BMEBT PhD Dissertation / Seminar by Abdul Kehail
When: Friday,
April 7, 2017
2:00 PM
-
4:00 PM
Where: Textiles Building 101E
Description: TITLE: PRODUCTION + DEGRADATION OF MICROBIALLY SYNTHESIZED POLY (HYDROXYBUTYRATE-CO-HYDROXYHEXANOATE) POLYMER: IMPACT ON MECHANICAL STABILITY + MEDICAL APPLICATIONS
ABSTRACT: Polyhydroxyalkanoates (PHAs) are a family of biodegradable, biocompatible polymers produced by many various species of microorganisms. Different types of PHA polymers possess different mechanical properties (e.g., strength and elongation properties), depending on the monomer composition and have been examined for use in medical applications, such as sutures, scaffolds and implants. The polymer poly(3-hydroxybutyrate) [PHB] and the copolymer poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) [P(HB-co-HHx)] were extensively examined in this study.
Copolymers varying in HHx monomer content (0 30mol%) were recovered from different Ralstonia eutropha strains. Mechanical properties of solvent-cast polymer samples were investigated. Our results show that with higher content of HHx monomer in the material, the more flexible and tougher the polymer, and the greater the reduction of crystallinity.
One of the major under-addressed issues associated with the use of biodegradable PHA polymers in resorbable medical products is the correlation between the mechanical properties and in vivo degradation over time. P(HB-co-17mol% HHx) matrices were either incubated with cultures of human embryonic kidney cells (HEK) for in vitro degradation studies, or inserted into Danio rerio (zebrafish) tissues for in vivo degradation studies. Also, the PHB homopolymer was subcutaneously implanted in mice. After removal from the animal tissue or cell culture environment at different intermittent time points, the strength, elongation, mass loss, and enthalpy of the polymer were tested, and scanning electron microscopy images were taken. Our results show that Youngs modulus of P(HB-co-17mol%HHx) during in vitro studies decreased gradually within 4 weeks, and in vivo breakdown resulted in a significant decrease in Youngs modulus and a mass loss of 59% within 7 weeks. Also, PHB incubated in mouse tissue exhibited slower degradation due to the strength and dense structure of the material. From these data, a mathematical model was generated using Rayleighs method of dimensional analysis. It was found that the developed model could predict the strength of the polymer during degradation when in contact with cells, and that strength predicted by the model follows the trend of our gathered experimental data.
ABSTRACT: Polyhydroxyalkanoates (PHAs) are a family of biodegradable, biocompatible polymers produced by many various species of microorganisms. Different types of PHA polymers possess different mechanical properties (e.g., strength and elongation properties), depending on the monomer composition and have been examined for use in medical applications, such as sutures, scaffolds and implants. The polymer poly(3-hydroxybutyrate) [PHB] and the copolymer poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) [P(HB-co-HHx)] were extensively examined in this study.
Copolymers varying in HHx monomer content (0 30mol%) were recovered from different Ralstonia eutropha strains. Mechanical properties of solvent-cast polymer samples were investigated. Our results show that with higher content of HHx monomer in the material, the more flexible and tougher the polymer, and the greater the reduction of crystallinity.
One of the major under-addressed issues associated with the use of biodegradable PHA polymers in resorbable medical products is the correlation between the mechanical properties and in vivo degradation over time. P(HB-co-17mol% HHx) matrices were either incubated with cultures of human embryonic kidney cells (HEK) for in vitro degradation studies, or inserted into Danio rerio (zebrafish) tissues for in vivo degradation studies. Also, the PHB homopolymer was subcutaneously implanted in mice. After removal from the animal tissue or cell culture environment at different intermittent time points, the strength, elongation, mass loss, and enthalpy of the polymer were tested, and scanning electron microscopy images were taken. Our results show that Youngs modulus of P(HB-co-17mol%HHx) during in vitro studies decreased gradually within 4 weeks, and in vivo breakdown resulted in a significant decrease in Youngs modulus and a mass loss of 59% within 7 weeks. Also, PHB incubated in mouse tissue exhibited slower degradation due to the strength and dense structure of the material. From these data, a mathematical model was generated using Rayleighs method of dimensional analysis. It was found that the developed model could predict the strength of the polymer during degradation when in contact with cells, and that strength predicted by the model follows the trend of our gathered experimental data.
Contact: BMEBT PHD Program
Topical Areas: University Community, Biology, Chemistry and Biochemistry, Bioengineering, College of Engineering