Mito-PN is a versatile dye. Dyes are crucial tools in biological experiments, aiding researchers in observing and analyzing cell structures, tracking biomolecules, assessing cellular functions, distinguishing cell types, detecting biomolecules, studying tissue pathology, and monitoring microorganisms. Their applications span a wide range from basic scientific research to clinical diagnostics. Dyes are also widely used in traditional fields like textile dyeing and emerging areas such as functional textile processing, food coloring, and dye-sensitized solar cells.

Probe Mito-PN (5 μM) in a phosphate-buffered solution (PBS, 20 mM, pH = 7.4) shows minimal fluorescence emission in its free state due to the spirolactone structure. Upon addition of ONOO?, a substantial fluorescence enhancement, approximately 40-fold at 630 nm, is observed. Remarkably, Mito-PN detects ONOO? rapidly, within less than 5 seconds, which is more efficient than the rhodamine and phenylhydrazine conjugation that requires about an hour. This quick detection facilitates probing the highly reactive and transient ONOO? in biological systems. Additionally, absorption spectral analysis reveals a significant increase at around 570 nm upon introduction of ONOO?.