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Two new cationic meso-thiazolium-BODIPY-based water-soluble and red-shifted fluorescent probes were constructed for the first time. They can monitor cellular viscosity in dual organelles and show aggregationinduced emission (AIE), which is ascribed to the efficient restricted rotation of meso-thiazolium in viscous or hindered systems. Probe 3 with an N-benzyl group shows better AIE as compared to probe 2 with an N-methyl group. [ABSTRACT FROM AUTHOR]

A lysosome-targeting dual-functional fluorescent probe was rationally designed and developed for imaging intracellular lysosomal viscosity and beta-amyloid. More importantly, the real-time tracking of the dynamic movement of lysosomes, as vesicle structures, has been achieved using Lyso-MC. [ABSTRACT FROM AUTHOR]

Four novel rhodamine-based fluorescent probes (RE1–RE4) were designed and synthesized for sensitive detection of Fe3+ in water. RE1–RE4 exhibited low detection limits in the range of 18.6 nM to 29.4 nM. In addition, the binding modes of the probes (RE1–RE4) with Fe3+ were proved to be 1 : 1 stoichiometry of the complexes by Job's plot and also their complexing ability was determined using the binding constants (RE2 ＞ RE4 ＞ RE3 ＞ RE1). RE2 was selected to study the proposed binding mechanism with Fe3+ by ESI-MS, 1H NMR and DFT calculations. Furthermore, RE2 was further utilized to detect Fe3+ in living cells and real water samples, indicating its promising prospect in biological and environmental fields. [ABSTRACT FROM AUTHOR]

A colorimetric and red-emitting fluorescent dual probe for G-quadruplexes was devised with a conjugated coumarin–benzothiazole scaffold. Its significant and distinct changes in both color and fluorescence enable the label-free and visual detection of G-quadruplex structures. In addition, this probe gives a distinct strong emission response to the nucleoli in fixed cells imaging, which might be attributed to the interaction between the probe and rDNA G-quadruplex based on the chromatin immunoprecipitation assay. All these results suggest its promising application prospects in the G-quadruplex research field. [ABSTRACT FROM AUTHOR]

A tailor-made colorimetric and red-emitting fluorescent dual probe for G-quadruplex nucleic acids was developed by incorporating a coumarin-hemicyanine fluorophore into an isaindigotone framework. The significant and distinct changes in both the color and fluorescence of this probe enable the label-free and visual detection of G-quadruplex structures. [ABSTRACT FROM AUTHOR]

Mitochondria are the most important energy supply centers in the cell, the changes in function and structure are implicated in many diseases. Among them, Aβ peptide, one of the targets of Alzheimer's disease, is closely related to mitochondrial autophagy, during the process of mitochondrial autophagy, the mitochondrial matrix will undergo acidification and the pH will be obviously reduced. Herein, a quinolinium-based NIR fluorescent probe QM12 was rationally designed and synthesized for the simultaneous imaging of Aβ aggregates and mitochondrial pH with different emission readout. The probe QM12 exhibited excellent selective toward Aβ aggregates, and can also trace the real-time changes of mitochondrial pH, which could serve as a promising tool for the pathological study of Alzheimer's disease, especially the cross talk between different biomarkers of Alzheimer's disease. [Display omitted] • A dual-functional fluorescent probe for Aβ aggregation and mitochondrial pH was reported. • The specific staining of Aβ plaques in the brain slice of AD mouse was achieved. • Probe QM12 can be used to monitor changes of mitochondrial pH. [ABSTRACT FROM AUTHOR]

The rapid detection of β-lactamases (Blas) and effective screening of Bla inhibitors are critically important and urgent for solving antibiotic resistance and improving precision medicine. Here a novel fluorescent probe CDC-559 was designed and synthesized, which can be used for the selective and direct detection of AmpC Blas. More importantly, it can realize screening the Bla inhibitors with sulbactam sodium and tazobactam as model compounds, and the half-maximal inhibitory concentration are 0.279 μM and 0.053 μM, respectively. CDC-559 can be applied not only to examine the resistance of bacterial strains, but also to categorize its mode of action specifically, which is consistent with the essential result of the Blas. The research suggests that CDC-559 probe has tremendous potential in the rapid detection of AmpC Blas as well as the strains with AmpC-encoded gene, which is instructive in promoting better antibiotic stewardship practices and developments. Unlabelled Image • A novel fluorescent probe, CDC-559, has been designed and synthesized. • CDC-559 can be used for the selective and direct detection of AmpC Blas. • CDC-559 can be screened for the Bla inhibitors. • CDC-559 can be applied not only to examine the resistance mode of the strains. [ABSTRACT FROM AUTHOR]

