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Synthesis of monoclinic Y 2 O 3 remains a challenging task due to complex formation conditions such as high pressure or high temperature environments. Monoclinic yttria exhibits better photoluminescence characteristics compared to the cubic phase and hence can be a better host for nanophosphors. Reports are available predicting the stability of monoclinic phase at low temperature in extremely fine particles. But experimental preparation of this phase at low temperature is not yet reported. Here we report the first-time preparation of monoclinic Y 2 O 3 at 90 °C using simple laboratory hot air oven. The synthesized nanoparticles exhibit intense PL emission in the blue region and hence can find applications in display industry. The band structure calculations were carried out using density functional theory and the excitonic Bohr radius was estimated using the electron as well as hole effective masses determined from band structure. The cytotoxicity studies reveal non-toxic nature the particles. The fluorescence imaging experiments show that the material is capable of emitting blue fluorescence in L6 skeletal cell lines and it ensures the applicability of this material in the biomedical field. [ABSTRACT FROM AUTHOR]

[Display omitted] Fluorescent red-emissive carbon dots (RCDs) were synthesized using the solvothermal method with citric acid as a carbon source, N , N -dimethylformamide as a nitrogen source, and formamide as a solvent. The as-synthesized RCDs show red fluorescence in an aqueous solution and have an excellent stability towards photobleaching as well as extremely low cytotoxicity and are successfully used for cell and zebrafish imaging. The results indicate that RCDs have potential applications in both in vitro and in vivo bioimaging. [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]

Ammonia is a common toxic gas in industrial and agricultural production, which will cause harm to the environment and human health in certain extent. Here, a novel fluorescent probe (R)- 1 based on 1,1′-binaphthol (BINOL) was synthesized for real-time, on-site and quantitative detection of ammonia. The mechanism study shows that the functional groups of –CHO and –OH on (R)- 1 interact with ammonia, which changes the electronic state of the probe molecule and excites strong fluorescence. A test strip for rapid detection of ammonia was developed, which changed from light yellow to reddish brown under natural light after interacting with ammonia, thus realizing the rapid detection and easy visualization of ammonia. Meanwhile, bioimaging experiments shows that probe (R)- 1 can detect exogenous ammonia in cells. [Display omitted] • Specific selective fluorescence recognition of ammonia. • Fast response time (300 s) and high sensitivity (0.96 ppm). • A test strip for real-time and visual detection of ammonia. • Exogenous ammonia fluorescence imaging of cells. [ABSTRACT FROM AUTHOR]

[Display omitted] • Multifunctional CDs were prepared hydrothermally from eco-friendly Coccinia Grandis. • EC-Dots exhibited uniform globular shape with an average size of 4 nm (QY of 17 %). • EC-Dots emit bright fluorescence that is dependent on the excitation wavelength. • The current research provided a new platform in the field of bioimaging. • Also, the EC-Dots are a versatile component in various types of fluorescent ink. This study adopted an eco-friendly approach for the one-step hydrothermal conversion of sustainable Coccinia grandis into well-dispersed, uniform-sized carbon dots. The resulting eco-friendly carbon dots (EC-Dots) were harnessed for bioimaging and fluorescent ink applications. EC-Dots exhibited an average size of 4 nm. Further, cytotoxicity assessments on live nematodes revealed cell viability > 95 %. In-vivo studies showed excellent uptake and their ability to emit light in multiple colors, including blue, green, and red, achieved by adjusting the excitation wavelength. Additionally, the EC-Dots exhibited robust fluorescence in aqueous solutions and exceptional resistance to photobleaching, rendering them highly effective for generating fluorescent ink for drawing and writing. Thus, this research showcases an environmentally sustainable, cost-effective, and straightforward hydrothermal method for creating biocompatible EC-Dots with diverse hydrophilic properties. These synthesized EC-Dots stand as a promising platform for applications in fluorescent ink and in vivo bioimaging, offering a high level of safety with minimal cytotoxicity. [ABSTRACT FROM AUTHOR]

[Display omitted] • A novel peptide-based fluorescent probe DNC for sequential detection of Hg2+ and S2− was synthesized. • The detection limits of Hg2+ (8.4 nM) and S2− (5.5 nM) were significantly low. • DNC were successfully applied for sequential detection of Hg2+ and S2− in living cells and zebrafish. • DNC achieved selective and sensitive sensing toward Hg2+ and S2− on test strips. • Smartphone with RGB Color Picker was employed to analyze the different Hg2+ and S2− concentrations. Mercury ions (Hg2+) and sulfur ions (S2−), have caused serious harm to the ecological environment and human health as two kinds of highly toxic pollutants widely used. Therefore, the visual quantitative determination of Hg2+ and S2− is of great significance in the field of environmental monitoring and medical therapy. In this study, a novel fluorescent "on–off-on" peptide-based probe DNC was designed and synthesized using dipeptide (Asn-Cys-NH 2) as the raw material via solid phase peptide synthesis (SPPS) technology with Fmoc chemistry. DNC displayed high selectivity in the recognition of Hg2+, and formed non-fluorescence complex (DNC- Hg2+) through 2:1 binding mode. Notably, DNC- Hg2+ complex generated in situ was used as relay response probe for highly selective sequential detection of S2− through reversible formation-separation. DNC achieved highly sensitive detection of Hg2+ and S2− with the detection limits (LODs) of 8.4 nM and 5.5 nM, respectively. Meanwhile, DNC demonstrated feasibility for Hg2+ and S2− detections in two water samples, and the considerable recovery rate was obtained. More importantly, DNC showed excellent water solubility and low toxicity, and was successfully used for consecutive discerning Hg2+ and S2− in test strips, living cells and zebrafish larvae. As an effective visual analysis method in the field, smartphone RGB Color Picker APP realized semi-quantitative detections of Hg2+ and S2− without the need for complicated device. [ABSTRACT FROM AUTHOR]

[Display omitted] • A novel rhodamine-based chemosensor RB-Gly-4-NAP (RGN) was prepared for multi-ion detection. • The sensor enables highly selective detection of Hg2+ and trivalent cations (Fe3+, Al3+, Cr3+) across different channels. • Theoretical calculations confirmed the efficacy of the sensor in coordinating with Fe3+, Al3+, Cr3+, and Hg2+. • The sensor shows excellent sensitivity to Fe3+, Al3+, Cr3+, and Hg2+, with LODs of 10.20, 14.66, 58.78, and 73.33 nM. • The sensor has been successfully applied to actual water samples and bioimaging (cell imaging and zebrafish imaging). A novel rhodamine-based multi-ion fluorescent sensor, RGN, was designed and synthesized for the highly selective detection of mercury ions (Hg2+) in ethanol and water systems, as well as trivalent cations (Fe3+, Al3+, and Cr3+) in acetonitrile and water systems using a two-step Schiff base reaction method. Nuclear magnetic titration experiments and theoretical calculations demonstrated that the sensor achieved the detection of the aforementioned metal ions through the fluorescence turn-on phenomenon induced by lactam ring-opening. Density functional theory (DFT) calculation results showed decreased HOMO-LUMO energy gaps and increased dipole moments, indicating the effective coordination of the sensor with the corresponding metal ions to form more stable complexes, thereby achieving detection objectives. Furthermore, the fluorescence turn-on sensor RGN exhibited relatively low detection limits, with limits of detection (LOD) for Fe3+, Al3+, Cr3+, and Hg2+ being 10.20 nM, 14.66 nM, 58.78 nM, and 73.33 nM, respectively. Finally, practical applications of sensor RGN in environmental water samples, L929 cells, and zebrafish were demonstrated, indicating its potential for detecting and tracking Fe3+, Al3+, Cr3+, and Hg2+ in environmental samples and biological systems, with prospects for biomedical applications in the diagnosis and treatment of heavy metal ion-induced diseases. [ABSTRACT FROM AUTHOR]

