An enzyme-modified gelatin/silver nanoparticle composite biomaterial was prepared in this work.The silver nanoparticles were prepared in aqueous solution at first.Then

the blend of gelatin and silver nanoparticles was used as the composite matrix

and microbial transglutaminase (mTG) was employed as the biological modifier.Atomic force microscopy tests show that silver nanoparticles are distributed uniformly on the surface of the composite material

and no obvious aggregation of silver nanoparticles was observed.Vial inversion tests and rheological measurements both confirm that the gel formation and the covalent junctions of the composite can be triggered by microbial transglutaminase.Microbial transglutaminase can crosslink gelatin molecules by catalyzing the transamidation of glutamine and lysine residues to form covalent junctions.The mTG-modified gelatin/silver nanoparticle composite material has better stability in aqueous medium at a moderately high temperature due to the formation of covalent junctions and crosslinks.The results of tensile tests show that the tensile strength of mTG-modified gelatin/silver nanoparticle composite films increases after enzymatic modification.In addition

compared with the mTG-modified gelatin material lacking silver nanoparticles

the mTG-modified gelatin/silver nanoparticle composite material shows better in vitro antibacterial activity against Staphylococcus aureus. The viable cell number of Staphylococcus aureus of mTG-modified gelatin/silver nanoparticle composite material decreases by 60.15%.With its improved antibacterial activity

stability in aqueous medium

and mechanical strength

this mTG-modified gelatin/silver nanoparticle composite material could be a promising candidate in future applications of skin biomaterial.