A biocompatible chitosan-based fluorescent polymer for efficient H 2 O 2 detection in living cells and water samples.

As a biomarker of oxidative stress, hydrogen peroxide (H ₂ O ₂ ) plays a complex role in organisms, including regulating cell signaling, respiration, the immune system, and other life processes. Therefore, it is important to develop a tool that can simply and effectively monitor H ₂ O ₂ levels in organisms and the environment. In this work, naphthalene fluorophores with a borate structure were introduced into chitosan (CTS) azide, and a CTS-based fluorescence sensor (CTS-HP) was designed for sensitive H ₂ O ₂ detection. The biocompatibility and degradability of CTS endowed CTS-HP with reduced biotoxicity compared with organic fluorescent dyes, and the substitution degree of fluorophores on the CTS chains was 0.703. The randomly coiled chain structure of the CTS-HP probe enabled the boronic acid recognition sites on the fluorophores to achieve the enrichment of analyte H ₂ O ₂ through a synergistic effect. Therefore, the probe CTS-HP (10 μg mL ^-1 ) exhibited a 21-fold fluorescence enhancement and good detection limit (LOD = 8.98 nM) in H ₂ O ₂ solution, reaching the maximum fluorescence response faster (within 16 min). The probe also successfully achieved the fluorescence imaging of endogenous and exogenous H ₂ O ₂ in zebrafish and living cells and labeled the recovery experiment of H ₂ O ₂ in real water samples (recoveries rates of 90.93-102.9 % and RSD < 3.09 %).
Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.
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