Novel nanomicelles originating from hydroxyethyl starch-g-polylactide and their release behavior of docetaxel modulated by the PLA chain length

A novel drug carrier was synthesized through grafting polymerization of hydroxyethyl starch (HES) and d,l-lactide. By changing the molar ratio of HES and d,l-lactide, HES-g-PLA copolymers with different chain lengths of PLA can be obtained. Their chemical structures were characterized by FT-IR and 1H NMR. Through self-emulsification combined with solvent evaporation, HES-g-PLAs self-assembled into micelles with uniform sizes ranging from 65 to 130 nm, depending upon the chain length of PLA. In vitro release profiles of docetaxel-loaded HES-g-PLAs meet first-order release kinetics via a mechanism of diffusion and polymer chain relaxation. The size of the micelles and the amount of drug loading can be controlled by varying the chain length of PLA. Another significant result is that release rates of docetaxel can be also modulated by changing the chain lengths of the PLA segments.