Construction Of SERS Probe And Its Application In Bacterial Detection And Antibacterial Performance

It is well known that the rapid detection of bacteria and antimicrobial activity studies are both crucial for food safety,environmental monitoring and human health.Surface enhanced Raman spectroscopy?SERS?sensor has been highly concerned in the field of biological analysis for theadvant ages of high sensitivity,good optical stability,fast detection speed,wide detection range and high-resolution"fingerprint"information of biological samples.On the other hand,there are many kinds of multifunctional nanoprobes which have been applied on the antibacterial research.In this study,we established gold and silver core-shell nanoparticles?Au@Ag NPs?SERS probe for bacteria detection and antibacterial research.The concrete content are as follows:?1?The hydrophobic SERS substrate based on Au@Ag NPs was used for bacterial detection:using Au@Ag NPs with silver shell thickness of 7nm as SERS probe and Trichlorodecylsilane?TDS?modified glass slide as hydrophobic substrate,the hydrophobic SERS substrate based on Au@Ag NPs was constructed by self-assembly of nanoparticles;different bacteria have different Raman fingerprint peaks.Based on this,when the concentrations of Escherichia coli?E.coli?,Staphylococcus aureus?S.aureus?and Pseudomonas aeruginosa?P.aeruginosa?are in the range of 1×10⁵CFU/m L to 1×10⁸CFU/m L,it shows a certain linear relationship between the corresponding SERS intensity and the logarithmic concentration of bacteria with the minimum detection concentration of bacteria is 10³CFU/m L;on the basis,three kinds of bacteria above mentioned can be effectively distinguish by SERS data combined with discriminant analysis.?2?Study on the etching of Au@Ag NPs and its antibacterial activity:Au@Ag NPs with excellent SERS performance was used in antibacterial research of bacteria.To achieve the antimicrobial effect,we used potassium ferricyanide?K₃[Fe?CN?₆]?as silver etching agent,then oxide etched the silver shell of Au@Ag NPs and released Ag⁺.On the basis of that,a nanometer probe which combines bacterial detection and antibacterial effects was constructed.The result showed that the Ag⁺generated by Au@Ag NPs etching has a broad-spectrum antibacterial effect,and the minimum inhibitory concentration?MIC?of gram-negative bacteria?E.coil and P.aeruginosa?was 1.43?mol/L,while the MIC was 2.86?mol/L for S.aureus.Under the same conditions,the minimum bacteriostatic concentration of single tetracycline molecule on E.coil was 4.50?mol/L,and that of S.aureus was 2.81?mol/L.Through these comparisons,it is indicated that Au@Ag NPs has better antibacterial properties after etching silver shell.