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[Display omitted] • Ratiometric peptide-based fluorescent probe DKA with large Stokes shift (230 nm) was developed. • DKA demonstrated absorbance ratiometric and fluorescent "off-on" sensing for Hg2+ with low LOD of 13.4 nM. • DKA -Hg2+ complex was applied to sequential detect S2− with good selectivity and excellent sensitivity.. • DKA performed well in sequential detecting the distribution of Hg2+ and S2− in living cells. • DKA was used to visually and semi-quantitatively recognize Hg2+ and S2− by smartphone-assisted detection platform. In this work, a new ratiometric fluorescent probe DKA was synthesized based on the double sides of lysine backbone conjugated with alanine and dansyl groups. DKA exhibited fluorescence ratiometric response for Hg2+ with high sensitivity (13.4 nM), specific selectivity (only Hg2+), strong anti-interference ability (no interference), fast recognition (within 60 s) and wide pH range (5–10). The stoichiometry of binding of DKA and Hg2+ was determined to be 1:1 via Job's plot, ESI-HRMS and 1HNMR titration analysis. Subsequently, the in situ formation of DKA -Hg2+ complex was used for highly selective detection of S2− as a novel fluorescence "on–off" probe, and the lowest detection limit for S2− was 12.9 nM. In addition, DKA possessed excellent cells permeation and low toxicity, and fluorescence imaging of Hg2+ and S2− was performed in living Hacat cells. Most importantly, the digital imaging using a smartphone color recognition APP indicated that DKA could semi-quantitatively and visually detected Hg2+ and S2− without expensive equipment. [ABSTRACT FROM AUTHOR]

[Display omitted] • A convenient approach to construct excimer emissive luminogens was established. • A double-bond linker between π-moiety and side-moiety is essential for AIE. • The structure-luminescence relationship was elucidated. • The high-resolution image of living Hela cells was observed. The excimer emission based on discrete π-stacked dimers of polycyclic π-systems has generated significant interest in the structure-luminescence relationship of excimers owing to their ultra-large Stokes shift. Herein, a series of excimer emissive luminogens were obtained by conjugating different polycyclic aromatic aldehydes (anthraldehyde, pyrenealdehyde and perylenealdehyde) with triphenylmethylamine. In crystalline states, all the molecules were arranged in the form of π-stacked arene dimers which were spatially isolated from each other by the bulky triphenylmethyl groups, and thus emitted bright excimer emission. The anthracene and pyrene derivatives showed fluorescence enhancement responses to grinding and the enhanced fluorescence could recover to the original state upon heating. The aggregation-induced emission (AIE) properties of them were dependent on the shapes and sizes of the polycyclic aromatic groups. The pyrene derivative showed the most excellent excimer-based AIE behavior among them. All of them were more apt to exhibit the excimer emission when formed nanoparticles with pluronic F-127 than that without pluronic F-127. Furthermore, PETP was utilized for bioimaging of living Hela cells and the high-resolution image was observed. [ABSTRACT FROM AUTHOR]

[Display omitted] • A phenothiazine coumarin based fluorescent probe (WX-Lyso) for the detection of ClO– was synthesized. • WX-Lyso displayed a low LOD (0.99 µm) and rapid responsive time to ClO– (<5 s). • WX-Lyso was proved successfully has good lysosomal-targeting and imaging abilities to ClO– in Hela cells. A new phenothiazine coumarin based probe WX-Lyso for detection of ClO– was developed. The probe showed obvious aggregation-induced emission (AIE) characteristic and exhibited a highly selective and sensitive turn-on fluorescence signal at 544 nm for ClO– with a large Stokes shift of 144 nm. The limit of detection (LOD) of ClO– was measured as low as 0.99 μM and a good line equation was obtained in the 0–50 μM concentration range. The detection mechanism was elucidated FT-IR, ESI-MS analysis and DFT. Furthermore, the probe had been demonstrated successfully has good lysosomal-targeting and high-contrast imaging abilities, which has the potential to become a new chemical tool and provide help for detecting ClO– in living systems. [ABSTRACT FROM AUTHOR]

This work presented a FRET-ICT based fluorescent probe (named NTC) composed of coumarin-benzothiazole as the acceptor and 4-nitrobenzo[ c ][1,2,5] oxadiazole (NBD) as the donor for the detection of SO 2 derivatives in NIR. Probe NTC possessed superior performance including selectivity, quickly response toward SO 3 2−/HSO 3 − and high energy transfer efficiency (94 %). The test strips provided a simple and effective tool in detecting the presence of bisulfite. Besides, NTC was applied to test the sulfur dioxide derivatives in food samples and cells. [Display omitted] • A NIR ratiometric fluorescent probe NTC was developed to detect sulfur dioxide derivatives. • NTC had a large Stokes shift of 150 nm and 94 % energy transfer efficiency. • NTC possessed good selectivity and sensitivity toward sulfur dioxide derivatives. • NTC was applied to detect sulfur dioxide derivatives in test strips, food samples and cell imaging. [ABSTRACT FROM AUTHOR]

[Display omitted] • The hydrogen sulfide NIR fluorescence probe (DCM-H 2 S) was designed and synthesized. • The probe DCM-H 2 S can specifically recognize H 2 S with a large emission wavelength (681 nm) and a large Stokes shift (121 nm). • The probe DHPC showed rapid response and high sensitivity (0.13 μM). • The probe DCM-H 2 S has been successfully applied to live cell imaging for real-time, dynamic tracking of exogenous and endogenous H 2 S. The signalling molecules of hydrogen sulphide (H 2 S) play an important role in a variety of physiological and pathological processes, and its abnormal concentration causes Down's syndrome, Alzheimer's disease and diabetes mellitus. Thus, the development of an effective detection tool is of vital importance and challenge. In this paper, we synthesized a new "turn-on" hydrogen sulfide near-infrared fluorescent probe (DCM-H 2 S). Remarkably, this probe demonstrated an unanticipated level of selectivity for hydrogen sulfide (H 2 S) over other analytes, rendering it suitable for the precise determination of H 2 S in both in vitro and in vivo settings. Expectedly, the probe exhibited unexpectedly heightened selectivity for H 2 S compared to other analytes, making it a viable option for the specific determination of H 2 S in both in vitro and in vivo applications. With the addition of H 2 S, the probe exhibited distinct turn-on near-infrared (NIR) fluorescence intensity alterations in the DMSO/H 2 O system, together with a high sensitivity (LOD = 0.13 μM) and large Stokes shift (121 nm). More importantly, the probe has been successfully applied to bioimaging for real-time, dynamic tracking of exogenous and endogenous H 2 S. The outcomes showed that the probe (DCM-H 2 S) provides a rapid and effective detection tool for monitoring H 2 S in vivo. [ABSTRACT FROM AUTHOR]

In most biophysiological processes, sulfur dioxide (SO 2) is an important intracellular signaling molecule that plays an important role. The change of SO 2 in cells are closely related to various diseases such as neurological disorders and lung cancer, so it is necessary to develop fluorescent probes with the ability to accurately detect SO 2 during physiological processes. In this work, we designed and synthesized a multifunctional fluorescent probe TIS. TIS has excellent properties such as near-infrared emission, large stokes shift, excellent SO 2 detection capabilities, low detection limit, high specificity and visualization of color change before and after reaction. Simultaneously, TIS has low cytotoxicity, good biocompatibility, clear cell imaging capability and mitochondrial targeting ability. In addition, the ability of TIS to be applied to different material surfaces for latent fingerprint fluorescence imaging was also explored. TIS provides an excellent method for the accurate detection of SO 2 derivatives and shows great potential applications in near-infrared cellular imaging and latent fingerprint fluorescence imaging. (a) TIS response mechanisms for HSO 3 −. (b) application of TIS. [Display omitted] • A NIR emission fluorescent probe with AIE characterization. • TIS has long emission wavelength (795 nm) and large Stokes shift (265 nm). • Dual detection channel for SO 2 derivatives accurate detection. • Superior colocalization effect on mitochondrial (0.86). • Clear three-level finger imaging capability. [ABSTRACT FROM AUTHOR]

