Electrochemical detection of aflatoxins using a ZnO nanowire-modified biosensor with a droplet-based approach

Abstract

Aflatoxin contamination poses significant health risks and food safety concerns, and necessitates the development of rapid, sensitive, and cost-effective detection methods. This study reports the development of a portable, cost-effective electrochemical biosensor using zinc oxide (ZnO) nanowires synthesized via the Horizontal Vapor Phase Crystal (HVPC) growth technique for the detection of multiple aflatoxin types. The sensor integrates a droplet-based cyclic voltammetry (CV) system with a ZnO-modified working electrode on a disposable printed chip. Morphological and elemental characterization confirmed the formation of high-purity ZnO nanowires with diameters predominantly below 100 nm. The sensor exhibited a wide and stable potential window (–0.48 V to +2.00 V), hydrophobic surface properties, and Ohmic electrical behavior. Electrochemical measurements revealed four distinct redox peaks, corresponding likely to the mixed standard of AFB1, AFB2, AFG1, and AFG2, with anodic and cathodic responses increasing linearly across the 5 % to 50 % aflatoxin dilution range, which is approximately from 5ppb to 50ppb. The calibration curves yielded high linearity (R² > 0.97), and the calculated limits of detection ranged from 4.35 to 15 ppb—below the FDA’s 20 ppb regulatory threshold. With a rapid response time (∼57 s) and minimal sample volume (10 μL), this sensor offers a practical alternative to traditional chromatographic or spectroscopic methods. Although this study was limited to standard solutions, the findings demonstrate strong potential for real-time aflatoxin monitoring in food and agricultural settings, particularly in resource-limited environments.