3D plasmonic SERS aptasensor for rapid detection of aflatoxin B1 combined with Au@Ag bimetallic nanostars and Fe3O4@MoS2 magnetic nanoflowers

As a virulent metabolite, aflatoxin B1 (AFB1) presented in various cereal grain is tightly implicated in severe human diseases. In this study, 3D plasmonic nanohybirds of Raman molecule 4-mercaptobenzoic acid (4-MBA) embedded and AFB1 aptamer-modified bimetallic nanostars as SERS probes bound to magnetic nanoflowers were fabricated and demonstrated as a high-performance SERS-active aptasensor to quantitatively analyze AFB1. Bimetallic Au@Ag SERS plasmonic nanoprobes with enhanced properties were capable of enhancing discriminative Raman peaks of 4-MBA. Then, the integration of iron tetroxide nanoparticles (Fe3O4 NPs) and molybdenum disulfide nanosheets (MoS2 NShs) with huge specific surface area constituted stable 3D Fe3O4@MoS2 plasmonic nanoflowers, facilitating the bind of numerous aptamer-based SERS probes via the non-covalent interaction between MoS2 NShs and aptamer, which were ideal candidates for SERS-active substrates. Additionally, Fe3O4 NPs as magnetic core endowed 3D nanocomposites with specific magnetic separation characteristic that caused the collected SERS hotspots to exhibit superior signal response, and further strengthening the sensitivity in a complex food matrix. Aptamer-target AFB1 specific recognition triggered linearly diminished 4 MBA signal intensity (I4-MBA) on the substrate to achieve a low detection limit of 58.9 pg/mL. Furthermore, the sensor has the potential to be a promising monitoring tool for other trace contaminants.