In Vitro Biodegradation of Poly(Lactic-co-Glycolic Acid) Porous Scaffolds

A protocol in which the condition is close to the in vivo pH environment was established for in vitro degradation evaluation of biodegradable porous scaffolds. Degradation of PLGA sponges was evaluated with the protocol. The PLGA sponges degraded with incubation time. For the first 12 weeks, the weight loss increased gradually and then remarkably after 12 weeks. In contrast, the number-average molecular weight (Mn) decreased dramatically for the first 12 weeks, and then less markedly after 12 weeks. Thermal analysis showed that the glass transition temperatures (Tg) decreased rapidly for the First 12 weeks, and the change became less evident after 12 weeks. These results suggest that the degradation mechanism of PLGA sponges was dominated by autocatalyzed bulk degradation for the first 12 weeks, and then by Surface degradation after 12 weeks. Physical aging was observed during incubation at 37 degrees C. The heterogeneous structure caused by physical aging might be one of the driving forces that induced autocatalyzed bulk degradation. The protocol suppressed extreme changes of the pH and will be useful in the degradation evaluation of porous scaffolds for tissue engineering.