Preparation Of SERS Active Substrate And Its Application In Simultaneous Detection Of Multiplex Nucleic Acids

Nucleic acids are important biomolecules,whose sequences’minor changes may result in disease.A disease may not only be associated with a single nucleic acid,therefore it is essential to accurately detect multiple nucleic acids simultaneously.Surface-enhanced Raman scattering(SERS)is a molecular spectroscopy technique,which can provide distinguishable Raman fingerprint peaks for multiplex analytes,hence it can be used to simultaneously detect multiple nucleic acids.It is well known that the SERS signal of the silver substrate is strong but unstable,however,gold-silver bimetallic nanoparticles can solve the above problem.The article mainly has the following two parts of research content.The first part is synthesizing two kinds of SERS active substrates:Au@Ag core-shell nanosnowman and plasma gold island substrate,referred to as Au@Ag nanosnowman and gold substrate.Au@Ag nanosnowman is synthesized by guiding Ag shell growth onto the Au nucleus by DNA,forming a uniform nanostructure similar to "snowman".Au@Ag nanosnowmen are separately modified three kinds of sulfhydryl Raman dyes(MPY,NBT,MBN)to prepare three SERS tags,which produce characteristic peak signals of 1004 cm-1,1335 cm-1 and 2226 cm-1,respectively.The gold substrate is synthesized by seed-guided method,whose surface has a large number of nano-structured gold islands,which generates strong SERS signal,and combines with the punched PDMS film to prepare reactors.In the second part,the two SERS substrates aforementioned are used for simultaneous detection of multiple nucleic acids.The prepared SERS tag and the gold substrate are separately modified by thiol DNA to form the signal probe and the capture probe,both of which are simultaneously detected three prostate cancer-related genes(miDNA-141,miDNA-21,miDNA-7d)by the sandwich hybridization strategy.The designed sensor has high sensitivity,whose limit of detection(LOD)is as low as 0.839 fM(3N/S).In addition,it has good specificity,which can distinguish between single base mismatch and double base mismatch.Furthermore it has strong anti-interference ability,which obtains good detection results in 20%human serum.