Search

Mercury(II) is highly toxic thus the selective and sensitive detection of Hg(II) is important. This research article deals with the synthesis and characterization of the fluorogenic system based on diselenide containing rhodamine by single crystal XRD. The probe has been used for selective detection of Hg(II) in aqueous media with detection limit of 62.3 nM. The reaction of the Hg(II) with the probe induces opening of the spirolactam ring triggering fluorescence turn-on response. This reaction causes color change of the probe solution from colorless to pink. In addition, the probe showed the reversible binding behavior with Hg(II) and S2−. The effectiveness of the probe was evaluated using prostate cancer cell line through live cell imaging. [ABSTRACT FROM AUTHOR]

A benzothiazole-modified quinoline Schiff base fluorescent probe TQ was prepared by a condensation reaction, and characterized by using IR, NMR, ESI-MS. The fluorescence emission of probe TQ was weak, while displaying a strong emission at 517.5 nm in the presence of Zn2+. The fluorescence enhancement was highly selective toward Zn2+ over other common cations, with a detection limit as low as 69.5 nM. The results of Job's plot curve implied that the coordination ratio of probe TQ to Zn2+ was 1 : 1, and the possible coordination mode was proposed by means of 1H NMR titration, mass spectrometry and DFT calculations. In addition, the probe can be used for the detection of Zn2+ in living cells and real water samples. [ABSTRACT FROM AUTHOR]

Fluoride is both necessary and potentially harmful in excessive amounts, making its detection crucial. Fluorescent probes provide a sensitive and selective means for this purpose. In this study, we developed and synthesized a fluorescent probe for LDT using phenothiazine derivatives and aryl vinyl nitrile. Initially non-fluorescent, the probe undergoes a Si–O bond breakage in the presence of fluoride ions, resulting in the formation of a larger conjugated system and subsequent fluorescence emission. The probe exhibits superior selectivity and sensitivity towards fluoride ions, with a detection limit of 0.35 µM. Moreover, cellular imaging experiments demonstrated the probe's effectiveness in recognizing fluoride ions within HepG2 cells. [ABSTRACT FROM AUTHOR]

Glutathione (GSH) plays a crucial role in various physiological processes and its imbalances are closely related to various pathological conditions. Probes for detection and imaging of GSH are not only useful for understanding GSH chemical biology but are also important for exploring potential theranostic agents. Herein, we report a fast intramolecular thiol-activated arylselenoamides (FITA)-based fluorescent probe using 2,4-dinitrophenyl alkylthioether as a sulfydryl-selective receptor for the first time. The fluorescence of the probe was low due to the double effects of PET, while the probe exhibits an 86-fold fluorescence enhancement at 460 nm after GSH activation and a detection limit of 0.95 μM. Furthermore, the probe is low-toxic and capable of imaging cellular GSH. This work further expands the design and applicability of the FITA-based platform, offering a new thiol-deprotection strategy for development of fluorescent probes. [ABSTRACT FROM AUTHOR]

Green nanotechnology, which uses carbon nanomaterials for environmental remediation, is the pioneer among the prevailing approaches for the production and characterization. In the present study, highly fluorescent carbon dots (CDs) from Ruta Graveolens (ARH‐CD) is developed, and its efficacy as a fluorescent sensor and biomarker is investigated. They act as a fluorescence sensor for Hg2+ over an extensive concentration range of 1 picomolar (pm) to 1 molar (m), with a detection limit as low as 26.75 pm. The studies reveal ARH‐CD as an effective biomarker for intracellular toxicity analysis and a fluorescent probe for multi‐colored (blue, green, and red) imaging of HEK293 cell lines. After 24 h of incubation, it is found that the ARH material reveals noticeable biocompatibility and visible fluorescence, with a viability of 98.88% at 5 µg mL−1 and over 78.33% even at a concentration of 100 µg mL−1. The IC50 value for the MTT assay for cell viability results is calculated to be 224.56 ± 4.67 µg, which further confirms the appreciable biocompatibility of the ARH‐CD. The obtained samples are effective in being inspected for the intracellular detection of Hg2+ and serve as a possible candidate for cell imaging. [ABSTRACT FROM AUTHOR]

Water-soluble N-doped fluorescent (FL) carbon dots (ACDs) were successfully fabricated hydrothermally using ampicillin sodium as sole precursor. The produced ACDs exhibit satisfactory optical behavior, favorable photostability, and acceptable water solubility. With bright blue emission at 450 nm, the ACDs were utilized for multivariate sensing Fe3+ and Cu2+ based on the synergistic effect of the inner filter effect (IFE) and static quenching with detection limits of 0.31 μM and 0.26 μM, respectively. The practicality of ACDs has been verified by the successful determination of Fe3+ and Cu2+ in real water and living cells. These findings confirm the feasibility of the proposed ACDs as FL sensors for efficient and selective detection of Fe3+ and Cu2+, which present promising prospects for real-time monitoring these two metal ions in environmental and biological systems. [ABSTRACT FROM AUTHOR]

Phosphate is widely used in industry and agriculture fields. However, excess accumulation of PO43− causes several adverse effects on the human body and ecological environment. Consequently, it is important to develop a simple method for the detection of PO43− concentration in the ecological environment and in vivo. Herein, two caffeic acid derivative-based fluorescence probes (BAM-HM and BAM-HH) were developed for the detection of phosphate. The BAM-HM probe could detect phosphate via fluorescence enhancement at 500 nm, with the detection limit being 0.612 µM. Meanwhile, the BAM-HH probe showed a significant turn-on signal at 450 nm after the addition of phosphate, and the detection limit was calculated to be 0.318 µM. The sensing mechanism was determined by 1H NMR and MS. Furthermore, the two probes (BAM-HM and BAM-HH) were applied for PO43−detection in living cells and water samples. [ABSTRACT FROM AUTHOR]

The novel Fe doped carbon dots(Fe-CDs)with good photoluminescent properties were rapidly synthesized by microwave-assisted method with ferric citrate and polyethyleneimine as raw materials. The results show that the Fe-CDs have good stability under the conditions of broad pH range from 3 to 9, high ion strengths and long storage time. The prepared Fe-CDs can easily penetrate and accumulate into the cell, which can be used as effective probe for biological imaging of A549 cells. The Fe-CDs display distinct peroxidase-like (POD) activities, which is evidenced by the catalyzed oxidation of 3, 3', 5, 5'-tetramethylbenzidine(TMB)into blue oxidized products in the presence of H2O2 . A colorimetric method for the determination of H2O2 established based on the results. Under optimal reaction conditions, the colorimetric method for H2O2 detection is constructed with good linear relationship from 0 to100. 00 μmol/L and detection limit down to 0. 13 p. mol/L. The highly selective and ultrasensitive method is successfully applied to detect H2O2 inside A549 tumor cells with good recoveries of 98. 4％-102. 8％, which can verify the proposed method. [ABSTRACT FROM AUTHOR]

Fluorometric determination of different biologically, industrially, and environmentally important analytes is a powerful technique because this technique has excellent selectivity, high sensitivity, rapid photoluminescence response, low cost, applicability to bioimaging, and low detection limit. Fluorescence imaging is a powerful technique for screening different analytes in the living system. Heterocyclic organic compounds have been extensively used as a fluorescence chemosensor for the determination of different biologically important cations like Co2+, Zn2+, Cu2+, Hg2+, Ag+, Ni2+, Cr3+, Al3+, Pd2+, Fe3+ Pt2+, Mn2+, Sn2+, Pd2+, Au3+, Pd2+, Cd2+, Pb2+ and other ions in biological and environmental systems. These compounds also showed significant biological applications such as anti-cancer, anti-ulcerogenic, antifungal, anti-inflammatory, anti neuropathic, antihistaminic, antihypertensive, analgesic, antitubercular, antioxidant, antimalarial, antiparasitic, antiglycation, antiviral anti-obesity, and antibacterial potency. In this review, we summarize the heterocyclic organic compounds based on fluorescent chemosensors and their applications in bioimaging studies for the recognition of different biologically important metal ions. [ABSTRACT FROM AUTHOR]

