Study On Rapid Visual Analysis And Detection Of Pathogenic Staphylococcus Aureus And Disease Markers

Pathogenic microorganisms and cancer have the significant impact on human health.It is significant to study and design a series of experimental methods to detect them.Gold nanorods,gold nanorod composite nanomaterials and gold nanoparticles have good optical and chemical properties,and its surface is easy to be modified.It can be used as a research basis for many microorganisms and disease markers detecting.Based on the local surface plasmon resonance property?LSPR?of gold nanorods and the peroxidase-like activity of nanoparticles,a highly sensitive visual detection method was constructed,and the experimental conditions were further optimized to achieve the detection of staphylococcus aureus,intestine,toxin B,prostate specific antigen,glucose,insulin.The main tasks as follows:?1?The fluorescent eggshell membrane gold nanoclusters?AuNCs-ESM?were prepared by a simple and low-cost method using eggshell membrane as template.The glutathione?GSH?can regulate the peroxidase mimetic activity of AuNCs-ESM based on the quenching effect of sulfhydryl compounds on the fluorescence intensity of AuNCs-ESM.The catalytic activity of the mimetic enzyme can also be regulated by the immune reaction,and the target molecule can be used to adjust the catalytic site of the peroxidase-like activity.Based on this,a method for detecting enterotoxin B?SEB?was established.The detection range of the method is 0.4-20 ng/mL,and the detection limit is 0.12 ng/mL.The method was applied to the determination of enterotoxin B in actual samples?flour,corn,rice?,and the spiked recoveries were all within the normal range,indicating that the method is highly sensitive and accurate for the detection of enterotoxin B.Moreover,the staphylococcus aureus was adsorbed to the surface of the eggshell membrane based on the adsorption of eggshell membrane on bacteria,and the Staphylococcus aureus DNA aptamer based on the modified gold nanoclusters can specifically bind to Staphylococcus aureus.Through the color reaction of gold particles,qualitative detection of Staphylococcus aureus was achieved.?2?Based on the surface plasmon resonance properties of gold nanorods,a biosensor for the detection of PSA by gold nanorod composite nanomaterials was prepared.The surface complex plasmon resonance of gold nanorods is used to enhance the peroxidase-like activity of gold nanorod composite nanomaterials,and the purpose of rapid colorimetric detection of PSA is achieved.The sensor also detects the PSA in the actual sample,and the results are basically consistent with the results of the hospital reference value,which has strong practicability and provides a great platform for the detection of tumor biomarkers.?3?Based on the characteristics of the controllable and easy-modification of gold nanorods,a copper-based nanorod complex peroxidase-like activity was obtained,and a biosensor was established to detect glucose,insulin,and combined detection of serum.A method of glucose to insulin concentration ratio.On the one hand,under the action of glucose oxidase,glucose produces hydrogen peroxide?H₂O₂?,which is catalytically decomposed by peroxidase-like activity to produce hydroxyl radicals,thereby oxidizing the chromogenic substrate 3'-3'-5'-5'-Tetramethylbenzidine?TMB?changes the color of the solution to achieve the purpose of detecting glucose.The detection limit of glucose is 2.5×10^-6mol/L.On the other hand,the copper-containing nanorod complex is linked to an insulin aptamer modified with a thiol group,and is bound to insulin by antigen-antibody specific binding,and the insulin is further detected according to the target molecule?insulin?regulating peroxidase-like activity.The detection limit of insulin was 0.014?U/mL.The sensor was applied to the determination of glucose and insulin in serum.The results were in good agreement with the results of hospital standard methods,indicating the feasibility of the method.The sensor can also jointly detect glucose and insulin in serum.By measuring the concentration ratio of the two,it can distinguish between type 1 and type 2 diabetes,so as to better monitor the two substances in the treatment of diabetics in real time.The content and variation indicate that the analysis of actual samples based on copper-containing nanorod composites has the potential to be simple,economical,and accurate,and has certain potential value for the treatment of diabetes.