[Display omitted] • Three novel fluorescence chemosensors were developed for Hg2+ determination based on dethioacetalization reaction. • Sensors displayed highly sensitive and selective to Hg2+ in aqueous system with low detection limit. • Sensor was successfully applied to detect Hg2+ in real water samples and herb extract samples. • Sensor is capable of monitoring Hg2+ in living cell. Mercury ion is one of the most harmful metal ions with significant hazards to the environment and human health. Thus, the development of innovative, sensitive, and selective sensors to help address the detrimental impacts of heavy metal contamination is necessary. In this work, we present three new chemosensors based on the deprotection reaction of the thioacetal group for distinguishing Hg2+ in environmental samples. These chemosensors show good photophysical properties with high quantum yield in aqueous medium. These prepared chemosensors were employed as fluorometric sensors for the determination of Hg2+ through the quenching of fluorescence emission due to the Hg2+-induced hydrolysis of the thioacetal to the aldehyde group. In the presence of Hg2+, chemosensors showed an emissive color transformation from blue fluorescence to non-fluorescence under UV light, which was readily seen by the visual eye. These chemosensors also exhibited highly distinctive selectivity toward Hg2+ over other interfering metal ions, with detection limits of 1.1 ppb, 13.4 ppb, and 12.7 ppb. Moreover, the practical applicability of chemosensor was successfully demonstrated in real water samples and herb extract samples. [ABSTRACT FROM AUTHOR]

According to DFT calculations, the coordination ratio (1:1) and mechanism of action (PET) of NRh6G-FA with Cu2+ were further investigated and elucidated. NRh6G-FA has been successfully applied to the detection of Cu2+ in CHM samples, "naked eye" identification and bioimaging of Cu2+ in living MCF-7 cells. [Display omitted] • A near-infrared rhodamine-like probe NRh6G-FA responsive to Copper (II) ions was designed and synthesized. • The responses of NRh6G-FA to Cu2+ were thoroughly confirmed by Job's plot, ESI-HRMS and DFT calculations. • NRh6G-FA can be successfully applied to recovery experiments and "naked eye" detection of Cu2+ in Chinese herbal medicine. • NRh6G-FA has low cytotoxicity and can be used for the detection of Cu2+ in living cells. Copper is one of the common among the heavy metal pollution in Chinese herbal medicine (CHM). So, it is essential to develop rapid and accurate testing method to quantify the Cu2+ content in CHM. Herein, we prepared a coordination-based near-infrared fluorescent probe (NRh6G-FA) by introducing a hemicyanine dye in rhodamine 6G scaffold. NRh6G-FA had a high sensitivity, anti-interference performance, fast response (within 60 s), visualization (from light yellow to green) for Cu2+ and excellent sensing performance for the detection of Cu2+ at low concentrations (LOD = 0.225 μM). The most likely mechanism was verified on the basis of Job's plot, ESI-HRMS and DFT calculations. NRh6G-FA could be successfully applied for the detection and "naked eye" recognition of Cu2+ in CHM samples. Moreover, NRh6G-FA was used to visualize Cu2+ in living MCF-7 cells by confocal fluorescence 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]

Herein, we synthesized green luminescent nitrogen (N) and sulfur (S) co-doped carbon dots (N, S-CDs) which could realize the monitor of 4-nitrophenol (4-NP) and pH. The N, S-CDs can be designed as a fluorescent probe for sensitive detection of 4-NP in water samples with linear ranges of 0–85 µM and a detection limit of 0.037 µM. Moreover, the fluorescence intensity of N, S-CDs is sensitive to pH and shows a linear relationship with pH values ranging from 3.50 to 7.25 and 7.25–12.00, accompanied with a significant color variation of the N, S-CDs solution from colorless to brown. Finally, the proposed N, S-CDs have also been applied to monitor the 4-NP in oocysts due to its low cytotoxicity. Scheme 1. Schematic diagram of the synthesis and application of the N, S-CDs. [Display omitted] • N, S-doped carbon dots (N, S-CDs) with green emission were synthesized by one-step hydrothermal method. • N, S-CDs can be used as a bifunctional sensing platform for the detection of pH and 4-nitrophenol (4-NP). • The detection of 4-nitrophenol (4-NP) in water samples were successfully realized by using N, S-CDs. • N, S-CDs can also be used for cell imaging. Using p-aminophenol and dithioacetamide as precursors, green luminescent nitrogen (N) and sulfur (S) co-doped carbon dots (N, S-CDs) are prepared by hydrothermal method with the quantum yield (QY) of 7.1 %. Superior properties of the N, S-CDs including high photostability, outstanding biocompatibility, and desirable biological penetration were found, which could realize the monitor of 4-nitrophenol (4-NP) and pH. The N, S-CDs can be designed as a fluorescent probe for sensitive detection of 4-NP in water samples with linear ranges of 0–85 µM and a detection limit of 0.037 µM. Moreover, the fluorescence intensity of N, S-CDs is sensitive to pH and shows a linear relationship with pH values ranging from 3.50 to 7.25 and 7.25–12.00, accompanied with a significant color variation of the N, S-CDs solution from colorless to brown. Finally, the proposed N, S-CDs have also been applied to monitor the 4-NP in oocysts due to its low cytotoxicity, providing a great capacity for various targets molecules detection. [ABSTRACT FROM AUTHOR]

In this study, an amphiphilic polymer FA-CS-DBA-CHO with aggregation-induced emission (AIE) feature was prepared by introducing 4-(diphenylamino)benzaldehyde derivative (DBA-CHO), imine bond and folic acid (FA) to the molecular structure of chitosan (CS). The amphiphilicity drove the polymer to self-assemble into micelles, and paclitaxel (PTX) could be solubilized in the hydrophobic core. Due to the excellent AIE effect, FA-CS-DBA-CHO exhibited strong cellular imaging capability. The pH-sensitive imine bond in the polymer allowed for accurate drug release in acidic environment. Both in vitro and in vivo studies demonstrated that the PTX-loaded FA-CS-DBA-CHO micelles could significantly inhibit the growth of tumor cells but without any notable toxicity. This micellar system was excellent carrier for bioimaging and chemotherapeutic drug delivery. [Display omitted] • An Aggregation-induced emission (AIE)-featured chitosan derivative was prepared. • The polymer could self-assemble into micelles and solubilize paclitaxel. • The micelles exhibited AIE imaging, tumor targeting and pH-responsive properties. • The micelles would be superior carriers for biological imaging and chemotherapy. [ABSTRACT FROM AUTHOR]

In this contribution, a novel AIE monomers 2-(4-styrylphenyl)− 1,2-diphenylvinyl)styryl)pyridine (SDVPY) with smart fluorescent pH-sensitivity basing on tetraphenylethylene-pyridine were successfully synthesized for the first time, subsequently, a series of amphiphilic copolymers PEG-PY were achieved by reversible addition-fragmentation chain transfer (RAFT) polymerization of SDVPY and poly(ethylene glycol) methacrylate (PEGMA), which would self-assemble in water solution to form core-shell nanoparticles (PEG-PY FONs) with about 150 nm diameter. The PEG-PY FONs showed obvious fluorescence response to Fe3+, HCO3- and CO 3 2- ions in aqueous solution owing to their smart pH-sensitivity and AIE characteristics, and their maximum emission wavelength could reversibly change from 525 nm to 624 nm. The as-prepared PEG-PY FONs showed also prospective application in cells imaging with the variable fluorescence for different pH cells micro-environment. When PEG-PY copolymers self-assembled with the anti-tumor drug paclitaxel (PTX), the obtained PY-PTX FONs could effectively deliver and release PTX with pH-sensitivity, and could be easily internalized by A549 cells and located at the cytoplasm with high cytotoxicity, which was further confirmed by the Calcein-AM/PI staining of dead and alive A549 cells. Moreover, the flow cytometry results indicated that the PY-PTX FONs could obviously induce the apoptosis of A549 cells, which further showed the great potential of PY-PTX FONs in the application of tumors therapy. • A novel AIE monomer SDVPY was successfully prepared, which showed obvious pH-sensitivity. • The desirable PEG-PY copolymers by RAFT polymerization exhibited the promising application in ions detection and bioimaging. • Moreover, the PY-PTX FONs could effectively deliver and release PTX with pH-sensitivity and high cytotoxicity. [ABSTRACT FROM AUTHOR]

[Display omitted] Carbon quantum dots (CQDs) with an average diameter of 3 nm, exhibiting blue photoluminescence, have been obtained from commercial conductive carbon black by a cost-effective and straightforward exfoliation method using dry ball milling in the presence of sodium carbonate. As a secondary abrasive medium, sodium carbonate provides effective exfoliation of carbon black with a high degree of CQD graphitization and plays an essential role in the functionalization of CQDs with oxygen groups. Due to the low toxicity of CQDs against HeLa cancer cells (cell viability above 90% at a CQD concentration of 200 μg cm−3) and the ability to penetrate cells and emit blue light, CQDs are possibly suitable for biological imaging of cells. [ABSTRACT FROM AUTHOR]