[Display omitted] • A novel ratiometric peptide-based fluorescent probe DWPH was developed. • DWPH showed highly selective ratiometric response to Hg2+ and S2− in 100 % aqueous solutions. • Low detection limits for Hg2+ (24.6 nM) and S2− (23.3 nM) were obtained. • DWPH were successfully used to determine Hg2+ and S2− in living cells and zebrafish. • Smartphone-assisted detection platform could achieve visual assay of different Hg2+ and S2− concentrations. A new ratiometric peptide-based fluorescent probe DWPH was designed and synthesized, comprising dansyl fluorophore as a fluorescent dye, and tripeptide backbone (Trp-Pro-His-NH 2) as a recognition group. The addition of Hg2+ caused the maximum emission peak of DWPH to blue shift from 560 nm to 510 nm. DWPH exhibited large Stokes shift (230 nm), satisfactory water solubility (100 % aqueous medium), good selectivity (only Hg2+), high sensitivity (24.6 nM), rapid response (within 50 s) and strong anti-interference ability for Hg2+ detection over a wide pH range (7–11). Additionally, the complex DWPH -Hg2+ as a relay response probe could also be applied to S2− according to displacement approach. Notably, the detection limit for S2− was calculated as 23.3 nM, exhibiting that DWPH showed great potential for environmental monitoring and bioimaging. In addition, DWPH were successfully used to determine Hg2+ and S2− in living cells and zebrafish based on excellent permeability and low cytotoxicity. What's more, the gradient concentration color changes of Hg2+ and S2− were combined with the smartphone APP to obtain red–green–blue (RGB) values, thus enabling rapid semi-quantitative detection of Hg2+ and S2− without expensive instruments. [ABSTRACT FROM AUTHOR]

[Display omitted] • The probe EDPH specializes in the detection of H 2 S with high selectivity, high sensitivity and good detection limits. • The probe EDPH has been shown to have applications in intracellular fluorescence imaging. • Purine-based fluorescent probes for the detection of H 2 S are a new direction. Hydrogen sulfide (H 2 S) is a gas with a toxic odor that plays an irreplaceable role in physiological activities within the mammalian body. Therefore, it is important to do the distribution and quantitative detection of H 2 S in mammalian cells. In this paper, a fluorescence probe (EDPH) based on purine scaffold was designed and synthesized with high sensitivity and good selectivity. H 2 S induced ether bond breakage in EDPH , resulting in a significant redshift of the absorption band (from 370 nm to 500 nm) with a Stokes shift of 130 nm. After the addition of H 2 S, the fluorescence intensity of EDPH showed a good linear correlation with the concentration of H 2 S, which enabled the quantitative detection of H 2 S with a low limit of detection (41 nM). Finally, the EDPH was applied to the cellular Hele, and the probe has good cellularity imaging capability for the detection of H 2 S in living systems. [ABSTRACT FROM AUTHOR]

[Display omitted] • Two TPE fluorescence probes with morpholine/pyrrolidone group were synthesized. • TPE-Ma and TPE-Py exhibited AIE character and lysosome targeting capability. • Two-photon fluorescence nanoprobes labels lysosomes in MCF-7 cells. Lysosomes are essential cellular organelles, serving vital functions in cellular metabolism and degradation. The design of specifically targeting lysosomes probes with aggregation-induced emission (AIE) characteristics using two-photon excitation techniques is significance and challenging work. Here we designed and synthesized two tetraphenylethylene (TPE)-based AIE fluorescence probes, naming TPE-Ma and TPE-Py , with TPE as the matrix and morpholine (Ma) or pyrrolidone (Py) as the targeting group. These probes exhibit a significant Stokes shift, low cytotoxicity, two-photo fluorescence imaging and lysosome-specific targeting capability ensuring their suitability for fluorescence imaging applications. To enhance the water solubility and cellular accumulation of TPE-Ma and TPE-Py in tumor cells, we employed a biocompatible polymer 1,2-distearoyl- sn -glycero-3-phosphoethanolamine-N-[methoxy(polyethylene glycol)-2000] (DSPE-mPEG 2000) as a nanocarrier. By encapsulating TPE-Ma and TPE-Py within DSPE-mPEG 2000 , we successfully developed two AIE fluorescent nanoprobes known as DSPE@ TPE-Ma and DSPE@ TPE-Py. The results demonstrated that fluorescent nanoprobes DSPE@ TPE-Ma and DSPE@ TPE-Py possess excellent cell permeability, biocompatibility, superior photostability and specific targeting towards lysosomes in MCF-7 cells. Our findings highlight the potential of these fluorescent nanoprobes as effective tools for two-photon fluorescence imaging and targeted detection of lysosomes in cancer cells. [ABSTRACT FROM AUTHOR]

The filamentous protein 'actin' plays an essential role in maintaining a proper cellular health and any disruption in its structure and dynamics may induce the growth and metastasis of cancerous cells. Recent studies have shown that, actin can serve as a potential therapeutic target and an indicator to examine the efficacy of modern chemotherapeutic agents. In this regard, the microscopy imaging of actin using fluorescent dyes can pave the way toward development of efficient drugs for cancer treatment. Herein, we report the synthesis of an organic fluorescent dye (BCH) which shows good selectivity toward F-actin at physiological pH. The dye displays a large Stokes shift (∼232 nm), strong emission intensity, good photostability and great sustainability over a wide pH range of 2–10. The dye can directly bind and localize in the actin-rich region of gut, testes and eye of a model organism, Drosophila melanogaster in both living and fixed cells and enable their confocal microscopy imaging without using any actin binding domain. Interestingly, the BCH dye is proved to be nontoxic in the tested organism and has been successfully employed as a potential tool to visualize cellular actin in living tissues of larva and pupa of the organism. [Display omitted] • A benzil biscoumarinyl hydrazone based fluorescent dye has been synthesized. • The dye can bind and image cellular filamentous actin directly without any binding domain. • The dye is proved to be nontoxic in model organism Drosophila melanogaster. • The dye has been successfully employed to visualize cellular actin in living tissues of larva and pupa of the organism. [ABSTRACT FROM AUTHOR]

[Display omitted] • Tetraphenylimidazole (TPI)-based styryl dyes TPI-In , TPI-Bt , and TPI-Qu exhibited polarity sensitivity. • TPI-Qu and TPI-Bt were viscosity-sensitive with extremely high fluorescence quantum yields in a dense environment. • The hues of TPI-In , TPI-Qu , and TPI-Bt solutions changed in response to their acidic and basic nature. • Only TPI-Qu and TPI-Bt fluoresced more brightly in high-viscosity cellular environments. Fluorescence probes have grown to be incredibly popular tools for measuring viscosity because of their high sensitivity, ease of use, and capacity to detect a microscopic scale. In this study, we developed a new line of excited-state intramolecular proton transfer (ESIPT)-based styryl fluorescent dyes based on tetraphenylimidazole (TPI) for measuring cellular viscosity. These dyes have good photophysical properties, including significantly large Stokes shifts and sensitivity to the hydrogen-bonding donor/acceptor solvent, according to the ESIPT characteristic. By observing variations in fluorescence, TPI-Bt , and TPI-Qu demonstrated exceptional sensitivity to viscosity in a water/glycerol system and substantial sensitivity to pH in a buffered water system. Furthermore, first-principles computations, crystallography, and application in living cells all supported the behaviors of the dyes in viscous environments. [ABSTRACT FROM AUTHOR]

[Display omitted] • A new benzobodipy based fluorescent probe for HOCl has been designed and developed. • The probe has excellent sensitivity with a fast response to HOCl. • The probe was applied to the fluorescence imaging of HOCl in HeLa cells and zebrafish. Hypochlorous acid (HOCl) is a significant reactive oxygen species within biological systems, and its anomalous metabolism has been linked to a range of diseases. Therefore, it is crucial to track and monitor the concentration of HOCl in living organisms to understand its biological functions and study its pathogenic mechanisms. In this study, we developed a photoinduced electron transfer (PeT) mechanism-based benzo-fused bodipy fluorescence probe, named BBy-Se , for highly sensitive and selective detection of HOCl in aqueous solutions. BBy-Se demonstrated a good turn-on fluorescence response to HOCl by specifically oxidizing the selenium atom. It exhibited significant Stokes shift (82 nm), low detection limit (10.9 nM) and rapid response (less than 10 s). Furthermore, the probe was successfully employed for real-time fluorescence imaging of HOCl in living HeLa cells and zebrafish, as demonstrated by the bioimaging results. The development of BBy-Se presents a new approach to explore the biological roles of HOCl and offers a valuable tool for studying its function in diseases. [ABSTRACT FROM AUTHOR]

[Display omitted] • A fluorescent probe based on 1,3,5-Triazine was designed and synthesized to detect Hg(Ⅱ). • The novel fluorescent probe exhibited high selectivity, good stability, large Stokes shift (100 nm). • The novel fluorescent probe has been successfully used for cell and zebrafish imaging. • The novel fluorescent probe has successfully detected Hg(II) in tobacco. Non-biodegradable, bioaccumulative, and highly toxic, mercury(II) poses a significant threat to both ecosystems and human health. Extensive data indicates that even extremely low levels of Hg(II) can cause significant harm to human health. In this paper, the thiocarbonate specific recognition site was used for the detection of Hg(II), which was successfully synthesized by the hydroxyl group of 1,3,5-Triazine with phenyl chlorothiocarbonate. The probe exhibited advantages of high sensitivity (0.253 μM), good selectivity, large Stokes shift (100 nm), and good biocompatibility. The probe TzAr-Nap-Hg successfully fluorescently imaged Hg(II) in cells, zebrafish and tobacco, making it possible to detect the content of Hg(II) in agricultural and sideline products. [ABSTRACT FROM AUTHOR]

