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Despite increasing awareness of the biological impacts of long-chain fatty acyl-CoA esters (LCACoAs), our knowledge about the subcellular distribution and regulatory functions of these acyl-CoA molecules is limited by a lack of methods for detecting LCACoAs in living cells. Here, we report development of a genetically encoded fluorescent sensor that enables ratiometric quantification of LCACoAs in living cells and subcellular compartments. We demonstrate how this FadR-cpYFP fusion "LACSer sensor" undergoes LCACoA-induced conformational changes reflected in easily detectable fluorescence responses, and show proof-of-concept for real-time monitoring of LCACoAs in human cells. Subsequently, we applied LACSer in scientific studies investigating how disruption of ACSL enzymes differentially reduces cytosolic and mitochondrial LCACoA levels, and show how genetic disruption of an acyl-CoA binding protein (ACBP) alters mitochondrial accumulation of LCACoAs., (© 2021 Wiley-VCH GmbH.)

Surface enhanced fluorescence (SEF) is observed with very high contrast (100-200) from single E. coli bacteria cells labeled with Carbon nanodots (CDs), on aluminum foil and aluminum film. Likely, it is the first application of organic CDs in SEF. SEF with 633 nm excitation delivered a much higher contrast than SEF with 532 nm excitation. Contrast is the ratio of the fluorescent intensities of labeled CDs to unlabeled (control) cells. High contrast with CDs is also observed on the gold film, silicon, and glass. Enhancement factor (EF) is the ratio of the signal on the metal substrate to the signal on the glass. Single E. coli cells, labeled with commercial graphene quantum dots (GCDs), demonstrated higher EFs (44 on gold, 35 on Al film), but at least one order of magnitude lower contrast (7-10 on aluminum and gold) than cells labeled with organic CDs. Therefore, organic CDs can be a good choice for cell imaging/labeling, capable of achieving a signal to noise (standard deviation of the control) as high as 700 on Al film. Overall, aluminum foil and film are highlighted as inexpensive but efficient substrates for Metal Enhanced Fluorescence, particularly MEF of bacterial cells stained with CDs.

Developing a specific and sensitive method for endogenous hydrazine detection in living systems is valuable to understand its various pathological events. In this work, two novel fluorescent chemosensors (C1, C3) based on triphenylamine Schiff-base derivative and reference dyes (C2, C4) were prepared in relatively high yield (more than 72% yield). The aggregation induced emission (AIE) properties of sensors were investigated through UV-Visible, dynamic light scattering, X-ray diffraction, fluorescence spectrophotometric analyses as well as scanning electron microscope images (SEM). The results indicated that probes C1 and C3 exhibited strong AIE property in DMF/H 2 O (1:1, v/v) mixture system with brilliant yellow fluorescence emission (560 nm) observed under 365 nm UV lamp. The experiments of sensing indicated that probes C1 and C3 possessed the sequentially detecting abilities for hydrazine with high sensitivity, specificity as well as an extremely low detection limit (55.1 nM), which was due to blocking of AIE process of probes C1 and C3 by special chemical reaction (-CHN- moiety transformed into -CH 2 -NH- group) after hydrazine addition, resulting in the increase in water solubility and a weak emission in aqueous media. Furthermore, 1 H NMR, SEM and fluorescence titration experiment was also conducted to confirm the sensing mechanism. For biological application, probes C1 and C3 presented a good bio-imaging performance and showed the similar fluorescence quenching after adding hydrazine. Therefore, the probes are suitable for the fluorescence imaging of exogenous hydrazine in HeLa cells., Competing Interests: Declaration of competing interest We declare that we have no financial and personal relationships with other people or organizations that can inappropriately influence our work, there is no professional or other personal interest of any nature or kind in any product, service and/or company that could be construed as influencing the position presented in, or the review of, the manuscript entitled., (Copyright © 2020 Elsevier B.V. All rights reserved.)

