY 14203

The emergence of multidrug resistant bacteria and invasive fungal infections has severely undermined the efficacy of antibiotics causing high rates of morbidity and mortality in immune-compromised patients. One of the

primary reasons of multidrug resistance is attributed to the role of efflux pumps in transporting out the antibiotics.

New classes of anti-infective agents have to be developed targeting the rate of resistance and virulence factors. Natural products have always been at the forefront of novel anti-infective agents. Flavonoids are a highly diverse

group of plant secondary metabolites, ubiquitously found throughout the plant kingdom. The overall goal of the

project is to synthesize stereo-selective flavonoids and elucidate their antibacterial and antifungal properties of natural and non- natural flavonoids. We have synthesized non natural flavonones using substitutions in the B ring

and investigated its potential antibacterial and antifungal activities. We found out substituted flavonones exhibited

significant anti-fungal activities on C.neoformans. The effect on E.coli and B.Subtilis was much pronounced in

presence of efflux pump inhibitors PAβN and NMP than without them suggesting active efflux of these compounds. We predict that other classes of flavonoids like dihydroflavonols, leucocyanidins and flavon-3-ols

will exhibit better efficacy due to various degrees of ring hydroxylation, substitutions and bond saturation. To

meet out this goal, aforementioned classes of flavonoids are synthesized using three different engineered E.coli strains in a bioreactor harbouring FHT, DFR and LAR genes. Our second goal is intend to optimize and scale up

the fermentation protocols to achieve higher production levels.

Key Words: Flavonoids, Multidrug resistant bacteria, efflux pump inhibitors, fermentation, metabolic engineering, anti-fungals


http://www.smbs.buffalo.edu/microb

p. 18

15. Systematic optimization of Escherichia coli metabolic pathway to increase flavanone yields

and productivity based on genome-scale metabolic simulation

Peng Xu, Mattheos A. G. Koffas


Systematic optimization of Escherichia coli metabolic pathway to increase flavanone yields and productivity based on genome-scale metabolic simulation was carried out in this study. Disruption of TCA cycle

identifies three single mutant strains which can improve the naringein production without compromising cell

biomass. Single knockout of sucC, fumB or fumC increased naringenin production by 20-30% compared with wild type strain, whereas knockout of mdh, acnA or acnB adversely decreased naringenin production up to 30-

50%. Precursor pathway augmentation reveals that co-expression of acc and pgk or gapA can lead to a nearly

200% increase in naringenin production. However, overexpression of pyruvate dehydrogenase multienzyme

complex failed to improve naringenin production. By combining the beneficial mutants together with overexpression targets based on the genom-scale computational model, strains carrying fumC and sucC double

mutant in the acc, pgk and gapA overexpression background can lead to a highest titer of approximately 390 mg/l

of naringenin, which is about 4.6-fold increase compared with the initial parent strain (85 mg/l). Cellular malonyl-CoA level was increased about 3.2-folds in the best naringenin producers. Synergistic effects of gene

knockout and overexpression on naringenin yield were investigated according to a quantitative analysis. Gene

coupling coefficient can be drawn to evaluate impacts of multiple genetic interventions on cell phenotype change.

20 22 24 26 28 30 32 34 36 38 400.15

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p. 19

16. Identification of Important α1,3 Fucosyltransferases in Regulating Human Selectin

Mediated Adhesion: Cooperation of either FT-IV or FT-IX with FT-VII

Alexander Buffone, Jr., Kyle P. McHugh, Nandini Mondal, Sriram Neelamegham


Leukocyte adhesion during inflammation is initiated by the binding of sialyl Leiws-X [sLeX] type

carbohydrates expressed on leukocytes, to E-/P-selectin borne on the inflamed endothelium. While the role of

mouse glycosyltransferases (GlycoTs) in constructing sLeX has been studied using knockout models, the role of

corresponding human enzymes is not defined. Using lentiviral delivered shRNA and FT-GFP fusion constructs,

we quantified the contributions of three myeloid α1,3 fucosyltransferases (FT-IV, -VII, and –IX) in selectin mediated adhesion. Over-expression studies quantified the ability of HEK293T cells bearing both human PSGL-1

and one of the FT-GFP‟s to bind E-/P-/L-selectin in rolling assays. shRNA sequences were screened against each

enzyme by expression of FT-GFP in the mammalian Golgi in combination with flow cytometry, RT-PCR, and GlycoT activity assays. Efficient shRNA screened in this manner were stably co-expressed along with DsRed in

human leukocytic HL-60 cells. Even though the overall extent of fucosylation was not altered, the loss of these

enzymes efficiently perturbed specific glycan structures. Knocking-down FT-VII or FT-IV specifically reduced sLe

X and Le

X expression by 75% and 90% respectively, while FT-IX did not alter either. The silencing of FT-VII

and to a lesser extent FT-IX regulated E- and L-selectin mediated cell adhesion in both static and rolling assays.

Static P-selectin binding was not altered but loss of FT-VII and to a lesser extent FT-IV disrupted P-selectin

mediated rolling in micro-chamber assays. Overall, the study combines over-expression and silencing techniques to quantify the tandem effects of FT-IV/-VII in regulating P-selectin and FT-VII/-IX in L-/E-selectin binding.

Key Words: Leukocyte, Sialyl Lewis X, fucosyltransferase, selectin, shRNA

17. FRET and flow cytometry based assays to measure plasma protease activity

Shobhit Gogia1, K. M. Dayananda

1, Gian Paolo Visentin

2, Sriram Neelamegham

1

1Department of Chemical & Biological Engineering, State University of New York at Buffalo, Buffalo, NY 14260

2GTI Diagnostics, Waukesha, WI 53186, USA

Email: [email protected], [email protected], [email protected], [email protected]

The cleavage of the A2-domain of Von Willebrand Factor (VWF) by the metalloprotease ADAMTS13

regulates VWF size in circulation. If ADAMTS13 is nonfunctional either because of mutations or because of

autoantibodies that inhibit its action, it leads to the formation of platelet-rich microthrombi in blood vessels. This condition is termed as Thrombotic Thrombocytopenic Purpura (TTP). We seek to develop robust, rapid and cost-

effective assays for determination of ADAMTS13 activity. We generated a set of novel molecules called „VWF-

A2 FRET proteins‟, where variants of YFP (Venus) and CFP (Cerulean) flank either the entire VWF-A2 domain (175 amino acids) or truncated fragments (141, 113, 77 amino acids) of this domain. These proteins were

expressed in E. coli in soluble form, and they exhibited Fluorescence/Fӧrster Resonance Energy Transfer (FRET)

properties. Results show that: i) Introduction of Venus/Cerulean itself did not alter VWF-A2 function. ii) The

smallest FRET protein, XS-VWF, detected plasma ADAMTS13 activity down to 10% of normal levels. Tests of acquired and inherited TTP could be completed within 30 min. iii) VWF-A2 conformation changed progressively,

and not abruptly, upon increasing urea concentration. Overall, VWF-A2 FRET proteins can be applied both for

the rapid diagnosis of plasma ADAMTS13 activity, and as a tool to study VWF-A2 conformation dynamics. Taking the cue from FRET studies, we are also redesigning the smallest substrate of A2 domain (called VWF77)

for it to be used as a diagnostic tool in flow cytometry as well.

Key Words: Von Willebrand Factor, ADAMTS13, TTP, VWF-A2 domain, FRET-based assay, Flow cytometry-

based assay

p. 20

18. Quantifying Site Specific O-Glycosylation using Flow Cytometry: The case of leukocyte

PSGL-1

Chi Lo, Sriram Neelamegham



An O-linked glycan located near the N-terminus of the leukocyte surface antigen P-selectin glycoprotein ligand-1 (PSGL-1, CD162) binds selectins (a family of adhesion molecules) with high affinity under fluid shear.

This binding contributes to leukocyte recruitment at sites of inflammation. Specific metabolic and RNAi methods

to modulate the N-terminal glycan of PSGL-1 may yield new anti-inflammatory therapies. Efforts to quantify the effect of specific treatments on site-specific glycosyation are complicated by the presence of multiple O-glycans

on the mucinous protein. Addressing this limitation, specific peptide probes (pp) with unique sites of O-

glycosylation can be engineered on leukocytes and using flow cytometry, changes in glycan structure can be

quantified. To this end, two PSGL-1pps were prepared. First, a poly-histidine tag followed by a proteolysis site was inserted between the PSGL-1 N-terminal fragment and the remaining glycoprotein. For the second pp, the

extracellular portion of PSGL-1 excluding the N-terminal fragment was replaced by a human-IgG1 heavy chain.

Both types of PSGL-1pps were expressed on the surface of human promyeloid HL-60 cells. PSGL-1pps generated using this method could be immunoprecipitated onto cytometry-beads using a combination of lysis and

proteolysis protocols. Site-specific changes in glycosylation, in response to metabolic treatments, could be

followed using anti-carbohydrate mAbs and lectins. In selected cases, the effect of metabolic treatment on PSGL-1pp function could be assessed by silencing endogenous PSGL-1 while simultaneously expressing PSGL-1pp.

Overall, the approach of combining recombinant protein expression with flow cytometry may be a useful tool to

detect and quantify changes in site-specific glycosylation.

