Harnessing a MMP-sensitive fluorescent probe for in-situ and reversible monitoring MMP alteration in dual color based on aggregation/monomer mechanism.

BACKGROUND

Mitochondria are highly dynamic organelles which exhibit multiple functional states. The mitochondrial membrane potential (MMP) plays a vital role in sustaining mitochondrial functions and serves as an indicator of cellular health and viability. So, monitoring of MMP variations in real time is vital for gaining insights into mitochondria-associated biological events. The direct dual-color visualization of MMP alteration could decrease errors resulting from non-uniform staining and instrumentation inconsistencies. Nevertheless, achieving in-situ and direct detection of dynamic MMP changes in dual color is still a significant challenge.

RESULTS

In this study, a new fluorescent probe for in-situ, direct, and dual-color visualization of mitochondrial membrane potential was designed and synthesized via an aggregation/monomer mechanism. QI displayed green and red emission color in diverse state, and the viscosity-responsive behavior made it suitable for high-fidelity visualization. Under physiological conditions, QI selectively labeled mitochondria in red channel, reflecting normal MMP levels. When MMP collapsed, green-channel signals appeared and red fluorescence weakened, indicating the loss of MMP. This allowed in-situ and direct visualization of the reversible MMP alterations triggered by the CCCP (carbonyl cyanide 3-chlorophenylhydrazone) or H2O2 at multiple time points in dual color. Thus, QI enabled to track MMP alterations during apoptosis in view of the loss of MMP in apoptosis.

SIGNIFICANCE AND NOVELTY: Compared with other probes for visualization of MMP, this probe could in-situ and direct visualization of the reversible MMP alterations in dual color. The ability of QI to dual-color visualize MMP alteration and monitor their dynamics in diverse physiological processes holds considerable values, potentially advancing research about MMP-associated physiology and pathology.