Research On Silver/Graphene Oxide-based Multi-mode Antibacterial Nano-composites

Nano-technology provides a novel strategy for the development of new antibacterial agents due to high specific surface area.Therefore,nano-antibacterial agent has high efficiency antibacterial properties and been widely studied and applied.Graphene is 2 two-dimensional honeycomb lattice materials composed of single-layer carbon atoms with sp2 hybridization and compact packing.Graphene oxide(GO),as a derivative of graphene,has excellent adsorption property,biocompatibility and other characteristics,Graphene oxide-based antibacterial composite materials have been aroused great concern in the field of biological medicine.Silver,as an important inorganic antibacterial agent,is particularly promising because of their unique bactericidal properties including broad-spectrum antibacterial property,high antibacterial activity,good durability and anti-drug resistance.In this paper,two kinds of antibacterial nano-composites with multiple antimicrobial action were fabricated by anchoring Ag NPs or silver halide nano-particles onto graphene oxide and by introducing contact-killing poly 4-vinyl pyridine quaternary ammonium salt.Silver nano-particles loaded magnetic graphene oxide nano-composites,N-alkylated poly(4-vinylpyridine)(NPVP),a cationic polymer,was firstly applied for the surface modification of Fe3O4 nano-particles.Then the modified Fe3O4 nano-particles(Fe3O4@NPVP NPs)combined with graphene oxide through simple electrostatic binding.Subsequently,deposited Ag nano-particles(Ag NPs)procedure was carried out,forming the multiple and recyclable anti-bacterial nano-composites(MGO@NPVP-Ag).The synthesized nano-structures were well characterized by Fourier-transform infrared(FT-IR),X-ray powder diffraction(XRD)and Transmission Electron Microscope(TEM).The zeta potential measurement showed that the novel antibacterial nano-composites exhibited a capacity of reversing its surface charge from negative(physiological pH)to positive(acidic condition).Furthermore,the incorporation of magnetic Fe3O4 NPs into the nano-systems facilitated the cyclic utilization of GO-Fe3O4@NPVP-Ag by magnetic separation.The antibacterial properties of MGO@NPVP-Ag nano-composites were evaluated with Gram-negative Escherichia coli and Gram-positive Staphylococcus aureus(Inhibition zone testing,MIC and Time-kill test,etc).Moreover,the cytotoxicity of MGO@NPVP-Ag nano-composites was studied using NIH-3T3 cells.The results showed that the MGO@NPVP-Ag nano-composites exhibited excellent antibacterial properties that two kinds of bacteria were totally inactivated after contact 120 min.And MGO@NPVP-Ag nano-composites exhibited low cytotoxicity,even at 25 times MIC’s concentration,the survival rate of the NIH-3T3 cells was still up to around 75%.Silver bromide nano-particles loaded graphene oxide nano-composites,NPVP and NP(VP-co-HEMA)were firstly obtained by homopolymerization and copolymerization.Then a simple and novel technique of on-site precipitation of AgBr was used to synthesize the polymer/nano-particle composites.Subsequently the polymer coated silver bromide nano-particles combined with graphene oxide through simple electrostatic binding to form the multiple and anti-bacterial nano-composites(GO-NPVP@AgBr and GO-NP(VP-co-HEMA)@AgBr).The synthesized nano-structures were well characterized by Fourier-transform infrared(FT-IR),X-ray powder diffraction(XRD),Transmission Electron Microscope(TEM)and X-ray photoelectron spectroscopy(XPS).The antibacterial properties of two kinds of nano-composites were evaluated with Gram-negative Escherichia coli and Gram-positive Staphylococcus aureus(Inhibition zone testing,MIC and Time-kill test,etc).Moreover,the cytotoxicity of two kinds of nano-composites was studied using NIH-3T3 cells.The results showed that the GO-NP(VP-co-HEMA)@AgBr nano-composites exhibited a bit better antibacterial properties and low cytotoxicity,even at 800 μg/mL,the survival rate of the NIH-3T3 cells was still to around 81.45%.Thus,it is proposed that the nano-composites can be used as a promising rapid bactericide in antibacterial fields.