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[Display omitted] • The study focuses on detecting diethyl chlorophosphate (DCP), a toxic simulant for nerve agents. • TPAHY and TPAPD were developed as ICT based sensors for DCP with detection limits of 23.31 nM and 28.42 nM. • TPAHY is utilised for on-the-spot DCP detection, showing yellow-to-orange colour shifts and orange fluorescence. • TPAHY is also explored in Hela cell imaging, expanding its applications beyond detection. Detecting diethyl chlorophosphate (DCP), a highly toxic chemical simulant for nerve agents like Sarin, Soman, and Tabun, is crucial due to its prevalence in warfare scenarios, as well as its presence in contaminated soil and air. Traditional detection methods often struggle with sensitivity and versatility, limiting their effectiveness in real-time, on-the-spot applications. Effective detection is vital for safety, environmental monitoring, and mitigating the risks associated with these hazardous substances. There is a pressing need for advanced sensors that can offer high sensitivity, specificity, and practicality in various environments. In our study, we developed and introduced two ICT-based fluorocolorimetric sensors, TPAHY and TPAPD, designed for the detection of DCP. These sensors exhibit remarkable sensitivity, with limits of detection (LOD) at 23.31 nM for TPAHY and 28.42 nM for TPAPD. TPAHY proves to be an efficient sensor for the on-spot DCP detection, showcasing practical applications such as fluorescent sprays, pens, and detection devices. Upon addition of DCP, TPAHY undergoes a distinct colorimetric shift from yellow to orange, coupled with an enhancement of orange fluorescence. Conversely, TPAPD demonstrates a colorimetric transition from colourless to yellow and experiences fluorescence quenching from blue emission. To understand the underlying mechanisms, we conducted studies using density functional theory (DFT) and lifetime measurements, providing deeper insights into the sensor behaviours. The development of TPAHY and TPAPD provides reliable, sensitive, and versatile solutions for monitoring DCP. TPAHY not only serves as a useful tool for detecting DCP in various field applications but also extends its utility to biological imaging, as demonstrated in HeLa cell studies. This dual functionality enhances its relevance for both environmental monitoring and broader scientific investigations. These sensors represent a significant advancement in the detection of toxic chemicals, offering improved safety and research capabilities. [ABSTRACT FROM AUTHOR]

CCT probes sensitive to low pH and low polarity were used to distinguish normal cells from cancer cells. [Display omitted] • Designed and synthesised a fluorescent probe, CCT. • CCT is responsive to both pH and polarity based on the mechanisms of intramolecular charge transfer (ICT) and photoelectron transfer (PET). • The probe consists of a naphthylimide fluorophore, a coumarin unit and a morpholine. • CCT corresponds to the low pH and low polarity microenvironment of cancer cells, which is favourable for bioimaging. Cancer is one of the deadliest and most complex diseases globally. It is well known that cancer cells exhibit a unique intracellular microenvironment characterized by low pH and low polarity compared to normal cells. Thus, dual-responsive fluorescent probe are more suitable for such complex and variable physiological environments than single-response probe. In this study, we designed and synthesized a dual-responsive fluorescent probe, CCT, which responds to both pH and polarity based on intramolecular charge transfer (ICT) and photoelectron transfer (PET) mechanisms.We synthesized probe CCT by combining naphthylimide, a coumarin unit, and morpholine through a six-step process. The PET mechanism between morpholine and naphthylimide renders probe CCT pH-sensitive. Additionally, the direct linkage of the polarity-sensitive units, coumarin and naphthylimide, creates a larger polarity-sensitive system. When both low pH and low polarity conditions are present, the fluorescence intensity of probe CCT is significantly higher than under separate conditions. This increased fluorescence intensity matches the low pH and low polarity microenvironment of cancer cells, facilitating bioimaging.Fluorescence imaging results demonstrate that probe CCT effectively distinguishes between cancer and normal cells, suggesting its potential as a powerful tool for early cancer diagnosis. [ABSTRACT FROM AUTHOR]

