Novel cationic meso-CF₃ BODIPY-based AIE fluorescent rotors for imaging viscosity in mitochondria

Abstract

Two novel meso-CF3 BODIPY-based fluorescent rotors have been rationally prepared and sensitively respond to viscosity in living cells with fluorescence “turn-on” effect, attributing to the special restricted rotation of meso-CF3...

Novel Meso-Benzothiazole-Substituted BODIPY-Based AIE Fluorescent Rotor for Imaging Lysosomal Viscosity and Monitoring Autophagy

“…Small molecular fluorescent probes have been a powerful and indispensable tool in biological imaging for monitoring the slight environmental changes in living systems, among which fluorescent rotors for tracing the cellular viscosity changes have attracted increasing attention due to their close relations with Alzheimer’s diseases, lysosomal storage diseases, neural degeneration diseases, and so forth. − Molecular rotors usually contained a typical structure with molecular internal rotations and thus quenched fluorescence emissions through non-radiative relaxations, and then, by viscosity or steric effects, molecular rotations could be efficiently restricted, resulting in fluorescence enhancements . In recent years, novel fluorescent probes for monitoring viscosity have been extensively explored − and some of them could display organelle-targeting effects. − ,,, What is more interesting, some of these fluorescent rotors could also exhibit aggregation-induced emission (AIE) property with enhanced fluorescence emissions through the restriction of intramolecular rotations. − As reported, AIE molecules often contain a tetraphenylethene or silole with rotatable phenyl rings, and most of them did not display viscosity-responsive properties. − Therefore, it remains important and novel to develop new strategies for AIE molecules to monitor cellular viscosity, which could be potentially used to diagnose the viscosity-associated diseases.…”

“…As an excellent fluorescent dye, boron dipyrromethenes (BODIPYs) showed high potentials as fluorescent molecular rotors due to their unique and easily modified structures and spectroscopic properties, such as tunable absorptions and fluorescence emissions from the visible to near-infrared (NIR) regions, high fluorescence quantum yields, and low toxicity in biological systems, ,, and thus have been used for the detection of viscosity , and reactive oxygen species by our group. Recently, BODIPY-based fluorescent rotors for viscosity have been reported, mainly depending on the rotation of meso -CF 3 groups, , meso -CO groups, , meso -phenyl groups, , CC, − CC, , and so forth. Among these, as shown in Scheme a, a fluorescent probe with a meso -CF 3 group reported by us showed good AIE properties by the decoration of a cationic group and has been used to sense mitochondrial viscosity .…”

Dense and Acidic Organelle-Targeted Visualization in Living Cells using a Viscosity-Responsive Fluorescent Probe Independent of the Twisted Intramolecular Charge Transfer Process

“…8 Microviscosity is most often visualized using so-called "molecular rotors". [9][10][11][12][13][14][15][16][17][18][19][20][21][22][23][24][25][26] Typically, molecular rotors have two energy local minima in the excited state; the locally excited (LE) state and the twisted intramolecular charge transfer (TICT) state. Since conformational change is necessary for transition from the LE to the TICT state, higher viscosities, which restrict molecular motions, tend to suppress the transition to TICT, resulting in viscosity-responsive fluorescence.…”

Fine Tuning of Multiphoton AIE Emission Behavior, Organelle Targeting, and Fluorescence Lifetime Imaging of Terpyridine Derivatives by Alkyl Chain Engineering

“…8 And then, a series of compounds with aggregation-induced emission (AIE) enhancement characteristics that do not emit fluorescence or show very weak fluorescence in dilute solutions but emit strong fluorescence in high concentrations or in the solid state, which can provide a new way for the application of lightemitting materials in high concentration conditions, were synthesized. 9,10 Therefore, it is imperative to develop a series of metal-free dyes with AIE characteristics that can be used in multiphoton fluorescence lifetime imaging.…”

“…Moreover, some multiphoton FLIM imaging agents have relatively few applications in time-resolved fluorescence imaging as they tend to aggregate in a low solubility medium, leading to aggregation-caused quenching (ACQ) and a reduced fluorescence quantum yield . And then, a series of compounds with aggregation-induced emission (AIE) enhancement characteristics that do not emit fluorescence or show very weak fluorescence in dilute solutions but emit strong fluorescence in high concentrations or in the solid state, which can provide a new way for the application of light-emitting materials in high concentration conditions, were synthesized. , Therefore, it is imperative to develop a series of metal-free dyes with AIE characteristics that can be used in multiphoton fluorescence lifetime imaging.…”