Synthesis and Application of Esterified Starch-g-Polylactic Acid as Drug Carriers

A novel copolymer was synthesized by modifying starch-g-polylactic acid (MSt-g-PLA). The results indicated that the starch was efficiently esterified by maleic anhydride (MAH) (2 wt.-%) with polyethylene glycol-400 (PEG-400, 1 wt.-%) as dispersant. Then MSt-g-PLA was synthesized by the reaction of modified starch with D, L-lactic acid. The copolymer was amphiphilic and its molecular weight was 4.789 x 10(4) (M-n), molecular weight distribution was 6.921 x 10(4) (M-w), and polydispersity index was 1.445 (PDI), respectively. Subsequently, CTX/MSt-g-PLA microspheres containing the model drug and cefotaxime sodium (CTX) were prepared. The appearance of the microspheres was smooth and regular. 90 % of particle size was under 150.3 mu m and mean diameter was 99.3 mu m. The degradation rates of microspheres increased with the increase of pH-value of the buffer. With the amphiphilic copolymer MSt-g-PLA as drug carrier, the microspheres had no burst during drug release, and had the similar sustainable release as the PLA carriers.