[Display omitted] • A solvent-dependent six-membered spirorhodamine probe has been firstly reported. • It exhibited dual channel responses for Cu2+ in CH 3 CN/H 2 O and ClO- in C 2 H 5 OH/H 2 O. • Detection limits were 36 nM for Cu2+ and 129 nM for ClO- in above two solvent systems. • The probe can be used to detect the concentration of Cu2+ in grape peel and A549 cells in vitro. To reveal the solvent dependence of six-membered rhodamine spirocycles (SMRS), a new probe SM-RB has been synthesized and investigated the spectral properties in different solvents upon the addition of various metal ions and anions. SM-RB exhibited high selectivity for Cu2+ in CH 3 CN/HEPES and ClO- in C 2 H 5 OH/HEPES solutions, respectively. The spectral changes of SM-RB in the presence of ClO- in C 2 H 5 OH/HEPES solution were much less than that of Cu2+ in CH 3 CN/HEPES. The detection limit of Cu2+ was as low as 36 nM (fl) in CH 3 CN/HEPES. The kinetic equilibration time (8 s) indicated that the two solvent systems did not delay the spectral response speed to Cu2+ and ClO-. Solvent systems influenced the pKa value of SM-RB in CH 3 CN/HEPES and C 2 H 5 OH/HEPES. The pKa value of SM-RB was 4.34 (±0.7) (Abs) and 4.75 (±0.14) (Fl) in CH 3 CN/H 2 O, but can't be exactly calculated by pH titration in C 2 H 5 OH/H 2 O. The reversibility and Job plot of SM-RB were investigated to propose the response mechanism of SM-RB with Cu2+ and ClO- in the two solvent systems. Finally, SM-RB not only can be used for the quantitative detection of copper ions in grape peel, but also can real-time monitor the fluctuation of Cu2+ in lysosomal pools. [ABSTRACT FROM AUTHOR]

[Display omitted] • A dual-response fluorescent probe RPT for detecting SO 2 and HClO is synthesized. • The fluorescent probe can monitor SO 2 and HClO with a wavelength difference of 85 nm. • The fluorescent probe has simple synthetic method and is easy to be obtained. • Fluorescent probe can image SO 2 and HClO in living cells (HeLa and RAW 264.7 cells). • Fluorescent probe can detect SO 2 and HClO in various water and food samples. Hypochlorous acid (HClO) and sulfur dioxide (SO 2) play vital roles in various fields, including living organisms, water samples, food and so on. High doses of SO 2 and HClO are seriously harmful to human and are associated with a variety of diseases. Therefore, monitoring the level of SO 2 and HClO in various fields is significant for exploring their roles. In this work, a novel dual-response fluorescent probe RPT for detecting SO 2 and HClO is successfully designed and synthesized, which is composed by pyrylium moiety and thiazine part. The fluorescent probe RPT can respectively monitor SO 2 and HClO by two well-separated emission wavelength with an obvious difference of 85 nm. The fluorescent probe RPT also displays desired properties such as simple synthetic method, high sensitivity and selectivity. In addition, as a biocompatible molecule, RPT has been successfully used for monitoring SO 2 and HClO in HeLa cells and RAW 264.7 cells in two different channels (red channel and green channel). More importantly, SO 2 and HClO levels in various water and food samples have been detected with satisfactory results. [ABSTRACT FROM AUTHOR]

