Preparation and characterization of pH-sensitive hydrogel for drug delivery system

In this paper, a new kind of pH-sensitive hydrogel based on poly(lactic acid) (PLA), methoxyl poly(ethylene glycol) (MPEG) and itaconic acid (IA) was prepared by heat-initiated free radical polymerization method without any organic solvent. The obtained macromonomers and hydrogels were characterized by H-1 NMR and FTIR. Detailed swelling behavior of hydrogels under variational pH-conditions revealed that the dynamic sensitivity of P(MPEG-PLA-co-IA-MEGMA) hydrogels [P(LE-IA-MEG) hydrogels] as well as the diffusional mechanisms might be causing the network expansion and collapse. In vitro drug release behavior was investigated using VB12 and paclitaxel (PTX) as model drugs, revealing that the P(LE-IA-MEG) hydrogel could control the diffusion of the drug. The prepared new kind of pH-sensitive hydrogel with great pH-responsiveness and good properties for drug delivery might have great potential application in smart drug delivery systems.