Development of pH-sensitive and antibacterial gelatin/citric acid/Ag nanocomposite hydrogels with potential for biomedical applications

This work aimed to prepare pH-sensitive and antibacterial drug releasing systems through a completely green route. To achieve this, the gelatin natural biopolymer was crosslinked with citric acid in the presence of Ag nanoparticles (NPs). Interestingly, Ag NPs formation and gelatin crosslinking were simultaneously occurred during annealing of samples without need for any toxic chemicals, which were confirmed by FTIR, UV-vis spectra, SEM and TEM observations. In addition, potential of the citric acid crosslinked-gelatin/Ag nanocomposite hydrogels was successfully explored for drug delivery applications using cefixime as a model drug. It was found that these hydrogels have pH-dependent swelling and drug release behavior with higher drug release at pH7.4 compared to pH1.2. Also, an antibacterial effect against the E. coli and S. aureus microorganisms was achieved by incorporation of Ag NPs into hydrogels. These hydrogels can be considered as stimuli responsive materials for oral drug delivery and wound dressing applications.