Although carbon dots (CDs) as a promising fluorescent nanomaterial have been studied for nearly twenty years, excitation-independent long wavelength emission CDs are rarely reported and are highly desirable for biomedical applications. Herein, we show that the excitation-independent, bright-orange-emissive, polyethylenimine-modified CDs (PEI-CDs) can be easily obtained by using 1, 2, 4-triaminobenzene and PEI as precursors through a simple hydrothermal method. PEI-CDs prepared under our experimental conditions are low-toxic and safe, and their cellular uptake can be observed via the red fluorescence of PEI-CDs appearing inside cells. Furthermore, PEI-CDs are able to bind spontaneously small interfering RNA (siRNA) to form the nano-complexes by electrostatic attraction. The PEI-CDs-siRNA complexes can effectively deliver the specific siRNA targeting hepatoma-derived growth factor (HDGF) into human glioblastoma cells, and therefore downregulate the expression of HDGF, which is considered as a potential target for glioblastoma treatment. Thus, the excitation-independent long wavelength emission PEI-CDs may constitute a new siRNA delivery carrier with imaging-trackable ability. [Display omitted] • Excitation-independent, bright-orange-emissive PEI-CDs are obtained. • An improved dialysis-precipitation method is used for purification of PEI-CDs. • PEI-CDs can bind siRNA to form the nano-complexes by electrostatic attraction. • PEI-CDs-siRNA complexes can deliver siHDGF into human glioblastoma cells. • PEI-CDs are a new siRNA delivery carrier with imaging-trackable ability. [ABSTRACT FROM AUTHOR]

The design of efficient synergistic therapeutic strategies for bacterial infection is highly desirable due to their high therapeutic efficiency and less side effects. In this study, a rapid and effective multi-mode antibacterial platform that integrates quaternary ammonium compounds (QACs), photothermal therapy (PTT) and photodynamic therapy (PDT) was developed. QACs can induce initial damage to the bacterial cell membrane and render it more sensitive to heat. During 808 nm laser irradiation, the generation of hyperthermia and reactive oxygen species (ROS) can induce the death of damaged Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus), and the corresponding bacterial killing efficiencies are approximately 99.36% and 99.98%, which exceed single-mode therapy. In vivo antibacterial and anti-infective assays proved that effective sterilization could accelerate the infected wound healing process, and the traumas healed well within 14 days after treatment with Cu-RCDs-C 35 and 808 nm irradiation. The wound healing area ratio was calculated to be 96%, which substantially exceeds the PBS + Laser, Cu-RCDs, and RCDs-C 35 +Laser groups. In addition, the cellular imaging experiment showed that Cu-RCDs-C 35 could also serve as a fluorescence probe in bioimaging due to its inherent luminescence. Therefore, the present study provides high-efficiency and multifunctional carbon nanomaterials as antibacterial and bioimaging agents. [Display omitted] • Cu-RCDs-C 35 integrated PTT, PDT, and quaternary ammonium to achieve triple synergistic sterilization effect. • Synergistic therapy could promote wound repair and prevent inflammation. • Cu-RCDs-C 35 exhibited low phototoxicity and excellent biocompatibility. • Cu-RCDs-C 35 integrated functionalities of antibacterial and bioimaging. [ABSTRACT FROM AUTHOR]

The fluorescent probe HOS for Hg2+ detection and its application to water sample detection and bioimaging. [Display omitted] • Development of a xanthene-based fluorescent sensor HOS for ratiometric fluorescence detection of Hg2+. • HOS is capable of detecting ultra-trace Hg2+ levels. • Successful determination of Hg2+ levels in shrimp and water samples. • HOS can be used to visualize Hg2+ in living cells, zebrafish and tobacco seedlings. In this paper, an Hg2+ detection probe, HOS , was prepared with a xanthene as the parent fluorophore. Hg2+-initiated thioacetal deprotection reaction is the detection mechanism of this probe. After testing, the probe HOS was able to accurately determine Hg2+ with a detection limit of 36 nM. It was successfully applied to the detection of Hg2+ in different water samples and shrimp samples, meanwhile, the filter paper strips prepared by HOS were obviously changed from light yellow to dark yellow under daylight, and from green to yellow under 365 nm UV light. Furthermore, probe HOS enabled Hg2+ bioimaging experiments on HepG2 cells, zebrafish and tobacco seedlings under laser confocal microscopy. [ABSTRACT FROM AUTHOR]

[Display omitted] • The probe 3-STF is first designed based on 3-thiolflavone. • The probe 3-STF exhibited a specific "turn-on" fluorescence response towards biothiols (Cys, Hcy, and GSH) with a large stokes shift of 140.6 nm. • The detection of biothiols did not suffer from the interference of other amino acids. • The detection mechanism was discussed in detail. • The probe 3-STF can be successfully applied to monitor endogenous and exogenous biothiols in HepG-2 cells. Abnormal levels of intracellular biothiol species, including glutathione (GSH), homocysteine (Hcy), and cysteine (Cys), are closely relevant to a variety of diseases. In this study, we first report the design and synthesis of a 3-thiolflavone-based probe 3-STF with an S–S linkage both as the fluorescence quenching agent and the recognition site. Upon treatment with biothiols, the S–S linkage was cleaved by nucleophilic attack of RS-, and 3 -STF exhibited a specific "turn-on" fluorescence response at 543.8 nm upon 390 nm excitation. Meanwhile, 3 -STF was proved to be highly sensitive and selective for the detection of biothiols over other nucleophiles such as amino acids and H 2 S. The sensing mechanism was further verified by 1H NMR and ESI-MS analysis. In addition, 3-STF with low cytotoxicity can be successfully applied to detect endogenous and exogenous biothiols in HepG-2 cells. [ABSTRACT FROM AUTHOR]

A new hemicyanine-based near-infrared "off-on" recognition Cu2+ fluorescent probe NRh-NP was designed and successfully synthesized. The structure of NRh-NP was characterized by NMR, ESI-HRMS and single crystal X-ray diffraction analysis. NRh-NP has high sensitivity, selectivity and a low limit of detection (33 nM as fluorescence sensor and 35 nM as UV sensor) to Cu2+. According to Job's plot and ESI-HRMS, the coordination ratio of NRh-NP to Cu2+ was 1:1. DFT theoretical calculations proved that the sensor mechanism was photo-induced electron transfer (PET). More importantly, NRh-NP has excellent membrane permeability and low cytotoxicity, which could be used not only for the detection of Cu2+ in human breast cancer cells (MCF-7), but also for imaging Cu2+ in living mice. [Display omitted] • The structure of NRh-NP was characterized by NMR, ESI-HRMS and single crystal X-ray diffraction analysis. • The responses of NRh-NP toward Cu2+ were fully proved by Job's plot, ESI-HRMS and DFT theoretical calculations. • NRh-NP has high sensitivity and selectivity with detection limit as low as 33 nM. • NRh-NP can be used for Cu2+ imaging in living cells and in vivo. [ABSTRACT FROM AUTHOR]

Graphene quantum dots, which possesses unique photoluminescence property, have received enormous attention for bio-sensor, photovoltaic devices and bioimaging application. However, synthesizing high-quality of GQDs remains a formidable obstacle in terms of the two conventional methods since the "top-down" method usually requires expensive raw materials while the "bottom-up" method suffers from incompatibility between quality and production. Thus, developing new strategies to trade-off these issues is promising for GQDs production. Here, we reported an ultrafast deflagration strategy by igniting Al and pentafluoropyridine mixture to prepare high-quality of carbon nanomaterials (CNs) with high graphitization, reaching a high yield of ∼3 g. Combining with a subsequent Hummer's exfoliation and dialyze method, the CNs materials were successfully exfoliated into the uniform-dispersed graphene quantum dots (D-GQDs) with size of 1∼2 nm. The as-prepared D-GQDs derivatives shows remarkable optical properties and it is successfully applied in fluorescence imaging of HeLa cells. Our results in this study highlighted the high efficiency of deflagration technique to prepare functional carbon-based nanomaterials, and proposed a facile and fast strategy for gram-scale synthesis. • A unique ultrafast deflagration synthesis for a low-cost and high-quality synthesis of graphite-based carbon materials. • A gram-scale synthesis of graphite-based materials reaching a high yield of ∼3 g. • Exfoliated graphene quantum dots (GQDs) for promising cell imaging application. [ABSTRACT FROM AUTHOR]

