Recent development of fluorogenic probes for carbon monoxide imaging in living cells

The identification as well as detection of small endogenously produced gaseous molecules, carbon monoxide (CO), as signal transmitters in living systems has discovered that these gases perform essential biological functions and are associated with various diseases in human. It is now recognised that chronic exposure to low levels of CO also poses a significant health risk. Thus the selective monitoring and detection of low levels of CO remains challenging for researchers. Although some traditional methods, e.g. gas chromatography, electrochemical analysis, and colorimetric detection, have been established for sensing CO but these methods are not able to selectively detect CO in living systems in a non-invasive manner. In contrast, detection by fluorescence techniques is highly attractive due to its high sensitivity and real-time detection approach in a non-destructive way. This review article covers the design of fluorogenic probes, mechanistic behaviour with CO and their application to CO sensing in living cells.