In this work, a hydrophilic naphthalimide-based fluorescence chemosensor (sensor 1) was synthesized for Cu 2+ recognition, in which 2-(2-aminoethoxy)ethanol was introduced to improve the hydrophily and Schiff base acted as the multidentate ligand for Cu 2+ . The effect factors, sensing mechanism and regenerability of sensor 1 for Cu 2+ sensing were systematically investigated. It was found that sensor 1 displayed a long emission wavelength of 532 nm upon excited in visible light region (436 nm), and the good water solubility made it utilized in aqueous media. It could selectively react with Cu 2+ over other common metal ions to form a 2:1 complex within 1 min and result in significant fluorescence quench. The fluorescence change was linear to 0.5-10.0 μmol L - 1 of Cu 2+ with a low detection limit of 3.74 × 10 - 8  mol L - . Moreover, in view of fluorescence "on-off-on" switches of sensor 1 induced by Cu 1 and EDTA, an IMPLICATION logic gate was constructed based on fluorescence mode with Cu 2+ in water samples as well as imaging cellular Cu 2+ . Moreover, in view of fluorescence "on-off-on" switches of sensor 1 induced by Cu 2+ and EDTA, an IMPLICATION logic gate was constructed based on fluorescence mode with Cu 2+ and EDTA as inputs., Competing Interests: Declaration of competing interest The authors declared that they have no conflicts of interest to this work. We declare that we do not have any commercial or associative interest that represents a conflict of interest in connection with the work submitted., (Copyright © 2020 Elsevier B.V. All rights reserved.)

Cobalt ions (Co 2+ ) are among heavy metals ions which cause pollution in environment because of their toxicity and improper degradation. In this work, a new fluorescent approach based on silicon nanoparticles (Si NPs) was designed for Co 2+ detection. The fluorescent Si NPs were prepared by mixing 3-aminopropyl trimethoxysilane (APTES) and basic fuchsin, and under the excitation of 400 nm, they emitted green fluorescence at 515 nm. The prepared Si NPs were highly soluble in water, stable to salt and pH, and their fluorescence emission was extremely constant, with the quantum yield of 2.28%. The detailed mechanism studies showed that Co 2+ effectively quenched the fluorescence of Si NPs by forming static complex. After optimizing the reaction parameters, a good linear relationship for Co 2+ was observed from 0.2 to 60 μM, and the limit of detection was 0.14 μM that is lower than the guideline announced by Department of Environmental Protection for drinking water (1.7 μM). The preparation method of Si NPs was cheap, rapid and simple, and the fluorescent approach was applied to determine Co 2+ in Yellow river water, drinking water, and industrial wastewater. Moreover, the Si NPs has good response to exogenous Co 2+ in HepG2 cell imaging., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2019 Elsevier B.V. All rights reserved.)

An efficient and stable fluorescent sensor is described for the detection and imaging of thiols. It is making use of silicon quantum dots (SiQDs) which can be rapidly prepared. They were characterized by transmission electron microscopy, X-ray power diffraction, Fourier transform infrared spectroscopy, X-ray photoelectron spectrometry. The SiQDs have an absorption maximum at 300 nm and displayed blue-green fluorescence with excitation/emission maxima at 410/480 nm. A mixture of SiQDs and 5,5'-dithiobis-(2-nitrobenzoic acid) (DTNB) exhibits strong fluorescence emission which however is quenched within 30 s of incubation with thiols. This is assumed to be due to an inner filter effect caused by the reaction of DTNB and thiols. The following thiols were tested: cysteine, homocysteine, and glutathione. The sensor has a linear response in the 3-100 μM thiol concentration range, and the LODs are between 0.80 and 0.96 μM. The sensor displays low cytotoxicity and was applied to fluorescence imaging of MCF-7 cells and Hela cells where it demonstrated excellent biocompatibility., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2019. Published by Elsevier B.V.)

Fluorescent pH probes are promising for both in vitro and in vivo pH detections in chemical and biochemical systems. Previously, the multi-color and whole cell pH sensing is a challenge for conventional fluorescent nanomaterials. In this work, we report an N, S co-doped carbon dots (N, S-CDs)-based fluorescent pH probe that can response to different incident light with tunable wavelength. The emission wavelength is tunable and correlated to the excitation wavelength, enabling self-adaptive multi-color sensing. The N, S-CDs was synthesized by a one-step hydrothermal method utilizing glucose, ammonium persulfate and ethylenediamine as precursors. The fluorescence of N, S-CDs shows a good linear relationship against pH values from 3.0 to 10.0 with a linear correlation coefficient of 0.996. The good biocompatibility and small size fulfill the demand of whole cell intracellular imaging. We have demonstrated that the N, S-CDs have successfully applied in HepG2 cells for the self-adaptive multi-color imaging., (Copyright © 2019. Published by Elsevier B.V.)

