BODIPY-Based Two-Photon Fluorescent Probe for Real-Time Monitoring of Lysosomal Viscosity with Fluorescence Lifetime Imaging Microscopy

Abstract

The viscosity of lysosome is reported to be a key indicator of lysosomal functionality. However, the existing mechanical methods of viscosity measurement can hardly be applied at the cellular or subcellular level. Herein, a BODIPY-based two-photon fluorescent probe was presented for monitoring lysosomal viscosity with high spatial and temporal resolution. By installing two morpholine moieties to the fluorophore as target and rotational groups, the TICT effect between the two morpholine rings and the main fluorophore scaffold endowed the probe with excellent viscosity sensitivity. Moreover, Lyso-B succeeded in showing the impact of dexamethasone on lysosomal viscosity in real time.

Small Molecular Fluorescent Probes for Imaging of Viscosity in Living Biosystems

“…Yu et al. developed a 4,4‐difluoro‐4‐bora‐3 a ,4 a ‐diaza‐ s ‐indacene (BODIPY)‐based fluorescent probe 30 for determination of lysosomal viscosity [57] . Probe 30 contained three sections: the BODIPY fluorophore, two hydrophilic polyethylene glycol (PEG) chains, and two morpholine groups.…”

Dithienothiophenes at Work: Access to Mechanosensitive Fluorescent Probes, Chalcogen-Bonding Catalysis, and Beyond

“…The insensitivity of the emission maxima to increasing order of the surrounding membrane nicely illustrates that the mode of action of fluorescent flippers differs from other membrane probes operating in the excited state by TICT (molecular rotors), ESIPT, PET, ICT (solvatochromisim), FRET, unbending, and so on 91,[154][155][156][157][158][159][160][162][163][164][165][166][167]…”

Functionalized BODIPYs as Fluorescent Molecular Rotors for Viscosity Detection

“…Another FMR 15 (Figure 2E; Li et al, 2018) with two morpholine moieties selectively detected lysosomal viscosity using FLIM. Similar to BODIPY 6 , the fluorescence lifetime (log τ) of BODIPY 15 linearly increased with the increased viscosity (Figure 2F, pH = 1).…”

“…(F) Fluorescence lifetime spectra of BODIPY 15 (0.5 μM at 590 nm) in various viscosities (pH = 1). Reproduced with permission from Li et al (2018), Copyright 2018 American Chemical Society.…”