Construction And Antibacterial Properties Of CuO-supported Silica Nanocapsule

Antimicrobial strategies based on reactive oxygen species(ROS)open new avenues to overcome the enormous challenges posed by antibiotics,including the lack of broad-spectrum antibiotics and the emergence of super-resistant bacteria.With the rapid development of nanotechnology,many nanomaterials with Fenton reaction activity,also known as analog peroxidase(POD)materials have become new stars in the field of antibacterial.As a new bactericidal material,metal oxides have been widely studied in the antibacterial field of nanomaterials because of their excellent catalytic activity.In view of the main problems the prevailing Fenton catalysis facing,for instance,the catalytic reaction should proced in a strong acidic environment,the catalyst has poor stability and low catalytic efficiency,nano-metal oxides with high Fenton-like activity and high stability were designed and developed in this paper,and their application as nondrug-resistant broadspectrum antibacterial materials were preliminarily studied.The in-depth study on the catalytic mechanism and antibacterial performance of cu-based nanocomposites were carried out.The main contents of this paper include:In chapter one:introduction.The main types of ROS and nano-enzyme are summarized,and the transformation betweeb the ROS into each other under the action of nano-enzyme are briefly discussed.The main synthesis methods and research status of copper oxide catalysts,and bimetal oxide catalysts were also summarized.In chapter two:synthesis and antibacterial properties of CuO-supported silica nanocapsules(CuO@SiO2NC).CuO@SiO2 NC with controllable particle size,good solubility and uniform dispersion were synthesized by loading copper oxide nanoparticles on the surface of soluble silicon dioxide nanoparticles by simple precipitation method.CuO NPs has a variety of simulated enzyme activities,and Cu+ and Cu2+can convert into each other to play various simulated enzyme activities,which can continuely to play a catalytic role.Due to the good catalytic activity of copper oxide,CuO@SiO2 NC shows superior Fenton-like catalytic activity in a wide range of pH.Due to the presence of Cu+,H2O2 can be obtained through the twoelectron reaction,so the system does not need to introduce H2O2 externally in the antibacterial process.In view of the excellent Fenton-like activity of CuO@SiO2NC,the antibacterial test was carried out in vitro under a neutral environment(pH=7.4),and showed extremely high bactericidal effect on staphylococcus aureus and Escherichia coli.The results show that CuO@SiO2 NC is a very good Fenton-like catalyst with high bactericidal activity in a wide range of pH.In chapter three:synthesis and antibacterial properties of CuO-CeO2 co-supported silica nanocapsule(Cu0.75Ce0.62O2@SiO2NC).In order to further improve the antibacterial activity of the catalyst and reduce the quantitative oxidation of Cu+ by O2,a thermodynamic and kinetic mass transfer strategy was adopted to improve the catalytic efficiency,that is,to create highly active sites by constructing heterogeneous Fenton system.By uniformly loading copper oxide and cerium oxide on the surface of SiO2 NC,we prepared the bimetallic oxide nanocomposite Cu0.75Ce0.62O2@SiO2NC,which shows excellent Fenton-like catalytic activity in a wide range of pH,without additional addition of H2O2.This excellent catalytic activity results from the charge transfer between the two metal oxide components,in which Cu+ and oxygen vacancy formation are mutually enhanced,resulting in a synergistic effect of H2O2 generation and catalytic formation of ·OH under slightly acidic conditions(pH=6.0).The bimetallic nanocomposite Cu0.75Ce0.62O2@SiO2 showed excellent antibacterial performance in the subsequent antibacterial experiments,with a very small minimum bactericidal concentration,and is an efficient broad-spectrum antibacterial material.