Key Words: glycosylation, PSGL-1, recombinant protein

19. The VWF Propeptide Binds and Inhibits the Function Of Multimeric VWF In Blood

Sri R. Madabhushi1, Chengwei Shang

1, K. M. Dayananda

1, Thomas E. Ryan


1

1 Department of Chemical and Biological Engineering, State University of New York at Buffalo, Buffalo, NY 14260 Email: [email protected] 2 Reichert Inc. 3362 Walden Ave., Depew, NY 14043

VWF propeptide (VWFpp), one of the proteolytic products of pre-pro-VWF, plays an essential role in the

N-terminal mul-timerization and storage of mature VWF (VWF) in the storage granules of endothelial cells and megakaryocytes. Following proteolysis in the Golgi, VWFpp and VWF are known to associate non-covalently

until their secretion into the plasma. In this study, we investigated the pH and Ca2+

dependence of VWFpp–VWF

interaction. Using Surface Plasmon Resonance, we observed a high affinity interaction (KD = 0.2nM & Koff > 10-5

sec-1

) at conditions mimicking the Golgi (pH 6.2 and 10mM Ca2+

). We also observed a significant, although weaker, interaction under physiological conditions of pH 7.4 and 2.5mM Ca

2+, KD being 24nM and Koff = 10

-3 sec

-

1. Absence of calcium abolished the interaction between these molecules. The dissociation curves at varying

Calcium (0-10mM) and pH conditions (6.2–7.8) followed a bi-exponential trend thus indicating at least two interaction sites within this molecular complex. Functional studies assaying the significance of VWFpp-VWF

interaction in whole blood showed partial inhibition of shear induced platelet activation in the presence of VWFpp

at concentrations > 2.5μg/ml. Addition of monoclonal antibodies against VWFpp restored the platelet activation to

normal levels. Together, the data suggests a regulatory role of VWFpp on the hemostatic function of VWF. Hence, apart from serving as diagnostic tool, VWFpp might control the extent of thrombus formation in the vasculature.

Key Words: Von Willebrand factor (VWF), VWF propeptide, platelets, Surface Plasmon Resonance, Dissociation constant, pH

p. 21

20. Design, testing and analysis of a novel microfluidic flow device that assays the mechanism

and dynamics of platelet adhesion and aggregation

Nandini Mondal1, Nicholis Geile

2, Kwang W. Oh


1

1 Department of Chemical and Biological Engineering, State University of New York at Buffalo, NY 14260 2 Department of Electrical Engineering, State University of New York at Buffalo, NY, 14260 Email: [email protected], [email protected], [email protected], [email protected]

Platelets are responsible for both protective hemostasis at the sites of vascular injury, and for the

formation of occlusive thrombi causing severe atherothrombotic diseases. Platelet aggregation is resulted by

changes in the biomechanical and biochemical environment at injury sites. The former includes the hemodynamic shear, platelet-platelet collision, and vessel wall geometry, and the latter includes sub-endothelial adhesion

proteins and locally released soluble platelet agonists. All these factors synergistically affect the platelet activation

and subsequent aggregation. Current study reports the development of a micro-fluidics based technology which provides physiologically relevant fluid flow conditions in which to measure platelet functionality. A theoretical

design of a micro-fluidic gradient generator capable of generating automatic temporal step changes in the agonist

concentration is also presented. Blood perfusion experiments performed in the flow-chamber show characteristic

platelet aggregation phenotype. Agonist dose dependent variations of the aggregation patterns are observed. This technology also provides a platform for validating a theoretical model for determining the mechanism and

dynamics of platelet adhesion and aggregation. A population balance equation (PBE) based model is developed

coupled with fluid flow equations in the varying shear field of a micro-fluidic chamber. The model considers aggregation and disaggregation of platelets due to particle collision during blood flow. Different numerical

solution techniques will be explored for solving the PBE. The model can be validated by comparing with the

particle size distribution obtained from the blood perfusion experiments in the microfluidic system. These studies

will increase our understanding of the mechanism of platelet aggregation, under normal conditions and during disease pathogenesis.

Key Words: Micro-fluidics, Platelet function assay, Platelet aggregation dynamics, primary hemostasis

21. Decreasing the size and increasing the throughput of glycosyltransferase activity assays

Shilpa A. Patil1, E. V. Chandrasekaran

2, Khushi L. Matta


1


2Roswell Park Cancer Institute, Buffalo, New York 14263

Glycosyltransferases (GlycoTs) constitute ~1% of the human genome. The coordinated action of these

enzymes results in the construction of various cellular carbohydrate structures. A previous systems-level study [FASEB J. 22:4154-67, 2008] demonstrated a semi-quantitative link between GlycoT activity and cell surface

glycan signatures. While conventional GlycoT assays performed in this work were tedious and since they

proceeded in large volumes, we developed strategies to miniaturize and automate this approach. Such studies

were conducted using an array of synthetic and natural carbohydrate substrates, and three families of GlycoTs (sialyl-, fucosyl- and galactosyl- transferases). Enzyme activity was measured using recombinant proteins and

breast cancer cell lysates. Successful strategies identified used: i) Pin-printing to enable activity assays in 0.1μL

volume, ii) Photo-fabricated micro-wells where reaction proceeds in 1μL volume, and iii) C18 pipette tips to enrich reaction product. The last method enables detection of low levels of glycoT activity. In all cases, following

reaction, acceptors were separated from unreacted radioactive donor using thin-layer chromatography, and the

extent of reaction was quantified using phosphor-imaging. The study highlights quantitative differences in the activity of enzymes from various breast cancer cells. The measured activity correlate well with carbohydrate

structures reported for these cells. The study also presents strategies to scale-down GlycoT assays since this is an

enabling technology for future systems-level investigations.

Key Words: Glycosylation, Glycosyltransferase assays, Cancer cells

p. 22

22. Developing Tools to Study the P-selectin Glycoprotein Ligand-1 Binding Interaction with

Selectins

Han-Wen Yang, Alexander Buffone Jr. , Sriram Neelamegham


Leukocyte recruitment from the blood stream to the sites of inflammation is mediated by interaction with

a group of receptors called selectins. P-selectin Glycoprotein Ligand-1 (PSGL-1) is expressed on leukocytes, is

the chief selectin counter-receptor, and binds to all three members (P-, E-, and L) with high affinity. Post-

translational addition of the tetrasaccharide sialyl Lewis x (sLex) epitope is critical for PSGL-1 to gain its selectin

binding function and its addition is catalyzed by a class of enzymes called glycosyltransferases (GlycoT‟s). Thus,

we developed several tools to study the effect specific GlycoT‟s have on the formation of the sLex structure, and

in turn the selectin binding. To this end, we modified a commercial vector to express multiple short hairpin RNA (shRNA) to knock-down expression of several gene targets. Specifically, we plan to express shRNA against three

specific members of the α1,3 fucosyltransferase family (FT-IV,-VII, -IX), which catalyse the addition of the

terminal fucose of sLex. DsRed will be co-expressed in the same plasmid as a fluorescent transduction reporter. In

order to check the effect on selectin binding after FT silencing, we developed a vector which expresses the lectin and EGF-like domain of either E-/P-/ or L-selectin as a fusion protein with a mouse IgG tail and His tag. This can

then be used, in conjuction with a secondary antibody, to probe the static binding levels of the silenced leukoctyes

to selectins in flow cytometry assays. Overall, this study describes the generation of useful tools to study loss of GlycoT function.

Key Words: P-selectin Glycoprotein Ligand-1(PSGL-1), sialyl Lewis x (sLex), Selectin, shRNA

p. 23

23. Construction and analysis of novel domain swapped streptavidin dimer

Cheng-Kuo Hsu, Kok Hong Lim, Sheldon Park


Email: [email protected].

Streptavidin binds biotin with femto molar affinity and is used widely in a variety of biological

application for detection, purification and immobilization. The structural basis of the high affinity interaction has

been investigated in previous studies, which have demonstrated W120 is essential for high affinity binding. For example, they have shown that mutating W120 to A, F, or K reduces the affinity by nearly seven orders of

magnitude (from Kd = 10-14

M of wt to 10-8

– 10-7

M of the mutant). The residue is exchanged between

neighboring subunits and participates in forming a ligand binding pocket in the associated subunit. However, the

precise mechanism by which W120 contributes to high affinity biotin binding is still not well understood, since mutating the residue also disrupts the tetramer formation. As a result, it is not clear if the main structural factor

behind high affinity binding is the quaternary structure of the molecule or the W120 contacts. Evaluating these

effects separately requires constructing mutants that currently do not exist. Streptavidin is a structural dimer of dimers that buries a significantly larger surface area at the dimer

interface than at the tetramer interface (3,029.1 Å2 vs. 1048.6 Å

2). However, the contacts across the dimer-dimer

interface, which give rise to domain swapping, may be sufficient to support stable association across the tetramer interface independent of dimer association. Forming a domain swapped dimer (DSD) based on the contacts at the

tetramer interface would allow us to evaluate the role of W120 independent of oligomerization, since would

contain two biotin binding sites similar to those in wild type tetramer, but it contains two biotin binding sites that

are structurally similar to those in wild type tetramer. In this study, we use yeast display and in vitro biochemical characterization to show that streptavidin can

form a novel domain swapped dimer across the dimer-dimer interface. To this end, we show that streptavidin

containing a sterically hindered mutation (T76R) at the native dimer interface can still associate to form a domain swapped dimer across the dimer-dimer interface by exchanging the W120-containing loop without the formation

of a native dimer. We measured the stability and biotin affinity of DSD and compared them to those of known

streptavidin monomer and wt tetramer. The melting temperature Tm = 40 ºC of the molecule is ~ 10 ºC higher than that of a monomer but still significantly lower than that of wt (75 ºC). The biotin affinity measured by

fluorescence polarization (Kd = 27.5 nM) is also significantly lower than that of wt. Therefore, other factors

besides W120 exchange and domain swapping contribute the bulk of biotin binding energy.

Key Words: Streptavidin, yeast display, disulfide trapping, domain swapped dimer

p. 24

24. Engineering High-Affinity Monomeric Streptavidin

Kok Hong Lim, Sheldon Park



The affinity of streptavidin biotin, Kd ~ 10-14

M, is one of the strongest noncovalent interactions known

between protein and a small ligand, and as such, has been of great interest from a structure-function study point of view for the last two decades. The nearly irreversible binding of biotin, and other biotinylated compounds, to

streptavidin also makes the streptavidin-biotin system a common tool in biotechnology and molecular biology,

where sensitivity and specificity of detection are essential. Yet, despite biochemical, structural, and computational

studies, the structural factors that contribute to high affinity biotin binding are not well understood. For example, W120 is often cited as the key contributor of high affinity biotin binding, but mutating the residue disrupts the

quaternary structure of the molecule, which must affect the interaction as well. The change in binding energy ( G

~ 9 kcal/mol) between wt and A120 mutant is also difficult to understand given the limited structural perturbation in the monomer structure and the maximum contribution expected from a single tryptophan residue to a binding

energy, G ~ 3 kcal/mol. Taken together, a model based on W120 alone as the key contributor of high affinity

binding is likely to be incomplete.