[Display omitted] • BTCMN is constructed by coupling of 2-(2́-hydroxyphenyl) benzothiazole (HBT) scaffold to dicyanoisophorone through a C C bond bridge based on ESIPT mechanism. • BTCMN showed super-fast response to H 2 S as compared to other current probes. • BTCMN displayed specific selection and low detection limit towards to H 2 S. • BTCMN has been successfully used for visualizing endogenous and exogenous H 2 S in the HepG2 cells with low cytotoxicity. Hydrogen sulfide (H 2 S) plays a crucial role in various physiological processes and is implicated in the pathogenesis of several diseases. The fluorescent probe (E)-2-(3-(3-(benzo[d]thiazol-2-yl)-2-hydroxy-5-methylstyryl)-5,5-dimethylcyclohex-2-en-1-ylidene) malononitrile (BTCMN) has been designed to image H 2 S in living cells using the excited-state intramolecular proton transfer (ESIPT) mechanism. This probe is developed by coupling 2-(2′-hydroxyphenyl) benzothiazole (HBT) with dicyanoisophorone through a H 2 S-responsive C C bond. Upon interaction with H 2 S, BTCMN exhibits a remarkable fluorescent change from red to green. BTCMN , which has shown exceptional performance in detecting hydrogen sulfide (H 2 S) with super-fast response times, large Stokes shifts (252 nm), specific selection towards H 2 S, and low detection limits. Importantly, BTCMN has been successfully used for visualizing endogenous and exogenous H 2 S in HepG2 cells with low cytotoxicity. These features collectively contribute to its effectiveness as a fluorescent probe for detecting H 2 S in living cells. [ABSTRACT FROM AUTHOR]

A highly selective and sensitive fluorescence sensor for fluorine ion from aluminium and boric acid codoped carbon dot was synthesized. [Display omitted] • Aluminium ion and boric acid codoped carbon dots was synthesized and characterized. • In the sensor, rich hydroxyl group from boric acid can anchored carbon dots and aluminium, which enhanced the water solubility and biocompatibility of sensor system. • The water soluble fluorescence sensor can detect fluorine ion in cell and zebrafish. Fluorine is one of the essential trace elements for human body, which is essential for calcification process in living organisms. In the paper, a "off–on" fluorescence sensor for fluorine ion based on aluminium ion and boric acid codoped carbon dots was synthesized and characterized. According to fluorescence analysis, the water-soluble sensor exhibited highly selective and sensitive for fluorine ion. In sensing process, F- could bind to Al3+ after the addition of fluorine ion, which resulted in the decomposition of Al-BA-CDs system, then intense yellow fluorescence signal appeared. Moreover, the fluorescence sensor exhibited low detecting limit (5.0 nanomolar level) by fluorescence titration spectrum. In addition, according to evaluate the fluorescence sensing properties of F- in HepG2 cell and zebra fish, this job greatly extended the use of F- sensor from aluminium ion and boric acid codoped carbon dots in organism. The work also provided an interesting idea for fabricating water-soluble fluorescence sensor for F-. [ABSTRACT FROM AUTHOR]

[Display omitted] • Herein we constructed and synthesized turn-on fluorescent probe NSP based on simple condensation reaction. • Probe on incubating with triphosgene in presence of 1 % Triethylamine (TEA) show maximum emission at 586 nm within ≤3 s. • The probe displayed both colorimetric and fluorescence response with phosgene (0.01 ppm). • The probe-loaded paper strips, allowed for the direct visualization of phosgene vapour from household bleaching powder. • The probe detect phosgene in living cells. Phosgene is a vital industrial gas that might substantially imperil public safety in the case of an accident or terrorist attack due to its extreme toxicity and history of use as a chemical warfare agent. Herein we built a simple photoinduced electron transfer-intramolecular charge transfer based turn-on fluorescent probe for ultrafast detection of phosgene within ≤ 3 s. The probe provides low detection limit (0.01 ppm) with distinct colour and fluorescence changes only in the presence of phosgene. With the help of a readily available colour smartphone app, the probe-loaded paper strips allowed for the direct visualization and quantitative measurement of phosgene vapour. Using the probe-coated strips to detect phosgene that evolved from common household bleach. Finally, the probe was utilized to detect phosgene in living cells. [ABSTRACT FROM AUTHOR]

