Ag nanopines over Al nanoneedle arrays enable high SERS sensitivity and reproducibility for molecular sensing

Abstract

In this study, highly uniform 3D Al nanoneedle arrays (AlNNAs) decorated with Ag nanopines are synthesized by anodization of Al foil with prior nanoimprinting and subsequent electrodeposition method, demonstrating remarkable surface-enhanced Raman scattering (SERS) property. The AlNNAs possess a highly ordered periodicity of 1 μm and nanoneedle height of 800 nm, making it an optimal supporting matrix to host Ag-NPs as SERS substrate. Such well-ordered Ag@AlNNAs SERS substrate with precisely electrodeposited Ag nanopines generate high density SERS host spots and abundant sites to adsorb target molecules. As a result, Ag@AlNNAs exhibit high sensitivity for rhodamine 6 G down to 10–13 M and good signal reproducibility with a relative standard deviation of 7.2 %, as well as an average enhancement factor of 4.23 × 109. For practical detection of pollutants, 10–8 M adenine, 10–12 M bisphenol in water, and melamine (10–7 M) in opaque milk are clearly identified by using the Ag@AlNNAs sensor. This study opens a bright way to fabricate SERS substrate with a good balance of sensitivity, reproducibility and cost, indicating promising potential for environmental monitoring and food safety.