A portable optic fiber aptasensor for sensitive, specific and rapid detection of bisphenol-A in water samples.

Bisphenol A (BPA) is a known endocrine disruptor and one of the most serious environmental contaminants, often present at low levels in various water sources. Therefore, it is very important and necessary to develop a fast, cost-effective, sensitive, and selective method for on-site detection of BPA. Herein, we developed a portable, evanescent, wave fiber-optic aptasensor for rapid, on-site detection of BPA with high sensitivity and selectivity. In this system, the probe DNA molecule, which is the complementary sequence of a small part of the BPA aptamer, was covalently immobilized onto the optical fiber sensor surface. Using an indirect competitive detection mode, samples containing different concentrations of bisphenol A were premixed with a given concentration of fluorescence-labeled BPA aptamer, which binds to bisphenol A with high specificity. Then, the sample mixture was pumped to the sensor surface, and a higher concentration of BPA led to less fluorescence-labeled BPA aptamer hybridized with surface immobilized probe DNA and thus to a lower fluorescence signal. The developed sensing system exhibits a sensitive response to BPA in the range of 2 nM to 100 nM with a low detection limit of 1.86 nM (0.45 ng ml(-1)) under the optimal conditions. The biosensors showed good reproducibility, stability, and selectivity for BPA detection. Finally, this proposed sensor was successfully employed to determine the presence of BPA in wastewater samples.