Investigation of swelling behaviors and effect of wound healing of IPN type hydrogels including chitosan-poly(acrylic acid) and poly(acrylamide)

In this study, interpenetrating network (IPN) type hydrogels at various compositions of acrylic acid (AA), acrylamid (AAm) and chitosan (CS) polymers were prepared. Ammonium persulfate / sodium metabisulfide (NH4)2S2O8 / Na2S2O5 redox pair was selected as initiator, and the hydrogels were synthesized by free radical polymerization. A certain amount of ethylene glycol dimethacrylate (EGDMA) for semi-IPN, and additionally variable amounts of glutaraldehyde for the full-IPN hydrogels were used as crosslinking agents. Swelling behaviors of the hydrogels were investigated by changing time, temperature and pH. Percentage swelling (S %) of all the hydrogels were increased with time and constant percentage swelling values were reached near 30 hours. For semi-IPN-type hydrogels, it was observed that the hydrogels including AA swollen much more than the hydrogels including AAm. It is also found that the full-IPN hydrogels had more swellable character than the semi-IPN-type hydrogels. No significant change in the percentage swelling values was observed by increasing the amount of CS. Chitosan-poli(acrylic acid) full IPN-2 [(CS-PAA)T-2] was determined as the most swollen hydrogel at pH=7.4 and 37 ºC.In the second part of the study, the effect of Epidermal Growth Factor (EGF) loaded chitosan-poli(acrylic acid) semi IPN-2 [(CS-PAA)Y-2], Chitosan-poli(acrylamide) semi IPN-2 [(CS-PAAm)Y-2] and (CS-PAA)T-2 hydrogels on wound healing was investigated, using L929 mouse fibroblast cells. The loading of EGF was performed by soaking method. The satisfactory results were obtained only just for the EGF loaded (CS-PAAm)Y-2. From the optical microscope examinations, it was observed that the cells adhered to the surface and spread by creating fibroblastic morphologies in a manner increasing by time.In the final part of the study, Piperacillin/Tazobactam was loaded to (CS-PAA)Y-2, (CS-PAAm)Y-2 and (CS-PAA)T-2 hydrogels by the soaking method. The release from the Piperacillin/Tazobactam loaded hydrogels at 37°C and pH=7.4 was monitored with UV spectrophotometer. It was observed that the hydrogel (CS-PAAm)Y-2 has released Piperacillin/Tazobactam in longer time compared to the other loaded hydrogels. From the kinetic data, zero order release has been determined for all hydrogels. The diffusion coefficient (D) of (CS-PAA)T-2 hydrogel which has faster releasing value, was calculated to be 3.53x10-6 cm-2/s.