Controllable biodegradation and drug release behavior of chitosan-graft-poly(D, L-lactic acid) synthesized by an efficient method

Controllable degradation is important for the biodegradable polymers used as drug carriers, because the drug release rate can be regulated by the degradation rate. Here, we synthesized chitosan-graft-poly(D, L-lactic acid) copolymers (CgPCs) with high MS PDLLA (molar substitution of poly(D, L-lactic acid)), which possessed controllable biodegradability for regulating the drug release rate. CgPCs with high MS PDLLA were prepared efficiently through an eco-friendly system of 1-ethy-3-methyimidazolium acetate (EmimAc)/4-Dimethylaminopyridine (DMAP). The MS PDLLA reached the maximum of 12.00 within 5 hours, which involved 2.91 of DS PDLLA (the degree of substitution of poly(D, L-lactic acid)) and 4.13 of DP PDLLA (the degree of polymerization of poly(D, L-lactic acid)). Importantly, the biodegradation rate of CgPCs could be regulated by the MS PDLLA . CgPCs with MS PDLLA of 3.98 showed good hydrophilicity and fast degradation leading to burst release of curcumin, whereas CgPCs with MS PDLLA of 12.00 exhibited relatively poor hydrophilicity and slower degradation resulting in sustained release of curcumin. This study provides some new possibilities for controllable biodegradation of drug carriers and optionality of burst or sustained drug release.