[Display omitted] • An "off–on" long-wavelength fluorescent probe is synthesized for Cys detection. • The probe has a large Stokes shift (211 nm) and reacted with Cys specifically. • The probe can monitor Cys fluctuations caused by redox imbalance in HepG2 cells. • The probe can be used for fluorescence imaging in cells and mice. In this research, an "off–on" long-wavelength fluorescent probe (DCMN-Cl) based on (E)-2-(3-(2-(6-hydroxynaphthalen-2-yl)vinyl)-5,5-dimethylcyclohex-2-en-1-ylidene) malononitrile (DCMN) is designed and synthesized for cysteine (Cys) detection. DCMN-Cl exhibits a large Stokes shift (211 nm) and shows rapid response and high specificity to Cys. The fluorescence initensity at 635 nm reveals a good linear relationship with Cys concentration in the 0 to 50 μM range, and the detection limit is as low as 159 nM. The probe is also used for fluorescence imaging of Cys in cells and mice. Moreover, the probe provided visual evidence of Cu2+ and curcumin-induced intracellular Cys fluctuations. [ABSTRACT FROM AUTHOR]

[Display omitted] • The conjugated structures of fluorescent dyes (NapPAs) were extended by the introduction of phenylethynyl, and the effects of different substituents at the p -position of phenylacetylene on the geometry, frontier orbital electron distribution, energy gap and photophysical properties of the dyes were studied. • Correlating the theoretical calculation results with the experimentally measured spectra, it was found the dyes exhibited the characteristics predicted by theoretical calculations, and various properties of the dyes could be regulated through structural modification during molecular design. • Two dyes (NapPA-LDs and NapPA-LDs-Lyso) with excellent photophysical properties (large Stokes shift, high polarity-viscosity sensitivity, good biocompatibility) were selected as fluorescent probes for bioimaging. • NapPA-LDs exhibited remarkable affinity towards LDs with excellent imaging effect, and enabled monitor the dynamic changes and movements of LDs in real time, helping to uncover previously unexplored cellular mechanisms. • NapPA-LDs-Lyso enabled simultaneous two-color imaging of LDs and lysosomes, which could monitor the dynamic changes, movements and dynamic behavior (aggregation, dissociation and fusion) of LDs and lysosomes in real time, and could serve as a potential tool to study the interactions and potential functions between LDs and lysosomes. A series of fluorescent dyes (NapPAs) based on 4-phenylacetylene-1,8-naphthalimide were synthesized and characterized, whose conjugated structures were extended by the introduction of phenylethynyl. Furthermore, changes in the photophysical properties of the dyes when substituents with varying electron richness were introduced at the p -position of phenylacetylene were studied. The theoretical calculation of the dye molecules was carried out by B3LYP functional and 6-31G(d,p) basis set, and the effects of different substituents at the p -position of phenylacetylene on the electronic structure and photophysical properties of the dyes were studied by theoretical calculation results. Theoretical calculations provided a reliable means of predicting the properties of dyes, which could help in the design of more efficient and novel dyes. To verify the practicability of the dyes, two dyes with excellent photophysical properties (large Stokes shift, high polarity-viscosity sensitivity, good biocompatibility) were selected as fluorescent probes for visualization of LDs and two-color imaging of LDs and lysosomes. Cell imaging showed that NapPA-LDs and NapPA-LDs-Lyso serve as excellent imaging tools to monitor the dynamic changes, movements, and behaviors of LDs and lysosomes in real time. Notably, NapPA-LDs-Lyso held promise as a potential tool to study the interaction between LDs and lysosomes. [ABSTRACT FROM AUTHOR]

[Display omitted] • Probe FBC-DS performed sufficient selectivity, fast response time, high sensitivity and a large Stokes shift to HClO. • FBC-DS was applied for imaging of exogenous and endogenous HClO in living HeLa cells and zebrafish with satisfactory performances. • FBC-DS was applied for corroborating that HClO could be an efficient marker for APAP-induced hepatotoxicity in the mice liver injury models. Drug-induced liver injury (DILI), as a classic acute inflammation, has attracted widespread concern due to its unpredictability and severity. Among the various reactive oxygen species, HClO has been used as a marker for the detection of DILI process. Thus, we designed and synthesized a "turn-on" fluorescent probe FBC-DS by modifying 3'-formyl-4'-hydroxy-[1,1'-biphenyl]-4-carbonitrile (FBC-OH) with N, N-dimethylthiocarbamate group for sensitively sensing HClO. Probe FBC-DS showed a low detection limit (65 nM), fast response time (30 s), an enormous Stokes shift (183 nm) and 85-fold fluorescence enhancement at 508 nm in the detection of HClO. Probe FBC-DS could monitor exogenous and endogenous HClO in living HeLa cells, HepG2 cells and zebrafish. In addition, probe FBC-DS has been successfully utilized in biological vectors for imaging acetaminophen (APAP)-induced endogenous HClO. Moreover, DILI caused by APAP is evaluated by probe FBC-DS through imaging over-expression of endogenous HClO in the mice liver injury models. All in all, we have every reason to believe that probe FBC-DS can be a potential tool to study the complex biological relationship between HClO and drug-induced liver injury. [ABSTRACT FROM AUTHOR]

[Display omitted] • Probes 1a-b for detection of thiophenols by ESIPT mechanism were constructed with diethylcoumarin–salicylaldehyde units. • They showed large Stokes shift (greater than100 nm) and one of them displayed NIR-emitting (670 nm) when detecting thiophenols. • Probes 1a-b could form inclusion complexes with M-β-CD. • The presence of M-β-CD reduced the detection limits of probes 1a - b towards thiophenols. Thiophenol and its derivatives are compounds with high toxicity to organisms and environmental pollution, so it is necessary to detect the level of thiophenols in the environment and biological samples. The probes 1a-b were obtained by introducing the 2,4-dinitrophenyl ether group into diethylcoumarin–salicylaldehyde based compounds. And they can form host-guest compounds with methylated β-cyclodextrin (M-β-CD), the association constants of inclusion complexes are 49.2 M−1, 125 M−1 respectively. The fluorescence intensities of probes 1a-b at 600 nm (1a) and 670 nm (1b) increased significantly in thiophenols detection. Meanwhile, with the addition of M-β-CD, the hydrophobic cavity of M-β-CD significantly increased the fluorescence intensity of probes 1a-b , thus the detection limits of probes 1a-b to thiophenols were reduced from 410 nM, 365 nM to 62 nM, 33 nM respectively. Whereas, the good selectivity and short response time of probes 1a-b towards thiophenols was not affected in the presence of M-β-CD. Moreover, probes 1a-b were used for further water sample detection and HeLa cell imaging experiments due to their good response to thiophenols and the results suggested that probes 1a-b had the potential to detect the content of thiophenols in water samples and living cells. [ABSTRACT FROM AUTHOR]

Peroxynitrite (ONOO−), as an important reactive oxygen species (ROS), plays a significant role in pathological and physiological processes, and abnormal levels of ONOO− will lead to many diseases. Thus, novel fluorescent probe for detecting ONOO− is in urgent need. Herein, we constructed a probe TPPB with aggregation-induced emission (AIE) characteristic based on triphenylamine and boronate group. The probe TPPB possesses remarkable performances including high selectivity in the presence of other ROSs, low detection limit (32 nM) and large Stokes shift (215 nm) toward ONOO−. Besides, probe TPPB shows low cytotoxicity and good imaging ability of ONOO− in living cells. [Display omitted] [ABSTRACT FROM AUTHOR]

This study reported a unique mitochondria-targetable phosphorescent 'on-off-on' probe, Ir-DPA, based on an iridium(III) complex derivative for the sequential and specific detection of Cu2+ and Cys in vitro and in vivo. Probe Ir-DPA was constructed by a lipophilic cation unit as the chromophore as well as the mitochondria biomarker and a dipicolylamine (DPA) group as the recognition unit for Cu2+, followed by removal of Cu2+ specifically in the presence of Cys. The probe itself was strongly emissive at 570 nm. Upon addition of Cu2+, marked quenching occurred as result of the binding of Cu2+ with DPA moiety of this probe, accompanied by a distinct naked-eye luminescence color change from orange yellow to colorless. Additionally, further addition of Cys, the displacement of Cu2+ from in situ generated Ir-DPA-Cu ensemble because of the large nucleophilicity of cysteine toward Cu2+ led to the release of probe, giving rise to the luminescence recovery, as well as a relevant chromogenic change from colorless to orange yellow. Ir-DPA showed a large Stokes shift of 200 nm and high selectivity and sensitivity for the rapid detection of Cu2+ and Cys under physiological conditions, with low detection limits of 0.04 μM and 1.21 μM for Cu2+ and Cys, respectively. More importantly, the probe successfully targeted mitochondria, sensitively detected Cu2+ and exogenously or endogenously generated Cys both in mitochondria of living cells and zebrafish. Finally, Ir-DPA was capable of quantifying Cu2+ level in water samples and the in situ generated ensemble identifying Cys in human serum. These results indicated the great potential of Ir-DPA for monitoring Cu2+ and Cys in environmental, biological systems, and mitochondrial processes. A mitochondria-targetable phosphorescent 'on-off-on' probe for sequentially and selectively detecting Cu2+ and cysteine has been achieved based on Cu2+-displacement reaction. [Display omitted] • A mitochondria-targetable phosphorescent 'on-off-on' probe for the specific detection of Cu2+ and cysteine was developed. • The probe exhibited a sequential orange yellow-colorless-orange yellow phosphorescent response to Cu2+ and cysteine. • The probe was successfully used for imaging Cu2+ and cysteine both in mitochondria of living cells and animals. [ABSTRACT FROM AUTHOR]