Cellular heterogeneity poses a major challenge for tumor theranostics, requiring high-resolution intercellular bioanalysis strategies. Over the past decades, the advantages of electrochemical analysis, such as high sensitivity, good spatio-temporal resolution, and ease of use, have made it the preferred method to uncover cellular differences. To inspire more creative research, herein, we highlight seminal works in electrochemical techniques for biomolecule analysis and bioimaging. Specifically, micro/nano-electrode-based electrochemical techniques enable real-time quantitative analysis of electroactive substances relevant to life processes in the micro-nanostructure of cells and tissues. Nanopore-based technique plays a vital role in biosensing by utilizing nanoscale pores to achieve high-precision detection and analysis of biomolecules with exceptional sensitivity and single-molecule resolution. Electrochemiluminescence (ECL) technology is utilized for real-time monitoring of the behavior and features of individual cancer cells, enabling observation of their dynamic processes due to its capability of providing high-resolution and highly sensitive bioimaging of cells. Particularly, scanning electrochemical microscopy (SECM) and scanning ion conductance microscopy (SICM) which are widely used in real-time observation of cell surface biological processes and three-dimensional imaging of micro-nano structures, such as metabolic activity, ion channel activity, and cell morphology are introduced in this review. Furthermore, the expansion of the scope of cellular electrochemistry research by innovative functionalized electrodes and electrochemical imaging models and strategies to address future challenges and potential applications is also discussed in this review. [Display omitted] • Recent progress of electrochemical science biological research. • Overview of molecular detection techniques ranging from extracellular to intracellular levels. • Overview of electrochemical imaging techniques for monitoring of structural characteristics. [ABSTRACT FROM AUTHOR]

• A novel NTR-responsive "turn off" fluorescent probe TPEDCH-PBN was designed. • TPEDCH-PBN exhibited typical aggregation-induced emission (AIE) properties. • TPEDCH-PBN showed high selectivity and low detection limit towards nitroreductase. • TPEDCH-PBN displayed time-dependent fluorescence quenching behaviors. • The molecular design strategy was elaborated by DFT and docking calculations. Nitroreductase (NTR) is frequently employed as a biomarker to assess the level of hypoxia in tumor tissues. To date, the majority of NTR-reactive probes have focused on the luminescence "turn on" characteristic, which has been plagued by background interferences. In this study, we present the first report of an NTR-responsive "turn-off" fluorescent probe, TPEDCH-PBN, based on AIEgen. This probe exhibits typical aggregation-induced emission (AIE) properties in high PBS fraction, which may be attributed to the restriction of intramolecular motions (RIM) effect. DFT/TD-DFT calculations were employed to determine the discrepancies in structure and electron density distribution among TPEDCH, TPEDCH-PBN OH and TPEDCH-PBN. Additionally, docking calculations were utilized to elucidate the structure-function relationship between the probe and NTR, revealing a favorable structural and spatial match. Photophysical investigations demonstrated the probe's high selectivity towards NTR with the detection limit of 0.68 μg/mL. The dynamic quenching process of TPEDCH-PBN upon NTR was examined, and the quenching constant Ksv was determined to be 53.6 g −1.L. In addition, the NTR detection ability of probe TPEDCH-PBN as well as its time-dependent fluorescence quenching behaviors were confirmed by cell imaging of probe in A549 cells. Overall, this study proposed a novel molecular design approach for the biomarker detection probe, which may prove to be more extensively applicable. Schematic Representation of the NTR-responsive turn-off fluorescent probe based on AIEgen and its bioimaging application [Display omitted] [ABSTRACT FROM AUTHOR]

The article highlights a quinoline-based probe for the detection of Cd2+ over other metal ions with a nanomolar level detection limit. Both DFT and TD-DFT studies were carried out to explore the sensing mechanism as well as the theoretical electronic spectra. The utilization of the probe in real-life applications has been investigated in live cells. [Display omitted] • A quinoline-based probe for the detection of Cd2+ in near-aqueous medium. • Binding mode is confirmed by single crystal XRD analysis. • Nanomolar detection limits of Cd2+. • DFT and TD-DFT analysis of both ligand and its Cd2+ complex. • Positive response towards bioimaging in live RAW 264.7 cell line. The present investigation highlights a quinoline-based small molecule probe (DEQ) for the detection of Cd2+ among other metal ions in near-aqueous media. The probe DEQ and its Cd2+ complex (DEQ-Cd) have been synthesized and characterized by all possible spectroscopic methods. The weakly emissive DEQ showed its strong emission in the presence of Cd2+, which is attributed to the photoinduced electron transfer (PET) along with the chelation-enhanced fluorescence (CHEF) mechanism. The 1:1 binding mode between ligand and Cd2+ is confirmed by single crystal XRD analysis, which is further supported by Job's plot and HRMS. The detection limit of the probe to recognize Cd2+ was found to be as low as 89 nM. Furthermore, DEQ can act as a reversible fluorescence probe with the off-on-off mechanism by the alternative addition of Cd2+ and EDTA. DFT and TD-DFT studies exposed the proposed mechanism after Cd2+ insertion and the obtained results for electronic spectra are in line with the experimental results. The response towards pH was quite interesting and allowed us to study its application in live cell imaging. With all the positive results, the proposed ligand DEQ can be used as a potential probe for the detection of Cd2+ in real-life applications. [ABSTRACT FROM AUTHOR]

[Display omitted] • Heteroatom-doped photoluminescent CDs was prepared by hydrothermal method. • NSB-CDs exhibited good water solubility, stability, biocompatibility, and less toxic. • NSB-CDs presented high sensitivity and selectivity towards Fe3+ ions and cysteine. • The limit of detection of the sensor NSB-CDs is 54.4 nM/Fe3+ and 4.9 nM/Cys. • NSB-CDs/Fe3+ ion and cysteine were promising multicolor imaging with HCT-116 cells. Herein, a simple hydrothermal synthesis is used to prepare multiple heteroatom-doped photoluminescent carbon dots (CDs) from thiourea (N and S source) and boric acid (B source) as precursors. The optical and physicochemical properties of the as-synthesized NSB-CDs were studied using UV–Vis, photoluminescence, TEM, FT-IR, XRD, Raman, and XPS analyses. The NSB-CDs exhibited excellent stability, high photostability, pH, and ionic strength tolerance; they retained their excellent stability independent of excitation. The NSB-CDs featured small sizes of approximately 3.2 ± 0.4 nm (range: 2.0–5.0 nm) as evidenced using TEM measurements. The NSB-CDs were used as a photoluminescent sensing platform to detect Fe3+ as well as cysteine (Cys) molecules. The competitive binding of Cys to Fe3+ resulted in NSB-CDs that retained their photoluminescence. For the rapid identification and quantification of Fe3+ and Cys, NSB-CDs were developed as a "switch-on" dual-function sensing platform. The linear detection range of Fe3+ was 0–20 μM (limit of detection [LOD]: 54.4 nM) and that of Cys was 0–50 μM (LOD: 4.9 nM). We also introduced a smartphone RGB analysis method for detecting low-concentration solutions based on digital images. The NSB-CDs showed no toxicity at 100 μg/mL. Photoluminescent probes for multicolor live-cell imaging can be used with NSB-CDs at this concentration, suggesting that NSB-CDs may be promising photoluminescent probes. [ABSTRACT FROM AUTHOR]

