Construction of gelatin/alginate hydrogels doped hemicyanine derivatives for photodynamic antibacterial application

Hydrogel systems based on natural polymer materials have provided alternative opportunities for preparing antimicrobial dressings. A composite antibacterial hydrogel system containing gelatin (Gel), alginate (Alg) and hemicyanine derivatives with different chain lengths (C3, C6 and C10) was constructed. The composite hydrogels have excellent swelling ability and low degradability due to the classical three-dimensional network structure. Because of the photosensitization ability of C3, C6 and C10, hydrogels containing these molecules can also effectively produce reactive oxygen species (ROS) under light. Importantly, the hydrogel containing C3 molecules that have higher spatial extension structure and shorter alkyl chain than C6 and C10 shows better photo-responsive antibacterial effect against drug-resistant Escherichia coli. The bacterial killing activity of the composite hydrogel system could be regulated by changing the alkyl chain length of the photosensitizers. This effective and photo-responsive composite hydrogel system is expected to be used for bacteria-infected wound repair and promoting wound healing. •Natural biomacromolecular hydrogels based on gelatin (Gel) and alginate (Alg) with various hemicyanines (Cn) were prepared.•Cn/Gel-Alg hydrogels possess excellent swelling capacity, high biocompatibility and ROS generation ability.•The variation of structure for hemicyanines causes the difference of Cn/Gel-Alg hydrogels in antibacterial performance.•Bacterial surface structure was damaged by Cn/Gel-Alg hydrogels with the aid of white light.