[Display omitted] • A novel open-type NIR fluorescent probe was reported for the detection of PhSH. • The probe shows high sensitivity and selectivity to thiophenol. • Probe shows a large Stoke shift and significant fluorescence enhancement. • Probe has been applied to the detection of PhSH in living cells and water samples. In this study, a NIR fluorescent probe based on ICT principles was developed for the detection of phenylthiophenol. An excellent fluorescent mother nucleus is constructed with tricyano groups, and benzenesulfonate was introduced as a specific recognition site for thiophene, which can be used for rapid detection of thiophenol. The probe has a significant Stokes shift (220 nm). Meanwhile, it had rapid response to thiophene and high specificity. The fluorescence intensity of the probe at 700 nm showed a good linear relationship with thiophene concentration in the range of 0 to 100 μM, and the detection limit was as low as 45 nM. The probe had also been successfully applied to the detection of thiophene in real water samples. MTT assay showed low cytotoxicity and excellent fluorescence imaging in live cells. [ABSTRACT FROM AUTHOR]

On the basis of classical Schiff base reaction, two novel and efficient fluorescent probes (DQNS , DQNS1) were designed and synthesized by introducing Schiff base structure into dis-quinolinone unit for structural modification, which can be used to detect Al 3+ and ClO −. [Display omitted] • The double-recognition fluorescent probes with the same site designed based on ICT and PET mechanism has the characteristics of simple synthesis method. • Preliminary speculation, the probe (DQNS) has continuity in identifying Al3+and ClO−. • The probes (DQNS) can primarily screen and analyze environmental samples and living cells containing Al3+and ClO−. On the basis of classical Schiff base reaction, two novel and efficient fluorescent probes (DQNS , DQNS1) were designed and synthesized by introducing Schiff base structure into dis-quinolinone unit for structural modification, which can be used to detect Al3+ and ClO−. Because the power supply capacity of H is weaker than that of methoxy, DQNS shows better optical performance: a large Stokes Shift (132 nm), identify Al3+ and ClO− with high sensitivity and selectivity, low detection limit (29.8 nM and 25 nM) and fast response time (10 min and 10 s). Through the working curve and NMR titration experiment, the recognition mechanism of Al3+ and ClO− (PET and ICT) probes are confirmed. Meanwhile, it is speculated that the probe has continuity for the detection of Al3+ and ClO−. Furthermore, DQNS detection of Al3+ and ClO− was applied to real water samples and living cell imaging. [ABSTRACT FROM AUTHOR]

The abnormality of Cys concentration in organism could lead to a series of diseases, so its effective detection is of great importance in disease diagnosis. Here we developed a novel ESIPT fluorescent probe HBT-IDAc based on the classic ESIPT fluorophore 2-(2′-hydroxyphenyl)benzothiazole (HBT) and indanone, which could selectively and sensitively detect Cys with a large Stokes shift up to 210 nm and the detection limit to 0.89 μM. In addition, the probe exhibited good anti-interference and low cytotoxicity, and has been successfully applied to monitor Cys in cells. • A novel ESIPT fluorescent probe for selective and sensitive detection of Cys was developed. • The probe has the large stokes shift (210 nm) and good LOD (0.89 μM) in aqueous environment. • The probe exhibits low cytotoxicity and has been applied for imaging Cys in cells. [ABSTRACT FROM AUTHOR]

Mercury ion (Hg2+) is highly toxic to the environment and organisms, therefore, monitoring and quantitative detection of Hg2+ is of great significance. In this work, a new fluorescent probe TPEH that integrated tetraphenylethene (TPE) and 2-(2 ′ -hydroxyphenyl)benzothiazole was designed and synthesised. In EtOH/HEPES (2:8, v/v, pH = 7.2) solution, TPEH displays fluorescence turn on detection of Hg2+ with the advantages of swift response (<100 s), high selectivity and strong disturbance-resistant, a large Stokes shift (220 nm), and low limit of detection (81.7 nM). The sensing mechanism was proved to be Hg2+-triggered releasing of the aggregation-induced emission (AIE)-active precursor compound 2. TPEH has been successfully applied to detect Hg2+ in seafood and tea, and image Hg2+ in living cells. In addition, TPEH can be used to detect the content of Hg2+ in actual water samples with the aid of smartphone. [Display omitted] • A new AIE-based fluorescent probe TPEH for Hg2+ detection has been developed. • TPEH has the advantages of rapid response (<100 s), a large Stokes shift (220 nm), and a low detection limit (81.7 nM). • TPEH can detect Hg2+ in seafood and tea, and image Hg2+ in living cells. • TPEH can detect Hg2+ in actual water samples with the help of smartphone. [ABSTRACT FROM AUTHOR]

The fluorescent probe with both aggregation-induced emission (AIE) and excited-state intramolecular proton transfer (ESIPT) shows significant advantages, such as no self-quenching at high concentration, large Stokes shift, high selectivity towards analyte etc. Based on tetraphenylethene and ESIPT structural modules, three AIE-ESIPT molecules containing one different atom (S, O, N) have been constructed in this paper. The effects of three atoms on the optical properties of fluorescent molecules have been investigated by fluorescence spectroscopy and X-ray crystallographic analyses. Interestingly, the cyclic detection of HCl and NH 3 gases can be achieved with the BTY-TPE -based portable test paper. In addition, BOY-TPE and HBIY-TPE can detect ClO− by naked eye with low detection limit, good biocompatibility. Three AIE-ESIPT fluorescent probes respectively containing S, O, N atoms have been synthesized. The effects of S, O, and N atoms on the optical properties of fluorescent molecules have been investigated by fluorescence spectroscopy and X-ray crystallographic analyses and DFT calculation. The results indicate that all three exhibit AIE and ESIPT properties, X-ray crystallographic analysis indicate a significant difference in molecular packing, which should be the dominant factor in the polymorph dependence of ESIPT luminescence. It is interesting to note that BTY-TPE -based test paper can be used for cyclic detection of HCl and NH 3 gases. In addition, BOY-TPE and HBIY-TPE can be used as intracellular probes for detecting ClO−.[ [Display omitted] ] • Three AIE-ESIPT double-mechanism fluorescent crystals have been synthesized. • Effects of S, O, and N on the properties of three fluorescent crystals were discussed. • BTY-TPE -based test strip could repeatable detect HCl and NH 3 gases. • Both BOY-TPE and HBIY-TPE with extremely low detection limit for detecting ClO−. • Both BOY-TPE and HBIY-TPE could detect ClO− in living cells. [ABSTRACT FROM AUTHOR]

[Display omitted] • A novel probe BD-C based on the FRET-ICT mechanism was designed to detect cysteine. • Probe BD-C had superior selectivity without the interference of other biological thiols. • Probe BD-C had large Stokes shift and the energy transfer efficiency reached 98.8%. • Probe BD-C had superior endoplasmic reticulum-targeting. Cysteine is an important thiol amino acid that is abundantly present in cells and has an important function in various life processes of the human body. Therefore, it is of great significance to develop an accurate method for monitoring cysteine concentration in cells. We designed and synthesized a novel FRET-ICT-based ratiometric fluorescence and colorimetric probe (BD-C) for detecting cysteine. As cysteine was gradually added, the fluorescence intensity of probe BD-C in buffer solution decreased at 614 nm and increased at 428 nm. The logarithm of the fluorescence intensity ratio to cysteine exhibited favorable linearity in the concentration range of 0.5–14.0 μM, with a detection limit of 395 nM. The energy transfer efficiency of this FRET system is up to 98.8%. BD-C demonstrated preeminent selectivity for cysteine and could specifically react with cysteine, though other sulfhydryl amino acids, such as GSH and Hcy, were present. Furthermore, BD-C exhibited outstanding targeting ability to the endoplasmic reticulum (ER) and was successfully applied in cellular imaging. [ABSTRACT FROM AUTHOR]

