The E-screen assay is the gold standard method to screen for xenoestrogens. The method is based on the binding of estrogenic compounds to the human estrogen receptor of MCF-7 cells, resulting in increased cell proliferation. The conventional method is easy to perform but involves multiple manual steps including cell labeling and requires up to 6 days to evaluate the estrogenic activity. Here, we present an impedance-based E-screen cell biosensor in which the MCF-7 cells are cultured on electrodes. Upon estrogen treatment, the increased cell proliferation is detected as an increase in the recorded impedance with time. The estrogenic activity of test compounds is measured by comparing the increased impedance during the exponential growth phase with the impedance recorded in a hormone-free medium, which demonstrates that the impedance increase is directly proportional to the 17β-estradiol concentration. Two different compounds were tested for their estrogenic activities, confirming the known xenoestrogen, bisphenol-A, and the absence of xenoestrogenic activity of the antifouling agent, Irgarol 1051. All impedance-based results are compared to results obtained with the conventional assay. The impedance E-screen cell biosensor is label-free, easier to use, enables real-time analysis, which provides growth kinetic information upon estrogen exposure, and results in a shorter analysis time.
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