The lack of a quantitative model to account for various contributions to the binding energy has limited the engineerability of the molecule. In contrast, an accurate model of the high affinity interaction can help rationally

design changes in the system to adopt the system for novel applications. It is important to note that tetramer

formation of streptavidin is critical for tight binding, and any mutations that disrupt the tetramer association inevitably reduces the affinity by many orders of magnitude, virtually rendering the molecule useless for most

applications. The aim of this project is thus to understand the dependency of biotin binding on oligomerization in

a manner that is consistent with known biochemical properties of protein-ligand interaction and use the knowledge to introduce mutations in streptavidin to design a monomer that exhibits high affinity toward biotin.

The study is an important test of the coupling between streptavidin quaternary structure and biotin binding as well

as our ability to engineer useful biophysical properties, such as biotin binding, under strict structural constraints,

i.e. absence of quaternary structure. Using molecular dynamics simulation, we show that tetramerization in part contributes to high affinity

binding by shielding the ligand binding pocket from the bulk solvent. The subunit association also reduces the

residue-specific root mean squared deviation (rmsd) of each monomer. We used these simulation results to develop two strategies to improve the affinity of a streptavidin monomer: i) design loop residues near the binding

pocket to limit the entry of solvent molecules to the binding pocket, ii) structurally stabilize the binding pocket by

introducing disulfide(s) and salt bridges. We present binding and melting temperature data that show that some of the designed molecules have higher biotin affinity and enhanced stability compared to a miniminally designed

monomer.

Key Words: streptavidin, quaternary structure, protein-ligand interaction, protein stability

p. 25

25. Stable streptavidin heterodimer containing complementary interfacial mutations

Jasdeep Mann, Sheldon Park



The quaternary structure of a protein often plays a critical role in determining its stability and function,

and as such, it may be possible to engineer novel proteins with useful structural and functional properties by manipulating their oligomeric structure. In this study, we tested if novel streptavidin with altered quaternary

structure can be engineered as a means for engineering new function. The native streptavidin tetramer is a dimer

of two structural dimers due to differences in various subunit interfaces. A structural dimer is formed from two monomers that bury a large surface area with interdigitating residues. Since surface complementarity plays an

important role in dimer association, we reasoned that a rationally designed pair of mutations at the dimer interface

should influence subunit association and thus modulate the quaternary structure of the molecule. In particular, we

tested if specificity can be rationally designed to convert the native homodimer to a novel heterodimer. A designed heterodimer can be used to build an entirely new class of streptavidin molecules containing distinct

subunits that are organized in a pre-determined manner according to specific design criteria.

Toward engineering specificity at the dimer interface, we used molecular modeling and dynamics simulation to evaluate different pairs of correlated mutations. Previous studies have demonstrated that the dimer

interface is robust against minor perturbations. To engineer new specificity, therefore, we introduced

combinations of “knob” and “hole” mutations that would significantly change the side chain packing at the

interface. We mutated S93 to M or R (knob) in one subunit, while simultaneously mutating L109 to G (hole) in the other subunit. These mutations are designed to be sterically complementary, and therefore, they should

selectively favor the heterodimer formation while destabilizing competing homodimeric structures.

We tested the design by yeast display and in vitro characterization. We used a technique that was recently developed in the lab (STUCKED) to show that the R/G pair forms a stable heterodimer on the yeast surface.

When the individual monomers are expressed and purified from bacteria, they preferentially form the target

heterodimer based on SDS-PAGE and gel filtration chromatography. We also analyzed the designed heterodimer using CD and fluorescence polarization to obtain denaturation temperature Tm and the affinity Kd for biotin,

respectively. The R/G dimer is significantly more stable than streptavidin monomer (Tm = 55 °C v. 30 °C) and is

fully functional. The successful design of a stable and functional heterodimer thus paves the way for its use as a

building block toward the construction of novel heterotetramers by controlling the specificity of subunit association.

Key Words: streptavidin, quaternary structure, knob into holes, disulfide trapping

p. 26

26. Application of population balance models to the bioreactor cultivation of stem cells

Diana Cadavid Olaya, Manolis Tzanakakis


Stem cell therapy is an appealing alternative to treat diseases such as Parkinson and diabetes. However,

treatment of these diseases requires the production of a large amount of cells (~1-2x109 per patient). Stirred

suspension bioreactors are an ideal culture modality for scaling up the production of stem cells allowing continuous monitoring and control of the culture environment. In this bioprocess, control of the stem cell

aggregate size is essential for optimal cell viability and differentiation potential.

Mouse stem cells were cultured as aggregates at different concentrations in static cultures. Size data were collected every day under no-shear conditions and several growth models were studied. The Gompertz equation

was found to adequately describe the growth of stem cells within aggregates. Aggregates were also cultured in

spinner flasks at different agitation rates and seeding cell concentrations. Size data were collected every day and

aggregate size distributions under shear conditions were generated. A population balance equation model was set up to predict the temporal evolution of aggregate size

depending on the rate of cell proliferation and collisions among cells and aggregates. Various expressions for the

collection kernel have been investigated and a coalescence frequency kernel was selected to model the interaggregate adhesion. The resulting aggregate size distributions will be compared with experimental data from

stem cell cultures. Such models are expected to be integral in the development of robust and scalable bioprocesses

for stem cells.

Key Words: aggregation, population balance model, stem cells, bioreactor

27. Expansion of human stem cells in a microcarrier bioreactor and their directed

differentiation toward pancreatic islet cells

Lye T. Lock, Manolis Tzanakakis

Department of Chemical & Biological Engineering, State University of New York at Buffalo, Buffalo, NY 14260

Human embryonic stem cells (hESCs) hold great promises as sources of therapeutics for a wide range of maladies such as Parkinson disease, myocardial infarction and diabetes mellitus. Of major importance for hESC-

based therapies to become a clinical reality is the development of bioprocesses for the expansion of stem cells and

their derivatives to large quantities.

Stirred-suspension bioreactors are scalable and allow for continuous monitoring and control of the culture conditions. To that end, microcarrier systems are characterized by a high surface area-to-volume ratio. We

demonstrated the use of a microcarrier stirred-suspension culture system for the propagation of pluripotent

hESCs. Stem cells seeded on microcarriers and cultivated for ~1 week in a stirred-suspension bioreactor remained viable (>85%) and grow by 32-fold while maintaining their pluripotency markers OCT4, NANOG, TRA-1-81 and

SSEA4.

Besides the scalable propagation of pluripotent stem cells, we developed differentiation strategies for directing hESCs differentiation along pancreatic islet lineages in bioreactor cultures. hESCs were exposed in a

stepwise manner to physiologically relevant factors, which are involved in the development of the embryonic

pancreas. The differentiating cells transitioned through definitive endoderm (DE), primitive gut tube (PGT), and

posterior foregut (PFG) cells with concomitant morphological and biochemical changes. Cells emerged expressing markers characteristic of each stage. Further differentiation of PFG cells on microbeads induced the

expression of pancreatic islet markers such as insulin (INS), PDX1, NKX6.1 and NGN3. Our findings warrant

further development of scalable bioprocesses for producing therapeutically useful cells from stem cells in clinically relevant quantities.

Key Words: stem cells, differentiation, microcarriers, bioreactor, pancreatic, islets.

p. 27

28. Engineering Pluripotent Stem Cells for Cardiac Cell Therapy

Abhirath S. Parikh, Donghui Jing, Manolis Tzanakakis


Bioprocessing stem cells (SCs) to implantable cardiomyocytes entails the development of efficient and

reproducible protocols and scale-up methods. Comparison between protocols (by gene expression and beating

curves) demonstrated more consistent and efficient differentiations when defined medium with growth factors were used over serum-based induction. Investigation of culture methods revealed that differentiation as embryoid

bodies (EBs) formed more beating areas than as monolayers. However, scale-up in bioreactors faces the issue of

control on EB size distribution. There is also the concern of unknown effects of hydrodynamic shear on cell differentiation and viability. For controlling these issues in bioreactors, encapsulation of the embryonic SCs in

alginate beads was explored. Compositions (1.1-1.5% alginate), size (0.4-1.0mm bead diameter), coating (e.g.

uncoated, poly-L-Lysine-coated) and core state (liquefied vs. solid core) were identified which were favorable to

EB formation, viability, growth factor treatment and control of aggregate size.

A protocol for differentiating human SCs was setup by the stimulation with physiologically relevant

growth factors (efficiency of ~45% in bioreactors as determined by flow cytometry). A mathematical framework for the differentiation process is being developed for optimizing the percent conversion. Initial efforts on the

development of theoretical framework and mathematical expressions are discussed. Methods for obtaining

numerical solutions of the model are being developed. Experimental data for validating model parameters are presented. Optimization studies are expected to reduce process costs and improve therapeutic effect.

Key Words: Bioreactor culture, stem cells, heart cells, population balance, encapsulation, directed differentiation

p. 28

29. Genomic analysis to identify and manipulate important signaling pathways in glial

progenitor cell fate determination

Suyog Pol1, Melanie O’Bara

2, Gregory Conway

2, Fraser Sim

2

1 Department of Chemical and Biological Engineering, State University of New York at Buffalo, Buffalo, NY 14260

Email: [email protected] 2Pharmacology and Toxicology Department, 113 Faber Hall, State University of New York at Buffalo, Buffalo, NY 14214 Email: [email protected], [email protected], [email protected]

The molecular mechanisms that underlie human glial progenitor cell (GPC) lineage commitment and

oligodendrocyte differentiation are poorly understood. CD140+ GPCs were previously shown to be capable of

differentiating into oligodendrocytes as well as astrocytes. We aimed to sub-divide GPCs into homogenous subgroups in progressive stages of forming oligodendrocytes. To this end a two color sort was performed on

human fetal GPCs based on cell surface molecule CD140 and the developed oligodendrocyte marker molecule

O4. CD140+/O4

- and CD140

+/O4

+ were shown to be capable of developing into both oligodendrocytes and

astrocytes. CD140-/O4

+ cells were strongly biased to develop into oligodendrocytes (Fig 1). Thus these three

populations represented distinct stages of oligodendrocyte lineage commitment and differentiation. Genomic

microarray analysis was performed on each of the CD140/O4 sorted population in order to understand signaling

pathways relevant in oligodendrocyte development (n≥3). Furthermore genomics analysis of human GPCs maturing into oligodendrocytes was applied to make a time course study of gene expression during the human

oligodendrocyte development program. CD140+

cells were observed to be expressing oligodendrocyte

transcription factors such as Olig2, Nkx2.2 and Sox10. The bi-potential CD140+

/O4- population expressed astrocytic and radial glial transcripts. Oligodendrocyte-biased CD140

+/O4

+ cells were enriched for markers of

maturing oligodendrocytes such as myelin transcription factor . Hence receptors and transcription factors enriched in CD140

+/O4

+ were considered relevant for oligodendrocyte fate determination in glial progenitor cells. In future

work we aim to target the above identified receptors using drugs and also upregulate select transcription factors to

derive oligodendrocytes.

