Visualizing Mitochondrial Membrane Potential with FRET Probes: Integrating Fluorescence Intensity Ratio and Lifetime Imaging.

Mitochondrial membrane potential (MMP) is crucial for mitochondrial function and serves as a key indicator of cellular health and metabolic activity. Traditional lipophilic cationic fluorescence intensity probes are unavoidably influenced by probe concentration, laser intensity, and photobleaching, limiting their accuracy. To address these issues, we designed and synthesized a pair of fluorescence molecules, OR-C8 and SiR-BA, based on the Förster Resonance Energy Transfer (FRET) mechanism, for dual-modality visualization of MMP.

Dual-Modality Imaging with a Zwitterionic Fluorescent Probe for Reversible Monitoring of Mitochondrial Membrane Potential Dynamics.

Traditional fluorescence intensity-based probes face challenges in accurately measuring mitochondrial membrane potential (MMP) due to intramolecular fluorescence quenching. In this work, we introduce a novel approach by incorporating quenching moieties within the zwitterionic probe to eliminate self-quenching interference, thus, enabling real-time and precise visualization of reversible MMP changes. We synthesized a zwitterionic fluorescent probe consisting of silicon-rhodamine (SiR) that was hydroxyl-substituted on the bay position of perylene diimides (PDIs) connected via a polyethylene glycol (PEG) linker.

Multicolor Tuning of Perylene Diimides Dyes for Targeted Organelle Imaging In Vivo.

The adjustment of the emission wavelengths and cell permeability of the perylene diimides (PDI) for multicolor cell imaging is a great challenge. Herein, based on a bay-region substituent engineering strategy, multicolor perylene diimides () were rationally designed and synthesized by introducing azetidine substituents on the bay region of PDIs. With the fine-tuned electron-donating ability of the azetidine substituents, these showed high brightness, orange, red, and near infrared (NIR) fluorescence along with Stokes shifts increasing from 35 to 110 nm.