[Display omitted] • The probe P-1 can selectively detect H 2 O 2 with colorimetric change. • the P-1 can be used for on-site and visual detection of H 2 O 2. • The P-1 can image H 2 O 2 in cells and distinguish cancer cells and normal cells. • The P-1 probe was applied to monitor H 2 O 2 of tumor in mice. We designed and developed the probe P-1 for detecting H 2 O 2. The probe can selectively detect H 2 O 2 with colorimetric change. In addition, the combination of portable test strips with a smartphone platform provided great convenience for on-site and visual detection of H 2 O 2 with satisfactory sensitivity and reliability. The P-1 can image exogenous and endogenous H 2 O 2 in cells and distinguish cancer cells and normal cells by fluorescence image of H 2 O 2 and flow cytometry. Meanwhile, the P-1 probe has been successfully applied to monitor H 2 O 2 levels of tumor in mice, and the results showed the level of H 2 O 2 in tumor tissue increased significantly. Therefore, P-1 provided a potential chemical tool to understand pathological and physiological mechanisms of diseases by imaging H 2 O 2. [ABSTRACT FROM AUTHOR]

[Display omitted] • The new probes with AIE characteristic for cell imaging. • The probe has high sensitivity in the presence of solvent shielding effects. • The probe has good reversibility for environmental testing and could be recycled. A new fluorescent probe TPA-DAP with aggregation-induced emission (AIE) characteristic based on 2,6-pyridinedicarboxylic acid was synthesized for the detection of paramagnetic ions (Cu2+, Co2+, Ni2+). In the DMF/PBS (5:95, v/v, pH = 7.40) solvent mixture, the fluorescence intensity exhibited a notable enhancement of over 3-fold when compared to DMF alone. Concurrently, fluorescence quenching phenomena were observed in the presence of Cu2+, Co2+, and Ni2+, with corresponding detection limits measured at 56.4 nM, 22.4 nM, and 26.5 nM, respectively. These detection limits were found to be lower than the prescribed thresholds for Cu2+ in Class I groundwater and Co2+, Ni2+ in Class III groundwater, multi-functional detection was possible. The coordination constants were 9.07 × 105, 3.63 × 105 and 5.69 × 105, respectively. However, in the DMSO system, the probe will be highly selective in the presence of solvent shielding effects. The probe showed more than 10-fold enhancement of fluorescence intensity in DMSO/Tris-HCl (5:95, v/v, pH = 7.00) compared to DMSO and specific detection of Cu2+ with a detection limit of 36.7 nM and a coordination constant of 4.35 × 105, and was cyclically detectable in the presence of EDTA. TPA-DAP was applied for the detection of Cu2+ in actual water samples and showed good biocompatibility and recyclability, making it suitable for water testing and test paper experiments, and also for a wide range of applications in the identification of Cu2+, Co2+, Ni2+ and other bioassays in cells and zebrafish. Solvents could be selected according to actual test requirements. [ABSTRACT FROM AUTHOR]

[Display omitted] • Characterization of cresyl violet fluorescence in plant cells. • Cresyl violet can be used to distinguish acidic endosomes and vacuoles. • Cresyl violet is more reliable to maps endosomes populations in plant leaf and root cells. • Cresyl violet in plant cells is highly photostable and is devoid of cytotoxic properties. The advent of fluorescent probes and the characterization of their photochemical properties in the past years allowed significant advances in the studies of spatiotemporal cellular processes within complex and crowded systems. Dyes are indeed extremely useful tools for the visualization of cellular and subcellular structures present in living cells, as well as to study their dynamic and molecular composition or physiological changes. There are some areas of plant cell biology that have been more challenging to explore due to the physiology and organization of certain endomembrane compartments. In this study we characterize the labeling properties of cresyl violet as quick and inexpensive imaging agent for tracking endosomes, vacuole compartments which are usually very differentiated and categorized as more acidic as well as acidic plant compartments. Its photobleaching, labelling and cytotoxic properties are compared with other well-known and currently most used synthetic and molecular probes. [ABSTRACT FROM AUTHOR]

