Electrospun biomimetic scaffolds of biosynthesized poly(β-hydroxybutyrate) from Azotobacter vinelandii strains. cell viability and bone tissue engineering

Abstract

Abstract Fibrous polymeric scaffold which comprise capabilities of biomimicry to the native tissue architecture are promising for achieving functional tissue-engineered products with minimal surgical implantation. In this chapter the focus is on fibrous electrospun scaffolds of biodegradable microbial poly(β-hydroxybutyrate), PHB, produced from a mutant Azotobacter vinelandii OPN strain. The morphology, wettability, and thermal properties of the fibrous scaffolds were characterized using optical and electron microscopy, thermogravimetric analysis, and calorimetry. Tuning voltage and solution concentration greatly influenced the final morphology of the scaffolds. On the other hand, wettability was strongly correlated to the pore structure while hydrophobic behavior was attained in an otherwise hydrophilic material. Aging, monitored at room temperature up to 11 months via degree of crystallinity, α, showed that fibrous scaffolds with homogeneous filamentous morphology exhibited an increase in crystallinity possibly due to the appearance of secondary crystals and the occurrence of physical degradation, leading to brittleness. Sterilization by either UV or autoclave did not affect physical properties. Biological assay showed that the fibrous scaffolds did not exhibit cytotoxic effects supporting growth and proliferation of human embryonic kidney 293 cells. Furthermore, in vitro studies showed that PHB scaffolds were also suitable for bone tissue engineering supporting adhesion and proliferation of normal human osteoblast cells. Finally, the fibrous bacterial PHB scaffolds proved to be more efficient than Petri dish cultures as they exhibited higher cell viability. More applications are envisioned for the biosynthesized PHB biomimetic scaffolds in bone tissue repair involving bone defects and guided bone regeneration.