Reusable aptamer sensors based on long period fiber gratings for detecting Bisphenol A at ultralow concentrations

Bisphenol A migrated from plastic products can function as an endocrine-disrupting compound, leading to serious diseases. The construction of rapid, cost-effective, and user-friendly sensors to accurately monitor BPA at ultra-low levels has great significance for protecting human health. Here, we proposed an aptasensor combined with long-period fiber gratings (LPFGs) for the label-free detection of BPA molecules. A long DNA aptamer against BPA molecules was selected and immobilized on the surface of the LPFG through chemical modification. When exposed to BPA solutions, the long aptamer provides a large conformation transition to amplify the perturbation of the refractive index near the fiber surface, which is conducive to producing a measurable shift of the transmission spectra and improving the sensitivity of the BPA detection. As a result, an ultralow detection limit of 0.232 ng/mL was achieved, which is lower than the standard limit (1.5 ng/mL) in drinking water set by European Union (EU). The proposed sensor offers an effective strategy for BPA detection, featuring the advantages of a simple structure, low cost, excellent reusability, high sensitivity, and reliability.