[Display omitted] • A new fluorescent chemosensor (SDAF) was developed for Al3+. • The SDAF has an ultralow detection limit (28 nM) and fast response time. • DFT studies were strongly confirmed the spectroscopy results. • The SDAF was successfully used to detect Al3+ in water samples, test-kits and living cells. A new fluorescent chemoprobe (SDAF) was successfully synthesized and utilized as a sensor for the recognition of Al3+ in EtOH:HEPES (3:2, v:v, pH: 7.0) media. The SDAF depicted a selective "turn–on" response at λ em = 467 nm to Al3+ over competitive cations, and the SDAF– Al3+ complex had a reversible response with F−. The limit of detection (LOD) was found about at nano–molar level (28.0 nM), demonstrating the sensitivity of the chemoprobe toward Al3+. The binding stoichiometry of SDAF –Al3+ was investigated by TOF–MS, Job's plot, 1H NMR and 13C NMR methods and found as 1:1. The recognition mechanisms of SDAF for the detection of Al3+ were the –C = N isomerization and photoinduced electron transfer (PET) mechanisms, and they were confirmed by density functional theory (DFT) computation. Furthermore, the SDAF was successfully employed in living–cell bioimaging and cytotoxicity, it was also utilized in Smartphone, test–kit and natural spring water (recovery values; 89.01 %– 96.33 %)applications. [ABSTRACT FROM AUTHOR]

[Display omitted] • The crystal structure of π–π stacking of red carbon nanosheets, and enhance the fluorescence properties of red carbon in aggregation state. • The fluorescence of red carbon can be quenched by the Fe3+ and recovered by ethylene diamine tetraacetic acid. • The red carbon can detect the Fe3+ with highly sensitive, rapid response, and anti-interference and cellular imaging. The subcarboxylated carbon (C 3 O 2) is a unique molecule that spontaneously polymerizes into highly conjugated fluorescence structures p(C 3 O 2) n , named "red carbon". This unique property, combined with its role as aggregation-induced emission luminogens, has allowed for a deeper exploration of their emission mechanism. Herein, both density functional theory calculations and experimental approaches to elucidate the crystal structure of π–π stacking in red carbon, thereby enhancing the fluorescence properties of p(C 3 O 2) n polymer in its aggregated state. The time-dependent density functional theory calculations and experimental observations indicate that the fluorescence of red carbon can be quenched by ferric ions (Fe3+) and subsequently restored by ethylenediaminetetraaceticacid (EDTA). This quenching process follows first-order reaction kinetics. On the basis of the coordination to metal ions from abundant heteroatoms on red carbon, the high sensitivity, quick responsive (1 min), sensitive detection (the lowest detection limit is 0.97 μM) for the Fe3+ were realized in red carbon, which provides inspirations for the design of new turn-on probes with high stability in detecting the Fe3+ in aqueous solution. Crucially, the red carbon as a light-up fluorescence probe can be employed for the Fe3+ sensing in living cells, which enlighten a new perspective for designing non-conjugated fluorescent polymers. This innovative approach opens up new avenues for developing probes that can detect Fe3+ with high precision and reliability in complex biological environments. [ABSTRACT FROM AUTHOR]

[Display omitted] • A framework nucleic acids (FNAs) fluorescent nanoprobe was constructed. • The detection of multiple DNA repair enzymes in living cells was realized. • This method exhibits good selectivity and high sensitivity. • The FNAs enter the cell autonomously and image UDG and APE1. DNA repair enzymes play pivotal roles in DNA damage repair. Imaging multiple DNA repair enzymes in living cells is significant for DNA damage repair-related biological study and disease diagnosis. Here, we constructed a framework nucleic acids (FNAs) fluorescent nanoprobe for imaging multiple DNA repair enzymes in living cells. Uracil DNA glycosylase (UDG) and human apurinic/apyrimidinic endonuclease 1 (APE1) were used as the target analytes. Two double-stranded DNA probes (dsDNA1 and dsDNA2) were designed. dsDNA1 contained four uracil (U) bases for UDG recognition and was labeled with black hole quencher2 (BHQ2) /cyanine5 (Cy5). dsDNA2 contained one apurinic/apyrimidinic (AP) site for APE1 recognition and was labeled with black hole quencher1 (BHQ1) /fluorophore carboxyfluorescein (FAM). To obtain the FNAs fluorescent nanoprobe, dsDNA1 and dsDNA2 were attached to two vertices of a DNA tetrahedron (a type of FNAs). Under the action of UDG and APE1, dsDNA1 and dsDNA2 were both dissociated, generating fluorescence of Cy5 and FAM. Among them, Cy5 indicated the activity of UDG and FAM indicated the activity of APE1. This method had good sensitivity to UDG and APE1, and the detection limits were 0.0012 U/mL and 0.057 U/mL, respectively. This method also exhibited high selectivity for UDG and APE1. When the FNAs fluorescent nanoprobe was endocytosed, it had little toxicity to normal and cancer cells. Furthermore, this method successfully achieved multiple imaging UDG and APE1 in cancer cells. This study provides a novel strategy for imaging multiple DNA repair enzymes and holds great potential in biological applications and clinical diagnosis. [ABSTRACT FROM AUTHOR]