[Display omitted] • A red-emissive fluorescent probe HBTI for reversible recognition of HSO 3 − and H 2 O 2 has been developed. • HBTI showed fluorescence on–off-on variations upon sequential addition of HSO 3 − and H 2 O 2. • HBTI is applicable to detect HSO 3 − in real food samples. • HBTI is mitochondria-targetable and can be used in cell imaging. Reducing agent SO 2 and oxidant H 2 O 2 are two essential substances in cells, and the balance between them is closely related to the survival of cells. SO 2 derivative HSO 3 − is often used as food additive. Therefore, simultaneous detection of SO 2 and H 2 O 2 is of great significance in biology and food safety. In this work, we successfully developed a mitochondria-targeted red fluorescent probe (HBTI), which has excellent selectivity, high sensitivity and large Stokes shift (202 nm). HBTI and HSO 3 −/SO 3 2− undergo Michael addition on the unsaturated C=C bond, and the addition product (HBTI-HSO 3 −) can react with H 2 O 2 to restore the conjugated structure. Fluorescence changes from red to non-emissive and then restores to red, and can be detected quickly and visually. In addition, HBTI has been successfully targeted mitochondria, and achieved dynamic reversible response to SO 2 /H 2 O 2 in living cells, and has been successfully applied to detect SO 2 in food samples. [ABSTRACT FROM AUTHOR]

Hypochlorous acid (HOCl) is a crucial reactive oxygen species in biological systems, and its abnormal metabolism is associated with various diseases. Therefore, it is essential to accurately detect HOCl to understand its biological function and develop related therapeutic strategies for diseases. In this work, we developed a novel fluorescence probe, BCy-S , based on the twisted intramolecular charge transfer (TICT) mechanism for rapid and sensitive detection of HOCl in an aqueous solution. The probe exhibited a significant turn-on fluorescence response to HOCl, with high selectivity, rapid kinetics (less than 40 s), large Stokes shift (about 170 nm), and low detection limit (35.2 nM), based on the specific oxidation reaction of HOCl with sulfur atoms. Additionally, the outcomes of the bioimaging experiment showed that BCy-S was capable of real-time fluorescence visualization of HOCl in living HeLa cells and zebrafish. The development of BCy-S presents a new tool for investigating the physiological function of HOCl and its pathological role in diseases. [Display omitted] • A new TICT-based HOCl fluorescent probe has been designed and developed. • The probe exhibits an excellent sensitivity, large Stokes Shift and low detection limit to HOCl. • The probe could be applied for real-time fluorescence imaging of HOCl in live HeLa cells and zebrafish. [ABSTRACT FROM AUTHOR]

[Display omitted] • A colorimetric and near-infrared fluorescent F- based on malononitrile isophorone derivatives have been designed and synthesized. • It can selectively make Si-O bond breakage probes that can respond specifically to F- and have high sensitivity with a detection limit of 6.59 × 10-7 mol/L. The probe YC-Si has a large Stokes shift at 678 nm (168 nm). • In cell imaging experiments it was demonstrated that YC-Si has cell permeability and low cytotoxicity and can be used to detect F- in living cells. In this study, we have successfully designed and synthesized a colorimetric and near-infrared fluorescent probe YC-Si for F- detection based on malononitrile isophorone derivatives which can selectively make Si-O bond breakage probes that can respond specifically to F- and have high sensitivity with a detection limit of 6.59 × 10-7 mol/L. The probe YC-Si has a large Stokes shift at 678 nm (168 nm). In cell imaging experiments it was demonstrated that YC-Si has cell permeability and low cytotoxicity and can be used to detect F- in living cells.. [ABSTRACT FROM AUTHOR]

• Two polarity-sensitive fluorescent probes (NNap-LD-Ⅰ , NNap-LD-Ⅱ) with D-A-D structures were accurately synthesized by a simple synthetic method. • The two fluorescent probes (NNap-LD-Ⅰ , NNap-LD-Ⅱ) exhibit good photophysical properties, such as bright fluorescence, large Stokes shift, and resistance to chemical interference. • Both fluorescent probes (Nap-LD-Ⅰ , Nap-LD-Ⅱ) easily penetrate the cell membrane, specifically localize and aggregate in lipid droplets and lysosomes with low cytotoxicity, and yellow and red fluorescent lipid droplets and lysosomes can be observed. • Both fluorescent probes (NNap-LD-Ⅰ , NNap-LD-Ⅱ) were further investigated for the separate targeting of lysosomes and lipid droplets in HepG2 cells. • Both fluorescent probes (NNap-LD-Ⅰ , NNap-LD-Ⅱ) can be used for imaging of zebrafish. Lipid droplets (LDs) and lysosomes, vital subcellular organelles in cells, played irreplaceable roles in the areas involved in the synthesis of cell membranes, the movement of substances and the transfer of energy. Moreover, the imbalance of LDs could cause the occurrence of certain diseases, such as cardiovascular disease, liver cancer, atherosclerosis and diabetes. LDs and lysosomes interact in some biological processes. In this work, two polarity-sensitive fluorescent probes (NNap-LD-Ⅰ , NNap-LD-Ⅱ) were developed and synthesized by simple 1,8-naphthalimide scaffold modifications, which exhibited large Stokes shifts (173 nm and 190 nm), viscosity, pH stability and interference resistance. Notably, they were biocompatible and showed good targeting for bioimaging. LDs, lysosomes in HepG2 cells and zebrafish could be marked by bright yellow and red fluorescence after incubation with probes (NNap-LD-Ⅰ , NNap-LD-Ⅱ). In addition, HepG2 cells were stained for NNap-LD-Ⅰ and NNap-LD-Ⅱ to monitor the corresponding reduction in the number of LDs in starvation-treated cells. Similarly, the targeting of the probes to the lysosomes was diminished during imaging after the cells were treated with chloroquine (CQ), resulting in a reduction in lamellar fluorescence. These remarkable characteristics suggested that the probes NNap-LD-Ⅰ and NNap-LD-Ⅱ were quite efficient fluorescent probes with good visualization of LDs and lysosomes. [ABSTRACT FROM AUTHOR]

• A novel NIR colorimetric-fluorescence probe was prepared for detection of hydrogen sulfide. • The probe showed rapid, specific and sensitive detection of hydrogen sulfide with a large Stokes shift. • The probe was capable of imaging hydrogen sulfide in living cells and mice. We presented here a novel near-infrared fluorescent probe based on 2-(2′-hydroxyphenyl)benzothiazole -dicyanoisophorone as fluorophore and 2,4-dinitrobenzenesulfonyl moiety as detection functionalized group for the discrimination of hydrogen sulfide (H 2 S). Probe L exhibited good specificity and sensitivity "turn on" response at 720 nm with a large Stokes shift (155 nm), rapid response (< 60 s) and low detection limit (3.15 × 10−7 M), which also could be identified by the naked eyes. Moreover, probe L was successfully used to image exogenous/endogenous H 2 S in cells and mice, which demonstrated its potential applications in living systems. A novel fluorescein based on 2-(benzo[ d ]thiazol-2-yl)phenol-dicyanoisophorone probe was constructed for the discrimination of hydrogen sulfide. The probe was applied for the rapid, sensitive, large Stokes shift, colorimetric and large near-infrared fluorometric determination of H 2 S, based on the displacement approach. The low cytotoxicity and excellent imaging performance was successfully applied for mitochondrial localization in living cells and endogenous and exogenous H 2 S detection in vivo. [Display omitted] [ABSTRACT FROM AUTHOR]

[Display omitted] • A near-infrared ratiometric fluorescent probe (DCPBCl 2 -Hz) was developed. • DCPBCl 2 -Hz exhibited excellent sensitivity and selectivity for hydrazine. • The probe can monitor gaseous hydrazine with a content down to 1 ppm (mg/m3). • The probe was applied for detecting hydrazine in solid and in live cells. Hydrazine (N 2 H 4) is a widely used raw material in the chemical industry, but at the same time hydrazine has extremely high toxicity. Therefore, the development of efficient detection methods is crucial for monitoring hydrazine in the environment and evaluating the biological toxicity of hydrazine. This study reports a near-infrared ratiometric fluorescent probe (DCPBCl 2 -Hz) for the detection of hydrazine by coupling a chlorine-substituted D-π-A fluorophore (DCPBCl 2) to the recognition group acetyl. Due to the halogen effect of chlorine substitution, the fluorophore has an elevated fluorescence efficiency and a lowered pKa value and is suitable for physiological pH conditions. Hydrazine can specifically react with the acetyl group of the fluorescent probe to release the fluorophore DCPBCl 2 , so the fluorescence emission of the probe system significantly shifted from 490 nm to 660 nm. The fluorescent probe has many advantages, such as good selectivity, high sensitivity, large Stokes shift, and wide applicable pH range. The probe-loaded silica plates can realize convenient sensing gaseous hydrazine with content down to 1 ppm (mg/m3). Subsequently, DCPBCl 2 -Hz was successfully applied to detect hydrazine in soils. In addition, the probe can also penetrate living cells and allow the visualization of intracellular hydrazine. It can be anticipated that probe DCPBCl 2 -Hz will be a useful tool for sensing hydrazine in biological and environmental applications. [ABSTRACT FROM AUTHOR]

