Development and characterization of pH-sensitive chondroitin sulfate-co-poly(acrylic acid) hydrogels for controlled release of diclofenac sodium

A & Oslash;tract The aim of the current study was to prepare pH-sensitive chondroitin sulfate-co-poly (acrylic acid) hydrogels (CSPAA-hydrogels) for controlled release of diclofenac sodium. CSPAA-hydrogels were prepared by free radical polymerization technique where chondroitin sulfate (CS) was used as polymer; ethylene glycol dimethylacrylate (EGDMA) and acrylic acid (AA) were used as cross-linker and monomer. Various structural features of hydrogels were evaluated by FTIR, XRD, TGA, DSC, and SEM, which confirmed the synthesis and stability of developed structures. FTIR studies confirmed the successful grafting of acrylic acid on the backbone of chondroitin sul-fate. XRD results showed that the high intensity crystalline peaks of drug were reduced by devel-oped hydrogel, thus no interaction of drug and hydrogel contents was observed. Thermal analysis revealed that the developed hydrogel network was more stable thermally than its basic ingredients (chondroitin sulfate). Sporous structure of CSPAA hydrogels was confirmed by SEM, correspond-ing to high swelling of hydrogels. Dynamic swelling indicated high swelling of hydrogels at pH 7.4 as compared to pH 1.2, as a result, high in-vitro drug release was shown at pH 7.4. Similarly, the drug release rate in pH 7.4 medium was significantly higher than that pH 1.2 medium. Kinetic mod- elling including zero order, first order, Higuchi and Korsmeyer-Peppas models were applied to know the release mechanism of drug from fabricated hydrogels. (c) 2021 The Author(s). Published by Elsevier B.V. on behalf of King Saud University. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).

Automated summary

The study successfully prepared pH-sensitive chondroitin sulfate-co-poly (acrylic acid) hydrogels for controlled release of diclofenac sodium. The hydrogels showed high stability and controlled release effect, with high swelling and drug release rate at pH 7.4.