In-Situ Immobilization of Silver Nanoparticles on Self-Assembled Honeycomb-Patterned Films Enables Surface-Enhanced Raman Scattering (SERS) Substrates

摘要

Surface-enhanced Raman scattering (SERS) is an important sustainable technique because of its ability to detect trace-level analytes including pesticides, heavy metals, explosives, proteins, pathogens, and other chemical and biological contaminants. In this paper, we report a facile approach to highly sensitive SERS substrates by combining hierarchically patterned micro- and nanostructures with silver nanoparticles (Ag NPs) adsorbed on poly(N,N-dimethylami- noethyl methacrylate) (PDMAEMA) surface. The patterned structures were fabricated using breath figures as dynamic templates in which polar block enriches at the rim of the pores. This characteristic of the breath figure method makes it possible to employ a simple coating technique to construct substrates decorated with Ag NPs, which have a diameter mostly ranging from 18 to 30 nm. Results indicate that the hierarchically ordered substrates show enhancement factors as high as 4 × 10~8. It is also found that the enhancement factors are concentration-dependent, relying on the ratio of the number of analytes to Ag NPs. Moreover, the prominent enhancement at Raman shift of ～614 cm~(-1) has been observed, which will be useful in the detection of analytes such as some kinds of pesticides and viruses with characteristic peaks in this Raman shift range (e.g., adenovirus). This proposed approach provides an effective, reproducible, electroless, and facile method for preparing high-quality SERS substrates.