In vitro hydrolytic and enzymatic degradation of nestlike-patterned electrospun poly(D,L-lactide-co-glycolide) scaffolds

A common problem in applying electrospun biodegradable polyester matrixes as tissue-engineering scaffolds is their serious shrinkage with degradation to reduce the porosity drastically. To ameliorate this problem, a nestlike-patterned poly(D,L-lactide-co-glycolide) (PLGA) nanofibrous (∼900 nm) matrix was proposed and fabricated by electropinning. Shrinkage studies demonstrated that the dimension change of nestlike-patterned fibrous membrane was much smaller than those of nonwoven and parallel-aligned fibrous membranes. And the robust framework of the patterned matrix helped to maintain its original nestlike topographical structure during degradation. Compared to hydrolytic-degraded specimens, the PLGA nanofibrous matrixes degraded in the presence of lysozyme showed larger weight loss but slower decrease in molecular weight. Besides, porous fibers with intact surface were detected by scanning electron microscopy after 20-week hydrolysis, and fibers with pores both inside and on surface were observed after enzymatic degradation for 12 weeks. Accordingly, the former presented a bimodal gel permeation chromatography (GPC) peak, while no bi or multimodal GPC peaks were found for the latter as degradation proceeded. These results indicated that an acid autocatalytic effect still existed in the hydrolysis of PLGA nanofibrous matrix. The presence of lysozyme could only accelerate the dissolution of degradation products with low molecular weight, but have no contribution to the chain scission.