Preparation Of Reactive Surface-enhanced Raman Substrate And Its Application In Drug Molecule/biomarker Analysis

Natural medicine molecules are endogenous active pharmaceutical ingredients extracted from natural plants,which have good biocompatibility,but poor water solubility,and are mostly fat-soluble.Biomarkers are a class of substances used to evaluate physiological and pathological processes,drug intervention responses,and the degree of damage to the body.They mainly include small molecules,DNA,RNA,enzymes,and proteins.Because these two types of substances are closely related to human survival and health,they have received close attention from the public and scientific workers,and the detection and evaluation of their content in a certain system has become a research focus.The standard methods used for small molecules of natural medicines are mostly chromatography or chromatographic chromatography;while for biomarkers due to their special biophysical and chemical properties,the standard methods used are mostly enzyme-linked immunoassay kits,PCR amplified genome sequencing,etc methods,but the pre-processing of these standard methods is complex and time-consuming.Surface-enhanced Raman spectra?SERS?technique has great application prospects in the detection of biological samples due to its advantages such as high sensitivity,high selectivity,and fastness.The commonly used SERS substrates,namely Au and Ag nanosols,are mostly synthesized by hydrothermal methods,which show hydrophilicity.Natural molecules with poor water solubility are difficult to approach hot spots on the surface of the substrate,resulting in poor enhancement effect.The markers,such as amino acids and enzymes,have a small Raman scattering cross-sectional area,making it difficult to measure their signals.In this paper,the functional modification of surface of SERS substrate is performed to introduce surface reactions or surface interaction forces with targer speies.Capturing small drug molecules by surface forces and fixing them into hot spots region on the substrate surface could enhance the Raman signal and the Raman signal changes can be transformed through the probe interacting with the modification layer after specific physicochemical and biochemical reactions of biomarkers on the substrate surface.Such reaction-based SERS strategy can be used to quickly and directly detect the target.The main research contents are stated as follows:1.Due to the poor water solubility of aristolochic acid I,its SERS signal on the surface of Ag nanoparticles is very weak.According to the reslut of molecular docking,it is found that there is a very strong hydrogen bonding force between bovine serum albumin?BSA?and aristolochic acid I.In this work,Ag@BSA core-shell nanoparticles were synthesized,and the non-covalent bond between bovine serum albumin and aristolochic acid I was used to capture and fix the target to the hot spot area on the SERS substrate to achieve the fast and sensitive detection of aristolochic acid I.2.Intracellular glutathione?GSH?levels are closely related to various diseases.There are many reports that compared with normal cells,the levels of glutathione in cancer cells show a high expression trend.Because GSH's own Raman scattering cross section is small,direct SERS detection of GSH is not sensitive.Au@MnO₂ nanoparticles were synthesized,and the modified ultra-thin manganese dioxide shell has both specific recognition of glutathione and signal conversion.SERS sensors based on Au@MnO₂-TMB can be specific for sensitive detection on glutathione and fast and reliable assessment of intracellular glutathione levels.3.Polynucleotide kinase?PNK?can catalyze the?-phosphate transfer of ATP to the 5'-phosphate end of DNA or RNA,that is,the phosphorylation of DNA end.This response is of great significance in nucleic acid metabolism,DNA damage repair,DNA replication and recombination.Au@Ag@MnO₂ nanoparticles were synthesized.The modified ultra-thin manganese dioxide nanosheet have graphene-like properties—adsorbing single-stranded DNA through the phosphate backbone,and desorping double-stranded DNA.After the specific reaction of the polynucleotide kinase,the introduction of another exonuclease?exo can specifically cleave phosphorylated double-stranded DNA from 5'to 3'to release single-stranded DNA,thereby achieving signal conversion.The SERS method can perform sensitive and specific detection of T4 PNK,and can be used for screening PNK inhibitors.