[Display omitted] • Cyanide exhibits a dual nature, serving as an industrial asset and causing an environmental threat. • The focus on cyanide detection increases as micromolar cyanide levels create fatal risks. • Colorimetric and fluorescent chemosensors offer quick, affordable, and portable detection of cyanide. • This review highlights colorimetric and fluorescent probes' significance in monitoring cyanide ions. • The survey was executed utilizing published reports from 2021 to 2023. Anions, specifically cyanide, occupy crucial roles in various biological, physiological, and industrial contexts. While cyanide is indispensable as a raw material in the synthesis of herbicides, resins, synthetic fibers, and the gold-extraction process, its widespread presence causes a significant threat to both environmental and social systems. Cyanide abundance in the environment arises not just from industrial effluents but also from the natural biological processes of fungi and algae. The dual nature of cyanide, serving both as a useful industrial component and a potential environmental hazard, highlights the importance of responsible management and regulation in its production and application. The detection of cyanide has become a matter of paramount importance due to its extreme toxicity and potential environmental contamination, where even micromolar levels can prove fatal to humans. In addressing this critical concern, researchers have focused on developing simple, inexpensive, and rapid detection methods, with chemosensors emerging as among the most promising solutions. These chemosensors rely on colorimetric and fluorometric responses, offering a synergistic combination that enhances the versatility of cyanide detection methodologies. Through novel design and synthesis, researchers have constructed a diverse range of chemosensors with tailored properties, such as high selectivity, low detection limits, and rapid response times. Especially, efforts have been directed towards making these detection systems portable and user-friendly, facilitating their practical implementation in real-world scenarios. This comprehensive review provides a focused examination of colorimetric and fluorescent probes designed for the specific and sensitive recognition of cyanide anions. Emphasizing their applicability in on-site portable strips and cellular imaging, the review aims to enhance readers' understanding of the critical need for monitoring cyanide ions in the context of human health and disease. The discussed probes are categorized into various classes, including small molecules, metal complexes, metal–organic frameworks (MOFs), macrocyclic compounds, nanomaterials, and polymer-based probes, each classified based on their structural properties and functional groups. Encompassing advancements made in the field from 2021 to 2023, the review underscores the progress achieved in developing these probes. Finally, the review addresses the potential future applications of colorimetric and fluorescent probes in detecting cyanide ions, pointing towards the evolving landscape of analytical techniques and their significance in advancing our ability to monitor cyanide levels effectively. [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]

[Display omitted] • A new pH-sensitive fluorescent probe 1 based on hemicyanine fluorophore is developed. • The probe can respond to pH with high selectivity and sensitivity. • The probe can solely illumine the lysosomes and detect the exogenous pH difference in live cells. • The probe can successfully monitor the pH changes during food spoilage. pH as an important parameter is closely related to many pathological processes and food freshness. In this paper, a new pH-sensitive fluorescent probe 1 based on hemicyanine dye was synthesized and used for the detection of pH in live cells and food spoilage. Under neutral and alkaline conditions, the phenolic hydroxyl group of the probe deprotonates, forming a closed spirocyclic structure and resulting in fluorescence quenching. Under acidic conditions, the probe maintains an open-loop structure and has intense fluorescence. The probe possessing good selectivity and stability can target lysosomes and visualize the exogenous pH in live cells. Furthermore, by using this probe, we successfully achieved the monitoring of pH in metamorphic process of shrimp and pork. This probe is expected to provide a good imaging tool for real-time detection of pH in live cells and food monitoring. [ABSTRACT FROM AUTHOR]