Dopamine β-hydroxylase (DBH) is involved in various neuronal transmission processes in the brain. Due to the severe diseases caused by abnormity levels of such important enzyme in human serum, sensitive and rapid detection of DBH at early stages is crucial, particularly for clinical analysis. Herein, we developed optical sensors for DBH that include the following: (i) a ratiometric fluorescence sensor that hybridizes the bovine serum albumin (BSA)-gold nanoclusters (BSA-AuNCs) and nitrogen doped carbon dots (N-CDs). The sensor proved to be highly selective and sensitive, achieving a linear range of 0.02–0.16 μg mL−1 and a limit of detection of 4.0 ng mL−1. In the presence of DBH, the fluorescence intensity of BSA-AuNCs (λ em = 615 nm) was remarkably quenched by DBH serving as a reporter signal, whereas the N-CDs fluorescence intensity at 440 nm was almost kept unchanged serving as a reference signal. The developed ratiometric sensor is capable of demonstrating a color change from pink to violet and blue with a gradual increase in DBH concentration, which is discernible by the naked-eye. A test strip is prepared for semi-quantitative assay and convenient use. Intriguingly, by taking advantage of the inter-AuNCs aggregation in the presence of DBH, (ii) a resonance light scattering (RLS) sensor was also developed based on the nanohybrid probe (detection limit 95 ng mL−1). Fluorescence imaging in PC12 cell lines demonstrated that the BSA-AuNCs could be utilized in visualization assay towards intracellular DBH. Additionally, the sensors were tested in a real matrix by spiking serum samples with satisfactory recoveries. Image 1 • Ratiometric fluorescence method for Dopamine β-hydroxylase was developed for the first time. • Dopamine β-hydroxylase assay was performed for the first time based on a nontoxic and simple method. • A resonance light scattering detection of Dopamine β-hydroxylase was developed. • A portable and visual test strip was developed for Dopamine β-hydroxylase as a point of care testing. • Cellular imaging of the BSA-AuNCs was achieved successfully on brain cells. [ABSTRACT FROM AUTHOR]

Pyrene-phenylglycinol tangled ratiometric sensor (R)-1 was developed for the detection of Al3+ ion over other metal ions. Ratiometric behaviour of (R)-1 for Al3+ ion explained through monomer emission and excimer quenching leads to avoiding the π-π interactions of bis-pyrene rings. Pull-push to push-pull binding mechanism is successfully explained by DFT and sensing of Al3+-ions demonstrated in living cells. The LOD of (R)-1 for Al3+ downs to nanomolar concentrations which is lower than the allowed concentration of drinking water set by the (World Health Organization) WHO. Image 1 • Probe (R)-1 selectively detects Al3+-ion via ratiometric approach and detection limit upto nanomolar range. • Pull-push to push-pull binding mechanism is supported by fluorimetry and DFT studies. • Probe (R)-1 act as a reversible ratiometric sensor for Al3+ ion in the presence of EDTA. • Sensing behaviours (R)-1 to Al3+ ion successfully applied into living cell imaging studies. [ABSTRACT FROM AUTHOR]

A new coumarin-based probe 3-acetyl-7-diethylaminocoumarinthiosemicarbazone (DCT) is synthesized for Al3+ fluorescence detection in CH 3 CH 2 OH/H 2 O (6 : 4, v / v). The fluorescence intensity at 428 nm was enhanced about 15-fold with the fluorescence changed from colorless to blue. The binding constantof Al3+ with DCT is 5.04 × 106 M−1. The limit of detection (LOD) of Al3+ is calculated to be 82 nM. Furthermore, the binding details are determined by Job's plot and ESI - MS studies, which indicated that a stoichiometric ratio of 1 : 1 complex is formed between Al3+ and DCT. Cell imaging confirmed that DCT could useful for detecting Al3+ in HepG2 cells. • Probe DCT is highly selective and sensitive towards Al3+in aqueous solution phase with LOD is 82 nM,which could monitor intracellular Al3+ levels. • The mechanism indicated that a ratio of 1 : 1 complex is formed between Al3+ and DCT. [ABSTRACT FROM AUTHOR]

Conjugated polymers for bioimaging and sensing chemical/biological reagents have received much attention owing to their outstanding photophysical properties. However, most conventional synthetic strategies result in aggregates of conjugated polymers with limited solubility in most common organic and aqueous solvents. Therefore, advancement in molecular design and synthetic pathways is required to tune the optical and solubility properties of the resulting conjugated polymers. Herein, a simple, general, and effective approach for the synthesis of water-soluble polypyrrole (PPy) is reported based on the chemical polymerization in the presence of a homologue series of dicarboxylic acids with different chain lengths as multifunctional dopant molecules, possessing two carboxylic acid groups which serve as both dopants and stabilizing agents. The role of dopant chain length on the emission properties of resulting water-soluble polymers has been investigated. Among the synthesized water-soluble polymers, succinic acid-stabilized polymer (PPy-Suc) showed the highest emission wavelength (λ em = 453 nm), high quantum yield (12.87), very good photostability and low cytotoxicity, suggesting its applicability in bioimaging and sensing applications. As a proof of concept, the PPy-Suc polymer was successfully utilized in cellular imaging. Moreover, a novel fluorescence iodide sensor with two linear ranges of 0.012–0.200 and 0.200–8.825 μM and a low detection limit of 9 nM was developed based on the prepared PPy-Suc polymer. The superior properties of the synthesized water-soluble polymers confirm the potential applicability of developed method as a general, facile and effective synthesis approach in preparation of water-soluble conjugated polymers with several potential applications. Image 1 • PPy structure was modified with introducing homologue series of dicarboxylic acids. • Dicarboxylic acids act as both dopants and stabilizers and prepared water-soluble conjugated polymers. • The synthesized polymer (PPy-Suc) was used for development of a sensitive and selective iodide ion fluorescence sensor. • The PPy-Suc polymer was successfully utilized in cellular imaging. [ABSTRACT FROM AUTHOR]

A novel imidazo[1,2-a]pyridine-rhodamine ratiometric fluorescent probe IP-Hg for Hg2+ based on a fluorescence resonance energy transfer mechanism has been developed. The probe has been proved to show high sensitivity and high selectivity toward Hg2+. Furthermore, it could be used for imaging Hg2+ in cells and in polluted water. Image 1 • A ratiometric fluorescent probe for sensing Hg2+ based on new imidazo[1,2-a]pyridine fluorophore has been synthesized. • The probe exhibits highly sensitivity and selectivity toward Hg2+ (LOD: 9.1 nM). • The ratiometric fluorescent probe displays a remarkable emission shift (220 nm). • The probe show low cytotoxicity and can image in cells. [ABSTRACT FROM AUTHOR]

A rhodamine B-based chromo-fluorogenic probe BOS is prepared with a good yield by condensating an o-diaminobenzene functionalized rhodamine derivative (RBO) and a large steric hindrance salicylaldehyde, and characterized by elemental analysis, infrared spectroscopy (IR), 1H and 13C NMR technology, and high resolution mass spectrum (HRMS). Spectroscopy experiments reveal that the probe can selectively and sensitively detect Al3+ from a variety of metal ions with a low detection limit of 1.855 μmol/L. Compared to traditional detection methods, BOS provides an inexpensive, rapid and straightforward way for Al3+ detection that can be distinguished by "naked eye". The MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl-2- H - tetrazoliubromide) assays and cell imaging experiments demonstrate that the sensor is low toxic and amicable for Al3+ sensing in living cells. Image 1 • A novel rhodamine-based probe BOS is designed and synthesized. • BOS is able to high selectively and sensitively detect Al3+. • The detection process can be identified through naked eye. • BOS is capable of detecting Al3+ in complex biological environment. [ABSTRACT FROM AUTHOR]

Three novel fluorescent viscosity probe L1–L3 with a D π A type were developed. L1–L3 displayed very weak emission in nonviscous media and remarkable fluorescence enhancement with the viscosity increased. Moreover, L1–L3 exhibited a direct linear relationship well between log (I / I 0) and the log η , which allowed us to quantitatively measure the environmental viscosity. Importantly, L1–L3 is suitable for visualizing the viscosity changes in living cells. A series of novel quinoline derivatives L1–L3 with a D π A type were developed as a fluorescent viscosity probe in vitro. L1–L3 displayed very weak emission in nonviscous media and remarkable fluorescence enhancement with the viscosity augment in the water/glycerol system, especially for L2. Different substituent units exhibit a considerable influence on the photophysical properties and response sensitivity of the probes to viscosity. Probes L1–L3 exhibited a direct linear relationship well between log (I / I 0) and the log η , which allowed us to quantitatively measure the environmental viscosity. Moreover, L2 modified with 1-butoxy-2-methoxybenzene has been certified to be more sensitive to viscosity because of moderate electron-donating ability. Cell imaging experiments illustrated that L1–L3 is suitable for visualizing the viscosity changes in living cells. As a result, the present work offers a strategy for rationally designing fluorescence probe for viscosity detection in living cells. [ABSTRACT FROM AUTHOR]