Detecting circulating tumor cells has exhibited great significance in treating cancers since its concentration is an index strongly associated with the development and transfer of the tumor. However, the present commercial method for CTC detection is still expensive, because special antibodies and complicated devices must be used for cell separation and imaging. Hence, it is quite necessary to apply alternative materials and methods to decrease the cost of CTC detection. In this article, we coated a cellulose acetate membrane with nanoparticles formed by the polymerization of melamine and furfural, creating a surface with nanoscale roughness for the highly efficient capture of the sparse CTCs in a blood sample. Subsequently, the CTCs on the surface can be quantitatively detected by colorimetry with the aid of a COF-based nanozyme. The detection limit (LOD) can be as low as 3 cells/mL, which is the lowest LOD among the colorimetric methods to our knowledge. Considering the low cost of fabricating the membrane for CTC capture and the robustness of nanozymes compared with natural enzymes, this CTC detection approach displays great potential to decrease the financial burden of commercial CTC detection. [ABSTRACT FROM AUTHOR]

Abstract Herein we have reported a fluorescent probe (MB-M) based on MB derivative for Cu2+ ions detection. The probe was well characterized by 1H NMR, 13C NMR and HR-MS spectrum. Probe MB-M showed naked-eyes recognition to Cu2+ as color change from colorless to indigo. The probe exhibited promising features such as high fluorescence and UV–vis selectivity, fast response (5 mint), workable at pH 2–7, and low limit of detection (LOD = 0.33 µM). Probe MB-M was also used for Cu2+ ions imaging in HepG-2 cells and detection in daily life (Test Strip and lake water). Moreover, non-covalent interaction (NCI) and quantum theory of atoms in molecules (QTAIM) analysis were used to study the interaction between MB-M and Cu2+ ions. By examining the electronic characteristics of the complex using natural bond orbital (NBO), electron density difference (EDD), and frontier molecular orbital (FMO) analysis, the sensitivity of MB-M towards Cu2+ ions were investigated. The results illustrated that the interactions between MB-M and Cu2+ ions involved chemisorption.

Herein we have reported a fluorescent probe (MB-M) based on MB derivative for Cu2+ ions detection. The probe was well characterized by 1H NMR, 13C NMR and HR-MS spectrum. Probe MB-M showed naked-eyes recognition to Cu2+ as color change from colorless to indigo. The probe exhibited promising features such as high fluorescence and UV–vis selectivity, fast response (5 mint), workable at pH 2–7, and low limit of detection (LOD = 0.33 µM). Probe MB-M was also used for Cu2+ ions imaging in HepG-2 cells and detection in daily life (Test Strip and lake water). Moreover, non-covalent interaction (NCI) and quantum theory of atoms in molecules (QTAIM) analysis were used to study the interaction between MB-M and Cu2+ ions. By examining the electronic characteristics of the complex using natural bond orbital (NBO), electron density difference (EDD), and frontier molecular orbital (FMO) analysis, the sensitivity of MB-M towards Cu2+ ions were investigated. The results illustrated that the interactions between MB-M and Cu2+ ions involved chemisorption. [ABSTRACT FROM AUTHOR]

Cuprous ions (Cu+) are essential for various biological activities. However, it is still a great challenge to detect Cu+ efficiently in cells in situ. As emerging 0‐D carbon photoluminescence nanomaterials, carbon dots (CDs) exhibit non‐toxicity and ultra stability, which shows great advantages in biosensing and bioimaging. In this work, CDs are prepared by a one‐step microwave‐assisted hydrothermal method. To enhance the selectivity and efficiency of the CDs‐based sensor, the NS4‐CDs are synthesized by surface modification of CDs using Cu+ chelating molecules. The NS4‐CDs, that carry specific detection molecules, exhibit remarkable selectivity and high sensitivity with an extraordinarily low detection limit (26 nmol L−1). It is noteworthy that the detection response is extremely fast, which only takes 20 s. The PL response mechanism of NS4‐CDs is also thoroughly investigated. In addition, the NS4‐CDs possess great biocompatibility and non‐cytotoxicity, which is vital for advanced cellular imaging applications. Finally, the NS4‐CDs are successfully applied to Cu+ detection in cells in situ. This work paves a new path for the design and efficient construction of CDs‐based biosensors for ion detection in cells, which expands the application area of carbon nanomaterials. [ABSTRACT FROM AUTHOR]

Hemicyanine dyes are an ideal structure for building near-infrared fluorescent probes due to their excellent emission wavelength properties and biocompatibility in biological imaging field. Developing a near-infrared fluorescent probe capable of detecting cysteine (Cys) was the aim of this study. A novel developed fluorescent probe P showed high selectivity and sensitivity to Cys in the presence of various analytes. The detection limit of P was found to be 0.329 μM. The MTT assay showed that the probe was essentially non-cytotoxic. Furthermore, the probe was successfully used as cysteine imaging in living cells and mice. [ABSTRACT FROM AUTHOR]

To monitor the biological function of H2S in real time, this investigation demonstrated the design and synthesis of a novel fluorescent probe integrated with cyanine and 2,4-dinitrophenol for the qualitative and quantitative detection of H2S. An NIR sensitive sensor (FS-HS-1) was provided with a straightforward process. Spectroscopy experiments elucidated that FS-HS-1 could selectively detect H2S in a PBS solution (containing 40% acetonitrile) with a 111-fold fluorescence enhancement at 715 nm (ex. 605 nm). The response towards NaHS occurred in less than 2 min, and the detection limit was confirmed to be as low as 4.47 ± 0.11 nmol/L. Furthermore, the probe is capable of monitoring changes in exogenous H2S concentrations within living cells with confocal and 2P imaging. [ABSTRACT FROM AUTHOR]

Ferric ion (Fe3+) serves as an essential and indispensable inorganic element in various biological process. Excess Fe3+ is harmful for biological systems and human health. Herein, highly sensitive carbon quantum dots (Fe-CQDs) for ferric ions were synthesized by a high-efficiency, one-step hydrothermal route utilizing L-arginine and citric acid. The prepared Fe-CQDs exhibited good water solubility, high photostability, and bright blue florescence with relatively high quantum yields (QYs) over 21.33% and a Stokes shift exceeding 100 nm. The functionalized Fe-CQDs offer rapid, sensitive, and selective recognition of Fe3+ with a linear relationship from 0.6 to 80 μM and a low detection limit of 0.2 μM. Moreover, the synthesized Fe-CQDs illustrated strong anti-interference properties in samples and buffer solutions. The developed sensor demonstrated high biocompatibility and was successfully applied for intracellular Fe3+ determination in SHSY5Y and HT22 cells, illustrating excellent imaging application. The present work provides a promising platform for the early clinical diagnosis of Fe3+-associated diseases. [ABSTRACT FROM AUTHOR]