Two probes, AIE-1 and AIE-2, were synthesized to investigate the effect of substitutional functional group on aggregation (aggregation-caused quenching (ACQ) or aggregation-induced emission (AIE)) and intramolecular charge transfer (ICT) behavior as well as on the cell imaging aspect. The yellow-color non-substituted probe AIE-1 showed weak charge-transfer absorption and an emission band at 377 nm and 432 nm, whereas the yellowish-orange color substituted probe AIE-2 showed a strong charge-transfer absorption and an emission band at 424 nm and 477 nm in THF solvent. The UV-Vis studies of AIE-1 and AIE-2 in THF and THF with different water fractions showed huge absorption changes in AIE-2 with high water fractions due to its strong aggregation behavior, but no such noticeable absorption changes were observed for AIE-1. Interestingly, the fluorescence intensity of AIE-1 at 432 nm gradually decreased with increasing water fractions and became almost non-emissive at 90% water. However, the monomer-type emission of AIE-2 at 477 nm was shifted to 584 nm with a 6-fold increase in fluorescence intensity in THF-H 2 O (1:9, v/v ) solvent mixtures due to the restriction of intramolecular rotation on aggregation in high water fractions. This result indicates that the probe AIE-1 shows ACQ and probe AIE-2 shows AIE behaviors in THF-H 2 O solvent mixtures. Furthermore, the emission spectra of AIE-1 and AIE-2 were carried out in different solvent and with different concentrations to see the solvent- or concentration-dependent aggregation behavior. Scanning electron microscope (SEM) and dynamic light scattering (DLS) experiments were also conducted to assess the morphology and particle size of two probes before and after aggregation. Both of the probes, AIE-1 and AIE-2, showed less toxicity on HeLa cells and were suitable for cell imaging studies. Density functional theory (DFT) calculation was also carried out to confirm the ICT process from an electron-rich indole moiety to an electron-deficient cyano-phenyl ring of AIE-1 or AIE-2.

Metal atom doping, an easy and convenient method, can optimize and tune the physical-chemical properties and photometrics of carbon dots (CDs). However, there are few reports on the preparation of metal-decorated CDs that give red emission and a high photoluminescence quantum yield (PLQY). Here, we demonstrate a zinc (existing in human body) ion-doping strategy to observably enhance the PLQY and lengthen the CD emission wavelength. The prepared Zn/ZnO-decorated CDs (Zn-CDs) produced red fluorescence (623 nm) with a superior PLQY of 40.3%. Through a series of analyses, Zn-CDs were confirmed to contain an oxidation state and reduction state of Zn doping into the internal defects and surface of Zn-CDs. More valuably, the Zn-CDs had excellent chemical stability, photo-stability, long-term storage stability, and high biocompatibility, and therefore could be used as a robust red fluorescence probe for high-quality cellular imaging., (© 2019 John Wiley & Sons, Ltd.)

Discrimination and quantification of intracellular biothiols, such as cysteine (Cys), homocysteine (Hcy), glutathione (GSH) under physiological conditions is significant for academic research and disease diagnosis. A new fluorescent probe (complex 1-Cu 2+ ) for discriminate detection of GSH was prepared by copper ions coordinate with coumarin carbohydrazide Schiff base derivative 1. In suitable buffer solution (CH 3 CN: HEPES = 3:2, v/v) and under appropriate pH condition (pH = 7.2-7.4), the UV-vis spectroscopy experiments showed that compound 1 and copper ion exhibited a 1:1 ratio binding mode and moderate binding ability. Fluorescence quenching of compound 1 was observed when it complexed with Cu 2+ ions. An obviously fluorescence restoration appeared after addition of GSH to the solution of probe, which also exhibited a highly selectivity relative to cysteine (Cys) and homocysteine (Hcy) in the amino acid competitive experiments. The minimum detection limit was calculated to 0.12 μM by fluorescent method, which was distinctly below the physiological concentration of GSH in live cells. Its biological application to detect the endogenous GSH was further proved by the HepG2 cell fluorescence image test., (Copyright © 2019 Elsevier Inc. All rights reserved.)

