In situ quantitative mapping of coding single nucleotide polymorphism on mRNA inside cells by SERS-fluorescence dual-mode probe

Surface Enhanced Raman Scattering (SERS) has potential in nucleic acid detection, but its ability on single nucleotide polymorphisms (SNPs) detection in the early diagnosis of diseases is still limited. In fact, there is few research about in situ detection of coding SNPs which are carried on mRNA. In this paper, we developed SERSFluorescence Dual -mode probes to achieve in situ quantitative mapping of intracellular cSNP. The probes were based on Au@Ag core-shell structure that possessed both excellent biocompatibility and localized surface plasmon resonance. Fluorescence can provide a rapid visualization of intracellular cSNP, while SERS can achieve its in situ quantification. The quantitation was conducted by comparing the SERS signals of the reporting molecule p-mercaptobenzoic acid and fluorescent molecule FAM, the detecting limitation of which can be achieved as low as 1.4 fM. This ratiometric detection is more accurate than traditional analysis based on signal intensity directly. It successfully achieved intracellular imaging of the G12D mutation site of KRAS gene in A549 cells, which can help to get the distribution of cSNP in single cell more clearly. And it also demonstrated the good mapping ability for biomolecules (1003 cm -1 for phenylalanine) simultaneously. In conclusion, this kind of probe could be used as a potential tool to monitor cSNP as well as biomolecules in multiple biological processes, which could provide reference for disease prediction.