We present two mitochondria-immobilized fluorescent probes ECPI-12 and IVPI-12 for long-term mitochondria visualization and tracking regardless of MMP changes.
Lipid droplets (LDs) and lysosomes are crucial for maintaining intracellular homeostasis. But single fluorescent probes (SFPs) capable of simultaneous and discriminative visualizing of two organelles above and their interaction in living cells are still challenging due to the lack of rational design strategies. To break this bottleneck, herein, we develop a reliable strategy based on a pH-sensitive intramolecular spirocyclization. As a proof of concept, an SFP CMHCH, which possesses a switchable hemicyanine/spiro-oxazine moiety induced by pH, has been designed and synthesized. In acidic environments, the ring-open form CMHCH exhibits red-shift emission and low logP value, whereas the ringclosed form CMHC displays blue-shift emission and high logP value in neutral or basic environments. Thus, the distinct different hydrophilicity/hydrophobicity and absorption/emission properties of these two forms enable targeting LDs and lysosomes simultaneously and discriminatingly. Very importantly, the dynamic process of lipophagy can be directly monitored with CMHCH. The success of CMHCH indicated that the spirocyclization strategy is efficient for constructing SFPs to LDs and lysosomes.
The mitochondrial membrane potential (MMP) definitely reflects mitochondrial function. Thus, it is very essential to found a physical parameter as MMP indicator. At present, available parameters are either fluorescent intensity of monochromatic probes such as rhodamine 123 or a ratio of fluorescent intensity at different wavelengths of dual-color dyes such as JC-1, but the inconvenience in practice as well as serious effect of loading concentrations on experimental results limited their application. To address this concern, herein,we found a reliable and easily obtainable colocalization coefficient (CLC) of a fluorescent probe as new MMP indicator and developed a target switchable fluorescent probe (Mito-Lyso) to attain the aim. Because of its intrinsic nature, Mito-Lyso exclusively stains mitochondria with normal MMP and a subsequent decreasing of MMP results in release of some Mito-Lyso. Importantly, the released Mito-Lyso can reversibly transfer between mitochondria and lysosomes. Thus, CLCs of Mito-Lyso and a commercial lysosomal probe (NIR-Lyso) can be MMP-dependent. CLCs gradually increased from 0.20 to 0.8 with the decreasing of MMP and then returned to 0.3 with the recovering of MMP, which better proves that the CLC is a valuable MMP indicator. Furthermore, both the design principle and action mechanism of Mito-Lyso has been explained in detail for the development of this type of probes.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.