Preparation Of Biodegradable Composite Nano-electrospun Membrane Based On Ag-Cu Bimetallic Nanoparticles And Study Of Antibacterial Properties

In the past few decades,the increasing in bacterial antibiotic resistance worldwide has posed a serious threat to public health.Poor sterilization and antibacterial methods may increase the risk connected with wound infection.Therefore,it is necessary to develop green and safe antibacterial textiles to protect wounds from the effects of drugresistant bacteria.Currently,polylactic acid(PLA)and polyvinyl alcohol(PVA)have been widely used in biomedical and skin tissue engineering fields due to the excellent biocompatibility and biodegradability.However,PLA and PVA do not have antibacterial properties,which limits their application in antibacterial materials.Generally,the antibacterial modification is one of the effective ways to solve this problem.Recently,the outstanding antibacterial properties of silver and copper nanoparticles have received widespread attention.They can interact closely with bacterial cells because they have smaller size,higher specific surface area,and a large release of free metal ions.Additionally,compared with the parent compounds,they have higher antibacterial activity than due to the mediated effect of nanoparticles.Therefore,they can be used as substitutes for traditional antibiotics to control pathogens,and are considered to be promising antibacterial nanomaterials.In this paper,silver nanoparticles(Ag NPs),copper nanoparticles(Cu NPs),silver copper mixed nanoparticles(Ag/Cu NPs)and silver copper bimetallic nanoparticles(AgCu NPs)were synthesized vis the eco-friendly reduction method,respectively.Then,these four types mental nanoparticles(NPs)were mixed with PLA spinning dope to prepare Cu NPs/PLA,Ag/Cu NPs/PLA,and Ag-Cu NPs/PLA composite nanoelectrospun membranes.Through characterization and analyzation,the results showed that the four synthesized NPs had excellent antibacterial properties,and could be uniformly dispersed on the surface of PLA nanofibers after being blended with PLA spinning solution.The fiber surface of the composite nano-electrospun membranes was rough and had many small pores.There existed only physical interaction between NPs and the PLA matrix.Compared to pure PLA nano-electrospun membrane,the hydrophilicity of Cu NPs/PLA,Ag/Cu NPs/PLA,and Ag-Cu NPs/PLA composite nanoelectrospun membranes was slightly improved.All of four composite nano-electrospun membranes had high antibacterial properties against Escherichia coli and Staphylococcus aureus.Among them,the antibacterial efficiencies of Ag-Cu NPs/PLA composite nanoelectrospun membranes was the best.Next,Ag-Cu NPs with different concentrations were added to the PLA spinning dope to prepare Ag-Cu NPs/PLA composite nano-electrospun membranes with different concentration ratios.The mixed dichloromethane and acetone were used as spinning solvent.After being tested and analyzed,the results showed that Ag-Cu NPs could be successfully mixed into the PLA spinning dope,and uniformly dispersed in PLA matrix.There existed many small holes on the fiber surface of the Ag-Cu NPs/PLA composite nano-electrospun membranes.Compared to pure PLA electrospinning membrane,the average fiber diameter and water contact angle of the composite nano-electrospun membranes decreased.The antibacterial efficiencies of the Ag-Cu NPs/PLA composite nano-electrospun membranes against Escherichia coli and Staphylococcus aureus increased with the increasing of the concentration properties of Ag-Cu NPs.When the concentration of Ag-Cu NPs was 7%,the antibacterial efficiencies of the composite nanoelectrospun membrane against Escherichia coli and Staphylococcus aureus had reached99.29% and 99.35%,respectively.For comparison,Ag-Cu NPs were mixed with PVA spinning dope using deionized water as solvent to prepare Ag-Cu NPs/PVA composite nano-electrospun membranes with different blending concentrations.After measurement and analysis,the results showed that Ag-Cu NPs could also be uniformly dispersed in the PVA matrix.When the concentration of Ag-Cu NPs added does not exceed 3%,the fiber surface of the PVA based nano-electrospun membranes is smooth.However,when the concentration of AgCu NPs was 7%,some serious adhesion occurred between the fibers,reflecting poor spinnability.There was only physical interaction between Ag-Cu NPs and the PVA matrix.When the concentration of Ag-Cu NPs was 5%,the antibacterial efficiencies of Ag-Cu NPs/PVA nano-electrospun membrane against both Escherichia coli and Staphylococcus aureus could reach 99.99%,showing high antibacterial properties.Compared to the AgCu NPs/PLA composite nano-electrospun membranes,the Ag-Cu NPs/PVA composite nano-electrospun membranes had higher antibacterial efficiencies against Escherichia coli and Staphylococcus aureus when the same concentration of Ag Cu NPs was added.In summary,after the addition of Ag-Cu NPs,biodegradable PLA-based and PVAbased composite nano-electrospun membranes can achieve high antibacterial efficiencies against Escherichia coli and Staphylococcus aureus.Compared with Ag-Cu NPs/PLA composite nano-electrospun membranes,the antibacterial efficiencies of Ag-Cu NPs/PVA composite nano-electrospun membranes can reach 99.99% under the lower adding concentration of Ag-Cu NPs.Moreover,the spinning solvent of Ag-Cu NPs/PVA composite nano-electrospun membranes is deionized water instead of organic solvent.Thus,Ag-Cu NPs/PVA composite nano-electrospun membranes with green and environmentally friendly preparation process is safer and more reliable in practical application.