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

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.