[Display omitted] • Synthesis and Aggregation Induced Emission property of Dodecyl Carbazole Barbituric Acid. • Designed novel FRET light harvesting antenna in 90 % aqueous solution by coupling AIEgen-DCBA and ACQphore- Rhodamine 6G using steady state and time resolved fluorescence measurements. • Picomolar range detection limit toward Hg2+ was achieved via FRET. • The excellent pH stability of DCBA and DCBA-Rh6G FRET pair spans from pH 3 to pH 11, rendering them suitable as turn on–off chemosensor in water at both acidic and basic environmental conditions. • The fluorescent probe is utilized for sensitive and selective detection of Hg2+ in real water samples, paper strips and MCF 7 cells. Aggregation Induced Emission (AIE) is an intriguing photophysical phenomenon exhibited by certain chromophores that are non-emissive in dilute solutions but are induced to emit light upon aggregation. A "Turn-on" emission has been observed in Dodecyl Carbazole-Barbituric acid conjugate (DCBA) with the addition of poor solvent like water. FRET between an AIE luminogen- DCBA as donor and Rh6G as acceptor has been investigated using steady-state and time-resolved fluorescence studies. There is a significant spectral overlap between the AIE emission of DCBA and the absorption spectra of Rh6G in 9:1 water to THF binary solution. DCBA AIE emission quenching upon addition of Rh6G is identified as due to FRET. The energy transfer efficiency is found to increase linearly with acceptor concentration, reaching an optimum efficiency of 43 %. It holds the promise of being a multiple-donor single-acceptor artificial light harvesting antenna, with an antenna effect of 20.5 %. The proposed FRET system demonstrates excellent pH stability in pH range of 3 to 11. This FRET pair can serve as a turn off fluorescent probe in real water samples and live cells for sensing of Hg2+ ions with high sensitivity, selectivity, and low cytotoxicity. The sensor is also effective for paper strip based Hg2+ detection. [ABSTRACT FROM AUTHOR]

[Display omitted] • A new quinoxaline-based turn-on fluorescent probe for biothiols was developed. • Detecting biothiols with at least 69-fold fluorescence enhancement. • The probe exhibited outstanding sensitivity and selectivity towards biothiols. • A promising tool for detecting endogenous and exogenous biothiols in living cells. Maintaining biothiols homeostasis is extremely important for the health of organisms. In this work, a pair of fluorescent probes (Acr-QX8A and Acr-QX9A) was designed and synthesized to monitor biothiols. The two probes applied the same fused four ring quinoxaline as the skeleton, benzyl carbamate as the linker and acryloyl group as the recognition site, whose only difference was the amino group's position on the skeleton. By comparing the optical properties, Acr-QX9A exhibited superior performances than Acr-QX8A and chosen for further studies. Probe Acr-QX9A displayed 180-fold, 135-fold and 69-fold fluorescence intensity enhancements upon interactions with Cys, Hcy and GSH respectively, owing to the release of fluorophore QX9A and the restoration of intramolecular charge transfer (ICT) process. Acr-QX9A showed good selectivity and excellent anti-interference, which could be served as the naked-eye colorimetric probe for biothiols detection. More importantly, the probe exhibited high sensitivity towards biothiols with outstanding detection of limits (75.2 nM for Cys, 92.7 nM for Hcy and 370 nM for GSH). Encouraged by the appreciable results in solutions, probe Acr-QX9A was then successfully applied as a promising tool for monitoring both endogenous and exogenous biothiols in living cells. [ABSTRACT FROM AUTHOR]

