Ultrasensitive SERS-immunochromatographic assay for pesticide detection using core–shell Au@Au nanoparticles: a 103-fold sensitivity boost over LFA

Abstract

This study presents a novel immunochromatographic assay (ICA) leveraging surface-enhanced Raman scattering (SERS) for ultrasensitive pesticide detection. The proposed method utilizes core–shell structured gold nanoparticles (Au@Au NPs) functionalized with antibodies as the SERS substrate, coupled with Raman reporter molecules (MPBN) to generate a robust spectroscopic signal. By exploiting the immunorecognition between target antigens and immobilized antibodies, Raman-tagged Au@Au NPs are captured on the ICA test line, enabling quantitative analysis of lambda-cyhalothrin, and the minimum detection limit in actual samples (green peppers) reached 1.33 ppb. Comparative studies demonstrated that the SERS-ICA method achieved a 10³-fold increase in sensitivity compared to the conventional LFA. Validation in complex matrices (grapes, eggplants, and green peppers) yielded recoveries of 92.85–118.25% and relative standard deviations (RSD) of 4.02–16.17%, confirming the method's exceptional specificity, accuracy, and applicability in real-world scenarios. This platform holds significant promise for rapid, on-site monitoring of trace contaminants in food safety and environmental surveillance.