Abstract A near-infrared distyryl boron dipyrromethene-based sensor bearing one bis(1,2,3-triazole)amino receptor has been synthesized. This probe selectively and quickly binds to Hg2+ and Cu2+ ions in CH 3 CN/H 2 O (5:1 v/v) and exhibits remarkably blue-shifted absorption and fluorescence bands due to the inhibition of the intramolecular charge transfer process. The fluorescence changes of this probe upon binding to Hg2+ or Cu2+ ion are totally different, undergoing a ratiometric fluorescence enhancement (for Hg2+) or a fluorescence quenching (for Cu2+) mechanism. The corresponding vivid color changes can be easily seen by the naked eye. This probe was further introduced into Hela cells for living cell imaging and found to discriminate Hg2+ and Cu2+ ions through two near-infrared fluorescence emission channels. These overall results indicate that this Click-derived near-infrared BODIPY-based probe is potentially useful for ratiometric and discriminative detection of Hg2+ and Cu2+ ions in solutions and living cells. Graphical abstract fx1 Highlights • A novel Click-derived near-infrared BODIPY-based fluorescent probe was prepared. • Ratiometric and differential changes were seen upon addition of Hg2+ and Cu2+ ions. • These remarkable changes could also be successfully observed in living Hela cells. • It can successfully distinguish Hg2+ and Cu2+ ions in living cells by two channels. [ABSTRACT FROM AUTHOR]

Abstract Fe3+ ions play an important role in both biological and environmental field. In this work, two novel rhodamine-based colorimetric and fluorescent probes (RBA2 and RBA3) were designed and synthesized for the efficient detection of Fe3+. Upon the addition of Fe3+, the fluorescence intensity of RBA2 and RBA3 enhanced 108-fold and 222-fold, respectively. RBA2 and RBA3 exhibited a low detection limit which could achieve 12.8 nM and 11.0 nM. In addition, the binding modes of RBA2 and RBA3 with Fe3+ were proved to be 1:1 stoichiometry in the complexes by Job's plot, ESI-MS and 1H NMR results. The complexing ability of RBA3 with Fe3+ excessed to that of RBA2 that was determined by the binding association constants, and highly consistent with DFT calculations results. Furthermore, RBA2 and RBA3 were further utilized to detect Fe3+ in living cells and real water samples, indicating their promising prospects in biological and environmental field. Graphical Abstract Unlabelled Image Highlights • Two novel rhodamine-based fluorescent probes for naked eye detection of Fe3+ were synthesized and characterized. • The binding modes of RBA2 and RBA3 with Fe3+ were proved to be 1:1 stoichiometry by Job's plot, ESI-MS and 1H NMR results. • The binding abilities of RBA2 and RBA3 with Fe3+ were investigated, consisting with DFT calculations. • These two probes can be used in three water samples and the living systems. [ABSTRACT FROM AUTHOR]

[Display omitted] • A series of GFP-based red-emissive fluorescent probes were rationally designed and prepared. • C25e displayed remarkable "turn-on" fluorescence at 624 nm with higher sensitivity upon binding with Aβ aggregates. • C25e showed good response towards viscosity with an obviously enhanced emission at 640 nm. • C25e showed good selectivity and a high signal-to-noise ratio for Aβ plaques compared to Thio-S. • C25e employed for monitoring amyloid-β induced mitochondrial viscosity changes for the first time. Alzheimer's disease (AD), with incurable neurodegenerative damage, has attracted growing interest in exploration of better AD biomarkers in its early diagnosis. Among various biomarkers, amyloid-β (Aβ) aggregates and mitochondrial viscosity are closely related to AD and their dual imaging might provide a potential and feasible strategy. In this work, five GFP-based red-emissive fluorescent probes were rationally designed and synthesized for selective detection of β-amyloid plaques and viscosity, among which C25e exhibited superior properties and could successfully image β-amyloid plaques and mitochondrial viscosity with different fluorescence wavelength signals "turn-on" at around 624 and 640 nm, respectively. Moreover, the staining of brain sections from a transgenic AD mouse showed that probe C25e showed higher selectivity and signal-to-noise ratio towards Aβ plaques than commercially-available Thio-S. In addition, the probe C25e was, for the first time, employed for monitoring amyloid-β induced mitochondrial viscosity changes. Therefore, this GFP-based red-emissive fluorescent probe C25e could serve as a dual-functional tool for imaging β-amyloid plaques and mitochondrial viscosity, which might provide a unique strategy for the early diagnosis of Alzheimer's disease. [ABSTRACT FROM AUTHOR]

