A Poly Adenine-Mediated Assembly Strategy for Designing Surface-Enhanced Resonance Raman Scattering Substrates in Controllable Manners

In this article, we introduce a Poly adenine (Poly A)-assisted fabrication method for rationally designing surface-enhanced resonance Raman scattering (SERRS) substrates in controllable and reliable manners, enabling construction of core satellite SERRS assemblies in both aqueous and solid phase (e.g., symmetric core (Au)-satellite (Au) nanoassemblies (Au-Au NPs), and asymmetric Ag-Au NPs-decorated silicon wafers (Ag-Au NPs@Si)). Of particular significance, assembly density is able to be controlled by varying the length of the Poly A block (e.g., 10, 30, and SO consecutive adenines at the S' end of DNA sequence, Poly A10/A30/A50), producing the asymmetric core satellite nanoassemblies with adjustable surface density of Au NPs assembly on core NPs surface. Based on quantitative interrogation of the relationship between SERRS performance and assemble density, the Ag-Au NPs@Si featuring the strongest SERRS enhancement factor (EF approximate to 10(7)) and excellent reproducibility can be achieved under optimal conditions. We further employ the resultant Ag Au NPs@Si as a high-performance SERRS sensing platform for the selective and sensitive detection of mercury ions (Hg2+) in a real system, with a low detection limit of 100 fM, which is similar to 5 orders of magnitude lower than the United States Environmental Protection Agency (USEPA)-defined limit (10 nM) in drinkable water. These results suggest the Poly A-mediated assembly method as new and powerful tools for designing high-performance SERRS substrates with controllable structures, facilitating improvement of sensitivity, reliability, and reproducibility of SERRS signals.