Group detection of phthalates from mulches: Two competitive aptamer-based electrochemical approaches

Phthalates, known as endocrine disruptors, are often contained in plastic-based materials and may enter food webs, threatening human health. In this study, an oligonucleotide-based competitive assay for phthalates detection was built on an electrochemical platform, based on poly(l-glutamic acid) and gold nanoparticles. Different assay formats were tested for achieving a fast and sensitive phthalates determination: specifically, the aptameric DNA sequence was immobilized, and a competition between the analytes and a complementary biotinylated DNA probe was carried out; a similar competition was also established between an immobilized probe and the aptamer in solution. In both cases, the biotinylated hybrids are coupled with a streptavidin-alkaline phosphatase conjugate, which catalyzes the hydrolysis of 1-naphthyl phosphate enzymatic substrate, and the electroactive product 1-naphthol was detected by differential pulse voltammetry. The developed biosensors were successfully applied to detect phthalates in soil and strawberries extracts, thus proving their suitability for both environmental and food analysis.