Biomineralized Ag-Au Core-shell Nanostructure For Antibacterial Application

Recently,food-borne diseases caused by food-borne pathogens occur constantly and seriously harm human health,which has become the number one food safety issue in China.Therefore,developing novel and efficient control technology for food-borne microbial has become one of the hot spots in the current food safety researches.Combining with nanotechnology,we developed a biocompatible Au-Ag core-shell nanocomposite via biomineralization of gelatin to control microbial contamination.The chemical antibacterial properties and photothermal sterilization performance were investigated.In details,the results of the study are as following:1.Preparation of Gelatin-Au-Ag core-shell nanostructureWith gelatin as biogenic reductant,chloroauric acid and silver nitrate as precursors,Gelatin-Au-Ag was prepared by a two-step biomineralization method.The as-prepared materials were then characterized by scanning electron microscopy(SEM),transmission electron microscopy(TEM),UV-vis spectrum and Fourier transform infrared spectrum(FT-IR).These results clearly confirmed the formation of gelatin-Au-Ag core-shell nanostructure.The preparation method is safe and easy to operate.Besides,the prepared nanocomposite has good dispersibility and colloidal stability,as well as good photothermal effect.2.Antimicrobial Activity of Gelatin-Au-Ag core-shell nanostructureThe chemical antibacterial and photothermal sterilization performance of nanocomposite were assessed using E.coli and S.aureus.Minimum inhibitory concentration(MIC)of Gelatin-Au-Ag towards E.coli and S.aureus were 2.4 ?g/mL and 9.6 ?g/mL,respectively.Moreover,combining with photothermal treatment,Gelatin-Au-Ag can kill 100% of E.coli even at a concentration of 2.4 ?g/mL,indicating that the unique photothermal property can significantly improve the antibacterial activity of Gelatin-Au-Ag.3.Antibiofilm Effect of Gelatin-Au-Ag core-shell nanostructureBy MTT and crystal violet staining methods,we further investigated the destruction and inhibition effect of Gelatin-Au-Ag towards biofilms of salmonella and S.aureus.The results indicate that our nanocomposite possesses powerful anti-biofilm activity.Moreover,the in vitro toxicity experiment demonstrated well biocompatibility of our nanocomposite.Therefore,these results suggest that this rational and facile biomineralization of Au-Ag nanomaterial with biogenic gelatin represents a feasible approach to regulate the toxicity of native Au-Ag nanomaterials.