Key Words: Oligodendrocytes , Microarrays, Development , Glial Progenitor Cells, CD140s , O4

Figure1:- The two color sorted GPCs

cultured in the presence and absence of

platelet derived fetal bovine serum

(pdFBS) or triiodothyronine (T3). a), b)

Percentage of O4+ve and GFAP +ve

cells 4 days after culture showing

bipotential nature of CD140+/O4- c)

percentage MBP +ve cells 4 days after

culture showing CD140+/O4+ is

relatively more biased to form developed

oligodendrocytes.





http://en.wikipedia.org/wiki/Triiodothyronine

p. 29

30. Roles of cell division and gene expression on stem cell population heterogeneity

J. Wu, Tzanakakis

Department of Chemical and Biological Engineering, State University of New York at Buffalo, NY 14260

The maintenance of pluripotency of embryonic stem cells involves precise and coordinated gene network

centered around transcriptional factors. The variability among cells in the expression of factors such as Nanog and

Oct4 leads to a heterogeneous population. As a result, understanding the source of population heterogeneity may help predict the development of embryonic stem cells into a particular cell fate. Recent studies show that, at the

single cell level, multistable states and random fluctuation (noise) in gene expression may give rise to

heterogeneity at population level. Besides, the partitioning of intracellular components at cell division may also contribute to the heterogeneity of cell population. Here, we studied the heterogeneity of Nanog expression in

human embryonic stem cells and used mathematical modelling to analyze the influence of cell division on the

population heterogeneity. First, a cell-sized population balance model is formulated to simulate cell proliferation

under steady state. Then the model incorporates the Nanog expression dynamics to reproduce the population heterogeneity. So the model takes into accounts both cell division and gene expression dynamics, which makes

possible comparison between division-resulted and noise-resulted heterogeneities. The results show that cell

division has significant influence on the population heterogeneity of embryonic stem cells, and cell division together with gene expression noise may jointly generate heterogeneity at the population level.

Key Words: population heterogeneity, noise, embryonic stem cell, cell division, population balance model

p. 30

MOLECULAR AND MULTISCALE MODELING

31. Monte Carlo Simulations to study effect of roughness on wetting

Vaibhaw Kumar, Jeffrey R. Errington



The aim of this study is to understand wetting properties of water on a rough surface using molecular

simulation techniques. The free energy of the system can give useful information about the wetting phenomena. Wetting properties like contact angle and surface tension can be obtained directly from the free energy

information of the system. This surface excess free energy is dependent on the surface density of fluid particles.

Monte Carlo simulations are done in order to obtain the free energy as the particle number probability distribution of the system. Transition matrix techniques coupled with Grand canonical, expanded ensemble and a new

technique called groove maker Monte Carlo simulations enable us to obtain contact angle over a wide range of

surface strength and temperature. The structured surface having different geometries and roughness factor are

modeled in the simulation. These simulation techniques enable us to draw the wetting diagram showing the link between the wetting properties on a flat surface vs. that on a rough surface.

Key Words: Free energy, Monte Carlo, grand canonical, expanded ensemble, Groove Maker

32. Using molecular simulations to study wetting behavior of ionic systems

Kaustubh Sunil Rane, Jeffrey R. Errington



We aim to study wetting behavior of ionic systems like ionic solutions and ionic liquids using Monte

Carlo simulations. Wetting studies of these systems are crucial for development of technologies like Lithium ion

batteries and open digital micro-reactors. Molecular simulations allow us to easily manipulate the characteristics of a system and give molecular level explanations for the theories and experimental observations. Currently we

are investigating the wetting properties of simple models of ionic liquids containing spherical ions interacting

with coulombic and Lennard Jones potentials. The grand canonical Monte Carlo (GCMC) simulations are used to

obtain surface excess free energy as a function of surface density. This free energy profile is used to determine wetting properties like contact angle and wetting temperature. For ionic systems, the calculation of coulombic

interaction involves heavy computations. To improve computing speeds, we are using the fine lattice approach

and are also planning to use graphic processing units (GPUs) in future. Our study will help in developing a computationally efficient method to study wetting behavior of ionic systems. We hope that such a method will be

important in wetting studies of room temperature ionic liquids (RTILs) which are considered attractive candidates

for many green technologies.

Key Words: ionic systems, wetting, Monte Carlo simulations

p. 31

33. Wetting of Alkanes on nanorough surfaces using Monte Carlo Simulation

Shyam Sridhar, Jeffrey R. Errington



Superoleophobic surfaces have generated a lot of interest due to their tendency to repel low surface

tension fluids such as alkanes. Understanding the phenomena of wetting is key to the development of

superoleophobic surfaces, self cleaning surfaces and other applications. Wetting of a fluid on a surface is governed by the relative strength of surface-fluid to the fluid-fluid interactions and the roughness of the surface

which is characterized by the structural features of the surface. Here, we try to understand the role of these

structural features and their influence on the wetting of alkanes at the nanoscale level. We focus on two different structural features: Rectangular and T shaped structures. T shaped structures have been reported to induce the

superoleophobic character, even to an oleophilic surface. The goal is to use molecular simulation to explain the

differences in the wetting behaviour induced due to different structural features.

Key Words: Wetting, Superoleophobic surface, Molecular simulation

34. Statistical thermodynamics of hard-sphere fluids inside small pores: A virial approach

Jung Ho Yang, Andrew J. Schultz, Jeffrey R. Errington, David A. Kofke


Email: [email protected], [email protected], [email protected], [email protected]

Virial treatments for fluids, in which properties are given as a series expansion in density, have a long

history. They are gaining new attention resulting from the development of Mayer sampling methods for computation of the series coefficients. Most of the focus of these treatments has been on the bulk, homogenous

phase, but there also have been formulations applicable to inhomogeneous phases, such as found in fluids under

confinement. The effectiveness of virial methods for these systems has received little attention. In the present work, a hard-sphere fluid confined to a slit-like pore with a hard wall in equilibrium with the bulk fluid is

considered. Even in such a simple system density is not uniform and other thermodynamic properties are far

different from those of homogeneous fluids. As for a homogeneous system, the grand partition function can be

expressed as an expansion in powers of the activity or of the density of the bulk phase in equilibrium with the pore. The activity expansion is essentially the same as that for a homogeneous system, but the density expansion

is not. In this work, we report the results of calculations of the surface virial coefficients. The first two

coefficients in this series are tested with the previous analytical values. We show that our approach is entirely satisfactory and that application to system of various shapes is possible. We evaluate and examine the cluster

integrals that contribute up to sixth order for the hard sphere system within slit-like hard wall. We use the results

to calculate the thermodynamic properties of confined fluids and compare with the results of grand canonical

transition-matrix Monte Carlo simulations.

Key Words: confined fluids, virial expansion, density distribution, surface tension

p. 32

35. A New Method for Calculating Free Energy of Solids

Nancy Cribbin1, David A. Kofke

2, Andrew J. Schultz

3


Email: [email protected], [email protected], [email protected]

A polymorph is a material which can crystallize in different forms, each of which has different

thermodynamic and transport properties, and kinetic behavior, though the chemical structure of the material does

not change. They are important in the pharmaceutical and specialty chemical industries, which desire a fast, reliable screening method which finds the most stable polymorph form.

Current screening methods rely on minimizing the energy of a system. However, this does not account for the effects of entropy, which may be significant. We are developing a fast, reliable method for determining the free

energy of a polymorph, which includes entropy effects.

Our new free energy perturbation method calculates the difference between the free energies of two systems of

different sizes, giving us the free energy per atom. We relate the coordinates of the two systems through the use

of normal modes, which describe the collective motions of the atoms, and are generated by a mathematical

analysis of the crystal lattices. Since the larger system has more modes, these added modes are coupled to a harmonic potential.

We present results for one dimensional hard rod systems and three dimensional soft sphere systems.

Key Words: Free energy, polymorph, normal modes

36. Signature for Structural Transitions: VEOS for Square Shoulder Potential model fluids

Venkata SM Josyula, David A. Kofke



Mayer Sampling Monte Carlo technique was applied to the square shoulder fluid of Malescio & Pellicane to calculate the virial coefficients, equation of state and internal energy along several isochores. Around the

temperature T=0.2, where structural transitions occurs between low-density triangular solid, striped aligned

dimers, trimers and striped aligned trimers, a sharp drop in the virial coefficients is observed. Also, there is a sudden discontinuity in the configurational energy, known as the RMPE criterion, which appears to be a signature

of structural transitions occurring from disordered phases to ordered phases at that temperature. Molecular

dynamics simulations are also carried out on the same fluid to calculate the pressure, equation of state and configurational energy. Results obtained from MD simulations validate the data obtained from virial equation of

state.

Key Words: structural transitions, square shoulder potential model, virial coefficients, molecular simulation

p. 33

37. Molecular Based Modeling of Associating Fluids via Calculation of Wertheim

Cluster integrals

Hye Min Kim, Andrew J. Schultz, David A. Kofke



The virial equation of state (VEOS) is known well as a great way to describe accurately the

thermodynamic behavior of non-condensed non-polar molecular fluids at low density. However, VEOS doesn‟t describe as well the thermodynamic behavior of short-range and strong directionally dependent associating fluids

such as water. In this work, we have applied Wertheim‟s multi-density formalism introduced in 1984 to the

Gaussian charge polarizable model (GCPM) of water as an alternative to the VEOS. The great appeal of Wertheim‟s formulation is that the equation of state derived from it accounts for the strong directional association

interaction between particles while maintaining the molecular level detail. Through Wertheim‟s association

approach, we can successfully express the pressure of the associating system as a series expansion in several

aggregation densities. We have examined the Wertheim equation of state (WEOS) for GCPM water based on Wertheim theory.

