Long Range Emissive Water-Soluble Fluorogenic Molecular Platform for Imaging Carbon Monoxide in Live Cells

Despite its murderous act, carbon monoxide (CO) is found to be a very crucial small gaseous messenger molecule in dictating prime biological and physiological processes. Determination of endogenous or exhaled CO levels can throw significant light on smoking status and can be used as a breath biomarker of inflammatory diseases. Therefore, fluorescence imaging of CO in biofluids will empower one with the minute details of various disease states that involve CO. Unfortunately, such efficient fluorescent probes are less in number and also associated with tedious protocols. This enticed our attention and inspired us to look upon developing perceptive imaging agents for CO in a living system. In this report, a resorufin-based "turn-on" orange emissive molecular probe has been successfully utilized to detect CO in an aqueous system. The mono protection of a resorufin unit with an allyl chloroformate furnished a weakly fluorescent small molecular probe P1. Further, the P1+Pd ensemble has been successfully developed in situ using PdCl₂ (as Pd²⁺) and utilized as a light-up signaling mechanism tool for the sensing of CO at the nanomolar level (62 nM) through deprotection mechanism. The probe selectively detects CO without any interference from other anions, gasotransmitters and fatty acids. The present integrated probe P1+Pd system has been found to be highly sensitive to detect CO in cellular systems as well.