Fluorescent molecular rotors play vital roles in understanding the function of cellular viscosity changes and its abnormal fluctuations are closely associated with many diseases. Despite numerous efforts spent, it remains an urgent and important topic to develop improved viscosity probes with near-infrared fluorescence, high sensitivity and low background. In this manuscript, for the first time, we reported two novel monostyryl boron dipyrromethenes (BODIPYs) bearing a rotatable trifluoromethyl group (CF 3) at the meso position and a triphenylphosphonium (4) or morpholine (6) substituent, which could successfully serve as highly sensitive and near-infrared-emitting fluorescent probes for imaging cellular viscosity in mitochondria or lysosome. These probes could be prepared through Knoevenagel condensation under mild conditions and showed negligible emissions in the low viscous solvents. However in high viscous glycerol, strong near-infrared fluorescence at 657 nm appeared, ascribed to the substantially restricted rotation of the CF 3 group. Their fluorescence intensity (log I) at 657 nm exhibited a good linear relationship with viscosity (log η) in the whole test range of 1–950 cP. Limit of detection for viscosity of mitochondria-targeting probe 4 was relatively lower than that of lysosome-targeting probe 6. These probes both showed no cytotoxicity and good mitochondrial or lysosomal localization. Interestingly, mitochondria-targeting probe 4 exhibited a remarkable intracellular fluorescence enhancement with viscosity increase induced by LPS or nystatin, which was better than lysosome-targeting probe 6. These two novel BODIPY-based fluorescent rotors provide a new strategy for developing near-infrared-emitting and organelle-specific fluorescent probes for cellular viscosity, which might be useful in exploring the functions of viscosity in various diseases. [Display omitted] • Two novel meso -CF 3 BODIPY-based NIR fluorescent probes for viscosity were rationally developed for the first time. • These two probes could sensitively detect the viscosity with low background. • Strong NIR emissions at 657 nm appeared ascribed to the restricted rotation of meso -CF 3. • These two probes sensitively respond to intracellular viscosity with good organelle localization. [ABSTRACT FROM AUTHOR]

A GFP Chromophore Analogue C25 could simultaneously probe lysosome viscosity and β‑Amyloid fibrils with distinguishable turn-on fluorescence signals. • A turn-on fluorescent probe for selective and simultaneous detection of Aβ fibrils and lysosomal viscosity was synthesized. • The FP chromophore was developed for detection of Aβ fibrils for the first time. • The probe can detect Aβ fibrils and viscosity with one-excitation and dual-emission. • The fluorescent imaging demonstrated its value of practical application. Alzheimer's disease (AD) is an incurable neurodegenerative disease. Better diagnosis of AD is extremely important for therapeutic interventions. The amyloid cascade hypothesis and its revised version identify insoluble β-amyloid deposition as a good diagnostic biomarker for AD. We hypothesize that lysosomal viscosity may also act as an auxiliary biomarker for AD based on literature research. Herein, we have successfully developed a FP chromophore analogue C25 as a dual-functional fluorescent probe which can respond effectively to the Aβ fibrils and enhanced lysosomal viscosity with distinguishable turn-on fluorescence signals around 570 nm and 600 nm, respectively. The probe C25 can also monitor the Aβ degradation in the lysosomes. The probe C25 can serve as a promising tool for developing early diagnosis and innovative therapeutics of AD. [ABSTRACT FROM AUTHOR]

A novel click-derived monostyryl BODIPY-based fluorescent probe has been prepared. Notably, upon exposure to Hg2+ or Cu2+, it exhibited remarkable blue-shifted absorptions from 592 to either 555 for Hg2+ or 502 nm for Cu2+ with distinct color changes from blue to purple for Hg2+ or yellow for Cu2+ in CH 3 CN/H 2 O. Interestingly, its fluorescence showed significant ratiometric (Hg2+) and ON-OFF (Cu2+) changes. Notably, the probe displayed ratiometric fluorescence from 690 to 602 nm with a 65-fold enhancement in fluorescence ratio of I 602 /I 690 for Hg2+ and underwent a substantial ON-OFF fluorescence for Cu2+. Furthermore, this probe was successfully used in Hela cells and could easily discriminate Hg2+ and Cu2+ through double-channel imaging. These overall results illustrate that this monostyryl BODIPY potentially serves as a remarkable colorimetric probe for fluorescent ratiometric and ON-OFF discriminative detection of Hg2+ and Cu2+ in solutions and living cells by a remarkable double-channel change. Image 1 • A novel monostyryl BODIPY-based probe was prepared through click reaction. • Colorimetric changes from blue to purple for Hg2+ or yellow for Cu2+ were easily seen. • It showed large ratiometric for Hg2+ and ON-OFF for Cu2+ fluorescence. • It successfully distinguished Hg2+ and Cu2+ in living cells by double-channel imaging. • A 37-fold enhanced ratio for Hg2+ and a sufficient quenching for Cu2+ were seen in cells. [ABSTRACT FROM AUTHOR]