Au@Pt NCs nanozyme-based multichannel sensor array coupled with smartphone for selective identification and on-site detection of imidacloprid.

Abstract

As a widely applied neonicotinoid insecticide, imidacloprid (IMI) necessitates portable residue monitoring to ensure food safety. Herein, a multichannel colorimetric sensor array was developed for selective IMI identification and quantification, employing Au@Pt nanoclusters (Au@Pt NCs) as the sole nanozyme sensing receptor. Rather than introducing multiple sensing materials, the proposed strategy extracts three characteristic absorption responses at 370, 450, and 652 nm from a single Au@Pt NCs-catalyzed TMB-H₂O₂ reaction to generate multidimensional cross-reactive fingerprints. The Au@Pt NCs provided sufficient peroxidase-like catalytic activity for signal generation, enabling five representative pesticides, including IMI and its structural analogues, to be successfully discriminated. Linear discriminant analysis achieved 100% classification accuracy as confirmed by cross-validation, while hierarchical cluster analysis further demonstrated clear clustering among the different pesticide groups. Moreover, capitalizing on the pronounced inhibitory effect of IMI on the nanozyme catalytic activity, a dual-mode detection platform integrating colorimetry with smartphone-based readout was established for IMI quantification. Under optimized experimental parameters, the limits of detection were 0.112 µg/L for the colorimetric mode and 1.236 µg/L for the smartphone-assisted approach. By converting the Au@Pt NCs mediated catalytic reaction into multidimensional analytical information, this work provides an affordable, portable, and practical strategy for pesticide discrimination and on-site IMI monitoring.