Preparation of chondroitin sulfate and polyvinyl alcohol hydrogels as drug carriers

The chondroitin sulfate/polyvinyl alcohol based pH-sensitive hydrogels (CHS/PVA hydrogels) were synthesized by a free radical polymerization technique for controlled delivery of diclofenac sodium up to 72 h. Polymers chondroitin sulfate and polyvinyl alcohol were crosslinked with monomer acrylic acid by a cross-linker ethylene glycol dimethylacrylate in the presence of initiator ammonium persulfate. The process of polymerization was continued for 24 h at 65 °C. Fourier transform infrared spectroscopy (FTIR) indicated successful polymerization and crosslinking among the hydrogel contents. Differential scanning calorimetric (DSC) and thermogravimetric analysis (TGA) studies demonstrated that fabricated hydrogel has higher thermal stability. The pH sensitivity of designed CHS/PVA hydrogel was investigated by performing dynamic swelling and in vitro drug release tests in pH 1.2, 4.6, and 7.4 medium. Maximum swelling was observed at pH 7.4 when compared to pH 1.2 and 4.6. The sequence of drug release from the developed hydrogel was; pH 7.4 > 4.6 > 1.2. It has been shown that porosity, swelling, and release rate of diclofenac increased with the addition of chondroitin sulfate and acrylic acid, while decreased with increasing PVA composition. Cytotoxicity studies showed that the prepared hydrogel has no toxic effect on T84. Therefore, it can be demonstrated from the results that the CHS/PVA cross-linked hydrogel can be considered as a potential delivery carrier for the controlled release of diclofenac sodium.