spring 2009 ee 710: nanoscience and engineering 14 ... xiv... · part 14: gold colloids and...

Spring 2009 EE 710: Nanoscience and Engineering

Part 14: Gold Colloids and NanoBioTechnologyCourse Texts:

Hornyak, et.al, Introduction to Nanoscience, CRC press, 2008 Chapter 12And Various Refereed SourcesAnd Various Refereed Sources

Instructor: John D. Williams, Ph.D.Assistant Professor of Electrical and Computer EngineeringAssociate Director of the Nano and Micro Devices Center

University of Alabama in Huntsville406 Optics BuildingHuntsville, AL 35899Phone: (256) 824‐2898Fax: (256) 824 2898Fax: (256) 824‐2898

email: [email protected]

1

G ld C ll idGold ColloidsIntroduction to Nanoscience:Introduction to Nanoscience:

Chapter 12

2JDW, UAHuntsville ECE, Spring 2009

Gold Colloid FormationGold Colloid Formation

• Turkevitch Route– HAuCl4 + (C6H5O7)Na3 Auo + oxidized products– Approx 5*10‐6 mol of HAuCl4 is dissolved in 19 ml of DI water and heated to boiling– 1 ml of 0.5% sodium citrate is added with constant stirring for 30 min– Solution undergoes color chagnes from yellow to clear to grey, purple, deep purple and finally ruby‐red.– Water is able to maintain the level of solution to 20 mlWater is able to maintain the level of solution to 20 ml

• Brust route– HAuCl4 + [CH33(CH2)7]4NBr(TOAB) + Toluene+ BaBH4 Auo– Start with an emulsion of water and toluene

4 0 *10 3 l f t t t l i b id (TOAB) i dd d t 80 l f t– 4.0 *10‐3 mol of tetraoctylammonium bromide (TOAB) is added to 80 ml of water – 9.0*10‐4 mol of HAuCl4 in 30 ml of water is added to the TOAB solution and stirred vigorously for 10 min– Aqueous phase is clear and the organic phase is orange– Sodium Borohydride is added dropwise to the mixture and the color changes from orange to white to

purple to dark redSolution is then stirred for 24 hrs to insure clusters are monodispersed– Solution is then stirred for 24 hrs to insure clusters are monodispersed

– The organic phase is then washed with sulfuric acid to neutralize the solution– TOAB is not considered to be a strong ligand and will readily undergo ligand exchange with stronger ligands

like thiols that covalently bind to the gold clusters.


Gold‐55: AuCl[P(C6H5)3] +B2H6Au [P(C H ) ] Cl +H B P(C H )Au55[P(C6H5)3]12Cl6+H3B‐P(C6H5)3

• Gaseous diborane is passed through a warm 150 ml solution of benzene containing 3.94 g of

• The Au55 product is a dark brown powder that is soluble in dicholoromethane and pyridine and insoluble in petroleum

AuCl[P(C6H5)3]

• Diborane is the best reducing agent but it also acts as a Lewis acid that binds phosphines

• Process limits the amount of free ligand available at ti d i th f th ti

ether, benzene and alcohols.

• In air the ligand –stabilized cluster decomposes to a solid gold amalgam and reverts back to its precursor state

• Spectroscopy shows that Au55 has 13 central atoms, 24 di t d i h l t 12 t di t d tany time during the course of the reaction

• Excess ligand concentration leads to smaller complexes and clusters which are undesirable

• Temperature is raised to 50oC after 40 min, and the colorless solutions turns brown

uncoordinated peripheral atoms, 12 atoms coordinated to phosphine ligands and 6 atoms coordinated to chlorine

colorless solutions turns brown

• Upon cooling a dark precipitate settles to the bottom of the now colorless solution

• The precipitate is filtered and rinsed with dichloromethane and filtered again through a Celitedichloromethane and filtered again through a Celiteto remove unwanted solids (colloidal gold)

• The product is reprecipitated slowly in 250 ml of pentane to ensure that the phosphine ligands that saturate the Au 55 cluster

• Overall yield of the process is 29%. The cluster is 2.1 nm in diameter (Au55 is 1.4 nm)


Attaching Au55 to DNAAttaching Au55 to DNA

• Triphynlphosphine ligands of the l d li d hcluster undergo ligand exchange readily in phase transfer reactions

• AuCl[P(C6H5)3] +B2H6Au55[P(C6H5)3]12Cl6+H3B‐P(C6H5)3


JDW UAH t ill ECE S i 2009

Interesting Au55 Ligand ReplacementInteresting Au55 Ligand Replacement

• Directly ties Au55 nanoparticles to a ili d !!!silicon quantum dot!!!

