Rational Design of MMP-Independent Near-Infrared Fluorescent Probes for Accurately Monitoring Mitochondrial Viscosity

Abstract

Mitochondrial viscosity affects metabolite diffusion and mitochondrial metabolism and is associated with many diseases. However, the accuracy of mitochondria-targeting fluorescent probes in measuring viscosity is unsatisfactory because these probes can diffuse from mitochondria during mitophagy with a decreased mitochondrial membrane potential (MMP). To avoid this problem, by incorporating different alkyl side chains into dihydroxanthene fluorophores (denoted as DHX), we developed six near-infrared (NIR) probes for the accurate detection of mitochondrial viscosity, and the sensitivity to viscosity and the mitochondrial targeting and anchoring capability of these probes increased by increasing the alkyl chain length. Among them, DHX-V-C 12 had a highly selective response to viscosity variations with minimum interference from polarity, pH, and other biologically relevant species. Furthermore, DHX-V-C 12 was used to monitor the mitochondrial viscosity changes of HeLa cells treated by ionophores (nystatin, monensin) or under starvation conditions. We hope that this mitochondrial targeting and anchoring strategy based on increasing the alkyl chain length will be a general strategy for the accurate detection of mitochondrial analytes, enabling the accurate study of mitochondrial functions.

A mitochondria-targeted fluorescent probe with viscosity sensitivity to distinguish between normal and cancer cells

“…Previous studies have reported that the ionic carriers, monensin (Mon), nystatin (Nys), and lipopolysaccharides (LPS), disrupt ion homeostasis, leading to mitochondrial dysfunction and viscosity changes. 36–40 In addition, carbonyl cyano-chlorophenyl hydrazone (CCCP) can also cause changes in mitochondrial viscosity. 41 Therefore, to investigate the monitoring of intracellular mitochondrial viscosity changes by YPE , we used different drug stimuli to regulate changes in the mitochondrial microenvironment.…”

Fluorophore Label-Free Light-up Near Infrared Deoxyribonucleic Acid Nanosensor for Monitoring Extracellular Potassium Levels

“…Due to their excellent biocompatibility and programmability, DNA nanostructures have been widely used in the construction of fluorescent DNA nanosensors and cell imaging. − Among them, the near-infrared (NIR) DNA nanosensors can avoid the influence of luminescence in the organism to the greatest extent and can also pass through the skin, fat, and other tissues to a greater extent, so NIR DNA nanosensors has its unique advantages in biological detection. − The sensing mechanism of traditional fluorescent DNA nanosensors mostly depends on the change in the distance between the fluorophore and quencher. As shown in Figure a, the change of target concentration leads to the change of DNA structure, which in turn changes the distance between fluorophore and quencher and produces fluorescence signal.…”

Long-Chain Fluorescent Probe for Straightforward and Nondestructive Staining Mitochondria in Fixed Cells and Tissues

“…It has been reported that the conjugated structure with long alkyl chains of different lengths may exhibit similar or distinct staining results. − Therefore, we synthesized DMPQ-n (n = 8, 10, and 14) to examine the effect of the alkyl chain length of the probes on their localization in fixed cells. The absorption and fluorescence spectra of DMPQ-n in different solvents are displayed in Figures S22–S24, and their optical properties are summarized in Table S2.…”