Degradation properties of chitosan microspheres/poly(L-lactic acid) composite in vitro and in vivo

Poly(L-lactic acid) (PLLA) is a popular biodegradable polymer, but the accumulated acid production by degradation is a bottleneck for its extended utilization. In this study, chitosan microspheres (CSMs) were introduced into PLLA porous matrices to manipulate the acid microclimate from PLLA degradation. In vitro and in vivo degradation were, respectively, performed in PBS and implanted into rat's subcutaneous. The results indicated that pH of CSMs/PLLA composites remained stable of around 7.50 in vitro until six weeks. With the increasing of CSMs, mass loss, water absorption of the composites increased, while Mv of PLLA decreased during in vitro test. Furthermore, CSMs/PLLA composites degradation in vivo could be speeded by the introduction of CSMs via obvious morphological destroy under H&E staining observation. These results indicated that incorporation of CSMs not only buffered the acidic microclimate but also improved the degradation of PLLA. The tunable degradation behavior and moderate degradation microclimate of CSMs/PLLA composites developed in the study would provide benefits for its biomedical application.