Portable electrochemical biosensing platform for rapid, on-site detection of zearalenone mycotoxin in grain corn and animal feed

Abstract

Zearalenone (ZEA) is a heat-stable estrogenic mycotoxin produced by Fusarium species that frequently contaminates cereal grains and animal feed, posing severe threats to food safety, livestock health, and agricultural economies. While laboratory-based detection methods are highly accurate, they are often time-consuming and unsuitable for the real-time, on-site applications required by smart agricultural systems. Here, we present a portable electrochemical biosensing platform designed for rapid, decentralized ZEA quantification in raw grain corn and processed poultry feed. Screen-printed carbon electrodes (SPCEs) were functionalized with a conductive polyaniline/gold nanoparticle (PANi/AuNP) nanocomposite, providing a high-surface-area matrix for stable anti-ZEA polyclonal antibody immobilization and accelerated electron transfer. Using differential pulse voltammetry (DPV) with an optimized 1:5 matrix-to-buffer dilution ratio to minimize matrix effects, the platform achieved a linear detection range of 0-200 µg/kg (ppb) with limits of detection (LOD) of 36.88 ppb in buffer and 57.66 ppb in matrix, aligning with international regulatory thresholds. The biosensor demonstrated high analytical accuracy with spiked recoveries between 80.19% and 93.92%, while functionalized SPCE strips maintained robust storage stability at room temperature for 14 days. The sensor strips were coupled with the handheld MARDIsense reader and a smartphone application for automated data processing and real-time cloud logging. Validation across 52 real-world agricultural samples (n=37 raw grains; n=15 feed/kernel matrices) demonstrated 100% categorical agreement and strong quantitative correlation (r=0.931, p<0.001) relative to reference ELISA. Crucially, epidemiological profiling revealed low contamination in pre-harvest field grains (94.6% <50 ppb) contrasting with severe contamination in processed poultry feed (50% > 100 ppb). This highlights the platform's vital utility for prioritizing post-harvest feed mill surveillance to safeguard the food supply chain.