Detection Of Escherichia Coli Based On Polymerase Chain Reaction And Surface Enhanced Raman Spectroscopy

Surface-enhanced Raman spectroscopy(SERS)has high detection sensitivity and can obtain molecular structure information of substances.Raman spectroscopy can avoid the interference of spontaneous fluorescence of biological samples in water and realize rapid non-destructive detection.In addition,narrow spectral peaks are conducive to multi-component analysis.SERS has been used in biological analysis,environmental analysis,food analysis,chemical reaction monitoring and other fields.However,there are still some problems in DNA detection basing SERS technology,such as inability to distinguish different sequences,low signal intensity and need for labeling with probe molecules.The purpose of this paper is to specifically amplify the signal by polymerase chain reaction(PCR)and enhance Raman spectra by using the hot spot effect in the gap of gold nanoparticles,to obtain SERS signal amplified by a high level and to establish a quickly,accurately and label-free DNA detection.In the first part,the main methods of bacterial detection,the basic principles of SERS,and its advantages and basic methods in analysis and detection were briefly introduced.The typical applications of SERS in biological analysis,chemical reaction monitoring,environmental analysis and food analysis were summarized.The combined detection technology of PCR and SERS,and surface plasmon resonance(SPR)effect in SERS detection were reviewed,and the applications of SERS technology in bacterial detection were also discussed.Finally,the research objectives and design ideas of this paper were elaborated.In the second part,a method for detecting target DNA based on PCR and SERS was developed.This method combined the molecular recognition ability of SERS technology and the amplification characteristics of PCR for the target DNA and used the particularity of double helix structure of double stranded DNA to achieve completely label-free DNA quantitative detection.The experimental results show that this method can detect target DNA quickly,accurately,specifically and sensitively,and detect trace DNA in blood successfully.In the third part,we detected Escherichia coli in human blood based on PCR and SERS.The method features simple operation,high specificity,and low detection limit,and even single bacteria in blood samples could be successfully detected.In the fourth part,we summarized the method of label-free bacterial detection based on SERS combining with PCR and outlined the application prospect of this method.