Carbazole - Rhodanine conjugate is an effective fluorescent host for silver ions through fluorometric transformation from green to red color with a hyperchromic emission. An intramolecular charge transfer process derived from carbazole towards rhodanine favors interaction of thiocarbonyl S and carboxylic acid O of the rhodanine moiety towards Ag + ion. Carbazole - rhodanine dyad accomplishes the lowest detection limit of 12.8 × 10 -9  M and high quantum efficiency. A fluorescence reversibility of the probe with I - ion surges reutilization of sensor molecule as an Ag + ion probe with minimal loss in the fluorescent efficiency. This fluorescent ligand is a biocompatible probe and is also a proficient candidate for fluorescent imaging of Ag + ion in live cells.

Zwitterion-modification, as a bioinspired strategy, provides greatly promising platforms for biological detection and sensor applications. A green, low-cost and straight-forward method for synthesis of highly fluorescent biomimetic carbon quantum dots (BCQDs) has been developed via pyrolysis of cytidine diphosphate choline (CDPC) and ethylenediamine. The BCQDs with a strong emission at wavelength of 450 nm shows ultrasensitive sensing capability for vitamin B12 with high selectivity. Using the fluorometric assay, the detection limit (DL) for vitamin B12 was found to be as low as 81 nM. Meanwhile, the results of 3-(4,5)-dimethylthiahiazo(-z-y1)-3,5-di-phenytetrazoliumromide (MTT), hemolysis measuring and morphological characterization of Red blood cells (RBCs) confirms the excellent biocompatibility of BCQDs. The imaging experiments of human cervical cancer cells (HeLa) certify that BCQDs could be served as an effective fluorescent sensing probe for label-free sensitive and selective detection of vitamin B12 in biological samples on account of their low toxicity and good biocompatibility. The BCQDs, further, were successfully applied to probe vitamin B12 in living cells, which broaden its potential application in vivo system., (Copyright © 2018 Elsevier B.V. All rights reserved.)

Luminescent nanomaterials are encouraging scaffolds for diverse applications such as chemical sensors and biosensors, imaging, drug delivery, diagnostics, catalysis, energy, photonics, medicine, and so on. Carbon dots (CDs) are a new class of luminescent carbonaceous nanomaterial that have appeared recently and reaped tremendous scientific interest. Herein, we have exploited a simple approach to prepare tuneable and highly fluorescent CDs via surface functionalization. The successful synthesis of CDs is manifested from several investigations like high-resolution transmission electron microscopy (HRTEM), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR) and X-ray photoelectron spectroscopy (XPS). The CDs exhibit excellent water solubility and with increasing nitrogen content fluorescence quantum yield increases whereas cell toxicity decreases. The CD synthesized at high temperature (180 °C) shows very high quantum yield (more than 56%). The tuneable optical properties of CDs are systematically studied using UV-vis and fluorescence spectroscopy. The cell viability evaluation and in vitro imaging study reveals that the synthesized CDs can be employed as a potential fluorescent probe for bio-imaging without further modification., (Copyright © 2017 Elsevier Inc. All rights reserved.)

Strong surface (metal) enhanced fluorescence (SEF or MEF) is observed from clusters and single E coli bacteria cells labeled with Carbon nanodots (CDs), which were synthesized from date pits. The enhancement factor (EF) for SEF of the cell clusters were close to 50 for both 533 and 633 nm laser excitation wavelength. Those EFs are ratios of emission peak areas from CD labeled cell clusters on gold film to the peak areas of the same batch cell clusters on glass substrate. SEF with 633 nm excitation performed better than SEF with 532 nm excitation, achieving higher fluorescence intensity and much higher contrast. The contrast as high as 66 for cell clusters on gold film is a ratio of fluorescent emission peak area measured at the CD labeled cell clusters to the fluorescent peak area measured at unlabeled cell clusters (autofluorescence) on the same substrate. The contrast with the background (S/N) or the ratio of fluorescent peak area measured at bacteria cells to area measured at bare substrate was as high as 200. This report may pave a way for the broader application of surface enhanced fluorescence and especially metal enhanced fluorescence imaging of CD labeled cells and other biological objects. Graphical abstract Carbon dots, synthesized from dates, are used for direct staining of E coli cells. Emission fluorescent spectroscopy of those CD labelled cells on gold film and glass, demonstrated enhancement factor about 50 for emission on gold as compared to glass, Excitation at 633 nm appears far superior to excitation at 532 nm in terms of contrast (up to 67) with unlabeled cells /control due to decrease in auto fluorescence of cells. Maximum Signal to noise ratio is 200.