• Au55[P(C6H5)3]12Cl6+12T8‐OOS‐SHAu55[T8‐OOS‐SH]12Cl6+12PPh3

• Product shows increased activation energy and electron tunneling at 0.26eV vs. 0.16eV for Au55


Large Scale Surfaces Generated from dBoron Ligand Groups

• Au55[P(C6H5)3]12Cl6+Na2[B12H11SH] Au55[(B12H11SH) Na2]12Cl6• Na+ ion makes the system water soluble so clusters can be dissolved and spun

onto metallic or glass surfaces at will

• Self organization is a function of concentration at the surface and film thickness


Interdigitated Au55 SystemsInterdigitated Au55 Systems

• Note throughout these discussions

– Sulfur or Phosphorous were used in every experiment toused in every experiment to bind to the Au nanoparticle.


Semiconductor Quantum Dot Formation

Inverse Micelle TechnologyInverse Micelle Technology• Semiconductor dots are polar and bind

well to thiol (sulfur) based chemistries• Clusters are formed by chemically

ti ti l i lcreating nanoparticles in nonpolar solutions. HOW?!?!?

• Use polar side of the ligand to bind polar precursors together into a micelle with the nonpolar terminals displayedwith the nonpolar terminals displayed outward into the nonpolar solvent

• Reactants then produce a semiconductor nanoparticle + secondary product that can be t t d i lt t li dextracted using alternate ligand

chemistry• Resulting product is stable and can be

spun onto a surface and self ordered


NanobiotechnologyNanobiotechnology


Cell MembraneCell Membrane

Each structure within the cell is separated by a membrane

(a lipid phospholipid bilayer)

Protein fused into these structures regulate gthe flow of chemical species (thus energy and information) throughout all of biology


ATP Motors

Molecular Motors: Turning the ATP motorRichard L. CrossNature 427, 407-408(29 January 2004)doi:10.1038/427407b ATP Motors


ATP Rotary MotorATP Rotary MotorDevice Fabricated on Silicon by Carlos Montemagno at Cornell in 1999Montemagno at Cornell in 1999


Myosin MotorsMyosin MotorsModel for Processive Motion of Mammalian Myosin VMammalian Myosin V

• http://www.sci.sdsu.edu/movies/actin_myosin_gif.html

http://lamp.tu‐

http://lamp.tu‐

graz.ac.at/~hadley/nanoscience/week6/Aktor_anim.gif

graz.ac.at/~hadley/nanoscience/week6/MT‐Gliding_low.gif

R. Vale, The Journal of Cell Biology Volume 163, Number 3, 2003, pp. 445‐450. 14JDW, UAHuntsville ECE, Spring 2009

Kinesin Motors14 different families of kinesin motors exist within known mammalian biological systems. Each family contains several variants

Double strand attached to two heavy terminal activated by ATP

Can also be used to move filaments. Example: Separation of chromosome microtubules during mitosis

Motion of microtubules w r t the cellw.r.t. the cell membrane is how cilia and flagelumare used to move

When activated, can be used to move larger molecules up and down a filament

cells

http://www.rpi.edu/dept/bcbp/molbiochem/MBWeb/mb2/part1/kinesin.htm#animat 15JDW, UAHuntsville ECE, Spring 2009

Dynein MotorsDynein Motors

http://video.google.com/videosearch?client=firefox‐a&rls=org.mozilla:en‐US ffi i l& h l &hl & d i + t & 1&i UTF 8& i 7 S 6lHUS:official&channel=s&hl=en&q=dynein+motor&um=1&ie=UTF‐8&ei=7x_eSc6lH‐CrtgfYn4WSAQ&sa=X&oi=video_result_group&resnum=4&ct=title#


spring 2009 ee 710: nanoscience and engineering 14 ... xiv... · part 14: gold colloids and...

Documents