A ratiometric fluorescent probe for the specific detection of carbon monoxide released from CORM-3 and induced by heme in living cells.

BACKGROUND

Carbon monoxide (CO), a crucial gaseous transmitter molecule produced during physiological metabolism, plays vital roles in various biological processes. Rapid, in situ, and sensitive detection of CO levels in living cells is therefore essential for elucidating its biological functions, unraveling disease mechanisms, and developing novel diagnostics and therapeutics. Organic small-molecule fluorescent probes have emerged as promising tools for CO detection due to their exceptional detection capabilities. However, many existing fluorescent probes still rely on heavy metal ions, employ single-channel signal detection, exhibit limited sensitivity and narrow linear detection ranges, and, in some cases, are incapable of detecting endogenous CO.

RESULTS

This study developed a coumarin-based fluorescent probe for the selective detection of CO. The probe functions through CO-induced nitroreduction, which leads to the cleavage of the p-nitrobenzyl group, thereby suppressing the ICT effect and inducing a fluorescence emission switch from near-infrared (650 nm) to cyan-green (538 nm). It demonstrates excellent ratiometric detection performance (F/F), with a low detection limit of 52.5 nM, a broad linear range (0-180 μM), remarkable selectivity, a suitable physiological pH range (7-10), and rapid response kinetics (<20 min). This probe has been successfully applied for the visualization of exogenous CO released from CORM-3 and the endogenous CO induced by heme stimulation. Moreover, it not only enables reliable detection of CORM-3 in serum, with recovery rates ranging from 96.87 % to 100.43 %, but can also be prepared into convenient sensing strips. When combined with a smartphone, it provides a point-of-care detection platform for CORM-3 through RGB analysis.

SIGNIFICANCE

This probe addresses the issues of heavy metal ion involvement, susceptibility to interference, low sensitivity, a narrow linear range, and the inability to detect exogenous and endogenous CO. Moreover, it can be immobilized on test strips for on-site detection of CORM-3 concentrations in solution via smartphone-based colorimetric applications. The probe serves as an outstanding tool for CO detection in bioanalysis and clinical diagnostics.