A rhodamine spirolactam derivative (1) bearing a hydrophilic carboxylic acid group is developed as a fluorescent chemodosimeter for bivalent mercury ions (Hg(2+)) in 100% aqueous solution. It exhibits a highly sensitive "turn-on" fluorescent response toward Hg(2+) with a 42-fold fluorescence intensity enhancement under 1 equiv. of Hg(2+) added. The chemodosimeter can be applied to the quantification of Hg(2+) with a linear range covering from 3.0 × 10(-7) to 1.0 × 10(-5) M and a detection limit of 9.7 × 10(-8) M. Most importantly, the fluorescence changes of the chemodosimeter are remarkably specific for Hg(2+) in the presence of other metal ions, which meet the selective requirements for practical application. Moreover, the experiment results show that the response behavior of 1 towards Hg(2+) is pH independent in neutral condition (pH 5.0-8.0) and the response is fast (response time less than 3 min). Furthermore, the ring-opening mechanism of the rhodamine spirolactam induced by Hg(2+) was supported by NMR, MS, and DFT theoretical calculations. In addition, the proposed chemodosimeter has been used to detect Hg(2+) in water samples and image Hg(2+) in living cells with satisfying results., (Copyright © 2016 Elsevier B.V. All rights reserved.)

Fluorescent organic nanoparticles (FONs) were facilely prepared from polyethylenimine and glucose at mild reaction condition, and further utilized for cell imaging with various fluorescent wavelengths. The as-prepared PEI-Glu FONs were fully characterized by a series of techniques including 1H NMR spectrum, X-ray photoelectron spectroscopy, Fourier transform infrared spectroscopy, transmission electron microscopy, dynamic light scattering, UV-vis absorption spectrum, and fluorescence spectra. Such FONs were demonstrated with intense fluorescence and high water dispersibility. Biocompatibility evaluation and cell uptake behavior of these FONs were further investigated, which proved excellent biocompatibility and made them promising for cell imaging., (Copyright © 2014 Elsevier B.V. All rights reserved.)

An aggregation induced emission dye (RNH2) with two amino end-groups was facilely incorporated into stable cross-linked fluorescent organic nanoparticles via room temperature anhydride ring-opening polymerization and consecutive cross-linking with polyethylene polyamine. Thus obtained RO-OA-PEPA FONs were characterized by a series of techniques including (1)H nuclear magnetic resonance, Fourier transform infrared spectroscopy, UV-vis absorption spectrum, fluorescent spectroscopy and transmission electron microscopy. Biocompatibility evaluation and cell uptake behavior of RO-OA-PEPA FONs were further investigated to explore their potential biomedical application. We demonstrated that such FONs showed high-water dispersibility, strong red fluorescence, stable uniform morphology (100-200 nm) and excellent biocompatibility, making them promising for cell imaging application., (Copyright © 2013 Elsevier B.V. All rights reserved.)

In this paper, LD-TCF, a targeting probe for lipid droplets (LDs) with a near-infrared emission wavelength and large Stokes shift, was fabricated for polarity detection by assembling a donor–π–acceptor (D–π–A) molecule with typical twisted intramolecular charge transfer (TICT) characteristics. Surprisingly, the fluorescence emission wavelength of the newly constructed probe LD-TCF was stretched to 703 nm, and the Stokes shift was amplified to 126 nm. Furthermore, LD-TCF could specifically answer the change in polarity efficiently and did not experience interference from other biologically active materials. Importantly, LD-TCF exhibited the ability to target lipid droplets, providing valuable insights for the early diagnosis and tracking of pathophysiological processes underlying LD polarity. [ABSTRACT FROM AUTHOR]

