Synthesis and characterization of star-shaped PLLA with sorbitol as core and its microspheres application in controlled drug release

The purpose of this study was to investigate the suitability of a six-arm star-shaped poly( l -lactide)s (s-PLLA) as controlled drug carriers for hydrophobic drug molecules. First, s-PLLA was synthesized by ring-opening polymerization of l -lactide using sorbitol as initiator and stannous octoate as catalyst. The structure and molecular weight ( M w ) of s-PLLA was characterized with 1 H NMR, 13 C NMR, and GPC. Second, rifampicin (RIF) used as a model drug was encapsulated within the microspheres of s-PLLA via oil-in-water emulsion/solvent evaporation technique. The morphology, drug encapsulation efficiency (EE), and in vitro release behavior of the prepared microspheres were studied in details. Results indicated that the average diameters of s-PLLA microspheres can be controlled between 8 and 20 µm by varying the copolymer's concentration or M w . The EE of RIF was mainly determined by the concentration of s-PLLA. The in vitro study showed that the burst release behavior can be depressed by increasing the M w of the s-PLLA. Present work suggests that the synthesized s-PLLA could be used as a new material for drug delivery. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132 , 42213.