Two kinds of carbon dots (CDs) with different solubility, aqueous soluble CDs (ACDs) and organic soluble CDs (OCDs), were produced at the same time by one step hydrothermal synthesis method using sorbic acid and proline as carbon precursor and nitrogen dopant, respectively. The synthesized CDs were characterized by means of UV, fluorescence, TEM, elemental analysis, IR and XPS et al. Based on the effective and proportional fluorescence quenching by Cr(VI), ACDs were successfully used as a high sensitive and selective probe for Cr(VI) detection. Internal filtration effect (IFE) played an important role in the quenching process. Under the optimal conditions, linear response for Cr(Ⅵ) was observed in the range of 0.5–100 μmol/L, and the calculated detection limit was 34 nmol/L. The method has been satisfactorily applied to detect Cr(VI) ions in real water samples of our campus. Then, the ACDs were further applied for cell imaging in B16F10 cells. Furthermore, OCDs were well dispersed into PMMA to fabricate OCDs/PMMA composites as fluorescent films. ACDs and OCDs were produced at the same time and their multi-functional applications were explored like Cr(Ⅵ) detection, bioimaging, and OCDs/PMMA films. Image 1 • Two kinds of CDs were simply synthesized by one-step hydrothermal method directly. • The fluorescence of ACDs can be selectively quenched by Cr(VI) and applied to detect Cr(VI) in real water samples. • The ACDs are successfully applied for cell imaging in B16F10 Cells. • The OCDs/PMMA composites have been fabricated as fluorescent films. [ABSTRACT FROM AUTHOR]

Hypochloric acid (HOCl) plays vital roles in cell signaling and homeostasis which involved in many related diseases. Therefore, the accurate detected level of OCl− for discussing the complex contributions of OCl− to human health is of great significance. In this study, a novel mitochondrion-targeting fluorescent probe DMI bearing a carbon-carbon double bond as an OCl−-responsive site has been developed. Probe DMI exhibited specific fluorescence response toward OCl− with fast response (within 4 s) and high sensitivity (detection limit is 0.05 μM), where the obvious color changes could be observed by the naked eye. More importantly, DMI could be applied in the bioimaging of OCl− in living A549 cells successfully benefited from its good sensing properties and low toxicity. Fluorescence co-localization test was further carried out and confirmed mitochondria-targetable ability of DMI which can be used for investigating physiological function of HOCl at organelle levels. Image 1 • Probe DMI is a mitochondria-targeting visual fluorescence probe. • DMI could highly sensitive and selective detected of hypochlorite. • The mechanism of DMI has been proved to be via oxidation fracture of C C. • DMI can be used to imaging of OCl− in living A549 cells. [ABSTRACT FROM AUTHOR]

Abstract A new highly selective and sensitive dual-mode sensor 3TD based on the conjugate of oligothiophene and barbituric acid moiety was developed for colorimetric and turn-on fluorescent detection of CN─. The sensor 3TD exhibited high specificity towards CN─ by interrupting its own ICT producing thereupon a large blue-shift in UV–Vis spectrum and remarkable "turn-on" fluorescence emission. The detection limit was 2.26 × 10─7 M, which is quite lower than the permissible level of CN─ in drinking water according to the WHO. The fluorescent detection of CN─ was well demonstrated by filter paper strips and silica coated TLC plates. Moreover, the sensor was also used to detect CN─ in environmental water and agro-products with satisfactory results. Most importantly, in terms of these advantages of colorimetric and turn-on fluorescent dual-mode, immediate response, excellent selectivity, high sensitivity, low cytotoxicity, and good biocompatibility, the sensor 3TD was successfully applied into CN− imaging in living cells, demonstrating its excellent value in practical application. Graphical abstract Image 1 Highlights • A new colorimetric naked-eye and turn-on fluorescent sensor 3TD was developed. • Sensor 3TD emerged strong response to CN− with rapid, selective, and sensitive characteristics. • Sensor 3TD could detect trace CN− in water, agro-products and test strips. • Sensor 3TD showed low cytotoxicity and was successfully applied to living cell imaging. [ABSTRACT FROM AUTHOR]

Ratiometric fluorescent probes based on FRET mechanism have attracted great attention due to their large pseudo-Stokes shifts and built-in correction for environmental effects. However, most donors failed to meet the requirement that the emission of the donor must overlap well with the absorption of the acceptor. Therefore, searching for new fluorophore to construct FRET system is in great need. In this paper, a new fluorescent dye pyrazolo[1,5- a ]pyridine was synthesized and used as a donor in the FRET system for ratiometric sensing of Cu2+. The probe is based on FRET and PET mechanism. It shows high selectivity and sensitivity toward Cu2+ (detection limit 30 nM). Furthermore, it was successfully used to detect Cu2+ in Glioma cells. Unlabelled Image • A ratiometric fluorescent probe for sensing Cu2+ based on new fluorophore pyrazolo[1,5- a ]pyridine has been synthesized. • The probe exhibits highly sensitivity and selectivity toward Cu2+ (detection limit: 23 nM). • The ratiometric fluorescent probe displays a remarkable emission shift (about 200 nm). • The probe can be applied to image in cells. [ABSTRACT FROM AUTHOR]

When diabetes is diagnosed, the majority of insulin-secreting pancreatic β cells are already dysfunctional or destroyed. This β cell dysfunction/destruction usually takes place over many years, making timely detection and clinical intervention difficult. For this reason, there is immense interest in developing tools to bioimage β cell mass and/or function noninvasively to facilitate early diagnosis of diabetes as well as to assist the development of novel antidiabetic therapies. Recent years have brought significant progress in β cell imaging that is now inching towards clinical applicability. We explore here the need to bioimage human β cells noninvasively in various types of diabetes, and we discuss current and emerging tools for bioimaging β cells. Further developments in this field are expected to facilitate β cell imaging in diabetes. Diabetic patients suffer from β cell failures that manifest in the loss of β cell mass and/or function. Presently, there is no clinically validated bioimaging probe for the measurement of human pancreatic β cells, which makes early detection of diabetes difficult. Multiple proposed β cell-specific markers have been targeted using radioactively labeled tracers or contrast agents detectable by MRI, PET, or SPECT. Emerging technologies also explore fluorescent low molecular weight probes to target β cells. Currently, many β cell bioimaging tools are studied in a preclinical setting in rodent models and provide valuable proof-of-concept to be further matured. A small number of potential β cell-specific probes have now reached clinical studies. Successful clinical translation could revolutionize the early diagnosis and treatment of diabetes. [ABSTRACT FROM AUTHOR]

Isatin-3-(7′-Methoxychromone-3′-methylidene) hydrazone (L) was synthesized based on chromone schiff base, and used to construct a novel sensor to detect Cr3+. Fluorescence detection experiments were carried out for a range of different concentrations of Cr3+ in aqueous solutions. A concentration calculation model was built on the basis of eliminating interference of excitation spectrum in the fluorescence spectra with mathematical method. Results showed that probe L displayed a 70 -fold fluorescence enhancement upon the addition of Cr3+ due to the photo-induced electron transfer (PET) effect. On the other hand, metal ions except Cr3+ did not cause significant change in either the absorption or the fluorescence spectrum of L. In addition, L showed a good selectivity to Cr3+ over other metal cations, especially Al3+ and Cu2+. The probe L can detect Cr3+ highly and selectively by the direct chelation enhanced fluorescence with a detection limit of 3.14 × 10−6 M. Furthermore, benefiting from their good water solubility and biocompatibility, cell imaging and real-time monitoring of Cr3+ in living HepG2 cells were successfully achieved. L was synthesized. Cell imaging of HeLG2 cells labeled with the as-prepared L– Cr 3+ revealed the potential applications as a biological probe. A novel of coumarin derivatives isatin-3-(7′-Methoxychromone-3′-methylidene) hydrazone (L) were synthesized to detect Cr3+. Cell imaging of HeLG2 cells labeled with the as-prepared L revealed the potential applications as a biological probe. [Display omitted] • The novel L was synthesized based on coumarin schiff-base conjugate. • L– Cr3+ shown obvious fluorescence change. • Imaging strained with L– Cr3+ confirmed that it could be to detect HepG2 cells. [ABSTRACT FROM AUTHOR]

