A chitosan-based fluorescent probe for biosensing and food sensing of hydrazine and hydrogel applications.

Hydrazine (N2H4) is a highly toxic industrial chemical that threatens food safety and public health via food chain accumulation. To address the scarcity of reliable detection tools for N2H4 in food and biological matrices, a chitosan (CTS)-based fluorescent probe (CTS-NI) was fabricated by covalently conjugating a naphthalimide fluorophore to modified CTS. The probe exhibits significant fluorescence enhancement at 558 nm toward N2H4, with a large Stokes shift (118 nm) and a low detection limit (2.03 × 10-7 M). Its biocompatibility and CTS-derived structural advantages enable sensitive and quantitative detection of N2H4 in food samples (shrimp, baijiu, strawberry, chicken) and biological systems (cells, zebrafish). Furthermore, CTS-NI-based hydrogels with integrated "detection-adsorption" functionalities were developed, broadening the probe's practical applications for food safety supervision.