[Display omitted] • A new benzo-bodipy based fluorescent probe for HClO has been designed and developed. • The probe has excellent sensitivity and a fast response to HClO. • The probe was applied to the fluorescence imaging of HClO in HeLa cells and zebrafish. Due to the highly significant biological activity of hypochlorous acid, the monitoring of its concentration in vivo has received extensive attention. In this work, a photoinduced electron transfer (PeT) based benzo-bodipy fluorescent probe BBy-T has been developed for the rapid, sensitive, and selective detection of HClO in an aqueous solution. Based on the HClO-specific oxidation reaction, BBy-T exhibited a distinct fluorescence turn-on response to HClO with a remarkable Stokes shift (84 nm), immediate response (less than 20 s), and low detection limit (13.7 nM). In addition, the bioimaging results indicated that the probe BBy-T could be applied to real-time fluorescence imaging of living HeLa cells as well as living zebrafish. [ABSTRACT FROM AUTHOR]

[Display omitted] • A new lysosome-targeted fluorescent probe FAP1 for the recognition of FA was developed. • Probe FAP1 showed high sensitivity and selectivity for detecting FA with a large Stokes shift (130 nm). • Probe FAP1 exhibited good biocompatibility and could be used to image FA in lysosome. Formaldehyde (FA) is one of reactive carbonyl species (RCS), which is involved in various physiological and pathological processes of organisms. Herein, a novel fluorescent probe (FAP1) containing lysosomal localization group for the detection of FA was designed and synthesized. The probe exhibited good fluorescence recognition performances for FA, such as large Stokes shift (130 nm), specific selectivity, good anti-interference ability, and low minimum detection limit (16 nM). It is worth mentioning that the probe has good biocompatibility and could be applied to the imaging detection of FA in lysosome. [ABSTRACT FROM AUTHOR]

In this work, by installing a bicyclic ring system into the skeleton of traditional coumarin-hemicyanines (CHC s), a new class of conformationally restrained coumarin-hemicyanines (RCHC s) were constructed, which showed dramatically improved fluorescence quantum yields (close to near-unity in CH 2 Cl 2), while retaining the large Stokes shifts of CHC s. The feature was also reflected in living cell imaging, where the representative RCHC s, i.e. RCHC1 and RCHC2 , showed significantly improved intracellular fluorescence brightness relative to control dye CHC1 , along with excellent lysosome and mitochondria targetability. Based on RCHC1 platform, a carboxy-functionalized derivative, i.e., RCHC1-COOH , was developed, and its potential in fluorescently discriminating between cancer and normal cells was demonstrated in terms of its specific accumulation in lipid rafts localized in plasma membrane and enriched in cancer cells. Based on RCHC2 platform, a photosensitizer (PS) RCHC2-I was exploited for photodynamic therapy (PDT) of tumor, which exhibited markedly enhanced singlet oxygen generating ability due to its strong propensity to form aggregates. In vitro and in vivo PDT assays proved that RCHC2-I could cause extensive cancer cell death and tumor ablation upon light irradiation. [Display omitted] • Conformationally Rigid coumarin-hemicyanines with improved quantum yields were developed. • Living cells loaded with these dyes showed obviously enhanced fluorescence brightness. • Imaging application in fluorescently discriminating cancer cells from normal cells was demonstrated. • Developed photosensitizer displayed enhanced 1O 2 -generating efficacy and cancer cell killing ability. [ABSTRACT FROM AUTHOR]

In this work, a novel FRET-based fluorescent probe (named CBC) was developed to detect bisulfite with outstanding selectivity by ratiometric method. Probe CBC exhibited excellent sensitivity toward HSO 3 − within 1 equivalent. The cell imaging of CBC indicated that it could detect exogenous and endogenous bisulfite with excellent photostability and low cytotoxicity. What's more, probe CBC realized the lipid droplet targeting. Therefore, probe CBC has the capacity to be used as a biological tool to monitor the bisulfite changes in vivo. [Display omitted] • A novel ratiometric fluorescent probe CBC was developed to detect sulfur dioxide derivatives. • CBC had a large Stokes shift of 230 nm and 95.7% energy transfer efficiency. • CBC possessed good selectivity and sensitivity toward sulfur dioxide derivatives. • CBC achieved detection sulfur dioxide derivatives in living cells and targeted lipid droplets. [ABSTRACT FROM AUTHOR]

Glutathione (GSH) is present in almost every cell in the body and plays various integral roles in many biological processes. The Golgi apparatus is a eukaryotic organelle for the biosynthesis, intracellular distribution, and secretion of various macromolecules; however, the mechanism of GSH in the Golgi apparatus has not been fully elucidated. Here, specific and sensitive sulfur-nitrogen co-doped carbon dots (SNCDs) with orange-red fluorescence was synthesized for the detection of GSH in the Golgi apparatus. The SNCDs have a Stokes shift of 147 nm and excellent fluorescence stability, and they exhibited excellent selectivity and high sensitivity to GSH. The linear response of the SNCDs to GSH was in the range of 10–460 μM (LOD = 0.25 μΜ). More importantly, we used SNCDs with excellent optical properties and low cytotoxicity as probes, and successfully realized golgi imaging in HeLa cells and GSH detection at the same time. [Display omitted] • SNCD shows excitation independent emission at 562 nm and has a large Stock shift. • SNCD has the outstanding selection, which can distinguish GSH from Cys and Hcy. • SNCDs could specifically target Golgi apparatus. • SNCDs can detect GSH while imaging Golgi apparatus. [ABSTRACT FROM AUTHOR]

• A series of iridium(III) solvato complexes with good water solubility are designed and synthesized. • They can be used for multicolor cytoplasm imaging of living cells. • Two-photon excited imaging and fluorescence lifetime imaging microscopy have been achieved. Fluorescence microscopy imaging provides an indispensable way to visualize morphological details in tissue with subcellular resolution. Of the various imaging agents currently available, heavy-metal complex based probes offer a powerful tool for live cell imaging, primarily due to their excellent photophysical properties, including evident Stokes shifts, high photoluminescence efficiency and relatively long emission lifetime of phosphorescent signals. Herein, we have designed and synthesized seven water soluble cationic iridium(III) solvato complexes (1 − 7) for live cell imaging. The emission colors of these iridium(III) complexes can be tuned from green to red in PBS buffer (phosphate buffered saline). In particular, multicolor phosphorescent imaging for cytoplasm staining of living cells has been realized. More importantly, two-photon excited imaging and fluorescence lifetime imaging microscopy have also successfully been applied for complex 7. [Display omitted] A series of iridium(III) solvato complexes (1 − 7) with good water solubility have been designed and synthesized for multicolor cytoplasm imaging of living cells. Furthermore, two-photon excited imaging and fluorescence lifetime imaging microscopy have also been achieved. [ABSTRACT FROM AUTHOR]

Organic fluorescent materials have attracted increasing attention for their applications in various fields. Design and synthesis of multifunctional organic fluorescent emitters based on simple molecular structure are still highly demanded and challenging. In this paper, we designed and synthesized six organic fluorescent molecules with polyaryl substituted imidazobenzothiadiazole structure. The substituents on imidazole ring have important effects on the optical properties. Compounds with N, N-dialkyl aniline moieties on imidazole ring could show obvious solvatochromic properties with relatively large Stokes shifts and low quantum yields. However, the fluorescent emissions of other compounds with phenol, 4-methoxy phenyl or methyl groups on imidazole ring are almost unaffected by the solvent polarity, and they can exhibit higher fluorescent quantum yields. Under acidic conditions, the fluorescence emission of these compounds can be gradually extinguished. In addition, the fluorescence emission can be recovered under basic conditions. Significant changes in fluorescence emission indicate that these molecules can be used as anti-counterfeiting inks. Further investigation showed that the compound with methyl group on imidazole ring can be used for latent fingerprint development. High-contrast fingerprint images are obtained on various substrate surfaces. It is also found that the compound with phenol moiety on imidazole ring can be utilized for lysosomes imaging in living cells accurately with high efficiency. This work provides a series of imidazobenzothiadiazole-based multifunctional organic materials with potential applications in security inks, latent fingerprint imaging and lysosome staining. Highly emissive imidazobenzothiadiazoles derivatives are synthesized, which show large Stokes shifts, solvatochromic and acidochromic properties. These compounds could be used as anti-counterfeiting inks, and applied for visualization of latent fingerprints and lysosomes imaging in living cells. [Display omitted] • Six imidazobenzothiadiazoles derivatives are synthesized. • These molecules show solvatochromic and acidochromic properties. • Compound 3f could be applied for visualization of latent fingerprints on various substrate surfaces. • Compound 3d could be used for lysosomes imaging in living cells. [ABSTRACT FROM AUTHOR]

