Synthesis And Antibacterial Properties Of Copper Nanomaterials

With the continuous development of nanotechnology,the application of inorganic nanomaterials as antibacterial agents has attracted the keen interest of many researchers.Different from gold and silver nanoparticles,copper nanomaterials not only have the advantages of abundant reserves and low price,but also have biocompatibility,which can reduce the limitations of application when used as antibacterial agents to a certain extent.In this paper,a series of copper,cuprous oxide and copper oxide nanomaterials were synthesized by liquid phase reduction and photoreduction method,which are simple and easy to operate,without the protection of inert atmosphere.The antibacterial properties and antibacterial mechanism of copper nanomaterials with different morphologies synthesized by different copper sources and preparation methods were studied and compared.The antibacterial properties and antibacterial mechanism of Cu₂O and Cu O with similar morphology and different composition were investigated.The details are as follows:1.Using copper acetate or copper nitrate as copper source,three kinds of copper nanomaterials with different morphologies were obtained by simple liquid phase reduction method or photoreduction method.The samples were characterized by SEM,XRD,TEM,XPS,UV-vis absorption spectrum,FT-IR spectrum and N₂ adsorption-desorption.The antibacterial properties of the obtained samples against gram-negative bacteria（Escherichia coli）and Gram-positive bacteria（Staphylococcus aureus）were tested by photometry,and the inhibition ability of the samples to colony growth was further observed by coating method and LSCM test.It was found that sample 1 had good inhibition effect on colony growth when it was tested for a long time（72 hours）antibacterial or reducing the amount of antibacterial agent.Sample 2 showed excellent antibacterial activity against Staphylococcus aureus,but could not inhibit the growth of E.coli.The antibacterial performance of sample 3 was lower than that of sample 1,which was obviously dependent on the reaction time and the amount of antibacterial agent.Combined with the results of a series of experiments,the antibacterial mechanism of different copper nanomaterials against the two bacteria was further studied.It was found that sample 1 could not only achieve the antibacterial effect by releasing Cu²⁺,but also the small nanoparticles could directly enter into the bacteria and play the antibacterial effect.Sample 2 can significantly inhibit the growth of Staphylococcus aureus by directly entering the bacteria with small particle size copper nanoparticles.Sample 3 achieved antibacterial effect only by releasing Cu²⁺.2.Cuprous oxide nanoparticles were synthesized by a simple liquid phase reduction method.After calcination,cuprous oxide nanoparticles with similar morphology were obtained.The samples were characterized by SEM,XRD,TEM,XPS,UV-vis absorption spectrum,FT-IR spectrum and N₂ adsorption-desorption.The antibacterial performance of the two samples under different antibacterial reaction time and antibacterial agent dosage was systematically tested.The growth inhibition of the colony was further observed by coating method,and the growth of the colony was more directly studied by LSCM test.The results show that Cuprous oxide has a higher surface area than Cupric oxide,and the Cu²⁺release rate is faster during the antibacterial process,which can effectively play the antibacterial performance during the rapid growth of bacteria.The antibacterial mechanism was further studied,and it was found that both of them could achieve antibacterial effect through the release of copper ions and antibacterial agent nanoparticles directly into the interior of bacteria.Cu₂O with larger surface area has higher dissolved concentration of copper ion and higher antibacterial rate.In addition,for the antibacterial agent of the same quality,Cu₂O has a higher copper content ratio than Cu O,and higher concentration of copper ions can be dissolved,which may be another important factor for the higher antibacterial rate of Cu₂O than Cu O.