Evaluation of natural polymers with permselective properties aiming at the development of biosensors for the detection of mycotoxins in food

Abstract

A biosensor combines the specificity of a biological component with the sensitivity of an electrochemical transductor. The variable inhibition showed by aflatoxin and other mycotoxins towards acetyl choline esterase (AChE) can be exploited in a multi-enzyme biosensor design: the more AChE is inhibited by mycotoxins, the less choline is oxidized by choline oxidase (ChO) to betaine aldehyde and H2O2. Hence, the H2O2 oxidation signal is influenced by the presence of mycotoxin. In the present study, AChE and ChO were co-immobilized onto a Pt/Ir electrode surface coated with different electrosynthesized polymers. In order to prevent signal of interferents, ortho-phenylendiamine (oPD) is currently utilized. Quite regrettably, this compound is highly carginogenic and alternative, non toxic, polymerizing compounds would be highly desirable. We have tested different permselective films generated by non-toxic natural monomers belonging to phenylpropanoids and C2-symmetric dimers. The compounds were electropolymerized by constant potential amperometry (CPA) and by cyclic voltammetry (CV) and characterized by scanning electron microscopy (SEM) and permselectivity analysis. Differences in permselectivity towards H2O2 over ascorbic acid and dopamine were detected in poly-monomers and poly-C2-dimers. The presence of a 2-propenyl chain in the phenol ring seems to enhance permeselectivity and electrocoating quality. A bi-enzyme sensor with AChE/ChO coated with these natural compounds may therefore represent a promising analytical device for mycotoxin detection in agricultural and food matrices. *The first two authors have equally contributed to the present work.