In view of the important physiological role of HSO 3 − and H 2 O 2 , it is of great significance to develop fluorescent probes to detect HSO 3 − and H 2 O 2 in aqueous medium. We herein report a new fluorescent probe (E)-3-(2-(4-(1,2,2-triphenylvinyl)styryl)benzo [d]thiazol-3-ium-3-yl)propane-1-sulfonate (TPE-y) possessing benzothiazolium salt based on tetraphenylethene (TPE) moiety with aggregation-induced emission (AIE) characteristics. TPE-y can sequentially recognize HSO 3 − and H 2 O 2 through colorimetric and fluorescence dual-channel response in HEPES (pH = 7.4, 1% DMSO) buffer solution, and exhibits high sensitivity and selectivity, a large Stokes shift (189 nm), as well as a wide applicable pH range. The detection limits of TPE-y and TPE-y-HSO 3 for HSO 3 − and H 2 O 2 are 3.52 μM and 0.15 μM, respectively. The recognition mechanism is verified by 1H NMR and HRMS methods. Furthermore, TPE-y can detect HSO 3 − in sugar samples, and can image exogenous HSO 3 − and H 2 O 2 in living MCF-7 cells. TPE-y can relay detect HSO 3 − and H 2 O 2 , which is of great significance to maintain the redox balance in organisms. [Display omitted] • A long wavelength emissive AIE-based fluorescent probe TPE-y has been developed. • TPE-y displays sequential recognition to HSO 3 − and H 2 O 2 with colorimetric and fluorescent dual responses. • TPE-y can alternately recognize HSO 3 −/H 2 O 2 in a high water content media. • TPE-y can be applied to detect HSO 3 − in food samples and cell imaging. [ABSTRACT FROM AUTHOR]

The abnormal expression of cytochrome P450 2J2 (CYP2J2) is closely related to the proliferation of human cancer cells. In this study, a red-emitting probe with an aggregation-induced emission (AIE) effect for the quantification of CYP2J2 was developed by modifying the typical AIE fluorescent group tetraphenylethylene (TPE) through two-step synthesis. Upon addition of CYP2J2, the probe underwent O-demethylation and spontaneously 1,6-elimination reactions of p-hydroxybenzyl that allowed it to alter its photophysical properties, thus realizing light-up detection of CYP2J2 with extremely large Stokes shift (236 nm), excellent sensitivity and selectivity, low detection limit (1.09 nM). Moreover, this new AIE-active probe with good biocompatibility was admirably employed to tracking endogenous CYP2J2 in living cells. • An AIE-based fluorescent probe (TPE-Bn) was designed to detect CYP2J2. • This probe showed significant Stokes shift (236 nm), good photostability, excellent sensitivity and selectivity, and low cytotoxicity. • This probe can be used to visualize endogenous CYP2J2 in living cells and tissues. [ABSTRACT FROM AUTHOR]

[Display omitted] • Aggregation-induced emission characteristics. • Highly sensitively and selectively detect Cu2+ ions. • Stronger interaction with Cu2+ ions and lower limit of detection. • A large Stokes shift (247 nm). • Living cell imaging of Cu2+. In this work, an AIE-active tetraphenylethene-based Schiff base fluorescent probe 3 with a large Stokes shift (247 nm) was designed and synthesized. It was found that the aggregated probe 3 exhibited very high selectivity and anti-interference ability for Cu2+ in PBS buffer (70% f w) through a fluorescence "turn–off" strategy. Job's plot and NMR analysis indicated the two phenolic hydroxyl groups of the benzene ring and the N atom (-CH=N-) on probe 3 interacted with Cu2+ ions in a 1:1 stoichiometric ratio. A comprehensive analysis of the Stern–Volmer and binding constant indicated a rather strong interaction between probe 3 and Cu2+ ions. Probe 3 illustrated excellent sensitivity toward Cu2+ under ppb level (4.5 nM) and achieved more than 95% recovery in river, lake and tap water toward estimation of Cu2+ ions in the analytical applications. Moreover, probe 3 was able to realize bioimaging of HepG2 cells and be quenched by intracellular Cu2+ ions, making it promising as a sensitive Cu2+ sensor for organisms. [ABSTRACT FROM AUTHOR]

Sulfur dioxide (SO 2), as a known important sulfur oxide in RSS, has an essential role in achieving the homeostasis of organisms. The development of a highly sensitive and selective fluorescent probe for monitoring SO 2 is of great interest in understanding its pathophysiology. Herein, we developed a new near-infrared FRET-based fluorescent probe QD , in which quinolinium fluorophore was selected as the donor and the dicyanoisophorone fluorophore was selected as the acceptor. Probe QD had dual colorimetric and ratiometric fluorescence, larger Stokes shift (277 nm) and longer emission wavelength (677 nm). The fluorescence spectrum showed that QD was highly selective and sensitive with excellent linear response concentration range of 2.5–80 μM. Importantly, probe QD allowed detection of SO 2 derivatives and bioimaging of lysosome-targeted in live cells. [Display omitted] • Showing a strong NIR fluorescence. • Large Stokes shift of 277 nm and wide detection rang of 2.5–80 μM. • Showing high sensitivity and selectivity. • Achieving the dual colorimetric and ratiometric fluorescent strategy. • Achieving the detection of exogenous and endogenous SO 2 derivatives in living cells. [ABSTRACT FROM AUTHOR]

Herein, we reported a novel probe with near-infrared fluorescent emission (750 nm) and a large Stokes shift (118 nm) for the detection of H 2 S. The probe can specific and sensitive detection (LOD as low as 4.5×10–8 M) of H 2 S, accompanying an ideal color changes from purple to green natural light, which could rapid detect HS– over other analytes through the "naked eye". The probe was successfully be utility for H 2 S image in cells and mice. [Display omitted] • The novel NIR probe was developed based on the nucleophilic substitution mechanism. • The probe can specific and sensitive detection of H 2 S, accompanying color changes from purple to green. • The probe can be used as a useful tool for studying the physiological and pathological phenomena related to hydrogen sulfide. As a kind of gas signal molecules, H 2 S is related to in human health and disease. Herein, we developed a novel probe with near-infrared fluorescent emission (750 nm) and a large Stokes shift (118 nm) for the detection of H 2 S. The probe can specific and sensitive detection (LOD as low as 4.5 × 10–8 M) of H 2 S, accompanying an ideal color changes from purple to green natural light. Based on the advantages of excellent cell permeability and cytotoxicity data, the probe was be utility for H 2 S image in cells and mice. [ABSTRACT FROM AUTHOR]

Gene expression and regulation in which RNA is an essential participant can be visualized by imaging RNA with fluorescent probes. However, most of the reported fluorescent probes for RNA have defects such as short emission wavelength, small Stokes shift, poor selectivity, low sensitivity, and poor membrane permeability. Herein, a NIR (710 nm) cationic fluorescent probe PCTP with D-π-A structure and large Stokes shift (285 nm) using 9-phenylcarbazole as an electron donor and pyridinium salt as an electron acceptor was designed and synthesized. Titration experiments and enzyme treatment experiments demonstrate that PCTP can differentiate RNA from DNA in solution and cells, the fluorescence intensity of PCTP increases by a maximum of 52.2 times after binding to RNA and the detection limit is 2.17 μg/mL, showing high selectivity and sensitivity to RNA. Furthermore, with low cytotoxicity, good biocompatibility and high photostability, PCTP is able to trace 4T1 cell proliferation in vitro to 9 generations and trace 4T1 cell in mice for 22 days. The probe provides a potential tool for RNA imaging and long-term cellular tracing. • a NIR (710 nm) cationic fluorescent probe PCTP with D-π-A structure and large Stokes shift (285 nm) was designed and synthesized. • The fluorescence intensity of PCTP increases by a maximum of 52.2 times after binding to RNA and the detection limit is 2.17 μg/mL. • PCTP can differentiate RNA from DNA in solution and cells, showing high selectivity and sensitivity to RNA. • PCTP is able to trace 4T1 cell proliferation in vitro to 11 generations and trace 4T1 cell in mice for 22 days. [ABSTRACT FROM AUTHOR]

The novel V-shaped donor-π-acceptor-π-donor compounds bearing an aldehyde group (1Pip , 2EtO , and 3TEG) were designed, synthesized, and evaluated as the two-photon excited fluorescence probes for the selective detection of cysteine (Cys). Their structures were fully characterized by 1H NMR, 13C NMR, FT-IR, and HRMS. The optical properties of the target compounds in various solvents were studied in details and the time-dependent density functional theory calculations were performed to shed light on their electronic structures. It is found that all of them exhibit large Stokes shifts (6331-10047 cm−1). 1Pip and 3TEG are capable of detecting Cys with high selectivity, good anti-interference ability, and favorable two-photon absorption performance. The limits of detection were determined to be equal to 0.15 μM for 1Pip and 0.73 μM for 3TEG. The possible recognition mechanism was also validated by 1H NMR and HRMS. One- and two-photon fluorescence imaging experiments indicate that 3TEG shows more satisfactory cellular membrane permeability than 1Pip , and it can successfully visualize the endogenous and exogenous Cys in living cells. These results imply that 3TEG has potential as a two-photon fluorescence probe for detecting Cys in biological samples. [Display omitted] • Three novel D-π-A-π-D type two-photon absorption compounds were developed to detect Cys. • 3TEG shows high selectivity to Cys, favorable two-photon absorption property, large Stokes shifts, and good biocompatibility. • 3TEG has been successfully utilized to image endogenous and exogenous Cys in living cells. [ABSTRACT FROM AUTHOR]

