pH responsive release of curcumin from photocrosslinked pectin/gelatin hydrogel wound dressings

The aim of this study was to develop hydrogel wound dressings made of photocrosslinkable pectin and gelatin with pH dependent release of curcumin, an antimicrobial agent. Methacrylated forms of pectin and gelatin (PeMA and GelMA, respectively) were synthesized, and hydrogels were prepared with different compositions (1:1, 1:2 and 1:3 v/v ratios of PeMA and GelMA) by UV exposure. Pure GelMA was used as control group. Average pore diameter of hydrogels with the highest PeMA content (P1:G1) was 43 μm. All hydrogels showed about 90% swelling. P1:G3 demonstrated the highest stability (retained about 37% of their initial weight after 21 days incubation in PBS), a reasonable compressive modulus (ca. 22 kPa), oxygen permeability (7.44 mg/mL) and preventing ability for bacterial penetration. Therefore, P1:G3 hydrogels were chosen and loaded with curcumin for further studies. In aqueous medium (10 mM PBS, pH 7.4), about 4 times faster release of curcumin was observed than that in medium with pH 5.0. Since infected wounds have alkaline pH compared to healthy tissue, faster release at basic medium is preferable for wound grafts. Disk diffusion tests proved antibacterial efficacy of the hydrogels against S. aureus and E. coli. Live/Dead and Alamar blue assays conducted with L929 fibroblasts showed cytocompatibility of the hydrogels. It was concluded that curcumin loaded P1:G3 hydrogels are promising candidates as wound dressing materials to be further tested in the treatment of infected and chronic wounds.