Poly Adenine-mediated Controllable Silicon-based Sers Sensor And Application Of Mercury Ions Detection

Gold and silver nanoparticles(NPs) are widely recognized as well-established surface-enhanced Raman scattering(SERS) substrates. Many studies have revealed that multiple hot spots of Au/Ag-based SERS substrates could largely contribute enhancement factor(EF). In addition, efficiently coupled hot spots are considered as another significant contributor to the EF, which could be readily obtained via controlling the inter-particle distance. Accord ingly, several strategies have been developed to produce Au/Ag assembly with strong plasmonic coupling of enormous hot spots. New strategies are still in high demand for rationally designing Au/Ag assembly SERS substrates in controllable and reproducible manners. In this article, we presented the Poly A- mediated strategy as high-efficacy means for constructing Au/Ag assembly substrates in controllable and reliable manners. As proof-of-concept applications, the resultant Ag-AuNPs@Si was further employed for selec tive, sensitive, and reliable detection.We presented the Poly A- mediated strategy as high-efficacy means for constructing Au/Ag assembly surface-enhanced Raman scattering(SERS) substrates in controllable and reliable manners, i.e., symmetric core(Au)-satellite(Au) nanoassemblies(Au-AuNPs) in aqueous phase, and asymmetric Ag-AuNPs-decorated silicon wafers(Ag-AuNPs@Si) in solid phase. Of particular significance, AuNPs can be readily assembled with AgNPs with controllable assembling density, and Au/Ag assembly with tunable inter-particle gaps can be readily regulated through simply varying the length of Poly A, fabricating controllable SERS substrates with high selectivity and reproducibility. As proof-of-concept applications, the resultant Ag-AuNPs@Si featuring superior SERS enhancement factor and better reproducibility was further employed for selective, sensitive, and reliable detection of mercury ions(Hg2+) in real water, with a low detection limit, which was significantly lower than the detection range of established inductively coupled plasma atomic emission spectroscopy(ICP-AES), and comparable to the best or smallest value ever reported for a SERS method.These expetimental results suggest the Poly A- mediated assembly method as a kind of new and powerful tool for designing high-performance SERS substrates in controllable and reliable manners, facilitating improvement of sensitivity, reliability, and reproducibility of SERS signals, which would be helpful for both SERS-based basic studies and practical applications, including food security, disease diagnosis as well as environment monitoring and so forth.