PREPARATION AND CHARACTERIZATIONS OF A NOVEL COPOLYMER BASED ON AN EMULSION SOLVENT EVAPORATION METHOD

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) (mass fractions, w = 2 %) with polyethylene glycol-400 (PEG-400, w = 1 %) as the dispersant. Then MSt-g-PLA was synthesized by employing the modified starch to react with D, L-lactic acid. The copolymer was amphiphilic and its molecular mass and molecular-mass distribution were 4.789 x 10(4) (M-n), 6.921 x 10(4) (M-w) and 1.445, respectively. Subsequently, CTX/MSt-g-PLA microspheres containing the model drug and cefotaxime sodium (CTX) were achieved. The appearance of the microspheres was smooth and regular. Some 90 % of the particle size was under 150.3 pm, and the mean diameter was 99.3 mu m. The degradation rates of the microspheres increased with the increase of the pH value of the buffer. With the amphiphilic copolymer MSt-g-PLA as a drug carrier, the microspheres had no burst during the drug release, and had a similar sustainable release to the PLA carrier.