Hypochlorite is a kind of endogenously produced reactive oxygen species (ROS) in the human immune system and plays a crucial role in many pathophysiological processes. In this work a novel fluorescent probe derived from 6‐methylthio coumarin was designed and synthesised for detection of hypochlorite in acetonitrile/phosphate‐buffered saline (MeCN/PBS) (1:1, v/v, pH 7.4) medium. The probe displayed high specificity toward hypochlorite over other ROS analytes, rapid response to hypochlorite within 30 s, and a broad applicable range of pH 3–8. The detection limit was calculated to be 1.48 μM. Application of this probe for in vitro Hecat cell imaging to detect hypochlorite ions was confirmed. A sensing mechanism based on thioether to sulfoxide oxidation by hypochlorite was proposed and demonstrated. The study presented an effective approach for construction of highly efficient hypochlorite chemosensors from hydrophilic methylthio‐substituted coumarins considering their facile access. [ABSTRACT FROM AUTHOR]

A fluorogenic aptamer (FA)-based hybridization chain reaction (HCR) could provide a sensitive and label-free signal amplification method for imaging molecules in living cells. However, existing FA-HCR methods usually face some problems, such as a complicated design and significant background leakage, which greatly limit their application. Herein, we developed an FA-centered HCR (FAC-HCR) method based on a remote toehold-mediated strand displacement reaction. Compared to traditional HCRs mediated by four hairpin probes (HPs) and two HPs, the FAC-HCR displayed significantly decreased background leakage and improved sensitivity. Furthermore, the FAC-HCR was used to test a non-nucleic acid target, apurinic/apyrimidinic endonuclease 1 (APE1), an important BER-involved endonuclease. The fluorescence analysis results confirmed that FAC-HCR can reach a detection limit of 0.1174 U/mL. By using the two HPs for FAC-HCR with polyetherimide-based nanoparticles, the activity of APE1 in living cells can be imaged. In summary, this study could provide a new idea to design an FA-based HCR and improve the performance of HCRs in live cell imaging. [ABSTRACT FROM AUTHOR]

This article presents the distinctive butyrylcholinesterase (BChE) fluorescent probe P5, designed via a targeting-site method. This method was proposed to enhance the affinity of the probe for BChE by targeting the peripheral anionic site (PAS) of BChE. By mimicking the natural substrate butyrylcholine, the structure of the probe was optimized by introducing a positive charge. Fluorescent probe P5, selected from a series of designed fluorescent probes P1–P6, exhibited excellent affinity and specificity towards BChE, enabling rapid detection within 5 min with a low detection limit of 16.7 ng/mL. Furthermore, this probe can distinguish between normal cells and Alzheimer's disease (AD) model cells, and demonstrated good imaging results in a P12 cell AD model. The results of this study indicate that this novel fluorescent probe could serve as a promising tool for the rapid detection of BChE and accurate AD diagnosis. [ABSTRACT FROM AUTHOR]

This research centers on the development and synthesis of a longwave fluorescence probe, labeled as 60T, designed for the simultaneous detection of hydrogen sulfide, cysteine/homocysteine, and glutathione. The probe showcases a swift response, good linearity range, and heightened sensitivity, boasting that the detection limits of the probe for Cys, Hcy, GSH and H2S were 0.140, 0.202, 0.259 and 0.396 μM, respectively. Notably, its efficacy in monitoring thiol status changes in live MCF-7 cells is underscored by a substantial decrease in fluorescence intensity upon exposure to the thiol trapping reagent, N-ethyl maleimide (NEM). With an impressive red emission signal at 630 nm and a substantial Stokes shift of 80 nm, this probe exhibits remarkable sensitivity and selectivity for biothiols and H2S, indicating promising applications in the diagnosis and surgical navigation of relevant cancers. [ABSTRACT FROM AUTHOR]

A water‐soluble polymeric pyrene‐based polythioacetal (PTA‐Py) with thioacetal units in the main chain is simply synthesized by direct polycondensation of 3, 6‐dioxa‐1, 8‐octanedithiol, 1‐pyrene formaldehyde, and mPEG2k‐SH. The probe PTA‐Py shows a good fluorescence response to Hg2+ ions due to the Hg2+‐promoted deprotection reaction of thioacetal groups to regenerate the original 1‐pyrene formaldehyde compound. After adding Hg2+ to the PTA‐Py solution, the fluorescence intensity (FI) gradually increases with increasing concentrations of Hg2+. Compared with other metal ions, the probe exhibits high sensitivity, good selectivity, and rapid response to Hg2+. The low detection limits are 12.3 nm in ethanol‐PBS buffer and 13.3 nm in water, respectively. The results imply that the simply synthesized water‐soluble polymeric probe had potential applications in the rapid detection of Hg2+ ions in aqueous solutions. Moreover, the polymeric PTA‐Py shows high sensitivity for CH3Hg+ with detection limits of 26.5 nm in ethanol/PBS buffer. In addition, PTA‐Py can efficiently detect Hg2+ ions in HeLa cells. The results demonstrate that a valuable method is developed for biocompatible polymeric sensors for Hg2+ ions in biological and environmental samples. [ABSTRACT FROM AUTHOR]

A fluorescent probe Y((1,1'-([1,1'-biphenyl]-4,4'-diylbis(3-(2-hydroxyphenyl)-4,5-dihydro-1H-pyrazole-5,1-diyl)) bis(ethan-1-one))) was designed and synthesized, which could be used to Cu2+ and Fe3+ sensors. Through the study of optical properties, the probe Y shows good selectivity and sensitivity to Cu2+ and Fe3+ in aqueous tetrahydrofuran solution [10.0 mM HEPES, pH 7.4, THF-H2O = 9:1(v/v)] with has excellent anti-interference performance, and its detection limits were 0.931 uΜ for Cu2+ and 0.401uΜ for Fe3+. The coordination mechanism of probe Y with Cu2+ and Fe3+ was speculated and verified at DFT level and HRNM. By Hela cytotoxicity and imaging tests, probe Y not only has good biocompatibility, but also can be used for sensing Cu2+ in cells. [ABSTRACT FROM AUTHOR]

This work presents a coumarin-anthracene-based chemodosimeter L for the selective detection of Arginine (Arg) via hydrolysis of the imine bond of the Schiff base L. Significant changes in the emission and absorption spectra of L were observed during the detection of Arg. Chemodosimeter L displayed an impressive detection limit of 0.46 μM for Arg by the emission spectral titrations. A combination of UV-Vis, emission, and mass spectral studies, as well as excited-state lifetime measurements, and quantum yield calculations illustrated Arg-assisted dosimetry of L. The sensing of Arg by L was employed in cell imaging and for the colorimetric detection and paper test strip-based practical detection methods. This work presents a chemodosimeter L based on a coumarin-anthracene platform for the selective detection of amino acid arginine. [ABSTRACT FROM AUTHOR]

Hydrogen sulfide (H2S) is a toxic gas derived from the sulfur industry and trace H2S in the environment can cause serious ecological damage while inhalation can cause serious damage and lead to disease. Therefore, the real-time and accurate detection of trace sulfur ions is of great significance for environmental protection and early disease detection. Considering the shortcoming of current H2S probes in terms of stability and sensitivity, the development of novel probes is necessary. Herein, a novel metal-organic frameworks (MOF)-based material, UiO-66-NH2@BDC, was designed and prepared for the visual detection of H2S with rapid response (< 6 s) and low detection limit of S2− (0.13 µM) by hydrogen bonding. Based on its good optical performance, the UiO-66-NH2@BDC probe can detect S2− in various water environments. More importantly, UiO-66-NH2@BDC probe realize imaging S2− in cells and live zebrafish. [ABSTRACT FROM AUTHOR]

