Highly sensitive and label free on-site monitoring immunosensor for detection of Aflatoxin B₁ from real samples

Aflatoxin B₁ (AF-B₁) are toxins secreted by secondary metabolites of molds that have adverse effects on humans and animals resulting in huge economic losses. Here we report on field useable, cost effective and direct electrochemical sensor based on conducting polymer composite electrode, Poly (3,4-ethylenedioxythiophene): polystyrene sulphonic acid (PEDOT-PSS) for label-free detection of AF-B₁. Structural and morphological characterization of composite electrodes were carried out using XRD and SEM. We compared two different electroanalytical techniques namely, transient capacitance and differential pulse voltammetry, to select the most prominent technique for analyzing the mycotoxin easily. For direct detection of AF-B₁, transient capacitance measurement at 77 and 1000 Hz was employed wherein sensor showed linearity in 18.18-300.0 ng mL^-1 range at 77 Hz for AF-B₁. Best limit of detection (LOD) for AF-B₁ was 55.41 ng mL^-1 (369 pM) at 77 Hz with very good repeatability. DPV showed linearity in the range 18.18-342.85 ng mL^-1 with LOD 435 pM. For demonstration of application of this sensor directly using minimum sample preparation, AF-B₁ sensing has been confirmed successfully using white button mushrooms and okra stored at ambient conditions. Sensor response with real samples suggest usefulness of sensor to monitor stored farm products easily.