Integration of highly ordered plasmonic nanocavity array structure with the electrostatic driving force for dynamic control of SERS signals and label-free detection of λ-DNA

With the rapid development of nanoscience and nanotechnology, surface-enhanced Raman spectroscopy (SERS) is widely used for the detection of analyte molecules and biomolecules in liquids. However, due to the plasmonic near-field effect, the key challenge of SERS detection in liquids is to attract target molecules in solutions into the plasmonic "hot spots". In this work, the SERS-active substrates (Ag@AAO) with excellent signal sensitivity and uniformity were successfully prepared by sputtering Ag films on anodized aluminum oxide (AAO) templates. Subsequently, integrating the substrate into a liquid chamber, the movement of target molecules in the liquid was effectively controlled by the electrostatic driving force, and the enrichment, separation and detection of R6 G molecules on the plasmonic "hot spots" were realized in a single device. The integrated system can dynamically control the SERS signal of low-concentration R6 G solution (10^-10 M and 10^-11 M). Moreover, the label-free direct detection capability of the integrated system for 30 ng/µL λ-DNA (dsDNA) is expected to greatly expand the application potential of SERS technology in biomolecular sensing and genetic engineering.