β-cyclodextrin/spiropyran-functionalized optical-driven hydrogel film for bisphenol A detection in food packaging.

Bisphenol A (BPA), an endocrine disruptor, is widely used in food packaging materials, including drink containers. Sensitive detection of BPA is crucial to food safety. Herein, we have developed a novel optical-driven hydrogel film sensor for sensitive BPA detection based on the displacement of spiropyran (SP) from β-cyclodextrin (β-CD) cavity by BPA followed by the photochromism of the released SP. The released SP converts to the ring-opened merocyanine form which shows an enhanced red fluorescence in the dark. The sensor demonstrates a linear detection range from 0.1 to 20 μg mL with a limit of detection at 0.027 μg mL and a limit of quantification at 0.089 μg mL. Notably, the proposed β-CD/SP hydrogel can be reused due to the reversible isomerization of SP and the reversible host-guest interaction. This sensor also shows good performance for BPA determination in real samples, indicating its great potential for food safety monitoring.