To represent the behavior of realistic water efficiently, we have used the Wertheim‟s three association site model

to represent 2 hydrogen and 1oxygen sites. To evaluate the cluster integrals in VEOS and WEOS, we employ Mayer Sampling Monte Carlo simulation method proposed by Singh and Kofke. We could obtain WEOS

successfully up to fourth order in the densities. We compare the results to behavior determined for the same

model by molecular simulation, and to experimental data for water.

Key Words: Mayer-sampling; equation of state; GCPM water; hydrogen bonding

p. 34

38. Efficient computation of virial coefficients for effective screening of quantum-mechanical

models

Katherine R. S. Shaul, Andrew J. Schultz, David A. Kofke



As integrals over configuration space, virial coefficients are complementary to the assessment tools most

often considered in the development of quantum-mechanical models: the location and magnitude of energy

minima. The second and third virial coefficients, B2 and B3, have long played an important role in the

development of classical molecular models for simple fluids because these quantities can be computed rapidly from a model and extracted reliably from experimental pressure-density-temperature data. Computation of Bn

directly from quantum-mechanical models is uncommon because of the time required to sufficiently explore the

required potential energy surface. Rather, Bn is typically computed from classical potentials fit to the quantum-mechanical data. As the potential energy surface becomes more complex, either through the introduction of more

molecules or the consideration of rotational or intramolecular degrees of freedom, the fidelity of these fits worsen

and become more sensitive to the form of the selected classical model. We present novel approaches for efficient computation of virial coefficients to facilitate direct

consideration of quantum-mechanical models. Because the cheapest of quantum-mechanical theories, density

functional theory, is unable to describe the long-range dispersion essential to many systems of interest, we employ

a model with a supplemental dispersion component informed by experimental atomic polarizabilities and semi-empirical dimer energies. Specifically, we consider the Becke-Johnson dispersion model including C6, C8, and

C10 coefficients within the framework suggested by Kannemann and Becke (2009). We present virial coefficients

for this model of argon and detail strategies for coping with the complications that arise for multiatomic molecules.

Key Words: virial coefficient, molecular model, Mayer-sampling Monte Carlo, integral-equation theory, density functional theory

p. 35

39. Efficient, precise and accurate methods of calculating solid-phase free energies by

molecular simulation

Tai Boon Tan, Andrew J. Schultz, David A. Kofke



Free energy is an important element in evaluating the stability of a solid crystal. A stable form of

crystalline solid occupies an atomic/ molecular packing that gives the lowest free energy. The existing reliable

free-energy calculation methods usually involve lengthy thermodynamic integration procedures. To improve the calculation efficiency, we present two different solid-phase free-energy calculation methods – harmonic

perturbation and harmonically targeted temperature perturbation, which enable us to calculate the absolute free

energy of a crystalline solid by applying two-stage free-energy perturbation approaches on a harmonic approximation.

Harmonic Perturbation. We examine the ability of two-stage free-energy perturbation methods to yield

solid-phase free energy using a system of harmonically coupled particles as a reference. We consider two

perturbation techniques that compute the free energy difference between the target and reference systems, specifically the overlap sampling as optimized by Bennett, and umbrella sampling optimized in a similar fashion.

Failure of the method is observed for large system sizes, where the phase-space difference between the target and

reference systems becomes pronounced. We note however that small-system perturbations can be added to large-system harmonic analysis to yield accurate large-system results.

Harmonically targeted temperature perturbation. We examine a method for computing the change in free

energy with temperature of a crystalline solid. In this method the free energy difference between nearby

temperatures is calculated via overlap-sampling free-energy perturbation with the Bennett‟s optimization. Coupled to this is a harmonically targeted perturbation that displaces the atoms in a manner consistent with the

temperature change, such that for a harmonic system the free-energy difference would be recovered with no error.

A series of such perturbations can be assembled to bridge larger gaps in temperature. An absolute free energy is then computed by implementing the series to near-zero temperature, where the harmonic model becomes very

accurate. This method is shown to provide very precise results.

Key Words: free energy perturbation, solid-phase free-energy calculation, entropy, crystal stability

40. Solubility in Supercritical Fluids from Virial Equation of State

Shu Yang, Andrew J. Schultz, Katherine R.S. Shaul, David A. Kofke

Department of Chemical and Biological Engineering, State University of New York at Buffalo, Buffalo, NY 14206 Email: [email protected], [email protected], [email protected], [email protected]

The main purpose of this project is to describe the behavior of supercritical fluid and the solubility of

solute in supercritical region utilizing the virial equation of state (VEOS). The solubility of hexane in supercritical

carbon dioxide was explored as a specific example. The rapid convergence of virial expansion in terms of density based on van der Waals equation of state demonstrates the plausibility of this method. Virial coefficients up to the

fourth order of both pure CO2 and hexane-CO2 binary system at 353.15K were calculated via the Mayer Sampling

Monte Carlo method. A new technique was introduced to calculate virial coefficients of hexane because the

intramolecular interactions are significant and it is necessary to model hexane as flexible molecule instead of a rigid body. The supercritical CO2-rich phase was modeled with the VEOS, while the condensed liquid was

modeled as an ideal solution with parameters established via a single point on the solubility curve. Results

showed that although no critical point appeared in the virial series expression, the coexisting subcritical phase reproduced well simulation data for the same model obtained previously by Gibbs-ensemble molecular

simulation.

Key Words: supercritical fluid, virial coefficient, Mayer Sampling Monte Carlo, flexible molecule

p. 36

NANOSCALE MATERIALS SCIENCE AND ENGINEERING

41. Block copolymer - silica nanohybrids

Biswajit Sarkar, Vinithra Venugopal, Paschalis Alexandridis


Amphiphilic block copolymers of the poly(ethylene oxide)-poly(propylene oxide) (PEO-PPO) family

self-assemble in water (selective solvent for PEO) into (core-shell spherical) micelles, and, at higher concentrations, into cubic, hexagonal, and lamellar lyotropic liquid crystals. These nanostructures could be

utilized for the spatial organization of nanoparticles to form hybrid nanocomposite materials. Fundamental

questions pertaining to the nanoparticle-polymer interactions (as affected by the nanoparticle surface chemistry and size remain open and formulate the objectives of our investigation. We are exploring the effects of

nanoparticles (surface chemistry, size, and loading) on the critical micelle concentration in dilute PEO-PPO-PEO

solutions and the stability and structure of ordered phases formed by concentrated aqueous block copolymers. In particular, we are interested in the use of solvents in facilitating nanoparticle loading, equilibration, and long-

range structural alignment of the nanocomposite. We discuss here systems of silica nanoparticles dispersed in the

micellar and lyotropic liquid crystalline phases formed by poly(ethylene oxide)- poly(propylene oxide) block

copolymers in water and its mixtures in organic solvents. Our studies combine macroscopic observations with microscopic measurements (using fluorescence spectroscopy and small-angle X-ray scattering), and aim to relate

the experimentally controlled parameters (particle size, pH, and solvent) with the location of nanoparticles in

block copolymer mesophases. Solvent- regulated block copolymer-nanoparticles hybrids have interesting repercussions on the development of solvent based processing of block copolymer nanoparticle composite

materials.

Key Words: Block copolymer nanocomposite, Pluronic, Silica nanoparticles, critical micelle concentration, Lyotropic liquid crystals, Fluorescence spectroscopy, Small angle x-ray scattering

42. Self-Assembly of Block Copolymers in Ionic Liquids

Aikaterini Tsoutsoura, Paschalis Alexandridis


In the context of developing self-assembly as a useful approach to the synthesis and manufacturing of

complex systems and materials, our group has a long-standing interest on the utilization of selective solvents for

the modulation of the organization of amphiphilic molecules such as block copolymers and surfactants. Room-

temperature ionic liquids (ILs) have emerged recently as solvents with unique properties, including high thermal stability and low vapor pressure. We are studying the self-assembly of nonionic block copolymers in ionic liquids,

as affected by their chemical composition and intermolecular interactions, and as reflected in the

formation/stability and structure of ordered (lyotropic liquid crystalline) phases. Fundamental knowledge of self-assembly and nanoscale organization in ILs will impact their potential applications in synthesis, separations,

batteries, and specialty products.

p. 37

43. Efficient Synthesis of Well-Defined Functional Polylactide-Based Nanoparticles and

Nanocapsules by Thiol-Ene Reaction via Miniemulsion

Chih Kuang Chen, Jiong Zou, Lu Yu, Efrosyni Themistou, Paschalis Alexandridis, Chong Cheng


Polymeric nanoparticles and nanocapsules have attracted significant interests for critical applications in biomedical and other areas. Controlled cross-linking within nanoscopic templates has allowed the synthesis of

these nanomaterials with three-dimensional covalent architectures. Correspondingly, synthetic efficiency depends

on not only the reaction or polymerization techniques but also the template conditions. In this project, a novel and highly efficient method for the preparation of well-defined polymeric nanomaterials was established by strategic

combination of UV-induced thiol-ene click reaction with transparent miniemulsion templates. Allyl-

functionalized polylactide and poly(ethylene oxide)-b-polylactide were synthesized by ring-opening copolymerization, and then converted into biodegradable nanoparticles and nanocapsules with well-controlled

dimensions and morphologies by 30 min of UV-irradiation of the transparent miniemulsion crosslinking systems.

The well-defined nanostructures of these nanomaterials were verified by DLS, TEM and tapping-mode AFM

characterizations. High extents of reactions were confirmed by FT-IR analysis. These biodegradable nanoparticles and nanocapsules are expected to have minimized long-term health and environmental impacts and

may serve as idealized scaffolds for drug delivery. Moreover, the synthesis of allyl-functionalized PLA with

positive/negative charges or charge conversion functionality by thiol-ene functionalization is ongoing. Using charged and crystallized miniemulsion nanodroplets as templates to adsorb the functional PLA with opposite

charges for thiol-ene crosslinking, charged biodegradable nanocapsules will be further obtained and may be

utilized as novel nanocarriers for the delivery of gene and other charged agents.

