Preparation And Performance Control Of Kaolinite-based Antibacterial Composites

Kaolinite has a natural layer structure,excellent physical and chemical properties,and good biocompatibility.It has great application potential in the field of antibacterial biomedicine.This thesis focuses on the problem of antibiotic resistance of bacteria and studies the preparation and performance regulation of kaolinite-based antibacterial materials.Kaolinite-based antibacterial materials were prepared by loading oxides,metal ions and organic substances onto kaolinite,and the antibacterial properties of kaolinite-based antibacterial composites and the regulation mechanism of kaolinite’s antibacterial properties of escherichia coli were investigated by using small angle neutron scattering,atomic force microscopy,and other research methods as well as mouse animal experimental models,providing theoretical guidance for the application of clay mineral materials in the field of antibacterial biomedicine.Kaolinite was calcined at different temperatures to prepare kaolinite samples.The antibacterial mechanism and wound-healing effect of calcined kaolinite were investigated.The results show that the stronger the interaction between kaolinite and bacteria,the more obvious the mechanical effect of kaolinite on bacterial membrane,and the stiffness of bacterial membraneκchanges from 0.107 to 0.506,the interaction between kaolinite and bacteria resulted in the decrease of cell membrane elasticity and the increase of membrane stiffness.The results of small angle neutron scattering show that the length of the carbon-containing functional group and the hydrogen-containing functional group in the membrane structure increased by 93?and 140?respectively,and the phospholipid bilayer in the bacterial membrane was forced to be elongated by the effect of kaolinite,and the cell membrane was damaged by extrusion.The number of exosomes secreted through the bacterial membrane is also reduced due to the destruction of bacterial membrane structure,which affects the biochemical function of exosomes.The destruction of the bacterial membrane leads to the inability of exosomes to transmit bacterial toxins,which reduces the infection of bacteria on the wound inflammation.The greater the action of kaolinite on bacteria,the more obvious the antibacterial effect,the lighter the inflammatory reaction of the wound,and the better the wound healing effect.Zinc oxide was loaded onto the surface of kaolinite by hydrothermal method to explore the regulation of kaolinite surface on the antibacterial property of zinc oxide.The results show that the kaolinite surface can change the height,morphology,crystallinity and lattice orientation of zinc oxide through interaction with zinc oxide.The interface effect of zinc oxide particles on the surface of kaolinite is weaker,the height of zinc oxide nanoparticles is 1 nm,and the lattice spacing is 0.10 nm.Zinc oxide nanoparticle lattice grows along the c-axis of the crystal,forming more（0001）crystal faces or（0001）terminal crystal faces.The stronger the interface interaction between zinc oxide and kaolinite,the higher the zinc oxide nano particles are,and the lattice spacing is 0.15 nm.Zinc oxide nanoparticles grow directionally along the a-axis（<1000>direction）,thus increasing the proportion of polar surfaces,zinc oxide polar surfaces,and active oxygen yield.The stronger the interface force of kaolinite zinc oxide,the more stable the zinc oxide in aqueous solution,and the more obvious the antibacterial effect.The zinc ion/kaolinite composite antibacterial material was prepared by loading zinc ion on the kaolinite modified by heat treatment.Zinc ion clusters are affected by the polarity of the kaolinite surface.The larger the surface polar free energy is,the breaking force between zinc ion clusters and the kaolinite surface is 2.5 n N.The larger the distribution space of hydrated zinc ion clusters is,the more conducive to the disordered distribution of hydrated zinc ions.At this time,the inherent mobility of zinc ions is 3.402×10^-4cm²V^-1S^-1。The surface polar free energy is too small.The breaking force between the zinc ion cluster and the kaolinite surface is 58 p N.The kaolinite surface cannot provide more distribution space for the distribution of zinc ions,but can only conduct short-term ordered and long-term disordered distribution.At this time,the inherent mobility of zinc ions is 2.937×10^-4cm²V^-1S^-1。Kaolinite arranges the distribution space of zinc ions through the surface effect to achieve the controlled release of zinc ions on the material surface.At the same time,the interaction between composite materials and bacteria improves the delivery ability and utilization efficiency of antibacterial agents,thereby effectively improving the antibacterial effect of materials.To realize the slow release of antibacterial agents in antibacterial materials and the selective effect on bacteria,and reduce the toxicity to normal cells.Carbon nitride/kaolinite composites were prepared by calcining and dehydroxylation of carbon nitride on kaolinite.The structure shows that the surface interface between kaolinite and carbon nitride has a polar effect.The stronger the polar effect is,the radius of the cross section of carbon nitride is 140,and the fractal dimension is 2.34.The smoother and more orderly the distribution of carbon nitride on the surface of kaolinite is;When the polar effect between the kaolinite surface and carbon nitride is smaller,the cross-section radius of carbon nitride is 110,and the fractal dimension is 2.4,and the carbon nitride structure is more curly.The polar interaction between kaolinite and carbon nitride changes the structure of carbon nitride.The quantum yield of sample CN（4.63%）is higher than that of composite CNK450（3.38%）,which improves the non-radiative energy conversion of excitons and the yield of triplet excitons.This leads to the composite material producing singlet oxygen even in the dark,playing a key role in the healing of infected wounds,and accelerating the rate and efficiency of wound healing.Based on the natural layere structure and rich surface characteristics of kaolinite,this paper realized the performance regulation of kaolinite composites through structural modification and functional design,providing new ideas for the high-value processing of clay minerals and the development of new nano biomedical materials.Figures 88,Tables 3,References 256.