Synthesis and performance of pH-sensitive hydrogel microspheres and in vitro evaluation as potential drug carriers

To accelerate the response rate of smart hydrogels to the environmental conditions, a novel pH-sensitive p(PEGMA-g-MAA) hydrogel microsphere with the controlled shapes and sizes were developed. Such monodispersed microspheres were synthesized via free radical polymerization under the protection of a multilayer stability system. The pH-responsibility of hydrogel microspheres was tested with the hydrogel bulk as a control. In vitro release studies were conducted in the simulated gastric fluid and intestinal juice with bovine serum albumin (BSA) as a model drug. The large specific surface areas endowed hydrogel microspheres a faster pH-responsibility than that of hydrogel bulk. In vitro release profiles showed that over 90 % BSA were released from hydrogel microspheres under the alkaline conditions (pH 7.4), which was faster than those from hydrogel bulks. In sum, the rapid pH-responsibility and ideal drug release profile could shorten the lag time to steady plasma-drug concentration, which was beneficial to increasing the therapeutic effect of the drugs.