Microbially-derived nanofibrous cellulose polymer for connective tissue regeneration

Among a vast array of biomaterials investigated for tissue engineering applications, bacterial cellulose (BC) has not been evaluated in depth, despite the material's strong potential of applicability in the field of biotechnology. In this study we investigate the effect of sugar concentration and culture duration on physical and mechanical properties of BC. BC was grown in culture media with different glucose concentrations (weight percent) of 1.25%, 2.50%, 5.00%, 10.00%, 15.00% and also in media with fructose concentration of 5.00%. The swelling ratio of harvested BC sheets did not change significantly with concentration of glucose or the type of sugar (fructose vs glucose). Swelling ratio did not change significantly with culture duration either. Cellulose production rate was significantly higher (p < 0.05) at 5.00%wt. glucose concentration compared to other groups. Ultimate tensile strength (309.3 +/- 32.8 MPa) and Young's modulus (3.1 +/- 0.6 GPa) of BC sheets harvested from the medium with 5.00%wt. glucose concentration were the highest among all treatment groups. Bacterial removal process and testing condition (wet/dry) did not affect the mechanical performance of the bacterial cellulose significantly. X-ray diffraction data demonstrated higher crystallinity for samples cultured in media with 5.00%wt. glucose concentration. Viability/cytotoxicity, proliferation, and cells' metabolic activities demonstrated BC to be biocompatible. Cells attached, spread, and proliferated with time on bacterial cellulose. Results of this study showed 5.00 wt% glucose concentration is the optimum concentration of sugar in media to produce BC with highest strength and modulus compared to other concentration. High mechanical strength along with biocompatibility present bacterial cellulose as an invaluable material for use in tissue engineering of load bearing connective tissues such as tendons and ligaments.