Key Words: polylactide, ring-opening polymerization, miniemulsion, thiol-ene reaction, crosslinking

p. 38

44. Synthesis and Self-Assembly of Janus Double-Brush Copolymers

Yukun Li, Jiong Zou, Efrosyni Themistou, Chong Cheng


Having densely grafted macromolecular structures, brush polymers have attracted considerable attention

due to their interesting nanoscopic features and significant application potentials. Brush polymers can exhibit a

broad variety of morphologies, such as cylindrical morphologies, core-shell morphologies, or even Janus morphologies. With unique macromolecular architectures, Janus double-brush copolymers with each backbone

unit qualitatively carrying two blocks with diverse properties were prepared and studied. Two types of diblock

macromonomers with norbornene (NB) monomer functionalities at block junctions were synthesized. Amphiphilic macromonomers with poly(ethylene glycol) (PEG) and poly(lactide) (PLA) blocks were obtained by

the esterification reaction of acid-functionalized PEG to introduce NB group and hydroxyl functionality, followed

by ring-opening polymerization (ROP) of LA. Another type of macromonomers with polystyrene (PSt) and PLA

blocks were synthesized by simultaneous ROP of LA and reversible addition-fragmentation transfer (RAFT) polymerization of St via a NB-functionalized RAFT-ROP agent. Ring-opening metathesis polymerization

(ROMP) of these macromonomers was conducted using Grubbs‟ 3rd generation catalyst as initiator. The

resulting double-brush copolymers have well-controlled backbone lengths and narrow molecular weight distributions. Using DLS and TEM as analytic tools, the self-assembly behaviours of these double-brush

copolymers and their precursor macromonomers were studied. Their Janus morphologies were confirmed by

TEM analysis of the annealed samples. Potentially these Janus double-brush copolymers may be used for surface and interface-modification, or as novel templates for the preparation of asymmetrical nanomaterials.

Key Words: brush polymer, self-assembly, ring-opening polymerization, reversible addition-fragmentation

transfer polymerization, ring-opening metathesis polymerization.

( )nROMP

Grubbs' catalyst

Janus

p. 39

45. Synthesis, Characterization, and Biomedical Assessment of pH-Sensitive Brush Polymer-

Drug Conjugates for Cancer Therapy

Yun Yu1, Jiong Zou

1, Goran Jafr

2, Zachary A. P. Wintrob

2, Efrosyni Themistou

1, Paschalis

Alexandridis1, Alice C. Ceacareanu

2, Chong Cheng

1

1Department of Chemical and Biological Engineering, 2Department of Pharmacy Practice,

State University of New York at Buffalo, Buffalo, NY 14260

Created by the integration of nanotechnology with medicine, nanomedicines have been studied for disease

diagnosis and treatment with unprecedented precision and efficacy. Using polymer-based nanostructures as scaffolds, polymeric nanomedicines have attracted great attentions in recent years. The objective of this project is

to establish nanoscopic brush polymer-drug conjugates (BPDCs) as a new type of polymeric nanomedicine. A

variety of BPDCs with covalently linked moieties of paclitaxel (PTXL), a potent anti-cancer drug, were synthesized via ring-opening metathesis copolymerization of norbornene-functionalized poly(ethylene oxide)

macromonomer and PTXL-norbornene monomer conjugated through a pH-sensitive cycloacetal-based linkage.

Relative to PTXL, these water-soluble BPDCs can carry >1000 times of the drug moieties into aqueous systems.

The well-defined nanostructures of BPDCs were verified by characterization using dynamic light scattering and transmission electron microscopy. As discovered in drug release study through HPLC analysis of aqueous

solutions of BPDCs, release of PTXL from BPDCs was completed within ~6 h at pH of 5.5. In vitro biomedical

assessment illustrated that BPDCs had enhanced toxic effects of on more aggressive, metastatic breast cancer cells (4TMiller) relative to non-metastatic breast cancer cells (Hs578T). Since the polynorbornene backbones of these

BPDCs are non-degradable, currently efforts are made to prepare BPDCs with biodegradable polylactide-based

backbones by click reaction. These biodegradable BPDCs potentially may serve as anti-cancer nanomedicine with

minimized long-term side effects.

Key Words: brush polymer, polymer-drug conjugates, nanomedicine, responsive polymer, drug delivery

p. 40

46. Kinetic Study of Glucose hydrolysis and Characterization of Humins formed during this

process

Sushil K. R. Patil, Carl R. F. Lund


Email: [email protected], [email protected]; Web: http://www.eng.buffalo.edu/Research/catalysis/news/news.shtml

Cellulose, an important renewable resource, is a potential feedstock for synthesis of fuel, chemicals, drugs

and polymers. Hydrolysis of cellulose produces 5-hydroxymethylfurfural (HMF), levulinic acid and formic acid

as major products. The selectivity towards these platform chemicals is low due to the formation of insoluble solids called „humins‟ at various stages of this reaction. It is not clear as to how these solids are formed and what

their structure and properties are. The goal of this work is to understand the mechanism by which these humins

are formed and then perform kinetic studies on the hydrolysis reactions. Preliminary studies have been done on the comparison of humins formed during acid catalyzed hydrolysis and hydrothermal (no acid catalyst) treatment

of Glucose/HMF. The results indicate that the humins formed by both these processes have similar structure

having carboxylic and hydroxyl groups on the surface. The liquid products are characterized by HPLC (High

Performance Liquid Chromatography) and the humins by Fourier Transform Infrared spectroscopy (FTIR), Scanning Electron Microscope (SEM), X-ray Diffraction (XRD), Dynamic Light Scattering (DLS) and Thermo-

gravimetric analyzer (TGA).

Key Words: cellulose, hydrolysis, humins, 5-hydroxymethylfurfural, selectivity

47. Deactivation of Gold-Ferrochrome Very Low Temperature Water-Gas Shift Catalysts

Gaurav N. Vajani, Dongxia Liu, Carl R. F. Lund



Web: http://www.eng.buffalo.edu/Research/catalysis/news/news.shtml

Gold-ferrochrome catalysts are active for water-gas shift at temperatures below 200 degrees Celsius, but

they deactivate rapidly. The deactivation can be attributed primarily to two factors: sintering of the gold

nanoparticles present in the catalyst, and deposition of carbon on the surface of the catalyst. High resolution transmission electron microscopy and X-ray diffraction characterization of fresh and used catalysts provide

evidence for the former. The effect of reductive pretreatments using carbon-containing gases and carbon-free

gases and in-situ gravimetric studies under reaction conditions provide evidence for carbon deposition. Additional

characterization using BET, SEM and NEXAFS shows that the ferrochrome component of the catalyst is not altered significantly as the catalyst deactivates.

Key Words: Gold-ferrochrome, Deactivation, Sintering, Carbon Deposition


p. 41

48. Near Infrared High Quantum-Yield Luminescent Silicon Quantum Dots Coupled With

Gadolinium Ions for Biological Applications

ChingWen Chang1, Folarin Erogbogbo

1,2, Mark T. Swihart

1


Email: [email protected] 2Institute for Lasers, Photonics, and Biophotonics, State University of New York at Buffalo, 832 Natural Sciences Complex,

Buffalo, NY 14260

Luminescent tags and MRI contrast agents are desirable components in the rational design of

multifunctional nanoconstructs for biological applications. Luminescent biocompatible silicon quantum dots and

gadolinium chelates can be applied for fluorescence microscopy and MRI contrast enhancement, respectively. Here, we report the first synthesis of a silicon quantum dot and gadolinium ion nanocomplex for biological

applications. The nanoconstruct is composed of a PEGylated micelle, with hydrophobic silicon in the core, covalently bound to DOTA chelated Gd

3+. The nanoconstructs have an average hydrodynamic radius of 85 nm

(from dynamic light scattering, consistent with electron microscopy). Imaging of cellular uptake of the probes

verified that they maintain their optical properties in biological media. The QY of the NIR silicon quantum dots was 58% and the relaxivity (per Gd ion) of the resulting nanoconstruct was 2.4 mM

-1s

-1. The relaxivity per

nanoconstruct is calculated to be around 6000 mM-1

s-1

. These desirable optical and relaxivity properties of the

newly developed probe open the door for silicon quantum dots to be competitively used in future multimodal applications such as tumor imaging.

Key Words: Quantun Dots, Silicon, Quantum Yield, MRI, Gadolinium, Relaxivity

49. Controllable Synthesis of ZnO nanocrsytals

Xin Liu, Mark.T.Swihart


Zinc oxide is an important semiconductor with a wide, direct band gap (3.37eV) with a large exciton

binding energy of 60meV. Nanostructured ZnO is of interest for use in a broad range of electronic and optical

applications, including solar cells, piezoelectric generators, field-effect transistors, UV lasers, nano-devices, LEDs and bio-sensors.

In this work, we focus on developing general solution-method reaction models for controllable synthesis of

diverse ZnO nanostructures. These ZnO nanocrystals include 10nm nanoparticles, 5nm nanoparticles, dendritic

branch-like nanostructures, nano-needles, porous nanoparticles and other morphologies. Moreover, the as-prepared ZnO nanocrystals can have yellow, green, indigo, or blue photoluminescence, which results from

electrons trapped by surface oxygen vacancy defects of the ZnO nanocrystals. The relationship between the

surfactants capping the nanocrystals and the particles‟ luminescence is analyzed.

Key Words: zinc oxide, nanostructures, nanocrystals, luminescence

p. 42

50. Combustion-Driven Synthesis of Non-Oxide Nanoparticles in a High Temperature

Reducing Jet

William J. Scharmach1, Vasilis Papavassiliou

2, Perry Pacouloute

2, Ray Buchner

1, Mark T.

