Beta‐lactoglobulin Electrochemical Detection Based with an Innovative Platform Based on Composite Polymer

Abstract In this work, we present a new electrochemical disposable platform based on poly(aniline‐ co ‐anthranilic acid) (PANI/PAA) composite polymer coupled with an aptamer for sensitive detection of β ‐lactoglobulin. Firstly, PANI/PAA film was electrodeposited on the graphite screen‐printed electrode surface by cyclic voltammetry. The co‐polymer modified electrode was then employed as platform for the covalent immobilization of an amino‐modified aptamer. Various β ‐lactoglobulin solutions, with a fixed amount of biotinylated oligonucleotide complementary sequence, were dropped onto the aptasensor surface. A streptavidin‐alkaline phosphatase conjugate was then employed to trace the affinity reaction. After the addition of 1‐naphthyl‐phosphate enzymatic substrate, 1‐naphthol electroactive product was detected by differential pulse voltammetry. A decrease in the signal was obtained when the target concentration was increased, in according to a signal‐off approach. After optimization of key experimental parameters, a dose‐response curve was obtained between 0.01–1.0 μg mL −1 β ‐lactoglobulin concentration range. The limit of detection of 0.053 μg L −1 was obtained. Milk samples spiked with β ‐lactoglobulin were analyzed.