Excessive production of potent biological oxidants such as HOCl has been implicated in numerous diseases. Thus, it is crucial to develop highly specific and precise methods to detect HOCl in living systems, preferably with molecules that can show a distinct therapeutic effect. Our study introduces the synthesis and application of a highly sensitive fluorescence "turn-on" probe, Myco-OCl, based on the mycophenolic acid scaffold with exceptional water solubility. The ESIPT-driven mechanism enables Myco-OCl to specifically and rapidly detect (<5 s) HOCl with an impressive Stokes shift of 105 nm (λex = 417 nm, λem = 522 nm) and a sub-nanomolar (97.3 nM) detection limit with the detection range of 0 to 50 μM. The potential of Myco-OCl as an excellent biosensor is evident from its successful application for live cell imaging of exogenous and endogenous HOCl. In addition, Myco-OCl enabled us to detect HOCl in a zebrafish inflammatory animal model. These underscore the great potential of Myco-OCl for detecting HOCl in diverse physiological systems. Our findings thus offer a highly promising tool for detecting HOCl in living organisms. [ABSTRACT FROM AUTHOR]

Given the important role of carboxylesterase 2 (CES2) in the metabolism of various esters, it is of significance to develop a tool to determine endogenous CES2 activity in a rapid and highly selective manner. In this work, an "off-on" rhodamine-based fluorescent probe is reported as an effective tool for CES2 activity. Based on the substrate recognition preference of CES2 (large alcohol and small acyl groups), the probe with dimethyl carbamate as the recognition group performs well in terms of selectivity and sensitivity to CES2. The fluorescence switching control of the probe for CES2 was achieved by using the spirolactone structure of rhodamine. The probe shows the fast generation of a fluorescence signal at 634 nm upon hydrolysis of CES2 with excitation at 578 nm. The results showed a linear relationship between the fluorescence intensity at 634 nm and the CES2 activity from 0 to 4 μg/mL. The probe reacts rapidly with CES2, and the reaction is stable within 40 minutes. The probe is highly selective for CES2, with a detection limit as low as 0.303 μg/mL. In addition, the probe has currently been successfully utilized to evaluate CES2 activity in living cells. Hence, this probe is anticipated to be significant in identifying endogenous CES2 activity in intricate biological settings. [ABSTRACT FROM AUTHOR]

A diformylphenol Schiff base of triazole‐amine, 4‐methyl‐2, 6‐bis‐[(1H‐[1,2,4] triazol‐3‐ylimino)‐methyl]‐phenol (PTR) has been synthesised and characterised by spectroscopic data (ESI‐MS, UV‐vis, FT‐IR, NMR spectra). The probe, PTR, emits at 610 nm upon excitation at 380 nm and the emission is strongly intensified on interacting with Zn2+ ion in DMSO‐water (99:1, v/v; HEPES buffer, pH, 7.2) solution even in the presence of 15 other cations (Cu2+, Mn2+, Co2+, Ni2+, Pd2+, Cd2+, Pb2+, Hg2+, Fe3+, Cr3+, Al3+, Na+, K+, Ba2+, Ca2+) and the emission band has been shifted to 530 nm. The limit of detection of Zn2+, 0.30 μM is much lower than WHO recommended value (76 μM). The binding constant (Kd) is 4.2585 × 104 M−1. Selective and sensitive chemosensing behaviour of PTR to Zn2+ has been explained by switching off ESIPT quenching of the keto‐enol tautomerisation of the probe along with the chelation enhancement of fluorescence (CHEF) by binding with Zn2+. The Job's plot and NMR titration have been extended to measure the 1:1 M composition [PTR + Zn2+]. The energy calculation by the DFT computation of keto and enol isomers supports easy tautomerisation and helps ESIPT quenching by proton transfer. Intracellular Zn2+ ions in living cells of HEK293 (PBS: phosphate buffer saline; pH, 7.2) have also been identified by the probe, PTR, using fluorescence microscopic imaging technique. [ABSTRACT FROM AUTHOR]

Hydrogen sulfide (H2S) produced and metabolized by mitochondria is closely associated to human physiological function, but its mechanism is not fully revealed due to the difficulty in determining the dose of hydrogen sulfide. Therefore, fluorescent probes with both excellent mitochondrial targeting ability and rapid H2S detection are urgently needed. In this work, a novel fluorescent probe, TPAS-TN, was developed to detect H2S in mitochondria. TPAS-TN with a D–π–A structure had a large Stokes shift (213 nm), and possessed low background interference in cell imaging. By introducing a twisted triphenylamine group as the donor, TPAS-TN was endowed with AIE properties, and the positively charged pyridium unit was the acceptor, so that TPAS-TN exhibited good mitochondrial targeting ability and biocompatibility. Meanwhile, the π-bridge was composed of phenyl and dinitrophenyl (DNP) ether to make TPAS-TN exhibit "off–on" properties, low detection limit (69.5 nM), and high sensitivity and selectivity. Besides, TPAS-TN with the above characteristics was successfully applied to high-contrast H2S imaging in mitochondria. [ABSTRACT FROM AUTHOR]

[Display omitted] Carbon dots (CDs) have been extensively employed in biomolecule imaging. However, the imaging of biological enzymes with CDs has not been reported, which greatly limits their application in biological imaging. Herein, for the first time, a new type of fluorescent CDs is elaborately designed to realize the direct mapping of alkaline phosphatase (ALP) in cells. The obtained phosphorus and nitrogen co-doped CDs (P, N-CDs) generate specific structures including xanthene oxide and phosphate ester, thereby enabling P, N-CDs to be exclusively cleaved by ALP without auxiliary media. The fluorescence intensity of P, N-CDs can be specifically turned on in the presence of ALP, making them powerful probes for sensitive sensing of ALP activity with a detection limit of 1.27 U·L−1. Meanwhile, P, N-CDs possessing electron deficiency structure fulfill sensitive responding to polarity variations. The excellent photo-bleaching resistance and biocompatibility of the P, N-CDs are taken for directly mapping the intracellular endogenous ALP via turned-on fluorescence imaging, as well as real-time monitoring the polarity fluctuation in cells through ratiometric fluorescence imaging. The present work offers a new way to design and synthesize functional CDs for direct imaging of intracellular enzymes. [ABSTRACT FROM AUTHOR]

Nitrogen-doped carbon dots (NCDs) have been constructed in which coal washing wastewater is used as carbon precursor, tryptophan is added for nitrogen doping and surface functional together with polyethylene glycol. The nitrogen doping and surface functional with electron rich groups resulted in excellent fluorescent properties regarding stability, reversibility, printability with high quantum yield which not only enable the NCDs as fluorescent ink for advanced message encryption, but also realize specific on-off-on fluorescent sensing of Hg2+ and GSH as solution, hydrogel and filter paper sensors. The NCDs had a linear range of 0.01-100 μM and a detection limit of 6.27 nM (RSD 0.33%) for Hg2+ and the NCDs@Hg2+ had a linear range of 0.01–60 μM and a detection limit of 3.53 nM (RSD 1.53%) for GSH in sensing studies with aqueous solutions. In addition, with the low cytotoxicity and good biocompatibility NCDs have been successfully used for imaging Hg2+ and GSH in living MG-63 cells. The presented NCDs recycle waste coal washing water into worthwhile material which can be implemented as promising anti-counterfeiting and message encryption candidates as well as effective Hg2+ and GSH sensing, tracking and removing tools in complicated environmental and biological systems. [ABSTRACT FROM AUTHOR]