[Display omitted] • Water-soluble near-infrared QDs enable precise detection of intracellular copper ions with exceptional selectivity and sensitivity. • Low cytotoxicity and high biocompatibility of QDs ensure safe intracellular imaging applications. • Fluorescence bursts in response to changing copper ion content demonstrate QDs' excellent cellular imaging capabilities. • Synthesized QDs demonstrate stable and selective performance for precise quantification of copper content in biological systems. • This research contributes to understanding the physiological role of intracellular copper ions and advances biomedical imaging techniques. The detection and imaging of intracellular copper ions (Cu2+) play a crucial role in understanding their physiological implications and their involvement in various cellular processes. This study focuses on the synthesis and characterization of water-soluble near-infrared fluorescent CIS/ZnS core–shell quantum dots (QDs) with excellent biocompatibility and stability. The QDs exhibit exceptional selectivity and sensitivity for Cu2+ detection, allowing for precise quantification of Cu2+ content within biological systems. Furthermore, Co-incubation of the QDs with HeLa cells demonstrates their impressive cellular imaging capabilities, facilitated by fluorescence bursts in response to changing Cu2+ content. Overall, our proposed QDs are of great significance in advancing the research and application of near-infrared semiconductor quantum dots in biomedicine, and their near-infrared fluorescence properties and high fluorescence quantum yield (34.48 %) make them very advantageous for the precise detection of intracellular Cu2+ and cell fluorescence imaging. This research contributes to the understanding of copper ion dynamics within cells and opens avenues for further exploration of its role in cellular physiology. [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]

[Display omitted] • A single step of synthesis and assemble of lecithin-derived self-assemble carbon dots. • Enhanced photothermal and photoluminescence property. • Superior Theranostic efficiency after 24 h of incubation with enhanced retention. Photothermal therapy is a promising strategy for killing cancer cells, yet the use of carbon dots as a photothermal agent has limited its use due to the high excretion rate from the cancer cell due to its smaller size of less than 10 nm. In this study, we have developed a strategy for synthesizing self-assembled carbon dots with higher photothermal and lesser excretion from cells. Single-step synthesis of self-assembled carbon dots using thermal degradation method process using lecithin as carbon source. The self-assembly of lecithin-derived carbon dots is induced in the presence of water molecules. Excitingly, lecithin-derived self-assembly of carbon dots (LDSCD) shows superior photothermal efficacy even at low concentrations and fluorescence is red-shifted. Moreover, the LDSCD exhibits higher phototoxicity on incubation with cancer cells for two hours followed by near-infrared light exposure after twenty-four hours. The confocal images of the cells incubated with lecithin-derived self-assembly of carbon dots at two-time intervals (4 and 24 hrs) demonstrated higher retention of self-assembled quantum dots compared to the smaller-size carbon dots (<50 nm). [ABSTRACT FROM AUTHOR]

[Display omitted] • A mitochondria-targetable fluorescent probe for cysteine has been reported. • The probe displays high sensitivity and high selectivity for cysteine. • The probe can be utilized for determination of cysteine within the mitochondria of living cells. Cysteine (Cys) is of great significance in biological systems and in the process of mitochondrial function. Highly selective and specificity recognizable probes for mitochondrial Cys are still in demand. In this work, a new fluorescent probe for detecting mitochondrial Cys was developed based on a rhodamine derivative. In this probe, acrylate unit was selected as group of Cys recognition and quaternized pyridinium moiety was utilized as mitochondrial targeting group. The probe showed colorless in daylight and extremely weak fluorescence in 365 nm due to its spirolactone structure when Cys did not exist. In the presence of Cys, the probe exhibited orange in daylight and produced intensely green fluorescence in 365 nm owing to the formation of the conjugated xanthene structure. The probe exhibited specific recognition for Cys. There was an excellent linear relationship between fluorescence intensity at 540 nm of the probe and the Cys concentration from 4.0 × 10-8 to 1.0 × 10-5 mol⋅L-1. And the detection limit was estimated to be 1.57 × 10-8 mol/L. Moreover, the probe was almost non-cytotoxic, possessed targeting-mitochondria ability and could sense Cys at the cellular level. The good bioimaging ability makes the probe a potential tool for studying mitochondrial Cys in biological samples. [ABSTRACT FROM AUTHOR]