Detecting labile heme and ferroptosis through 'turn-on' fluorescence and lipid droplet localization post Fe sensing.

Iron, a crucial biologically active ion essential for metabolic processes in living organisms, plays a vital role in biological functions, and imbalances in iron levels can lead to various diseases. In this study, we have developed two simple "turn-on" fluorescent probes, NOPy and NOCN, for the quick and selective detection of Fe at nanomolar levels (LOD of 35 nM), accompanied by significant absorption and emission shifts, along with colorimetric demarcation. Both fluorophores exhibit an excellent "turn-on" emission response upon encountering Fe in the cells. Flow cytometry and confocal fluorescence imaging studies demonstrate enhanced fluorescence signals in response to labile iron, efficiently detecting heme during erastin-induced ferroptosis. Interestingly, we also observed that the product formed after Fe sensing localizes within the lipid droplets. These water-soluble and highly sensitive reactive probes, NOPy and NOCN, enable investigations of iron-dependent physiological and pathological conditions. The development of these probes represents an advancement in the field, offering a rapid and selective means for detecting Fe with minimal cytotoxicity.