Development and Characterisation of an Optimised Chitosan-Gelatin Hydrogel for Non-Viral Gene Delivery in Epidermolysis Bullosa (EB) Treatment

Epidermolysis Bullosa (EB) is a genetic skin condition characterised by blister formation on the skin and mucous membranes. Current treatments fail to target the underlying genetic mutations responsible for the condition. This IRC-EPS-funded project, in collaboration with DEBRA Ireland, aims to develop a topical gel containing collagen VII-encoding nanoparticles for targeted delivery into skin cells to stimulate collagen VII production. To date, we have formulated and characterised an optimal hydrogel carrier for delivery of the collagen VII-encoding nanoparticles comprising of chitosan-gelatin (CH:Gel) biopolymers. We evaluated various CH:Gel ratios, concentrations of citric acid as a crosslinking agent, and two chitosan variants with different deacetylation degrees (75DD% and 90DD%). Physicochemical analyses, including FTIR spectroscopy, zeta potential, rheology, and spreadability assessments, were conducted to evaluate the hydrogel. A crucial determinant for the hydrogel’s function as a non-viral gene delivery system is its surface charge. Typically, materials with higher zeta potentials exhibit superior interaction with negatively charged cell membranes, leading to enhanced cellular uptake and greater gene expression. The most promising hydrogel formulation, identified as CH-Gel with a 1:1 ratio, CH of 75DD% and 20% crosslinker, exhibited a zeta potential of 38.75 ± 1.5 mV. Importantly, the hydrogel formulation demonstrated favourable rheological properties, displaying non-Newtonian, shear-thinning behaviour, ensuring ease of application on the skin while preventing excessive fluidity and detachment. In conclusion, the optimised hydrogel formulation holds significant potential as a non-viral gene delivery carrier for the targeted delivery of collagen VII-encoding nanoparticles, contributing to the treatment of EB.