Metal cations such as Zn2+, Al3+, Hg2+, Cd2+, Sn2+, Fe2+, Fe3+ and Cu2+ play important roles in biology, medicine, and the environment. However, when these are not maintained in proper concentration, they can be lethal to life. Therefore, selective sensing of metal cations is of great importance in understanding various metabolic processes, disease diagnosis, checking the purity of environmental samples, and detecting toxic analytes. Schiff base probes have been largely used in designing fluorescent sensors for sensing metal ions because of their easy processing, availability, fast response time, and low detection limit. Herein, an in-depth report on metal ions recognition by some Schiff base fluorescent sensors, their sensing mechanism, their practical applicability in cell imaging, building logic gates, and analysis of real-life samples has been presented. The metal ions having biological, industrial, and environmental significance are targeted. The compiled information is expected to prove beneficial in designing and synthesis of the related Schiff base fluorescent sensors. [ABSTRACT FROM AUTHOR]

Mercury ion (Hg2+) contamination is very hazardous and harmful to the natural environment and human health. The development of small molecule fluorescent probes for the rapid detection of Hg2+ is of great significance. In the present work, an "AIE + ESIPT" mechanism-based benzothiazole derived fluorescent probe was applied to Hg2+ detection and displayed excellent selectivity, good anti-interference ability, low detection limit (2.85 × 10−9 M), and a large Stokes shift (170 nm) in the DMF/H2O mixture solution with fw = 60% H2O volume fraction. The fluorescence response mechanism, involving the desulfurization reaction of O-(2-(benzo[d]thiazol-2-yl)-6-formyl-4-methylphenyl)dimethylcarbamothioate (probe L) with Hg2+ to release the "AIE + ESIPT" fluorophore, was well established based on the UV-vis, 1H NMR, and HRMS spectral analyses. The practical application evaluation indicates that probe L could be used to precisely determine Hg2+ in live cell imaging, natural water, and seafood samples. [ABSTRACT FROM AUTHOR]

A new bis-spirocyclic rhodamine B derivative was developed as a near-infrared colorimetric and "turn-on" fluorometric chemodosimeter (1) with a large Stokes shift (70 nm) for Cu2+. In response to Cu2+, the solution of 1 displayed major absorption at 700 nm, from colorless to blue within ten seconds. At the same time, emissions at 580 nm (excitation at 520 nm) and at 770 nm (excitation at 650 nm) were turned on. Good linear relationships between absorbance at 700 nm, fluorescence at 580 and 770 nm and concentration of Cu2+ in wide ranges were obtained in both colorimetric and fluorometric analyses, with the detection limits of 0.57 μM, 9 nM and 28 nM, respectively. Irreversible ring-opening processes of 1 coordinated with Cu2+, followed by hydrolysis as well as acylated reaction were proposed. Furthermore, 1 was applied to image Cu2+ in HepG2 living cells and within the mitochondria of the cells in the roots of paulownia sprouts. [ABSTRACT FROM AUTHOR]

A NIR FUCL probe PT-1 was proposed and applied to visualization of drug-induced hepatotoxicity in living mice. [Display omitted] • A HSO 3 − activated NIR FUCL probe PT-1 was designed based on the xanthene dye. • PT-1 represents an anti-Stokes emission at 697 nm with 730 nm excitation. • PT-1 showed excellent sensitivity and low detection limit towards HSO 3 −. • PT-1 possesses excellent mitochondrial localization ability. • PT-1 was successfully used to evaluate drug induced hepatotoxicity in vivo. Bisulfite (HSO 3 −) plays an important role in life activities. Abnormal content of HSO 3 − may cause cardiovascular, cancer and other diseases. Frequency upconverted luminescent (FUCL) probes are a class of anti-Stokes luminescent materials with long-wavelength excitation and short-wavelength emission properties, which offer advantages in a range of applications due to their higher sensitivity and photostability. In addition, FUCL imaging has the advantages of high tissue penetration depth and low photo-damage, thus, it is more suitable for fluorescence imaging. In this work, a FUCL probe based on an xanthene fluorophore was designed and synthesised to detect HSO 3 −. The Probe PT-1 could respond to HSO 3 − and had high selectivity and sensitivity. It also exhibited a quenched FUCL signal. The detection limit of FUCL concerning HSO 3 − was 43 nM (λ ex = 730 nm), which is half the detection limit achieved under traditional excitation (93 nM, λ ex = 643 nm). Cell fluorescence imaging showed that PT-1 could effectively target mitochondria and monitor endogenous/exogenous HSO 3 − in living cells. More importantly, PT-1 was successfully used to monitor the level of HSO 3 − in mice with drug-induced liver injury through FUCL imaging. [ABSTRACT FROM AUTHOR]

A novel reversible fluorescent sensor (IPSe) for ClO− and H 2 S was firstly constructed with the selenium atom as the response site and the dicyanoisophorone as the fluorophore. The sensor IPSe could detect ClO− with good selectivity and sensitivity due to the oxidation reaction of the selenium atom triggered by ClO−. The recognition of IPSe to hypochlorite induced a hypsochromic shift of the absorption maximum from 420 nm to 380 nm. IPSe exhibited the prominent low detection limit of 55.3 nM for detecting ClO−, accompanied by distinct fluorescent attenuation. Moreover, H 2 S could efficiently return the fluorescence of the IPSe solution to the original level by H 2 S reducing selenoxide. The applications in real water samples, beverages and cell imaging verified that the IPSe was capable of monitoring the changes in the concentration of ClO−/H 2 S, which indicates that it is of great meaning to survey the biological functions of ClO− and H 2 S via IPSe. [Display omitted] • The sensor IPSe presented reversible fluorescence response toward ClO−/H 2 S. • The IPSe has been successfully applied to detect ClO−/H 2 S in real water samples. • The IPSe has been applied to fluorescence imaging ClO−/H 2 S in onion cells. • The synthesis of the novel fluorescence sensor IPSe was facile. HClO/ClO− and H 2 S are two kinds of momentous biological small molecules in the organism, and the redox balance between them is considerable for the physiological and pathological properties of organisms. Hence, it is very crucial to monitor the redox course between HClO and H 2 S. Herein, a reversible fluorescent sensor (IPSe) for ClO− and H 2 S was firstly constructed with the selenium atom as the response site and the dicyanoisophorone as the fluorophore. The sensor IPSe could detect ClO− with good selectivity and sensitivity due to the oxidation reaction of the selenium atom triggered by ClO−. The recognition of IPSe to hypochlorite induced a hypsochromic shift of the absorption maximum from 420 nm to 380 nm. IPSe exhibited the prominent low detection limit of 55.3 nM for detecting ClO−, accompanied by distinct fluorescent attenuation. Moreover, H 2 S could efficiently return the fluorescence of the IPSe solution to the original level by H 2 S reducing selenoxide. The experimental results show that the suggested method has high precision and accuracy for the detection of ClO− and H 2 S. The applications in real water samples, beverages and cell imaging verified that the IPSe was capable of monitoring the changes in the concentration of ClO−/H 2 S, which indicates that it is of great meaning to survey the biological functions of ClO− and H 2 S via IPSe. [ABSTRACT FROM AUTHOR]

