production of biodegradable polymers: polyhydroxyalkanoates part 2 dr. ipsita roy school of life...
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Production of biodegradable polymers:
Polyhydroxyalkanoates Part 2
Dr. Ipsita RoySchool of Life Sciences
University of Westminster, London, UK
Production of 3D-scaffolds using P(3HB)/Bioglass® composites
3-D composites produced using sugar leaching technique
Applications of the PHA produced in hard tissue engineering : production of PHA/Bioglass®/CNT
scaffolds
P(3HB) P(3HB)/Bioglass® 40wt% P(3HB)/CNT 2wt%
P(3HB)/CNT 4wt% P(3HB)/CNT 7wt% P(3HB)/Bioglass® 20wt%/CNT 8wt%
Electrical Properties of PHA/Bioglass®/CNT scaffolds
Four-point current-voltage measurements on P(3HB) and P(3HB)-based composites
Graph showing the decrease in electrical resistance as a function of carbon nanotube content.
S.K.Misra et al., 2007 Nanotechnology 18(7) doi:10.1088/0957-4484/18/7/075701
Acellular bioactivity of PHA/Bioglass®/CNT scaffolds
HA peaks
SEM micrograph of the composite showing the formation of hydroxyapatiteon the surface of the composite after two months of immersion in SBF
XRD patterns of (a) P(3HB) (b) P(3HB)/Bioglass®/CNT composite (c) P(3HB)/Bioglass®/CNT composite immersed in SBF for two months, showing the emergence of hydroxyapatite peaks marked by the arrowand the indicators.
S.K.Misra et al., 2007 Nanotechnology 18(7) doi:10.1088/0957-4484/18/7/075701
Drug delivery
Application of the bacterial PHAs in drug delivery
SEM image P(3HB) microspheres Particle size distribution analysis
Application of the bacterial PHAs in drug delivery
TEM images of the cross section of P(3HB) microsphere
Drug delivery via P(3HB) microsphere coated Bioglass® scaffold
Microspheres loaded with gentamycin
Bioactivity measurements of the P(3HB)microsphere coated composite
scaffold
Evidence of hydroxyapatite formationXRD analysis
Surface roughness of the P(3HB)microsphere coated composite
scaffold in SBF
White light interferometry (Zygo®) data
Gentamycin release from P(3HB) microspheres
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Time in hours
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mu
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Gentamycin release from uncoated Bioglass® scaffolds
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Time in hours
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Gentamycin release from P(3HB)microsphere coated composite
scaffolds
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0 200 400 600 800
Time in hours
Cu
mu
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Comparison of Gentamycin release kinetics
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Cu
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Compressed film of Tetracycline containing P(3HB) microspheres
SEM of the surface and cross section of the films
Cell viability on the P(3HB) microsphere films containing tetracycline using keratinocytes (HaCaT cell line)
HaCaT cell attachment on tetracycline loaded P(3HB) microsphere films
P(3HO)/nanobioglass solvent cast film for wound healing applications
Cell viability on the P(3HO)/nanobioglass films using keratinocytes(HaCaT cell line)
HaCaT cell attachment on P(3HO)/ nanoBioglass films
Conclusions
• Polyhydroxyalkanoates (PHAs) are a new emerging class of biodegradable and biocompatible polymers of natural origin.
• PHAs are currently being produced using Gram negative bacteria. We have pioneered the use of Gram positive bacteria, especially, Bacillus sp for the production of SCL-PHAs.
• Bacillus cereus SPV, a newly characterised strain of Bacillus, has been successfully used for the production of SCL-PHAs and in large scale. Cheap carbon sources have also been explored.
• Psuedomonas mendocina, a relatively unexplored bacteria has been successfully used for the production of a range of MCL-PHAs and in large scale
• The SCL-PHAs produced have been used in hard tissue engineering, drug delivery and wound healing
• The MCL-PHAs produced have been used in wound healing
Key workers:Dr.S.P.Valappil (polymer production from Bacillus cereus SPV)
Ms Ranjana Rai (polymer production from Pseudomonas mendocina and its applications in wound healing)Mr. Akarayonye Everest (polymer production from Bacillus cereus SPV)Ms Lydia Francis (drug delivery work and wound healing)Mr. Mikey Cheng (drug delivery work)Mr. Superb Misra (the composite work using Bioglass® for hard tissue engineering)
Current Collaborators:Professor A. Boccaccini, Imperial College London, UK; University of Erlangen-Neurenberg, GermanyProfessor R. Silva, University of Surrey, UKProfessor J. Knowles, University College London, UKProfessor T. Keshavarz, University of Westminster, UK
My Group
Thanks for your attention!