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−1 with a limit of detection at 0.027 μg mL−1 and a limit of quantification at 0.089 μg mL−1. 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.