Green-synthesised silver nanoparticle-loaded alginate/gelatin/aloe vera nanocomposite hydrogel films as wound dressings

Open wounds resulting from trauma, burns or complications of diabetes require dressings that keep the wound bed moist, limit infection and remain compatible with host tissue. Many reported hydrogel dressings satisfy some of these requirements but are limited by high cost, complex synthesis, weak mechanical behaviour or poor cytocompatibility. Although alginate, gelatin, Aloe vera and silver nanoparticles have each been used individually in dressing materials, their combination into a single, low-cost film, and the systematic study of how the alginate-to-gelatin ratio governs its properties with green-synthesised AgNPs, has not previously been reported. In this study, three nanocomposite hydrogel films based on alginate, gelatin and Aloe vera were prepared at ALG/GEL/AV mass ratios of 1/3/20, 2/2/20 and 3/1/20 (coded AGA13, AGA22 and AGA31, respectively), crosslinked with Ca²⁺ and loaded with 1% (w/w) silver nanoparticles. The AgNPs were green synthesised by reducing AgNO₃ with pomegranate (Punica granatum) extract; they were spherical, approximately 50-150 nm in size, with a mean hydrodynamic radius of 162.76 nm and a zeta potential of -41.83 mV, indicating a stable, weakly aggregating dispersion. Film behaviour was largely governed by the alginate content. As the alginate fraction increased, the films became denser and swelled less, so that equilibrium swelling and water retention both decreased in the order AGA13>AGA22>AGA31, with AGA13 reaching approximately 150% swelling and 65% water retention. Ethanol displacement indicated negligible open porosity for all films, in line with SEM. Over four weeks the films lost mass from about 78% (AGA13) to below 40% (AGA31), a range wide enough to match dressing lifetime to the intended application. None of the formulations was cytotoxic to L-929 fibroblasts in the indirect MTT assay, with viabilities of 115%, 110% and above 130% for AGA13, AGA22 and AGA31 relative to the control. Overall, AGA31 combined the slowest mass loss with the strongest fibroblast response, identifying it as the most suitable candidate for longer-term wound management.