The Synthesis,Biological Properties And The Application Of Au-ag Core-shell Structure Nanoparticles By Gallic Acid

Although nanotechnology has been developing rapidly in many fields,the calls of preparation of nanomaterials(raw materials,technology,products)for environmental friendly and harmless to human increase day by day with the improvement of people's environmental awareness.Based on the concept of green chemistry,this paper used natural plant extracts to prepare nanomaterials as well as explored its potential applications in biology,including antibacterial properties,cytotoxicity and catalytic activities.In this paper,Au@Ag nanoparticles were prepared by using gallic acid as a reducing agent.The results showed that the experiment was better to proceed under the original pH system.The optimal reaction temperature of gold nanoparticles should be at 70? in the first step while it's 60? in the second step.The morphology of nanoparticles generated by the reaction time of 15 minutes is more homogeneous.The addition of sodium tripolyphosphate as a protectant has an important effect on the formation of Au@Ag nanoparticles with good dispersibility and size.The mole ratio of gold and silver has a more significant effect on the formation of nanoparticles with core-shell structure.When Au / Ag molar ratio is 1:5,stable Au@Ag nanoparticles can be obtained.The antibacterial properties of Au@Ag nanoparticles were studied.The minimum inhibitory concentration of Au@Ag nanoparticles on Escherichia coli and Staphylococcus aureus was lower than that of silver nanoparticles.As well as the average diameter of the inhibition zones of Au@Ag nanoparticles for Escherichia coli and Staphylococcus aureus was larger than that of AgNPs.In conclusion,the antibacterial properties of Au@Ag nanoparticles were better than that of AgNPs.The cytotoxicity of Au@Ag nanoparticles were also explored.The MTT method was used to investigate the toxicity of gallic acid and Au@Ag nanoparticles on L-929 cells.Some enhancement effect on cell viability by Gallic acid was observed while cytoactives showed up and down slightly affect by Au@Ag nanoparticles with the increase of concentration.Generally,the cytotoxicity of Au@Ag nanoparticles is too big to be used in the field of product contact with the human body.The catalytic activity were found by the Au@Ag nanoparticles through comparative experiments.The results show that the optimal concentration of Au@Ag nanoparticles is 10mmol/L.The catalytic activity was best at 0.5% hydrogen peroxide.The optimal pH for the catalysis is about 9.Further study of catalytic activity of AuNPs and AgNPs were conducted using gallic acid and sodium citrate as reactant respectively.The conclusion is that the catalytic activity of AuNPs prepared by gallic acid is better than that by sodium citrate.However,the catalytic activities of both AuNPs and AgNPs were bad compared to Au@Ag NPs.Finally,we tried to apply the Au@Ag nanoparticles to the detection of glucose.The results show that,on the one hand,the OD value basically does not change with different concentration of glucose solution.On the other hand,the OD value of samples and blank hole was basically the same,indicating that the solution did not produce discoloration reaction.