[Display omitted] • Biocompatible fluorescent N,K,Ca-doped CQDs derived from Chenopodium album. • Fluorescence quantum yield up to 48.12 % was achieved. • Bioimaging of SH-SY5Y human neuroblastoma cells, bacteria, fungal, and plant cells. • The cytotoxicity and cell viability have also been examined. This study demonstrated an economical, ecologically sustainable, and simple method for producing biocompatible fluorescent carbon quantum dots (CQDs) co-doped with N, K, and Ca from bathua (Chenopodium album), a popular medicinal herb leaf extract and nutritious vegetable. The nearly spherical shaped CQDs were discovered to be 3–5 nm in size in nature, with a quantum yield of around 48.12%, robust photo-stability, and excellent water solubility. Various morphological, compositional, physicochemical and optical characteristics were investigated. Additional factors affecting the photoluminescence of CQDs, such as hydrothermal process parameters, pH, and solvent sensitivity, were investigated further. Moreover, the newly synthesized N, K, Ca-doped CQDs were demonstrated to be a useful fluorescent nanoprobe for in vitro cellular imaging of SH-SY5Y human neuroblastoma cells, as well as other living organisms such as bacteria, fungal, and plant cells, as a cost-effective alternative to organic or synthetic fluorescent probes. Cell survival and cytotoxicity were found to be acceptable, with 95% of SH-SY5Y and HCT-116 cells surviving and other organisms able to withstand higher doses (10.9 mg/mL) for up to 4 days. [ABSTRACT FROM AUTHOR]

To develop the construction of small organic fluorophores with full color-tunable luminescence through facile synthesis is highly imperative for applications. Herein, novel quinazolinone based BF 2 complexes (2a-2g) have been designed and synthesized. By modifying the structure of quinazolinone ligand, the synthesized boron difluoride dyes exhibited fluorescence in the almost full-color range of the visible spectrum (∼450–750 nm) both in solution and solid-state with good to excellent quantum yield. The influence of three electron donating substituents, such as methyl, methoxy and N,N -dimethylamino group, in quinazolinone core on the photophysical properties of BF 2 compounds was discussed. The position of substituent in quinazolinone has some influence on the emission efficiency, but has little influence on the absorption and emission of BF 2 compounds. Finally, 2g showed good cell compatibility and living cell imaging property. [Display omitted] • A novel quinazolinone-based BF 2 fluorescent dyes have been synthesized. • The BF 2 dyes exhibited fluorescence in full-color range (∼450–750 nm) both in solution and solid-state. • The highest solution fluorescence QY up to 0.99, the QY in solid state up to 0.50 • 2g showed bright deep red to NIR fluorescence in B16 cells. [ABSTRACT FROM AUTHOR]

" Vigna radiata " based green c-dots for photo dynamic therapy (PDT), multicolor imaging and sensing of Fe3+. • Nitrogen doped C-dots were prepared using " Vigna radiata " as a sole carbon precursor. • The as synthesized N@VRCD exhibits excellent quantum yield of ∼58%. • N@VRCD selectively sense Fe3+ with LOD of 140 nM. • N@VRCD acts as photosensitizer upon irradiation by generating photo-induced singlet oxygen. Fluorescent C-dots have drawn increasing attention due to their superior properties such as high aqueous solubility, optical absorptivity, favorable biocompatibility and appreciable photoluminescence. Nature offers various precursors for the synthesis of green C-dots like fruits, vegetables, flowers, animal derivatives and many more. Herein, nitrogen doped C-dots (N@VRCD) were developed by economical, one step hydrothermal method using " Vigna radiata " sprouts as sole carbon precursor and ethylenediamine as the nitrogen source, which was optimized for enhanced optical properties. To the best of our knowledge, N@VRCD shows excellent quantum yield ∼58%. Importantly, N@VRCD also exhibits significant light induced phototoxicity to cancerous cells which enable the possibility of using it as a potential theranostics agent. Further, the N@VRCD displays highly sensitive and selective sensing behaviour towards Fe3+ ions by getting fluorescence "turn-off" with the limit of detection as low as 140 nM. Moreover, N@VRCD shows biocompatible and hemocompatible nature with a potential of multicolor live cell imaging and intracellular Fe3+ detection which was validated by confocal microscopy and flow cytometry. [ABSTRACT FROM AUTHOR]

Thio urea based bifunctional probes for highly selective colorimetric Hg2+ and fluorescence "light-up" AcO− detection are presented here. Live cell imaging by the probe and AcO− is also discussed herein. • Thio-urea based probe for colorimetric Hg2+ and fluorometric AcO− ion detection. • ESI-MS and single crystal structural support for Hg2+ ion-promoted desulfurization. • Fluorescence light-up acetate ion detection through inhibition of PET. • Detection of AcO− at its low concentration and application in cell imaging. Two thio-urea based bifunctional probes (H 2 L1-S and H 2 L2-S) have been designed and fabricated for the colorimetric and fluorometric detection of mercury(II) and acetate ions respectively in DMSO media. Both the H 2 L1-S and H 2 L2-S were fully characterized by various spectroscopic techniques and the solid-state structure of H 2 L1-S was determined via single-crystal X-ray diffraction. The high sensitivity and selectivity of the probes for Hg2+ were achieved by the Hg2+ promoted desulfurization reactions utilizing the high thiophilic nature of mercury and was monitored by UV–vis spectroscopy. Most interestingly the desulfurized product was isolated and characterized by ESI-MS and single crystal X-ray diffraction. The probes H 2 L1-S and H 2 L2-S were found to be highly selective towards acetate ion (AcO−) in fluorescence channel. These probes showed a distinct fluorescence enhancement only in the presence of AcO− at 493 nm due to the inhibition of photo induced electron transfer (PET). Finally, the cytotoxicity study was carried out for biological application. The probe showed minimum cytotoxicity and was suitable for intracellular acetate ion imaging. [ABSTRACT FROM AUTHOR]

• A novel benzothiazole derivative BP was prepared for the relay quantification of Fe3+ and PPi. • Chemosensor BP displayed highly selective fluorescence "ON-OFF-ON" response to Fe3+ and PPi. • This chemosensor BP was applied to living cells imaging. A novel on-off-on fluorescence chemosensor BP based on benzothiazole for the relay recognition of Fe3+ and PPi was designed and synthesized. The chemosensor BP exhibited a high affinity to Fe3+ in the presence of other competing cations. The resultant BP -Fe3+ showed excellent recognition ability for PPi via Fe3+ displacement approach. The detection limits of BP for Fe3+ and BP -Fe3+ for PPi were estimated to be 2.59 × 10−8 M and 8.47 × 10−8 M, respectively. The low cytotoxicity and good cell-membrane permeability of BP and BP -Fe3+ complex makes them capable of Fe3+ and PPi imaging in living Hep G2 cells. [ABSTRACT FROM AUTHOR]

Abstract Polysiloxanes have excellent stability and biological relevance and are suitable for biological research. However, there were few polysiloxane-based fluorescent probes for bioimaging. This report successfully designed a new polysiloxane-based polymer fluorescent probe (RB-1) for the first time as a "turn-on" fluorescent probe response to Al3+ ion with highly sensitive and selectivity. Importantly, this probe could also apply both in cell and zebrafish imaging, indicating the huge application development prospects of polysiloxane-based fluorescent probes in future. Graphical abstract Unlabelled Image Highlights • A novel polymer fluorescence probe RB-1 for detecting Al3+ ions was designed based on the polysiloxanes. • The fluorescent probe RB-1 could specifically detect Al3+. • The fluorescent probe RB-1 could be used in human cervical carcinoma cells (HeLa) and zebrafish. [ABSTRACT FROM AUTHOR]

Abstract Hydrogen sulfide (H 2 S) has been considered to be involved in cytoprotective processes and redox signaling. It is very meaningful to track and analyze it in mitochondria. Herein, we report a novel "turn-on" mitochondria-targeting near-infrared fluorescent probe (Mito-NIR-SH) for detection of H 2 S in living cells, which was designed and synthesized by introducing 2,4-dinitrophenyl as fluorescence quenching group and H 2 S response moiety into Changsha near-infrared fluorophore (CS-OH). The structure of the fluorophore and the probe were characterized by 1H NMR, 13C NMR and mass spectrometry. Meanwhile, Mito-NIR-SH could quantitatively detect H 2 S at concentrations ranging from 0 to 30 μM with a detection limit as low as 89.3 nM, showing good chemical stability, fast "turn-on" response, selectively mitochondrial location, as well as high sensitivity and selectivity toward H 2 S. Based on this, it was successfully applied to imaging exogenous and endogenous H 2 S in living HeLa cells via confocal fluorescence microscopy. Graphical abstract fx1 Highlights • A novel chemically stable mitochondrial-targeting NIR probe has been synthesized. • Fast response to H 2 S with a large turn-on NIR fluorescence signal. • Located in mitochondria with high colocalization coefficient. • Image endogenous and exogenous H 2 S in live cells. [ABSTRACT FROM AUTHOR]