Swihart1

1Department of Chemical and Biological Engineering, State University of New York at Buffalo, Buffalo, NY 14260 2Praxair, Inc.: 175 E Park Dr., Tonawanda, NY 14150

We present a new flame-based aerosol reactor configuration that combines thermal decomposition and

hydrogen reduction to produce metal nanoparticles. This approach uses a fuel-rich hydrogen flame as a source of low-cost energy to initiate particle synthesis, but separates the flame chemistry from the particle formation

chemistry. Hot combustion products pass through a nozzle to produce a high-temperature reducing jet. A liquid

precursor solution is rapidly atomized, evaporated, and decomposed by the expanding jet, initiating particle formation. Particles are then quenched and collected downstream via filter. We have produced several different

metal nanoparticles including pure metals such as copper, silver, and gadolinium; alloys and multi-crystal

particles such as copper/silver hybrids; and semiconductors such as zinc oxide. By modifying the liquid precursor

injected into the reactor we can also produce controlled coatings on the particles. Coatings include copper hydroxide on copper and carbon on silver. The reactor can be also tuned to encapsulate nanoparticles in an

amorphous carbon material (Figure 1) that serves as a protective coating from oxidation and facilitates collection

of the particles. Nanoparticles are characterized by aerosol mobility distribution measurements, electron microscopy, and x-ray diffraction. Copper and silver serve here as a prototype for non-oxide materials that are

generally difficult to produce in flame-based reactors. This work demonstrates that such materials can be

produced in substantial quantities with particle diameters below 20 nm using this new reactor technology.

Key Words: Combustion, Nano, Nanoparticle, Spray Pyrolysis, Thermal Nozzle

Figure 1: Silver nanoparticles encapsulated in amorphous carbon coating

p. 43

51. Electrochemical Reduction of Ag2VO2PO4: Analysis of Discharge Products

Po-Jen Cheng1, Esther Takeuchi

2


Email: [email protected] 2Department of Chemical and Biological Engineering, Electrical Engineering, Chemistry State University of New York at

Buffalo, Buffalo, NY 14260, Email: [email protected]

Silver vanadium phosphorus oxide (Ag2VO2PO4) is a high-capacity cathode material for a lithium battery.

This cathode was studied in a cell using a lithium anode. When the lithium-based cell begins to discharge, the anode is oxidized and releases electrons. The cathode in the cell accepts electrons and is electrochemically

reduced. For Ag2VO2PO4, two silver ions (Ag+) may be reduced to form silver metal, and the vanadium ion (V

5+)

may be electrochemically reduced to form V3+

. Therefore, four electrons will be released by lithium anode for each cathode formula unit. For this battery we assign transfer of four electrons as 100% discharge. My study is

based on the discharge of battery, and focused on the morphology of silver particles on the cathode which form

during the process of discharge. The silver particles can be observed by optical microscope, and scanning electron microscope (SEM). On the other hand, I use X-ray Powder Diffraction to determine additional properties of the

cathode after discharge. In the future, I want to control different variables, such as discharge time, storage

temperature and open circuit voltage (OCV), to see how these factors would affect the silver particle formed on

the cathode.

Key Words: SVOP, silver, SEM, XRD, cathode

Fig1. The cathode after 75% discharge

p. 44

52. AgxVOPO4: a demonstration of the dependence of battery-related electrochemical

properties of silver vanadium phosphorous oxides on Ag/V ratios

Young Jin Kim1, Esther Takeuchi

2




As an effort to find a promising cathode material in batteries for implantable medical devices, we have

been studying a new family of silver vanadium phosphorous oxides (AgxVyOzPO4). We previously introduced the

first member of the silver vanadium phosphorous oxide family, Ag2VO2PO4, exhibiting high discharge capacity and high current pulse capability. Here we present the study of the electrochemical reduction of a new silver

vanadium phosphorous oxide material with a low Ag/V ratio, Ag0.48VOPO4·1.9H2O. On the discharge of

Li/Ag0.48VOPO4·1.9H2O electrochemical cells, they showed a high operating voltage and a characteristic multi-plateau voltage profile, which are desirable attributes in the applications for implantable medical devices. Further

ex-situ characterizations including X-ray diffraction, scanning electron microscopy, and four-point conductivity

measurements at various level of discharge were performed to investigate the discharge mechanism. After reduction of 0.37 electron equivalents, in-situ formation of silver metal nanoparticles constructing the conductive

network and an associated increase in conductivity were observed.

Key Words: silver vanadium phosphorous oxides, lithium batteries, electrochemical properties, silver formation, cathode material

Figure. Scanning electron micrograph of Ag0.48VOPO4·1.9H2O electrochemically reduced by 1 electron

equivalent displaying in-situ formation of silver metal nanoparticles

p. 45

53. Characterization and electrochemical reduction of a new silver vanadium phosphorous

oxide Ag2VP2O8: In situ formation of silver nanoparticles

Chia-Ying Lee1, Esther Takeuchi

2




The application of metal phosphate oxides as the cathode materials in lithium batteries has drawn much

recent attention since the metal cation could serve as the reduction center for electron transfer and the phosphate

oxide group could stabilize the structure. Silver vanadium phosphorous oxide (Ag2VP2O8) has a three dimensional structure with silver located in between the layers and tunnels constructed of vanadyl diphosphate

framework. The fundamental material properties of Ag2VP2O8 are explored here for the first time using

Differential Scanning Calorimetry (DSC), gas pycnometry and laser scattering particle size analysis. The first electrochemical tests of Ag2VP2O8 are also reported.

Successful discharge of Ag2VP2O8 as a battery material is achieved with capacity close to the theoretical value of 176 mAh/g. The molecular structure of the reduced material is further studied by X-Ray Powder Diffraction

(XRD) at different levels of discharge. Interestingly, silver nanoparticle formation during battery discharge is

observed from XRD and also evidenced by Scanning Electron Microscopy (SEM) and Energy-Dispersive X-ray

Spectroscopy (EDS). The battery behavior during discharge is also studied by polarization test and internal DC resistance (RDC) calculation. The resistance of the battery decreased significantly during the first two electron

equivalents of discharge which is consistent with the silver nanoparticle formation. This work demonstrated the

viability of Ag2VP2O8 as a cathode material in a lithium anode battery and affirmed our hypothesis that silver metal particles would be formed during discharge by a reduction-displacement mechanism.

Key Words: Electrochemical reduction, Lithium battery, Silver nanoparticles, Cathode material, Reduction-

displacement mechanism

Figure 1. In situ formation of silver nanoparticles

p. 46

54. A Novel Silver–Polymer–Carbon Composite Electrode for Nonaqueous Oxygen Reduction

Shu Han Lee1, Amy Marschilok

1,2, Esther Takeuchi

1,2,3

1Department of Chemical and Biological Engineering, 2Department of Electrical Engineering, 3Department of Chemistry

State University of New York at Buffalo, Buffalo, NY 14260

As the development of technology of electronic devices has progressed, a power source which has a smaller volume, higher energy content, and minimal environmental hazard is strongly needed. The lithium/air

battery is a possible candidate. The lithium/air battery is promising because it features theoretically high energy

density, flat voltage output, long shelf life, low cost, and does no harm to the environment. It has a high open-

circuit voltage of 2.91 V and the highest theoretical specific energy of 5200 Wh/kg, which is the highest among all the metal/air batteries and 9.8 times that of an ordinary lithium ion battery.

To realize the high energy density of the lithium/air battery, the slow oxygen reduction kinetics on the cathode

needs to be enhanced. New oxygen reduction catalysts and new air electrode strategies must be developed. A novel silver–polymer–carbon composite electrode is prepared, characterized, and utilized as cathode for oxygen

reduction in non-aqueous electrolyte solution. Results have shown an improved oxygen reduction activity over

the bare glassy carbon electrode or flat silver electrode.

Key Words: air electrode, oxygen reduction, nonaqueous electrolyte, composite electrode, battery

p. 47

55. Carbon Nanotube Sheets as Substrate for Lithium Vanadium Oxide Cathode Active

Material

Corey Schaffer1, Esther Takeuchi

2




Low rate, high capacity rechargeable batteries have mounting interest recently. Layered materials like

lithium vanadium oxide (figure below) provide high capacities but improvements to fade and cycle life can be

made. Toward that goal, lithium vanadium oxide was prepared using a low-temperature sol-gel synthesis method and deposited on carbon nanotube sheets for use as battery cathode material. Coin cells had first discharge

capacities of 350 mAh/g for carbon nanotubes samples compared with 340 mAh/g for coated foil samples. Cells

were cycle tested at several higher rates. Overall capacity retention rates for the carbon nanotube samples were approximately twice those for the coated foil samples. These data affirm the promise of using carbon nanotube

substrates in lithium ion batteries as both delivered capacity and capacity retention were improved over the

benchmark substrate.

Key Words: lithium vanadium oxide, sol-gel, cathode material, carbon nanotube

p. 48

56. Thermodynamics and Temperature Effects of Lithium Silver Vanadium Phosphorous

Oxide cells

Munish Kumar Sharma1, Esther Takeuchi

2




Lithium ion batteries have huge potential for power applications. These batteries are being used in

portable electronic, biomedical and aerospace applications. A single lithium battery is able to generate a potential

of 3.5-3.6 V and has a high specific energy of 200 Wh/kg. For solid state cathode materials, scientists have used different materials in the past. Some of them are silver chromate (Ag2CrO4), iodine (I2), and lithium iron

phosphate (LiFePO4). Out of these, silver vanadium phosphorous oxide (SVPO) (Ag2VO2PO4) is of great interest

to our research. The chemical and thermal stability of these cathode materials during electrochemical discharge is a key aspect for their desired performance. Therefore, we explored the thermodynamic aspects such as calculation

of Gibb‟s free energy of lithium intercalation (∆G), Enthalpy (∆H) and Entropy (∆S) of lithium intercalation to

address stability issues. The Li-SVPO cells were studied by AC-Impedance as a function of discharge and temperature to determine the activation energy (Ea) of redox reaction and overall cell resistance (R). AC-

Impedance is a highly accurate, non-destructive technique to study various electrochemical processes inside a cell

at any step of discharge process. It is used to quantify the various components of cell resistance such as ohmic

resistance with the help of an electric circuit model. The SVPO material was synthesized and characterized for purity. The future work involves further understanding the stability of SVPO in a battery environment.

