Preparation,Antibacterial Properties And Cytotoxicity Of Silver-containing Nanomaterials

Infectious diseases are among the diseases with the highest morbidity and mortality,and one of the largest health problems in the world,which seriously threatens public health and safety.Antibiotics are effective drugs for the treatment of bacterial infections.However,due to the abuse of antibiotics,many bacterial pathogens have developed drug resistance,and usually multi-drug resistance,which has led to increased medical costs,recurrence of infections and death of patients.Therefore,there is an urgent need to develop antibacterial agents,which have good antibacterial properties and do not produce drug resistance to replace conventional antibiotics.Silver-based antibacterial agents have the advantages of broad-spectrum antibacterial properties and no drug resistance,and have become one of the most studied and widely used antibacterial agents among many antibacterial agents.However,in recent years,studies have reported that silver-based antibacterial agents can produce certain toxicity to normal mammalian cells.Currently,silver-containing dressings are one of the most important biomedical products,used for burns,acute and chronic wound management,and to inhibit wound infections.Silver-containing dressings are classified as Class II medical devices,and their safety must be taken into account while ensuring their effectiveness.Based on this,the main research contents of this paper are as follows:1.Characterization,antibacterial properties and cytotoxicity of silver-containing dressingsThe main product of a biotechnology company is a silver-containing dressing,which accounts for about 25%of the country's market share.Entrusted by the company,we tested its products.SEM,EDS and XPS were used to detect the physical and chemical properties of silver-containing dressing products,in which the silver exists in the form of nano-silver.The most common E.coli and S.aureus were selected as test strains.The antibacterial properties of silver-containing dressings were tested by the national standard method.The MTT assay was used to determine the cytotoxicity of silver-containing dressings on mouse embryonic fibroblasts(NIH 3T3).The results showed that the antibacterial rate of the dressing on E.coli and S.aureus was 100%and 85.23%,respectively,after applying for 30minutes.However,the cytotoxicity grade is 4 and does not meet the safety requirements of Class II medical devices.Therefore,we conduct research on the antibacterial properties and cytotoxicity of the materials,hoping to solving the key technical problems in this field.2.Study on antibacterial properties and cytotoxicity of Au@Ag core-shell nanoparticlesUsing sodium citrate as a reducing agent and stabilizer,Au@Ag core-shell nanoparticles with particle sizes of 29.9±4.1 nm,56.5±6.7 nm and 84.7±8.7 nm were prepared by seed growth method.And the particle size,morphology,composition and stability of Au@Ag core-shell nanoparticles were characterized by UV-vis,TEM,and EDS.The MIC and antibacterial activity of Au@Ag core-shell nanoparticles of three particle sizes,29.5±4.1 nm,56.5±6.7 nm and 84.7±8.7 nm,were determined by constant broth dilution method,optical density method and agar diffusion method.The results show that the bactericidal ability and cytotoxicity of Au₂₀@Ag core-shell nanoparticles are higher than those of large-diameter Au₅₀@Ag and Au₈₀@Ag.And the bactericidal ability of Au₅₀@Ag is stronger than Au₈₀@Ag,but the difference in cytotoxicity between the two is not obvious.Therefore,Au₅₀@Ag core-shell nanoparticles are the best choice.3.Preparation and antibacterial properties of NH₂-MIL-101(Fe)silver-loaded materialMOF NH₂-MIL-101(Fe)is prepared and synthesized.Through chemical adsorption,an Ag⁺reservoir NH₂-MIL-101(Fe)-Ag⁺is formed with a storage capacity of 46.85 mg/g.IR,SEM morphology and EDS elemental analysis were carried out on the materials before and after adsorption.Then,their antibacterial properties and cytotoxicity were explored.The results show that NH₂-MIL-101(Fe)-Ag⁺has a strong bacteriostatic effect.The minimum inhibitory concentration against E.coli and S.aureus is 0.5 and 1?g/m L,respectively.When the silver content reached 32?g/m L,the relative cell viability remained above 85%.Therefore,within an appropriate concentration range,NH₂-MIL-101(Fe)-Ag⁺can effectively kill bacteria without cytotoxicity,and is expected to be applied in the field of biomedicine.