A Versatile Nonconventional Luminescent Material Based on Quaternary Ammonium Chitosan for Sodium Chlorite Detection and Cell Imaging

Abstract Nonconventional luminescent materials (NLMs) lacking extended π‐conjugated systems present a burgeoning field with vast potential applications in cell image, and chemical sensing. This work explores the synthesis, characterization, and promising applications of a novel NLM quaternary ammonium chitosan (QCS), in bioimaging and selective chemical sensing where solutions exhibit remarkable tunability in their photophysical properties, influenced by concentration, excitation wavelength, and temperature. Notably, applying static pressure to the solid sample significantly enhances its luminous efficiency, rising from 2.15% to 2.59%, inducing a redshift in emission, emission shifting from 436 to 452 nm after the force action. Furthermore, QCS demonstrates a highly specific fluorescent response toward sodium chlorite (NaClO₂) with negligible interference from common cations and anions. The detection limit for NaClO₂ reaches a low 0.297 mg L −1 , highlighting its potential for practical applications. Additionally, QCS exhibits excellent biocompatibility and low cytotoxicity, making it a compelling candidate for cellular imaging.