Biodegradation of a silkworm silk/PLA composite

Animal silks and poly(lactic acid) (PLA) are potential materials for biomedical and bioengineering applications. Biodegradability of these materials thus is important to minimize any extra pain of patients with bone defects due to second operations for removing those non-biodegradable implants. However, the control of their biodegradability and mechanical properties is essential to ensure a smooth load transfer from a depredating implant to neo-tissue. In this study, a biodegradation test on silk/PLA biocomposites was performed. Physical and mechanical properties, pH condition of the surrounding fluid and the morphology of fractured samples were studied at specific time points. It was found that there were no significant differences between the pH values of the solution and weight loss for both pure PLA samples and silk/PLA biocomposites. Moreover, with the reinforcement of silk fiber, stiffness and ductility of PLA were enhanced and a faster biodegradation rate was observed within the 4-month biodegradation period. It can be concluded that the biodegradation rate of implants can be altered and their mechanical properties can be enhanced by incorporation of silk fiber. This is a potential solution to match with the degradation rate of PLA to the regeneration rate of neo-tissues. (C) 2009 Elsevier Ltd. All rights reserved.