Synthesis and characterization of starch piperinic ester and its self-assembly of nanospheres

A novel amphiphilic starch piperinic ester (SPE) has been synthesized by coupling a carboxyl group on the piperic acid and a hydroxyl group on the starch backbone. The synthetic process includes three steps. Firstly, piperic acid was obtained by hydrolyzing piperine that was extracted from seeds of Piper longum L (a kind of traditional Mongolian medicine). Then, piperic acid was reacted with carbonyl diimidazole (CDI) under N-2 at 70 degrees C for 4 h to form an activated piperic acid. Finally, starch piperinic ester was obtained by the reaction of the activated piperic acid with water-soluble starch at 80 degrees C under N-2 for 24 h. The product was characterized by FTIR, NMR. It was found that the starch piperinic ester could easily form stable micelles in aqueous solution, and the spherical morphology of micelle was observed by ESEM. The results of DLS analysis proved that the micelle size depends on the composition of the amphiphilic polymer. Our results demonstrate that SPE has great potential in the drug controlled release delivery. (C) 2008 Wiley Periodicals, Inc.