[Display omitted] • MHB with cyanobiphenol fluorophore was synthesized and characterized. • MHB exhibits highly sensitivity fluorescence enhancement to Al3+/Zn2+ along with significant color changes. • MHB was successfully applied in the detection of Al3+/Zn2+ on real water, test paper and cell imaging. A facile cyanobiphenol based probe MHB was synthesized and determined by FT-IR, 1H NMR, 13C NMR, HRMS and X-ray Crystallography. The probe MHB exhibited fluorescence turn-on phenomenon accompany with obvious color change from dark bule to azure and blue-green upon the addition of Al3+ and Zn2+, respectively. The binding ratios between probe MHB and Al3+/Zn2+ was 1:1 determined by Job's plot, which was deeply investigated by FT-IR spectrum, 1HNMR titration and HRMS analysis. The detection limits of MHB to Al3+ and Zn2+ were 2.52 × 10−7 M and 1.74 × 10−7 M for Zn2+, respectively. The application experiments referring to real water samples, test paper and cell image showed that MHB was capable of qualitative and quantitative sensing Al3+/Zn2+ in environmental and biological system. [ABSTRACT FROM AUTHOR]

[Display omitted] • The low detection limit of the probe PIN indicates its good stability. • Zn2+ and Cd2+ ions could be quickly detected using probe PIN with high selectivity and immunity to interference. • Zn2+ and Cd2+ ion sin HepG-2 live cells could be imaged by probe PIN with low toxicity to cells. A colorimetric fluorescent probe, 4-(1H-imidazolo[4,5-f][1,10]phenanthroline-2-yl)-N, N-diphenylaniline (PIN), was designed, synthesized and characterized for the sensitive and selective detection of Zn2+ and Cd2+. The color of the solution changed from blue to yellow visible to the naked eye with the addition of Zn2+ and Cd2+. The probe PIN showed good anti-interference to Zn2+ and Cd2+ in the presence of a variety of metal ions, and the fluorescence intensity showed a good linear relationship with the concentrations of Zn2+ and Cd2+, with detection limits of 34.84 nM and 35.76 nM, respectively. The probe PIN complexed 2:1 with Zn2+ and Cd2+, and the complexation constants were 1.03 × 104 M−1 (PIN − Zn2+, R2 = 0.9971) and 1.50 × 104 M−1 (PIN − Cd2+, R2 = 0.9981), respectively. In addition, the PIN could be recovered by EDTA and could be effectively monitored for Zn2+ and Cd2+ at pH 4–11, with good results in actual water samples. The HepG-2 cells maintained over 95 % of viability after 24 h exposure to PIN, which identified the extremely low toxic of PIN and could be used for in vivo cell imaging. [ABSTRACT FROM AUTHOR]

[Display omitted] • A novel fluorophore NADCO with NIR emission, high quantum yield and large two-photon cross section was developed. • The NADCO-based fluorescent probe NADCO-DBS offers high sensitivity and better selectivity for H 2 S. • NADCO-DBS has excellent two-photon imaging effects and lysosome localization capability. • NADCO is conducive to the development of high-performance NIR two-photon fluorescence probes. Two-photon fluorescent probes offer key advantages for biological imaging, including deep tissue penetration, minimal photobleaching and photodamage, and low background interference. However, the emission wavelength of most two-photon fluorescent probes is within the blue-green region, which limits these advantages. Moreover, the few reported NIR two-photon fluorescent probes suffer from drawbacks such as low quantum yield, small two-photon cross section, and poor water solubility. To address these issues, we constructed a new two-photon fluorophore, NADCO, by combining naphthalimide and dicyanoisophorone. NADCO exhibits remarkable optical properties, including two-photon excitation wavelength of 900 nm, NIR emission wavelength of 706 nm, large two-photon cross section of 303 GM, and high quantum yield of 26.61 %. Considering the critical signaling role of H 2 S in living organisms, we further exploited this fluorophore to synthesize an H 2 S fluorescent probe NADCO-DBS. NADCO-DBS shows high sensitivity and selectivity for H 2 S with a detection limit of 12.3 nM. Additionally, NADCO-DBS demonstrates remarkable lysosomal targeting ability in cell imaging with a Pearson coefficient up to 0.94. This work provides a promising tool for exploring the physiological and pathological roles of H 2 S and lysosomes, and furnishes a novel approach for the development of high-performance NIR two-photon fluorescent probes. [ABSTRACT FROM AUTHOR]

[Display omitted] • NFS-CDs were prepared by a hydrothermal method using Flufenamic acid and L-Cys. • NFS-CDs were characterized by UV–Vis, PL, FTIR, XRD, TEM, HRTEM, and XPS analysis. • NFS-CDs/Hg2+ show high sensitivity with detection limits to be 18 and 67.5 × 10−9 M. • NFS-CDs/Hg2+ show notable antibacterial effect inhibiting S. aureus and E. coli. • NFS-CDs biocompatible, high viability (>98 %), strong fluorescence for Hg2+ ions. A simple, low-cost hydrothermal method was employed to synthesize highly fluorescent nitrogen-, fluorine-, and sulfur-co-doped carbon dots (NFS-CDs) using flufenamic acid and L-cysteine as precursors. The synthesized NFS-CDs exhibited dual emission peaks at 490 and 580 nm with a quantum yield of 24.7 %. They exhibit excellent stability, excitation-dependent fluorescent, and particle sizes ranging from 2 to 8 nm. The fluorescent chemosensor probe, NFS-CDs, showed strong selectivity and sensitivity for Hg2+ over other metal ions investigated in aqueous solutions (pH ∼ 7.4). Strong fluorescent enhancement at 490 nm and considerable quenching at 580 nm was observed in the presence of Hg2+ ions. The stoichiometric ratio of the NFS-CDs/Hg2+ complex was optimized to 1:1 according to the Benesi-Hildebrand and Stern-Volmer plot methods. The NFS-CDs exhibited a linear dynamic detection range from 0 to 10 × 10−6 M for Hg2+ ions with a lower detection limit of 18.0 and 67.5 × 10−9 M, respectively, at 490 and 580 nm. Practical applications of NFS-CDs in detecting Hg2+ ions in natural water samples showed high recovery rates (98.9–104.6 %) and low relative standard deviation (RSD ≤ 2.47 %). The NFS-CDs/Hg2+ achieved 78.7 ± 2.6 % and 83.4 ± 2.3 % antibacterial activity against E. coli and S. aureus as NFS-CDs/Hg2+ could damage the bacterial walls when they entered the bacteria. Furthermore, the NFS-CDs were used to detect Hg2+ ions intracellularly in HCT116 cells with low toxicity using live cell imaging. [ABSTRACT FROM AUTHOR]

A simple fluorescent quenching probe based on polyethylene glycol-400 capped sulfur quantum dots (PEG-SQDs) was fabricated to determine quercetin (QT) quantitatively. As anticipated, the PEG-SQDs exhibited favourable luminescent properties, stability and low cytotoxicity. QT effectively quenched the fluorescence of the PEG-SQDs through static quenching and the inner filter effect. Moreover, the PEG-SQDs showed rapid QT detection within a linear range of 0.100–45.0 μM, with a limit of detection of 0.014 μM (3σ/k). This fluorescent probe successfully detected QT in human serum, quercetin supplement capsules and red wine, achieving a standard recovery of 92.6 %–105 %. [Display omitted] • A sensitive nano-fluorescence sensing probe was constructed for quercetin detection. • The linear range of detection was 0.100–45.0 μM and the detection limit was 0.014 μM. • Accurate detection of quercetin could be achieved in serum, supplements, and red wine. [ABSTRACT FROM AUTHOR]

