pH-responsive chitosan/poly (vinyl pyrrolidone) based hydrogel composites: Antibacterial properties and release kinetics of diclofenac sodium

Development of effective hydrogels based anti-inflammatory drug delivery materials remains great challenge. In this study, diclofenac sodium (DS) was successfully encapsulated into chitosan (CS)/poly (vinyl pyrrolidone) (PVP) with glutaraldehyde crosslinked hydrogels. The characteristics of the hydrogel composites were characterized by swelling behavior, FTIR spectroscopy, hydrophilicity, and porosity test, SEM-EDX, X-ray diffraction, thermal stability, and mechanical strength methods. pH-dependent drug (DS) release behavior and the antibacterial activity of the hydrogel composites were examined. Typically, the interaction of polymer precursors, crosslinker, and drug compound occurred via hydrogen bonding. The cross-sectional SEM images demonstrated the pore formation in hydrogel matrix. Mechanical properties of hydrogel improved from 8.9 to 13.1 MPa due to crosslinking process and DS encapsulation. Insertion of diclofenac sodium improved the hydrophilicity as shown in the lowering of contact angle to 55.47°. Hydrogel samples showed promising antibacterial activity against Pseudomonas aeruginosa and Staphylococcus aureus with the zone of inhibition (ZoI) up to 21.8 ± 0.05 mm and 18.7 ± 0.09 mm, respectively. The controlled DS release from hydrogel composites at pH 4, 7 and 10 has maximum release amount of approximately around 10 %, 80 %, and 90 %, respectively. The kinetics and mechanism of drug release from hydrogels was followed Kosmeyer-Peppas and Higuchi models, indicating that the DS release from hydrogel was predominantly controlled by Fickian diffusion or swelling process. These results indicated that the pH-responsive hydrogels based on CS/PVP can be a promising candidate for drug delivery due to its high susceptibility to antibacterial activity.