Key Words: Thermodynamics, AC-Impedance, Activation energy

Fig.1 AC-Impedance of Li-Ag2VO2PO4 cell at 0% depth of discharge at 10, 20, 30, and 40

oC

p. 49

57. Layer-by-Layer Assembly of Clay with Strong and Weak Polyelectrolytes

Biswa Das, Marina Tsianou



Multilayered thin films have vast array of applications as packaging materials and surface coatings.

Layer-by-Layer (LbL) assembly is a bottom up nanofabrication technique popularly used to prepare these

multilayered films because of its ease of preparation and high degree of structural orientation. An in-depth understanding of the principles governing internal ordering and organization in these films will facilitate

generation of films with advantageous functionalities and properties. The presented work applies LbL technique

and takes advantage of electrostatic interactions to generate two component and three component multilayered assemblies. Two component multilayers were prepared with poly(diallyldimethylammonium chloride), PDDA, a

strong cationic polyelectrolyte and Laponite, a synthetic clay. Uniform layer growth and regular internal ordering

in the films was confirmed by UV-Vis Spectroscopy, Scanning Electron Microscopy (SEM) and X-Ray

Diffraction (XRD). Comparison of PDDA-Laponite bulk complex with the PDDA-Laponite multilayers established the structural superiority of LbL assemblies. Three component multilayers were prepared by

introducing poly(acrylic acid), PAA, a weak anionic polyelectrolyte and poly(styrene sulfonate), PSS, a strong

anionic polyelectrolyte, to PDDA-Laponite LbL assembly. The three component polymer-clay systems as opposed to the two component assemblies did not display structural regularity. The growth rate and film thickness

of PDDA-PAA-PDDA-Laponite multilayers was greater than that observed for PDDA-PSS-PDDA-Laponite

multilayers. The stark difference in layer growth and thickness is attributed to presence of PAA in the films. The lower charge density of PAA polymer chains results in larger amounts of PAA to be deposited for charge

compensation and less ordered arrangement of the building blocks.

Key Words: Layer-by-Layer (LbL) assembly, polyelectrolyte, clay

Photographic image of free standing PDDA-PAA-PDDA-Laponite multilayer film

p. 50

58. Effect of pH on Layer-by-Layer Film Growth

Adam Batchellor, Biswa Das, Marina Tsianou


E-mail: [email protected]

Layer-by-Layer (LbL) assembly is a means of creating multilayer thin films with built in functionality.

LbL assembly enables the use of substrates of various shapes and allows for the incorporation of a multitude of

different species with organic, inorganic and biological make-ups into the multilayer films. Electrostatic forces provide the means to create organized, assembled films on charged surfaces with little inter-layer or intra-layer

variation. In the present work, demonstration of the LbL technique was accomplished showing linear growth of

up to 20 layers using cationic polymer poly(diallyldimethylammonium chloride)(PDDA), anionic polymers poly(styrene sulfonate)(PSS) and poly(acrylic acid)(PAA), as well as the synthetic clay Laponite. The film

growth was measured using UV spectroscopy to compare the mass deposited on the substrate after a certain

number of layers. The results are in agreement with literature data for comparable systems where a similar

growth profile has been demonstrated. According to literature, strong polyelectrolytes such as PDDA and PSS have shown to be unaffected in

their growth behavior due to variations in pH. Our investigation focused on PAA, a weak polyelectrolyte, and

Laponite clay under various pH conditions to determine the effects these changes in the assembly condition would have on their growth in an LbL system. Both two component (PDDA/PAA and PDDA/Laponite) and three

component (PDDA/PAA/PDDA/Laponite and PDDA/PSS/PDDA/Laponite) systems were investigated and the

varying effect of pH between the two types of systems was studied. The effect of pH was significant for systems with PAA where a large change is the mass deposited can be observed. This is because of a change in charge

density, which was confirmed by FTIR measurements. The effect of pH on the mass deposited in Laponite

systems was not as significant as was observed for PAA systems. Zeta Potential measurements and Dynamic

Light Scattering (DLS) confirmed that a change in solution pH affected the electrophoretic mobility and hydrodynamic diameter of the Laponite dispersion. The incorporation of a third component resulted in a lessened

difference in the mass deposited within the corresponding pH-treated 2 component systems.

The results on the structural characteristics and properties of multilayers formed under different conditions can provide insights in the behavior of such films and their sensitivity to external stimuli in various

applications.

Key Words: Layer-by-Layer (LbL) assembly, polymer, polyelectrolyte, clay

59. Competitive Interactions in Surfactant Solutions: A Neutron Scattering Investigation

Ankitkumar Fajalia, Marina Tsianou



Micelles (self assembled structures of amphiphilic surfactant molecules) in aqueous solutions have been

extensively studied because of their ability to encapsulate hydrophobic species in their core. Controlling the release of the encapsulated species is essential for the potential application of these micelles as drug delivery

carriers. We have utilized the ability of cyclodextrins (CDs) to form inclusion complexes with hydrophobic

species in aqueous solution to investigate the interactions between CDs and self-assembled micelles. In the

present study, the effect of CDs on sodium dodecyl sulphate (SDS) micelles in aqueous solution has been studied using small angle neutron scattering (SANS) technique. SANS data analysis provides information on the effect of

CDs on structural parameters such as aggregation number, charge, shape, and size of the micelles, and elucidates

the mechanism by which CDs act.

Key Words: Small Angle Neutron Scattering (SANS), self assembly, surfactant, micellization, cyclodextrin (CD),

sodium dodecyl sulphate (SDS)

p. 51

60. Synthesis of Hollow and Porous Zinc Sulfide Spheres by Spray Pyrolysis

Sha Liu, Mark Kaus, Mark T. Swihart


Nanostructured zinc sulfide can provide unique photonic, electronic, and catalytic properties that are of

interest for applications ranging from bioimaging to photocatalysis. In the work presented here, we have prepared hollow or porous ZnS nanospheres by spray pyrolysis of inexpensive, water-soluble precursors with polymeric

additives used to template specific morphologies. Zinc acetate and thiourea are used as the precursors for ZnS

synthesis. These compounds can react to form bis-thiourea zinc acetate (BTZA) at around 50°C and then

precipitate from aqueous solution at higher temperature. ZnS is produced from the decomposition of BTZA. Addition of poly ethylene glycol methyl ether (PEG) into the aqueous precursor solution leads to formation of

hollow nanospheres. In this case, evaporation of water and precipitation of PEG and BTZA leads to a core/shell

structure, followed by pyrolysis of the PEG core upon further heating. Addition of polyvinylpyrrolidone (PVP) to the ZnS precursors produces porous particles. The pyrrolidone groups of PVP can coordinate to ZnS to form

PVP-ZnS nanocomposites, with PVP distributed throughout the spheres. Further heating leads to pyrolysis of

PVP, leaving behind porous ZnS nanospheres. In both cases, the size distribution of the nanospheres, from TEM

imaging, ranges from 20 nm to 200 nm. The particles have blue photoluminescence, characteristic of ZnS. Systematic variation of reaction temperature and ratios of ZnS precursors to polymer has been used to elucidate

the mechanisms of the formation of “hollow and porous” geometry. As a demonstration of encapsulation within

the hollow or porous nanostructures, gold nanoparticles were also to the precursor solution. HRTEM imaging showed that these are encapsulated into the center of the hollow nanospheres, and are distributed throughout the

porous nanospheres.

p. 52

The first CBE Graduate Research Symposium was held in 1998, organized on the initiative of

Professor Carl Lund, who was Department Chair at that time. It was held in the tight confines of the 2nd

floor of Furnas Hall, and was considered by all to be a great success, a happy occasion that instilled

pride in our department. The event has been held each year continuously since that time, each one

improving a bit on the last, and growing with the size of the department. Once we started eyeing the

Furnas elevators as a potential location for poster presenters, we figured it was time to move to a bigger

venue. As the Symposium has grown in ambition and scale, the effort needed to coordinate it has grown

commensurately, and we owe many thanks to those whose time and hard work have brought it together

this year.

First I would like to acknowledge the leadership and tireless efforts of the CBE Graduate Student

Association officers. Much of the legwork and logistics for bringing about the Symposium was

completed by students, in particular the 2009-10 CBE GSA President Kate Shaul, the 2010-11 CBE

GSA President Corey Schaffer, and graduate assistant Gaurav Vajani. They owe much to the

dedicated assistance of the CBE staff, most notably Darlene Innes and Pat Engel. Financial support

procured by the CBE GSA has been instrumental in enabling us to move the Symposium to the Center

for the Arts location, and provide refreshments that help us all enjoy the posters and the discussions even

more. We are grateful to the UB Graduate Student Association, the Graduate Chemistry Club, the

Taiwanese GSA, and the Communications GSA for their contributions.

Second I want to acknowledge the faculty members of the organizing committee, in particular

our junior faculty members Profs. Sheldon Park (Organizing Committee Chair), Marina Tsianou, and

Chong Cheng, who led or contributed to many of the planning activities for the event. Advice on

outreach was provided by some of our faculty with recent industrial experience, specifically Profs.

Esther Takeuchi and Mike Lockett. Outreach was further assisted by Dr. Marnie LaVigne and Ms.

Renata Bator at the UB Center for Advanced Technologies.

Finally I would like to thank the speakers and other participants who highlighted the

Symposium. This includes graduate students Gaurav Vajani (who was preparing his presentation even

while helping with organizing), and Eric Peng, both of whom fearlessly agreed to present their work in

this prominent venue. I would especially like to thank our keynote speaker, Dr. Jeff Siirola, who went

to great lengths to be able to attend and participate in this occasion with us. Thanks are also owed to all

of the CBE graduate students who worked so hard on their research over the years, and for presenting

their work through the many carefully crafted posters that fill the CFA atrium.

The Graduate Research Symposium continues to be a prideful occasion for our department. It is

a showcase for the excellence that we strive for in our scholarship and graduate education. We look

forward to many more years of this celebration of our research accomplishments.

David A. Kofke, Chair

Department of Chemical and Biological Engineering

Acknowledgements

graduate student symposiump. 2 paschalis alexandridis sriram neelamegham nae member • faculty...

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