In this study, we have designed and synthesized a highly efficient "turn-on" fluorescent probe W-1a, for detecting FA levels at both environmental and cellular levels. This probe exhibits high selectivity and sensitivity (with a detection limit of 0.91 μM and a response time of approximately 13 min). Additionally, the low toxicity of probe W-1a to cells demonstrates its suitability for cellular imaging applications. [Display omitted] • Successfully synthesized a formaldehyde-responsive "turn-on" fluorescent probe W-1a. • W-1a exhibits low cytotoxicity and can effectively monitor signal changes induced by endogenous/exogenous FA in cells. • W-1a has high selectivity and can be used for the detection of FA in indoor decoration materials and seafood products. Formaldehyde is a common volatile organic aldehyde that is widely present in building materials, furniture, and household products. It is also naturally produced in the body, where it plays various physiological and pathological roles. Long-term exposure to formaldehyde can lead to a range of health issues, including respiratory diseases, skin allergies, and even cancer. Despite growing concerns about formaldehyde exposure, existing detection methods often suffer from limitations such as low sensitivity and poor selectivity. Therefore, there is an urgent need for more efficient detection technologies. To address these issues, we have developed a novel "turn-on" fluorescent probe W-1a, which achieves high sensitivity and selectivity for formaldehyde detection through structural optimization. The reactivity between the probe and formaldehyde was quantitatively analyzed, with a detection limit of 0.91 μM. W-1a was successfully applied to visualize changes in formaldehyde levels in live cells. Furthermore, the probe demonstrated excellent recovery rates in both construction materials and real food samples, providing a reliable molecular tool for detecting harmful gases in the environment and ensuring food safety. [ABSTRACT FROM AUTHOR]

[Display omitted] • A FRET/TICT based multifunctional fluorescent probe was developed for the monitoring of SO 2 derivatives and viscosity. • JFT exhibited excellent sensitivity, selectivity, photostability and biocompatibility. • JFT can detects the endogenous SO 2 derivatives and viscosity levels in living cells. • JFT can senses HSO 3 −/SO 3 2− contents in real water, wine and food samples. SO 2 derivatives and viscosity are important intracellular indicators, which are closely associated with various physiological metabolisms in organisms. The unregulated contents of SO 2 derivatives and viscosity in vivo commonly related to some disorders. In this work, probe JFT was developed relying on FRET and TICT mechanisms for the simultaneous detection of SO 2 derivatives and viscosity. JFT can rapidly detect viscosity levels with continuously enhanced fluorescence signals at 582 nm basing on the increasing of viscosity. Moreover, JFT was also sensitive to the changes of SO 2 derivatives level with a low detection limit (61.5 nM), rapid responding time (with 16 min), excellent selectivity and anti-interference capacity. JFT could detect bisulfite in real water, wine and food samples with high accuracy and recovery rate. Cell imaging indicated that JFT could monitor the endogenous SO 2 derivatives and viscosity in mitochondria. Importantly, JFT could recognize the cancer cells basing on the cell imaging difference of JFT in AGS and GES-1 cells. [ABSTRACT FROM AUTHOR]

In the currently available approaches for intracellular uracil-DNA glycosylase (UDG) detection, their signal outputs usually rely on the cleavage of the residual AP sites in DNA probes by apurinic/apyrimidinic endonuclease 1 (APE1), whose expression level varies across different types of cells. Therefore, reliable visualizing detection of UDG in living cells remains challenging. Herein, a nanoprobe for imaging of intracellular UDG activity has been designed by taking advantages of both zeolitic imidazolate framework-90 (ZIF-90) and endonuclease III. ZIF-90 is used to deliver exonuclease III (Exo III) and hairpin DNA strands into cells. One of the hairpin strands (HP1) contains a deoxyuridine (dU) base in its stem region, while the other (HP2) was modified with FAM molecule and BHQ1 at its 3′ and 5′ ends, respectively. In the presence of UDG, the dU base in HP1 is excised to form an AP site. Exo III can cleave the AP site in HP1 to generate a stem-loop fragment, which can hybridize with HP2 to initiate the recycling digestion of HP2 by Exo III, resulting in amplification of the fluorescence signal and hence sensitive detection of UDG (limit of detection: 2.0×10−6 U/mL). Experimental results have demonstrated that the nanoprobe has merits of good biocompatibility, high sensitivity and selectivity. It realizes in-situ imaging of intracellular UDG without the involvement of APE1, is a promising alternative tool for UDG detection in fields of clinical diagnosis and biomedical research. [Display omitted] • A nanoprobe was designed for sensitive and selective imaging of intracellular UDG. • The nanoprobe consists of ZIF-90, Exo III and two types of hairpin DNA strands. • ZIF-90 served as a carrier for delivering both Exo Ⅲ and DNA strands into cells. • The nanoprobe has high sensitivity and selectivity for intracellular UDG detection. • It eliminates the dependence on APE1 enzyme in developing of UDG-sensing methods. [ABSTRACT FROM AUTHOR]

• A TPE-functionalized rhodamine chemdosimeter TRP has been synthesized with an AIE effect. • TRP shows ratiometric fluorescence to Hg2+ with high selectivity and well-resolved emission bands. • The LOD of Hg2+ is low down to 10.0 nM. • TRP can be used for tracing intracellular Hg2+ by ratiometric fluorescence imaging. In this work, a tetraphenyl ethylene functionalized rhodamine chemodosimeter, namely, TRP, has been designed, built, and structurally determined. The chemodosimeter exhibited an AIE effect in an EtOH-H 2 O mixture with the maximal emission intensity at 463 nm at a water fraction of 70 %. Then TRP was applied for ratiometric monitoring of Hg2+ ions in EtOH/H 2 O solution (v/ v = 3/7), presenting about a 35-fold fluorescence intensity ratio enhancement (F 649 /F 463), visible color changes, and well-resolved emission bands (187 nm). In addition, TRP showed high selectivity and sensitivity in Hg2+ ions sensing and achieved a limit of detection (LOD) of 10.0 nM, which was mainly attributed to the production of an oxadiazole functionalized and spirolactam ring opened rhodamine derivative-induced by Hg2+ ions. Significantly, using TRP as a tracer, ratiometric fluorescent detection of Hg2+ ion has been successfully conducted via living cell imaging, demonstrating its potential for practical applications in biological systems. We developed a chemodosimeter with AIE effect for selectivity, sensitive and ratiometeric sensing Hg2+ ions in vitro and in vivo. [Display omitted] [ABSTRACT FROM AUTHOR]

• A new benzil-based chemosensor was synthesized for colorimetric and fluorometric detection of Cu2+ ions. • The probe displayed high selective and low detection limit for Cu2+ ions. • The probe was applied for imaging of intracellular Cu2+ ions in living cells. • DFT calculations confirm the four-coordination configuration of Cu2+ ions. A novel benzil-based probe DBBQ containing two julolidine Schiff base arms was synthesized and demonstrated for its highly selective and sensitive detection of Cu2+ ions in CH 3 CN: HEPES buffers (3:2, v/v, pH=7.4). Upon the addition of Cu2+ ions, the absorption of the probe exhibited remarkable change in color from yellow to brown, which could be easily observed by the naked eyes. In addition, probe DBBQ displayed highly selective fluorescence quenching signal for Cu2+ ions over a wide range of competitive substances. The fluorescence intensity of DBBQ in CH 3 CN: HEPES buffer (3:2, v/v, pH=7.4) solution showed a good linear response relationship to Cu2+ ions in the range of 0–2.5 μΜ and low detection limit of 0.41 μM. The binding ratio between DBBQ and Cu2+ ions was determined to be 1:1. Probe DBBQ could be potentially used as a chemosensor for Cu2+ ions in living HepG2 cells. [Display omitted] [ABSTRACT FROM AUTHOR]

