Practical and versatile hypochlorite sensor using a xanthene scaffold: Integrating theoretical analysis with environmental and biological applications

A xanthene-based fluorescence and colorimetric sensor, HCC (2,3,6,7,11,12-hexahydro-1H,5H,10H-chromeno[2,3- f ]pyrido[3,2,1-ij]quinoline-13-carbaldehyde), was designed for the selective detection of ClO⁻. HCC exhibited detection limits of 0.36 μM in fluorescence and 3.0 μM in UV–vis analysis and demonstrated high selectivity against various anions and ROS. The ClO⁻ sensing mechanism was examined using ¹H NMR, ESI-MS, and DFT calculations, revealing that fluorescence quenching resulted from xanthene ring cleavage and π-conjugation disruption. The practical applicability of HCC was evaluated in water samples, test strip-based detection, and smartphone-assisted quantification. In addition, bioimaging experiments using zebrafish confirmed ClO⁻-induced fluorescence quenching in living organisms, while edible plant-based sensing demonstrated its utility in tracking ClO⁻ uptake through root absorption. Furthermore, HCC was successfully applied for ClO⁻ residue detection on mushrooms. These results suggest that HCC serves as a highly sensitive and versatile ClO⁻ sensor with potential applications in environmental monitoring, biological imaging, and food safety assessment.