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Abstract
Screen‐printed carbon electrodes (SPCEs) bearing a surface‐adsorbed antibody against aflatoxin B1 (AFB1) were used in a competitive immunoassay, based on competition of free analyte with a biotinylated aflatoxin B1 conjugate. Subsequent addition of streptavidin‐alkaline phosphatase (AP) conjugate, followed by a 1‐naphthyl phosphate substrate resulted in the production of the electrochemically active product, 1‐naphthol; this was oxidized using linear sweep voltammetry and constituted the measurement step. Investigations were carried out to test the suitability of reagents by enzyme‐linked immunoassay (ELISA) and to deduce the optimum blocking agent for the immunosensors. Using the electrochemical immunosensor, a calibration plot for AFB1 was obtained over the concentration range 0.15 to 2.5 ng/mL, giving a detection limit of around 0.15 ng/mL in buffer solution. The immunosensors were fabricated in an array configuration, suitable for use in conjunction with 96‐well microtiter plates; indeed, each step of the immunoassay was performed by dipping the electrodes into microwells. These results represent the initial studies towards the development of an automated instrument for multi‐analyte determinations using immunosensor arrays for mycotoxin detection and form the basis for further studies.
The authors wish to acknowledge the financial support of the Department for Environment, Food and Rural Affairs and the Home Grown Cereals Authority. This work was funded under the DEFRA Food Quality and Safety Link program FQS61—Rapid Analytical Systems for Raw Produce Quality and Safety Attributes: Phase 2 Mycotoxins. Nick Byrd (CCFRA) and Graham Johnson (Uniscan Instruments Ltd.) are thanked for their interest in the work and Mr. D. Corry (FAS) for photography.