Application And Analysis Based On SERS Amplification Characteristic Of Nanosilver-Biotin-Streptavidin Aggregates

In recent decades,due to the pollution of the living environment and the accelerated pace of life,the number of cancer patients has increased dramatically.However,if it can be detected and treated in the early stages of cancer,more than 80% of patients can be cured.Therefore,it is of great significance to study the early detection and diagnosis of tumors.The importance of microRNA(miRNA)disorders for disease progression and progression of disease,as well as the discovery of stable miRNAs in peripheral blood,make these short-sequence nucleic acids next generation biomarkers of the diseases for the diagnosis,treatment and prognosis.At the same time,some highly sensitive,safe and highly specific miRNA tumor marker detection technologies have been developed.Among them,the miRNA tumor marker detection protocol based on Surface-Enhanced Raman Scattering(SERS)technology has attracted more and more researchers’ attention because of its high detection sensitivity,good specificity and wide detection range.At present,how to further improve the sensitivity is still one of the main hotspots in the research of SERS marker detection.Therefore,designing a new sensitivity-enhanced SERS labeled detection protocol is of great significance for the SERS technology in early detection and diagnosis of tumors.This work,based on the "sandwich" type SERS structure,aims to further improve the detection sensitivity of miRNA tumor markers,according to the biological characteristics of the biotinStreptavidin(B-S)system,grafting the B-S system on the SERS sandwich structure achieved cascade amplification of the SERS signal,and highly sensitive detection of the specific tumor marker miRNA-21 associated with small cell lung cancer and mir-106 a associated with renal cancer.1.Detection of miRNA-21 and analysis based on SERS amplification characteristics of nanosilver-biotin-streptavidin aggregatesFirst,a 100 nm of silver film was deposited on the surface of the silicon wafer by electron beam physical vapor deposition(EBPVD)system,then the captured DNA was fixed thereon as substrate.Next,the probe was prepared by linking the prepared silver nanoparticles linked with 4-mercaptobenzoic acid(4MBA)molecule to the probe DNA modified with amino and biotin.Then,the sandwich structure of the substrate-target-probe was constructed by hybridization chain reaction for Raman detection.Finally,by adding streptavidin and a probe to the prepared sandwich structure to form a probe aggregate,then the amplification of the detection signal is achieved,and thedetection sensitivity was thereby further improved.The experimental results show that the detection limit(LOD)of this experiment is improved by 3 orders of magnitude to 38.02 fM through the multistage amplification of B-S system,and shows good specificity and reliability.2.Detection of mir-106 a and analysis based on dual SERS amplification characteristics of SiC@Ag substrate and silver-biotin-streptavidin nanoaggregatesSimilar to the above,a 100 nm thick silver film was deposited on the surface of the silicon carbide sandpaper by EBPVD technology,and the capture DNA was fixed on the surface of the silver film as a substrate,and the sandwich structure of the substrate-target molecule-probe was constructed for SERS detection.The primary signal amplification of the BS system has a detection limit of 0.60 fM,which also shows good specificity and reliability.It can be seen from the above that the combination of B-S system amplification technology and SERS-based detection technology has important reference value for obtaining highly sensitive tumor marker detection..