Effects of Au nanoparticles on thermoresponsive genipin-crosslinked gelatin hydrogels

Gold gelatin hydrogel nanocomposites crosslinked with genipin have been prepared, and the effect of citrate capped Au nanoparticles (NPs) as nanofillers in the crosslinking and swelling of gelatin and release of a model drug (methylene blue) from gelatin nanocomposites have been investigated. The citrate-capped Au NPs prevented the crosslinking reaction between the gelatin and genipin and resulted in less crosslinked hydrogels. Although less crosslinked, the Au gelatin nanocomposites swelled less than the unfilled crosslinked gelatin. The gelatin composites were optically active and thermo-sensitive in a temperature range acceptable for living cells. In vitro release studies demonstrated that the irradiation of the composite gels with monochromatic green light (λ = 532 nm, 100 mW) increases the release of the encapsulated methylene blue, most likely due to the photothermal effect of Au nanoparticles. This opens the possibility to explore the application of these nanocomposites as carriers in remotely controlled light-triggered drug release.