Abstract The new carbazole-based fluorescent probe CA-1 was designed and synthesized for the high selective detection of H 2 S based on HS− facilitated sulfur pyran resulting in UV–Vis and fluorescent spectra changes. At the same time, the probe showed good sensitivity to the detection of H 2 S with a low detection limit of 0.16 μM. The detection process can be monitored by naked eye: with the addition of H 2 S, the probe system changed from yellow to pink. Importantly, the probe could be applied in monitoring H 2 S in HepG2 cells and Chlorella. These results indicate that CA-1 can be used as a promising fluorescent probe for the detection of H 2 S in situ. Graphical abstract Unlabelled Image Highlights • HS− facilitated sulfur pyran realizing colorimetric and fluorescent hydrogen sulfide detection. • The probe showed high selectivity and sensitivity for hydrogen sulfide. • Fluorescent H 2 S imaging in HepG2 cells and Chlorella by CA-1 is further successfully applied. [ABSTRACT FROM AUTHOR]

Abstract A new simple and facile fluorescent ratiometric probe (probe 1) has been designed for the detection of cysteine (Cys). Probe 1 as the fluorophore contains a typical excited-state intramolecular proton transfer (ESIPT) dye. In probe 1 to restore the ESIPT process, the group of acrylate which acts as the recognition unit can block the ESIPT process and can be selectively achieved by Cys, which makes the probe as the ratiometric fluorescent detection for Cys in aqueous solution. This probe shows highly selectivity towards Cys over other biothiols including glutathione (GSH) and homocysteine (Hcy) because of specific cyclization between Cys and acrylate group, and having a detection limit of 42.3 nM. In addition, the experiment of cell imaging shows that probe 1 possesses low cytotoxicity and excellent cell permeability towards the living cells, and has been successfully applied to the ratiometric imaging not only for the endogenous but also for the exogenous cysteine in the living cells effectively. Graphical abstract A new simple and facile ratiometric fluorescent probe (probe 1) has been designed for detecting cysteine (Cys). Probe 1 can be synthesized by 2-(5-bromothiophen-2-yl)-3-hydroxy-chromen-4-one (compound 2) and acryloyl chloride. Probe 1 shows high selectively towards Cys due to the acrylate moiety as the recognized unit can distinguish Cys from Hcy and GSH by different reaction kinetics during the conjugate addition–cyclization reaction. The ratiometric fluorescent measurement can be achieved based on ESIPT process. To demonstrate the application of the probe 1 , in this manuscript, the probe 1 has been successfully applied to the ratiometric imaging for the intracellular and exogenous cysteine in living Hela cells. fx1 Highlights • Probe 1 synthesized by excited-state intramolecular proton transfer (ESIPT) dye. • Probe 1 shows remarkable properties including the ratio of dual emission, high selectivety and sensitivity for cys. • Probe 1 can be used not only detecting and imaging exogenous Cys but also endogenous Cys. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • PES contains a bisethylsulfane moiety and displayed high specificity for Hg2+ detection. • PES has been found to be an effective quantitative detector (LOD, 57 nM) for Hg2+. • PES can be successfully applied the turn-on detection of Hg2+ in vitro and in vivo. Abstract A novel fluorescent probe, PES , which contains a bisethylsulfane moiety, displayed high specificity for Hg2+ detection. With Hg2+, PES showed significant blue fluorescence enhancement, while the metal ions Al3+, Ag+, Cr3+, Ca2+, Cu2+, Co2+, Cd2+, Fe3+, Fe2+, Mn2+, Mg2+, Ni2+, Zn2+, and Pb2+ exhibited only negligible fluorescence change. PES has been found to be an effective quantitative detector (LOD, 57 nM) for Hg2+ in semi-aqueous medium based on the Hg2+-induced removal of bisethylsulfane. It resulted in a turn-on blue fluorescence response. The fluorescence enhancement induced by Hg2+ was observed over the pH range of 4–10. Our fluorescence cell-imaging experiments revealed the applicability of the new probe, PES , to be a reliable and effective fluorescent marker for Hg2+ in living cells. [ABSTRACT FROM AUTHOR]

Abstract Fluorescent carbon dots are optically unique materials that have many applications, including photocatalysis, drug delivery, and biosensing. In this work, carbon dots were synthesized in high yields from succinic acid and glycerol using a green, one-step hydrothermal method, and without the addition of acid or base catalysts. Blue- and green-fluorescence could be selected for simply by varying the reaction time, at quantum efficiencies of 11% and 7%, respectively. The blue-fluorescent carbon dots were tested as dual-mode sensors for the detection of ferrous ion (Fe2+) and hydrogen peroxide (H 2 O 2). They were shown to be selective to Fe2+ and H 2 O 2 in solutions, with limits of detection of 21.9 and 0.7 μM, respectively. The carbon dots were used to prepare paper-based sensors that can be used to determine Fe2+ and H 2 O 2 concentrations as low as 30 μM and 400 nM, respectively. Fe2+ and H 2 O 2 in several real water samples were determined with excellent recovery and repeatability. They were also demonstrated to be luminescent in the polymeric materials, giving them a wide range of potential solid-state applications. In the tests of cell imaging, they were shown to have excellent biocompatibility, with cell viability of 90% at carbon dot concentrations of up to 1 g L−1. Our carbon dots are thus suitable for use as chemical and intracellular probes. Graphical abstract Image 1 Highlights • Blue- and green-emitting carbon dots were prepared from succinic acid and glycerol. • Carbon dots were made in high yields without an acid or base reagent. • Carbon dots showed sub-micromolar dual-mode sensitivity towards Fe2+ and H 2 O 2. • Paper devices were demonstrated as portable, sensitive sensors for Fe2+ and H 2 O 2. • Solid-state luminescence and biocompatibility of carbon dots were excellent. [ABSTRACT FROM AUTHOR]

Abstract Rare earth is of great interest because of their unique optical properties, especially the rich luminescent spectra. In this study, we developed a facile one-pot microwave-assisted synthesis of luminescent Eu3 + doped TiO 2 nanoparticles and Tb3 + doped ZrO 2 nanoparticles. As a result, the emitting centers (Eu3 + and Tb3 +) were all well dispersed in the amorphous host oxide materials, leading to high luminescence. The obtained TiO 2 :Eu3 + and ZrO 2 :Tb3 + nanoparticles were then encapsulated into PLGA microparticles for bio-applications. These luminescent microparticles were then proven to be highly stable, biocompatible and of low cytotoxicity. We successfully demonstrated the bioimaging of live cells using the red-luminescent TiO 2 :Eu3 + nanoparticles and green-luminescent ZrO 2 :Tb3 + nanoparticles embedded PLGA microparticles. The microwave-assisted synthetic methodology can be further developed to be general method to prepare oxide nanoparticles. Highlights • Amorphous TiO 2 :Eu3 + and ZrO 2 :Tb3 + nanoparticles were synthesized by microwave assisted solvothermal treatment. • The obtained TiO 2 :Eu3 + and ZrO 2 :Tb3 + nanoparticles are highly luminescent. • PLGA encapsulation imparts high stability, low cytotoxicity and high biocompatibility. • These luminescent (red and green) nanoparticles are used for live cell imaging. [ABSTRACT FROM AUTHOR]

This work focused on design, synthesis and application of an AIE and FRET-based BODIPY pH sensor bearing large Stoke shift. The cyano-diphenylethylene- conjugated BODIPY derivative 4 was prepared by condensating 4-hydroxybenzene acetonitrile with 4-(diethoxymethyl)benzaldehyde and then following the typical procedure of synthesizing BODIPY derivative. Compound 4 exhibited strong fluorescence in all kinds of THF/H 2 O solutions due to the AIE and FRET effect. The Stoke shift of compound 4 was as large as 138 nm based on the excitation of cyano-diphenylethylene moiety and the emission of BODIPY moiety. Compound 4 showed good fluorescent response to the change of pH with the p K a value at 9.79. The mechanism of compound 4 as pH probe was confirmed by 1 H NMR spectra and theoretical calculation. Compound 4 was successfully used to CO 3 2− detection among 13 kinds of common anions both in solution and by tested strips. The experiments of living cell imaging suggested that compound 4 possessed superior bioimaging performance and presented sensitive change to pH values between 9 and 10 in living cells. [ABSTRACT FROM AUTHOR]