Study On Phosphopeptide And Mercury Ions By Surface-enhanced Raman Spectroscopy

Surface-enhanced Raman scattering?SERS?has attracted widespread attention in the fields of physical chemistry,analytical chemistry and biomedicine.In addition,it has the potential of single-molecule detection,which has a wide development space in the detection of ultra-sensitive biological molecules.This paper studied from the perspectives of organic biochemical molecules and inorganic ions.Taking phosphorylated peptides and mercury ions(Hg²⁺)as the research object,and using SERS technology as the detection method,label-free SERS detection was applied to the phosphorylated peptides closely related to cancer.Different probe molecules were constructed based on different principles to detect the phosphorylated tyrosine of the breast cancer marker epidermal growth factor receptor?EGFR?and inorganic Hg²⁺ions,respectively.This paper attempted to explore a method with high sensitivity,high accuracy and high specificity by studying the construction of SERS spectrum probes from both organic and inorganic aspects.The main research contents are as follows:1.Dynamic surface enhanced Raman spectroscopy?D-SERS?was obtained by using dynamic SERS detection technology with silver film or hydrophobic silver film as the enhanced substrate and mixing according to the ratio of tyrosine dipeptide:silver nanocolloid:magnesium sulfate solution=1:8:2.The best detection time point for detecting phosphorylated tyrosine dipeptide?PY-Y?can be obtained by analyzing the D-SERS spectra detected by PY-Y and non-phosphorylated tyrosine dipeptide?Y-Y?.And through the hydrophobic modification of the silver film,the phenomenon that the SERS peak of PY-Y was formed into a single band at 825cm^-1was more obvious,and the SERS signals were significantly enhanced.2.Based on the principle of antigen-antibody specific recognition,a"sandwich"structure of SERS probe was constructed,and the phosphorylated tyrosine of the breast cancer marker epidermal growth factor receptor?EGFR?was detected by using the synthesized gold-silver core-shell nanostructure colloid.A high-accuracy,high-specificity SERS assay for phosphorylation of tyrosine was achieved with a the limit of detection?LOD?of 0.02435?g/L.Using 4-mercaptobenzonitrile?4-MB?as internal standard molecule,the spectra of 4-mercaptobenzoic acid?4-MBA?were normalized by the peak intensity of 4-MB at the Raman peak of 2221cm^-11 in the bio-silence region.The linear relationship between concentration of phosphorylated tyrosine and SERS intensity was improved,and the correlation coefficient?R²?was increased from 0.8490 to 0.990.3.Based on the principle that Hg²⁺ions can specifically form a strong and stable thymine-Hg²⁺-thymine complex(T-Hg²⁺-T)with thymine?T?,using single-stranded DNA as a signal"switch",probe molecule was developed for the specific detection of Hg²⁺in the sample.The uniform and dense silver film substrate was synthesized by a simple and repeatable silver mirror reaction method to achieve high sensitivity and high specificity SERS detection of Hg²⁺ions.A limit of detection?LOD?of Hg²⁺ions by this sensor was1.35×10^-15M.