A Cell-Based Electrochemical Biosensor to Detect Sub-Nanomolar Levels of Environmental Pollutants

Abstract

Endocrine disruptors, dangerous contaminants found in many household products as well as in the environment, have garnered increasing attention due to their pervasiveness. These compounds are found in many products we use daily, including medications, plastics, and pesticides and are implicated in many health problems, including cancer, infertility, and diabetes. These chemically dissimilar compounds all target a small number of hormone receptors in our bodies, and this dissimilarity makes detection of these compounds a challenge. We have developed a novel detection strategy for estrogenic compounds that is both rapid and portable. Our platform is based on E. coli engineered to surface express a native estrogen receptor construct, enabling recognition of many structurally dissimilar compounds. The large size of the cell affords inherent signal amplification from impedance measurements upon binding to a modified electrode. We have detected sub-ppb levels of the native hormone estradiol and ppm levels of the endocrine disruptor bisphenol A (BPA) in complex solutions. As our system reports the total estrogenic activity of a sample rather than the concentration of specific components, we can measure the activity of unknown compounds, including chemicals released from a BPA-free plastic baby bottle following microwave heating. Importantly, this approach is broadly applicable to the detection of chemically diverse compounds that bind to a single receptor.