Styryl‐NIR Mitochondrial Probes with Rapid HOCl Detection in Live‐Cells

Abstract

Hypochlorous acid (HOCl) is critical for maintaining immune system balance, but it can harm mitochondria by hindering enzyme activity, leading to decreased ATP and increased cell death. In this study, we have designed a fluorophore with a pyridinium scaffold for selective staining of the mitochondria and to detect hypochlorite. The fluorophore exhibits strong solvatochromic emission due to intramolecular charge transfer and excellent sub-cellular localization in the mitochondria. Additionally, it shows a rapid response to HOCl with high selectivity among different reactive oxygen/nitrogen compounds with a detection limit of 2.31 μM. Moreover, it is also utilized for the exogenous and endogenous detection of HOCl in live cells, which may help study the role of hypochlorite in organelles at the cellular level. DFT and TDDFT calculations have been carried out to understand the relationship between the structure and properties of the cationic probes with respect to the α-cyano substitution and extension of π-conjugation. The selective detection of HOCl by C4 over other cationic probes has also been well-demonstrated, showing how the binding of HOCl affects the electronic properties of C4 through the analysis of non-bonding orbitals (NBO) population, electrostatic potential surface (ESP), and density of states (DOS) projected DOS investigations.

Detecting labile heme and ferroptosis through ‘turn-on’ fluorescence and lipid droplet localization post Fe2+ sensing

“…Following this, co-localization with Nile Red, a commercially available lipid droplet marker, indicates specificity to the lipid droplets because of the conversion of NOCN to NCN upon the addition of Fe 2+ . These results remain consistent with our previous work published earlier 43 (Fig. 10).…”

“…NCN, on the other hand, shows strong specificity towards lipid droplets. 43 However, the N -oxide derivatives NOPy and NOCN revealed minimal fluorescence in COS-7 cells [Fig. 6A and D].…”

“…This finding aligns with our earlier results of the localization of the NCN probe within the lipid droplets. 43…”

A two-in-one probe: imaging lipid droplets and endoplasmic reticulum in tandem

“…pentafluorophenyl 15 ) were also utilized for ER imaging due to their favourable interaction with biomolecules present within the endoplasmic reticulum. [16][17][18] However, the examples of molecular scaffolds that simultaneously image ER and lipid droplets along with concurrent examination of physiological processes are a few. The lipid droplets and ER consist of lipophilic membrane rich regions and differ in the amount of water content.…”

A multipurpose mitochondrial NIR probe for imaging ferroptosis and mitophagy

“…7–9 The positive charge allows accumulation within the negatively charged inner mitochondrial membrane, making them excellent tools for visualizing mitochondrial morphology and studying intracellular dynamics. Over the years, several mitochondrial targeting probes have been developed for studying morphology, dynamics, and analyte detection, 10,11 and physiological effects such as temperature, 12 micropolarity, 13 viscosity, 14–16 ferroptosis, 17 and mitophagy. 9,12,18 The deviations in the physiological processes could lead to malfunction or damaged mitochondria that the lysosomes shall recycle to maintain cellular homeostasis.…”