Preparation, characterization, and release behavior of aspirin-loaded poly(2-hydroxyethyl acrylate)/silica hydrogels

Poly(2-hydroxyethyl acrylate) (PHEA) is a polymer hydrogel that can be used as a biomaterial. In this study, PHEA/silica composites containing aspirin as a model drug were prepared, and their drug release behaviors were tested. 2-Hydroxyethyl acrylate (HEA) was first copolymerized with 3-(trimethoxysilyl) propyl methacrylate (MSMA) in the presence of ammonium persulphate and then condensed with silicic acid oligomer. The composites were characterized with Fourier transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM). In addition, water uptake and matrix erosion of PHEA/silica of different weight ratios were also investigated. The results indicated that the silica particles were well dispersed in PHEA hydrogels. The in vitro drug release test revealed that the release rate of aspirin decreased with the increasing content of silica. The drug release behaviors were analyzed by employing the power law, which showed that the release profiles were governed either by Case II diffusion or by anomalous diffusion. The 3-(4, 5-dimethylthiazol-2-yl)-2, 5-diphenyl tetrazolium bromide (MTT) assay of rabbit chondrocytes revealed that adding silica can improve the biocompatibility of PHEA to some extent.