Cysteine is an organic small molecule that plays an important role in human physiological processes. It is meaningful to detect it easily with high selectivity and sensitivity. In this work, a fluorescent probe Lyso-CDC based on chalcone fluorescent dyes for the effective detection of Cys in lysosomes was designed and synthesized. After adding Cys, the fluorescence of the probe Lyso-CDC at 568 nm was significantly enhanced, displaying a large Stokes shift (168 nm) and a color change from light yellow to bright yellow that was visible to naked eyes. The selectivity and sensitivity of the probe Lyso-CDC for Cys were much higher than other amino acids, and the detection limit for Cys was calculated to be 1.44 × 10−8 M. Furthermore, the probe Lyso-CDC possessed low cytotoxicity, excellent biocompatibility and outstanding lysosome targeting ability. The probe was successfully applied to detect Cys in lysosomes of living cells. [Display omitted] • Lyso-CDC was easy to synthesize. • Lyso-CDC specifically recognized Cys with a large Stokes shift of 168 nm. • Lyso-CDC had a low detection limit of 1.44 × 10−8 M for Cys. • Lyso-CDC has been successfully used to detect and image Cys in living cells. • Lyso-CDC was lysosome-targeting. [ABSTRACT FROM AUTHOR]

A simple fluorescent probe (TPE-1) based on the combination of tetraphenylethene (TPE) and 2-(2′-hydroxyphenyl)benzothiazole (HBT) was synthesized. TPE-1 possesses both aggregation-induced emission (AIE) and excited-state intramolecular proton transfer (ESIPT) characteristics. The TPE-1 aggregates exhibited rapid (10 s) and highly selective recognition of Cu2+ in THF/H 2 O (1:9, v/v, HEPES 20 mM, pH = 7.4) solution, and was induced an "on-off" change in the fluorescence. TPE-1-Cu 2+ complexes generated in situ can also be used as sensing ensembles for highly selective detection of H 2 S by Cu2+ displacement. As a result, the fluorescence of TPE-1 was recovered again, and an "on-off-on" fluorescence variation was used to relay Cu2+ and H 2 S recognition. The detection limits of the probes for Cu2+ and H 2 S are 9.91 × 10−8 M and 3.80 × 10−7 M, respectively. In addition, the probes can be applied to detect Cu2+ and H 2 S in some food samples and can also be applied to cell imaging experiments. Relay recognition of Cu2+ and H 2 S by a fluorescent probe regulated by AIE and its application in food and cell imaging. [Display omitted] • An AIE-based fluorescent probe TPE-1 was designed and synthesized. • TPE-1 can relay identify Cu2+ and H 2 S with high sensitivity, high selectivity, large Stokes shift, and low detection limit. • TPE-1 can rapidly relay responses to Cu2+ and H 2 S with on-off-on fluorescence changes. • TPE-1 is suitable to assay the Cu2+ and H 2 S level in water, seafood, tea and red wine samples. [ABSTRACT FROM AUTHOR]

A new fluorescent material was prepared by complexation of a D-π-A structural organic ligand with ZnBr2. The material exhibits good one- and two-photon excited fluorescence. One- and two-photon fluorescence imaging shows that HepG2 cytoplasm can be labeled by the fluorescent material. The results show that the material has great potential in fluorescence microscope imaging. [Display omitted] • A new material with zinc ion and π-conjugated organic ligands has been synthesized. • The complex shows good one- and two-photon excited fluorescence. • The material shows the value in fluorescence microscopy bioimaging application. • The experimental correlation between the solvent polarity and the Stokes displacement is described by the Boltzmann fitting method. A luminescent material with various optical properties based on a triphenylamine Zn(II) complex is described. The ultraviolet–visible absorption, one-photon excited fluorescence (OPEF) and two-photon excited fluorescence (TPEF) of the complex indicate that the material has good OPEF and TPEF properties. And the results of one- and two-photon HepG2 cells imaging experiments show the potential of the complex in fluorescence microscopy bioimaging. The experimental Stokes shift and the FWHM (full-width at half-maximum) in different solvents were correlated with the rMPI polarity of the solvent, and the perfect Boltzmann curves were obtained, where the Boltzmann correlation between Stokes shift and solvent polarity is reported for the second time. But the Boltzmann correlation between FWHM and solvent polarity is reported for the first time. In addition, the computational results indicate that, the covalent bond within the salt ZnBr 2 is strengthened by the coordination, and the newly formed coordination bond Zn-N is stronger than the original covalent bond Zn-Br. [ABSTRACT FROM AUTHOR]

Hypoxia is an essential regulator of cell metabolism, affects cell migration and angiogenesis during development and contributes to a wide range of pathological conditions. Multiple techniques to assess hypoxia through oxygen-imaging have been developed. However, significant limitations include low spatiotemporal resolution, limited tissue penetration of exogenous probes and non-dynamic signals due to irreversible probe-chemistry. First genetically-encoded reporters only partly overcame these limitations as the green and red fluorescent proteins (GFP/RFP) families require molecular oxygen for fluorescence. For the herein presented ratiometric and FRET-FLIM reporters dUnORS and dUnOFLS, we exploited oxygen-dependent maturation in combination with the hypoxia-tolerant fluorescent-protein UnaG. For ratiometric measurements, UnaG was fused to the orange large Stokes Shift protein CyOFP1, allowing excitation with a single light-source, while fusion of UnaG with mOrange2 allowed FRET-FLIM analysis. Imaging live or fixed cultured cells for calibration, we applied both reporters in spheroid and tumor transplantation-models and obtained graded information on oxygen-availability at cellular resolution, establishing these sensors as promising tools for visualizing oxygen-gradients in-vivo. • Bipartite cellular hypoxia sensors of O 2 -tolerant & -sensitive fluorescent proteins. • Genetically encoded reporters for intensity- or FRET /FLIM-based measurements. • Graded live-cell microscopic oxygen-imaging in vitro using dUnORS and dUnOFLS. • Optimal working range well within physiological cellular oxygen-concentrations. • Sensors visualized oxygen gradients in intracranial brain tumors ex vivo. [ABSTRACT FROM AUTHOR]

Lipid droplets (LDs) and lysosomes serve as important subcellular organelles, which plays an important role in a variety of physiological processes. The components in lipid droplets can be degraded by lysosomes, so it is of great value to study the relationship between LDs and lysosomes. However, simultaneous targeting of lipid droplets and lysosomal polymer fluorescent probes has hardly been reported. Therefore, we developed a novel polyethylene glycol fluorescent probe PEG-Nap-Lyso that could be applied to simultaneously track lysosomes and lipid droplets. PEG-Nap-Lyso was able to not only track cells in different physiological environments, but also differentiate live cells from dead cells by changes in the polarity of the intracellular microenvironment. In addition, the probe had the advantages of amphiphilicity, pH resistance, high selectivity, good stability (3600s), low biotoxicity and large Stokes shift (167 nm). These excellent properties made the fluorescent probe PEG-Nap-Lyso provided an effective way to study the relationship between LDs and lysosomes. [Display omitted] • A unique amphipathic PEG-based fluorescent probe PEG-Nap-Lyso was designed with a large Stokes shift (167 nm). • The novel fluorescent probe could target lipid droplets and lysosomes in living cells. • The novel fluorescent probe had been successfully used for dual-channel imaging to discriminate living and dead cells. • The novel fluorescent probe could tracking LDs in cells under different physiological conditions. Lipid droplets (LDs) and lysosomes serve as important subcellular organelles, which plays an important role in a variety of physiological processes. The components in lipid droplets can be degraded by lysosomes, so it is of great value to study the relationship between LDs and lysosomes. However, few polymer fluorescent probes targeting both lipid droplets and lysosomes have been reported. Therefore, we developed a novel polyethylene glycol fluorescent probe PEG-Nap-Lyso that could be applied to simultaneously track lysosomes and lipid droplets. PEG-Nap-Lyso was able to not only track cells in different physiological environments, but also differentiate live cells from dead cells by changes in the polarity of the intracellular microenvironment. In addition, the probe showed the advantages of amphiphilicity, pH resistance, high selectivity, good stability (3600 s), low biotoxicity and large Stokes shift (167 nm). These excellent properties made the fluorescent probe PEG-Nap-Lyso provided an effective way to study the relationship between LDs and lysosomes. [ABSTRACT FROM AUTHOR]