An electrochemiluminescence biosensor for the screening of environmental estrogens using a peptide probe targeting...

Screening of environmental estrogens (EE) is important for ecological safety and public health. Biosensors provide a new tool for rapidly screening EEs over animal tests and cell assays. Mimicking the molecular interactions of the estrogen receptor (ER) pathway in cells, an electrochemiluminescence (ECL) biosensor for EE screening was designed by using the activated ER as the biomarker of estrogenic activity and a peptide probe to recognize the activated ER. A peptide derived from the ER co-activator was first immobilized on a gold electrode surface. In the presence of an estrogenic chemical, ER (with His tag) was activated and induced to an active conformation, which was subsequently captured by the peptide. ECL labelling of the ER was achieved after the addition of Ru(bpy)₃²⁺ labeled anti-His tag antibody. The ECL response of estradiol displayed a sigmoidal-shaped curve, with an EC₅₀ of 15.1 nM and a detection limit of 4.6 nM, whereas tamoxifen did not show any response. Estrogenic activity of six perfluoroalkyl substances (an important class of environmental contaminants), including perfluorooctane sulfonamide (PFOSA), perfluorooctane sulfonic acid (PFOS), perfluorohexane sulfonic acid (PFHxS), perfluorooctanoic acid (PFOA), perfluorononanoic acid (PFNA), and perfluorodecanoic acid (PFDA), was evaluated by the biosensor. The order of activity was found to be PFOSA > PFOS > PFHxS > PFDA > PFOA > PFNA, which correlated closely with the results of cell assays. Recovery rate of PFOSA, PFOS, and PFHxS spiked in river water was 99.00 %, 97.49 %, and 97.28 %, respectively, demonstrating high reliability. The biosensor is faster, easier to perform, and more robust than conventional toxicity testing methods, providing a new approach for screening EEs.