[Display omitted] • A NIR fluorescent probe Nap-Cy was developed for dual-response detection of ONOO– and viscosity in lysosomes. • Nap-Cy possessed high sensitivity, low detection limit, and excellent selectivity toward ONOO–. • Nap-Cy was applied for imaging ONOO– and viscosity in living cells and zebrafish. Peroxynitrite (ONOO–) and viscosity are critical indicators of lysosome functionality, intimately linked to numerous diseases' pathophysiological processes. Hence, creating reliable analytical techniques to observe fluctuations in lysosomal ONOO– and viscosity is highly important. This study presents the development of a novel naphthalimide-based fluorescent probe, Nap-Cy , specifically designed to target lysosomes and simultaneously detect both ONOO– and viscosity. Nap-Cy displayed a near-infrared fluorescence "turn-on" response to viscosity (ranging from 1.0 to 1410 cp) with an approximately 400-fold increase in intensity. At the same time, it functioned as a ratiometric probe with high sensitivity for detecting ONOO–, featuring a quick response time of approximately 10 min, a low detection limit of 42 nM, a broad pH range (5–11), and excellent selectivity for ONOO– over other chemical and biological species. Additionally, Nap-Cy was successfully applied for fluorescence imaging to monitor ONOO– and viscosity variations in SH-SY5Y cells and zebrafish across multiple channels. This research introduces a valuable molecular probe for investigating the biological functions and interactions of ONOO– and viscosity within lysosomes. [ABSTRACT FROM AUTHOR]

The influence of multiple factors often leads to the unexpected performances of the designed AIEgens. It is difficult to precisely conclude the influence of the substituted sites and role of isomers on the photophysical properties of the AIEgens which therefore brings uncertainty in the molecular design strategies. Isomer engineering of AIEgens is a less explored domain. There are only a few reports that substantiate the effects and positions of the substituents on the AIE properties. The present investigation explores two isomeric benzofuran-derived luminogens GBY-1 and GBY-4 , both featuring a TPE moiety and showcasing AIE and AIEE properties respectively inherited from TPE. The isomeric effect resulting from TPE incorporation at different positions across benzofuran significantly influenced their photophysical properties, mechanofluorochromic properties, and AIE effect. Their distinctive luminogenic features were evident in mechanochromic property as well as in cancer cell imaging. GBY-1 was found to be uniformly dispersed in the cytoplasm, not co-localized with the nucleus, while GBY-4 accumulated near the cell membrane. Furthermore, post-functionalization of one of the luminogens, GBY-1 , derived another AIEgen, GBY-5 with a dramatic improvement in the PLQE along with its ability to selectively sense Fe3+ in aqueous environments, within a detection limit of 0.00035 mM. Isomeric engineering of benzofuran derived AIE luminogens resulted in a significant variation in their photophysical properties. Fusion of TPE to the benzofuran leads to mechanofluorochromic luminogen whereas side chain modification of the benzofuran with TPE offered better luminogenic property with altogether cell-imaging ability. [Display omitted] • Aggregation Induced Emission. • Cell-imaging. • Mechanofluorochromism. • Sensing. • pH responsive luminogen. [ABSTRACT FROM AUTHOR]

[Display omitted] • A colorimetric/fluorometric dual-channel probe YSQ has been developed for rapid and visual detection of Pb2+. • YSQ exhibited hypersensitive toward Pb2+ with rapid signal response (1 min). • Limit of detection (LOD) of YSQ for Pb2+ was as low as 18 nM. • YSQ could serve as a high-performance detector for Pb2+ in real environmental and biological samples. • The integration of YSQ and the smartphone provided a portable and low-cost method for Pb2+ ions detection. The development of specific and visually detectable fluorophores for the accurate and rapid Pb2+ recognization is crucial. In this study, we introduced a novel isophorone-derived fluorescent probe, (E)-2-(3-(3-formyl-4-hydroxystyryl)-5,5-dimethylcyclohex-2-en-1-ylidene)malononitrile (YSQ), rationally designed for prompt and high-quality Pb2+ detection. YSQ demonstrated noticeable red emitting fluorescence enhancement upon Pb2+ interactions (upon binding, τ avg 16.7 ns, Φ 12 %) with visible color changes discernible to the naked eye in MeOH/H 2 O (v/v 9/1, pH 7.4, 0.2 mM). The probe YSQ achieved a quite low detection limit (LOD) of 18 nM and a high association constant of 2.93 × 105 M−1 towards Pb2+ using fluorescence titration. We proposed a binding mechanism of YSQ with Pb2+ ions, supported by the density functional theory (DFT/TD-DFT), 1H NMR titration experiments, IR and HRMS analysis. In addition, a simple and affordable smartphone-supported specific Pb2+ detection technique was developed with visible color changes. Furthermore, this NIR emissive properties of YSQ offered broad potential applications in actual water sample and solid analysis, bio-imaging and test strips. [ABSTRACT FROM AUTHOR]

Qualitative and quantitative analysis of mercury at concentration levels as low as parts per billion (ppb) is a basic and practical concern. The vast majority of research in this field has centered on the development of potent chemosensor to monitor mercuric (Hg2+) ions. Mercury exists in three oxidation states, + 2, + 1 and 0, all of which are highly poisonous. In this study, (N1E,N2E)-N1,N2-bis(pyrene-1-ylmethylene)benzene-1,2-diamine (PAPM), a novel photoluminescent sensor based on pyrene platform was synthesized. Over the tested metal ions (Cd2+, Co2+, Cu2+, Mg2+, Mn2+, Ni2+, K+, Na+, Zn2+, Sr2+, Pb2+, Al3+, Cr3+ and Fe3+) the sensor responds only to Hg2+ by showing high selectivity and sensitivity. After treatment with mercuric ions at room temperature, the luminescence intensity of probe was quenched at 456 nm. The quenching of fluorescence intensity of probe upon addition of mercury is due to the effect of "turn-off" chelation enhanced quenching (CHEQ) by the formation of 1:1 complex. The ESI–MS spectrum and the Job's experimental results confirm the formation of 1:1 complex between PAPM and Hg2+. The detection limit and association constant of sensor for mercury is computed using fluorescence titration data and were found to be 9.0 × 10–8 M and 1.29 × 105 M−1 respectively. The practical application of sensor towards recognition of mercury(II) ions was explored through economically viable test strips and also using cell imaging studies. [ABSTRACT FROM AUTHOR]

Endogenous sulfur dioxide (SO2), as a gas signal molecule, has a certain physiological functions. Understanding the role of endogenous SO2 in human physiology and pathology is of great significance to the biological characteristics of SO2,which bring challenges to develop fluorescent probes with excellent performance. Herein, we rationally designed and constructed a novel near-infrared bioprobe benzaldehyde-benzopyrylium (BBp) by employing the nucleophilic addition benzopyrylium perchlorate fluorophore and benzaldehyde moiety by means of C = C/C = O group that serves as both fluorescence reporting unit. Probe BBp exhibit excellent sensing performance with fluorescent "On − Off"rapid response (100 s) and long-wavelength emission (670 nm). With the treatment of HSO3−, the color of BBp solution obviously varies from purple to colorless, and the fluorescent color varies from red to colorless. By the fluorescence and colorimetric changes, probe BBp was capable of sensitive determination HSO3− with low limits of detection (LOD) of 0.43 μM, realizing visual quantitative monitoring SO2 derivative levels. Due to the low phototoxicity and good biocompatibility, it was successfully applied to monitor SO2 derivatives and fluorescence imaging in HepG2 and HeLa living cells. Hopefully, this work supplies a new strategy for designing NIR fluorescent probes for quantitative determination SO2 derivatives in biological samples. [ABSTRACT FROM AUTHOR]