Study On Preparation Of Functionalized Nanoclusters And Their Interaction With Bacteria

In recent years,due to the small size and large surface area of nanomaterials,they have unique physical and chemical properties such as high electron transfer efficiency,excellent stability,and reliable biocompatibility.The rich application prospects of materials in the interaction with microorganisms provide a wide range of possibilities.Among them,the role of nanomaterials on microbial transmembrane electron transfer and bacterial fluorescence imaging are more researched.On the one hand,based on the fact that nanomaterials can increase the uptake rate of cells,the co-incubation of nanoparticles and microorganisms constitutes an inorganic-biohybrid system.Through the microbial extracellular electron transfer process(EET),the cell transmembrane electron transfer and cell metabolic rate are accelerated,and the transformation of electrical energy and chemical energy is realized,thereby enabling the generation of electrical energy,wastewater treatment,biosensing,etc.However,the research on the regulation of microbial metabolism and hydrogen production system by nanomaterials are relatively poor.On the other hand,more than 250 diseases in the world are caused by different pathogenic bacteria,and the efficient detection of pathogenic bacteria is an important guarantee for human life.Traditional methods for quantification and detection of pathogenic bacteria include plate counting and polymerase chain reaction.Existing localization imaging methods for living bacteria are mainly based on bacterial phagocytosis of quantum dots,and organic dyes or nanoprobes loaded on the surface of bacteria.However,these traditional methods for detecting pathogens have disadvantages such as time-consuming,cumbersome operations,and complicated separation systems.Due to the characteristics of large specific surface area and easy manipulation under external magnetic field,magnetic nanomaterials have attracted much attention in the isolation and enrichment of pathogenic bacteria.The combination of fluorescent labeling and magnetic enrichment technology can effectively improve the efficiency and sensitivity of pathogenic bacteria detection.Based on the above two points,the research content of this paper is mainly divided into the following two parts:(1)Prepared sulfur-doped carbon nanoparticles(SCNPs),studied the synergistic effect of nanoparticles and microbial electron transfer,and finally realized the regulation of nanomaterials on microbial metabolism and hydrogen production process.Sulfur-doped carbon nanoparticles were prepared by a top-down laser-assisted synthesis method,and an inorganic-biohybrid system was constructed by assembling SCNPs with Clostridium butyricum cells.The study found that under dark fermentation conditions,the hydrogen production performance of the SCNPs/bacteria mixed culture system was significantly enhanced,and the total hydrogen production was 12.5 times higher than that of bare bacteria;The degradation efficiency of Clostridium butyricum on methyl orange(MO)was further verified,and the degradation rate of the hybrid system could reach more than 90%within 12 h.The SCNPs engulfed by Clostridium butyricum have abundant surface charges,which improve the efficiency of electron transduction in bacterial cells,accelerate the metabolic activities of bacteria,and enhance the activity of hydrogenase.This method provides a simple and effective way to improve the electron transfer efficiency,reduce the energy loss during transmembrane diffusion,and construct a powerful whole-cell biohybrid hydrogen production system.(2)A gold nanoparticle-loaded porous magnetic nickel oxide nanosheet composite structure(Au/Ni O NSs)was prepared.Using the surface plasmon effect of gold nanoparticles(Au NPs)and the interaction between antigen and antibody,the magnetic separation and fluorescent labeling Combined,the rapid separation and detection of various pathogenic bacteria in complex samples is realized.First,porous magnetic nickel oxide nanosheets(Ni O NSs)were prepared by hydrothermal method and laser-assisted synthesis,and Au/Ni O NSs were prepared by photoreduction.Carboxyl groups and fluorescent ligands were used for surface modification,and NHS/EDC was used for antibody coupling,and finally functionalized FITC-Au/Ni O-Ab fluorescent probes were obtained.Bacteria were captured by functionalized probes,then enriched by magnetic separation,and the capture of bacteria was observed by confocal laser scanning microscopy(CLSM)imaging.The analytical method based on this functional probe can quickly separate and detect Staphylococcus aureus from mixed pathogenic bacteria within 0.5 hours,with a detection range of 2×10~9～2×10~2 cfu/m L and a detection limit of 200 cfu/m L,and demonstrated that this fluorescent probe has excellent selection specificity for Staphylococcus aureus in complex samples.This method has potential important value in the diagnosis of infectious diseases caused by pathogenic bacteria.