A novel in situ-formed hydrogel wound dressing by the photocross-linking of a chitosan derivative

In situ photopolymerized hydrogel dressings create minimally invasive methods that offer advantages over the use of preformed dressings such as conformability in any wound bed, convenience of application, and improved patient compliance and comfort. Here, we report an in situ-formed hydrogel membrane through ultraviolet cross-linking of a photocross-linkable azidobenzoic hydroxypropyl chitosan aqueous solution. The hydrogel membrane is stable, flexible, and transparent, with a bulk network structure of smoothness, integrity, and density. Fluid uptake ability, water vapor transmission rate, water retention, and bioadhesion of the thus resulted hydrogel membranes (0.1 mm thick) were determined to range from 97.0-96.3%, 2,934-2,561 g/m2/day, 36.69-22.94% (after 6 days), and 4.8-12.3 N/cm2, respectively. These data indicate that the hydrogel membrane can maintain a long period of moist environment over the wound bed for enhancing reepithelialization. Specifically, these properties of the hydrogel membrane were controllable to some extent, by adjusting the substitution degree of the photoreactive azide groups. The hydrogel membrane also exhibited barrier function, as it was impermeable to bacteria but permeable to oxygen. In vitro experiments using two major skin cell types (dermal fibroblast and epidermal keratinocyte) revealed the hydrogel membrane have neither cytotoxicity nor an effect on cell proliferation. Taken together, the in situ photocross-linked azidobenzoic hydroxypropyl chitosan hydrogel membrane has a great potential in the management of wound healing and skin burn.