This study presents an advanced integration of Multi-modal Raman Light Sheet Microscopy with zero-shot learning-based computational methods to significantly enhance the resolution and analysis of complex three-dimensional biological structures, such as 3D cell cultures and spheroids. The Multi-modal Raman Light Sheet Microscopy system incorporates Rayleigh scattering, Raman scattering, and fluorescence detection, enabling comprehensive, marker-free imaging of cellular architecture. These diverse modalities offer detailed spatial and molecular insights into cellular organization and interactions, critical for applications in biomedical research, drug discovery, and histological studies. To improve image quality without altering or introducing new biological information, we apply Zero-Shot Deconvolution Networks (ZS-DeconvNet), a deep-learning-based method that enhances resolution in an unsupervised manner. ZS-DeconvNet significantly refines image clarity and sharpness across multiple microscopy modalities without requiring large, labeled datasets, or introducing artifacts. By combining the strengths of multi-modal light sheet microscopy and ZS-DeconvNet, we achieve improved visualization of subcellular structures, offering clearer and more detailed representations of existing data. This approach holds significant potential for advancing high-resolution imaging in biomedical research and other related fields. [ABSTRACT FROM AUTHOR]

[Display omitted] Fluorescent microspheres are of significant interests due to their wide applications in biotechnology fields. However, their preparation presents several challenges, such as the need for dye labeling, the complexity of materials and often sophisticated preparation conditions. Here a simple process for hydrophilic and crosslinked polyurethane (CPU) microspheres, with carboxyl groups on the surface via one-step precipitation polymerization in 40 min, is presented. The microsphere size is easily adjusted by varying experimental conditions. CPU microspheres exhibit high thermal and pH stability with good redispersibility in water, and emit fluorescence without any modification or dye labeling. The emission mechanism is discussed. CPU microspheres are used as fluorescent probe to detect 4-nitrophenol (4-NP) based on their emission in UV light region, with excellent selectivity and sensitivity. In addition, they are reusable with detection limit unchanged after 7 cycles of reuses, a significant feature of this work. The mechanism of fluorescence detection is thoroughly explored and ascribed to the internal filtration effect. Based on the emission in visible light region, CPU microspheres are used as a model of PU microplastics (MPs) to visualize their biodistribution in HeLa and macrophage cells, as well as in zebrafish larvae, providing a reliable tracer for the visualization and tracking of PU MPs in organisms. [ABSTRACT FROM AUTHOR]

Fluorescent Carbon Quantum Dots (CQDs) are being used in medical applications, particularly in theranostics. These Carbon Quantum Dots have been gaining more attention lately due to their potential as an effective replacement for hazardous synthetic organic dyes in a variety of biomedical applications, including live cell imaging and diagnostics. In this study, highly fluorescent Carbon Quantum Dots by one pot microwave based green route with a size of less than 10 nm, was prepared from commercially available almond resin, Prunus dulcis and conjugated with honey as additional reagent for surface functionalization. They exhibit a deep blue emission on excitation at 350 nm with an elevated quantum yield at 61%. They possess atomic nature and basic features such as high photo-stability, varying fluorescence, greater biocompatibility, and better water solubility. These fluorescent labels exhibit faster cellular invagination without disturbing the cell stability. The CQDs present cell imaging capacity with multi-coloration for visualizing the fine architecture of the nucleus naming, the nuclear membrane and nucleolus, which is linked with their varied, surface structures such as amphiphilic property and higher positive charges. These characteristics with minimal invasion have made carbon quantum dots to become the spotlight in theranostics. They can be used as alternatives to synthetic dyes for fluorescence- related cell-imaging. The intriguing fact about this approach is that it opens the possibility of combining therapy and diagnostics into one unit, which can alter how some diseases are handled and, in turn, transform the field of healthcare. [ABSTRACT FROM AUTHOR]

A bilayer MOF reporter (ZIF-67@FAM-mRNA@ZIF-8) was synthesized, and the ZIF-67 was used as a carrier and fluorescent quencher to connect the FAM reporter through electrostatic adsorption and coordination effect. The ZIF-8 covering the outer layer can improve the stability of the probe and cell permeability, which helps the FAM reporter effectively release. After entering the cancer cells, the acidic environment in the cells induced the decomposition of ZIF-8. The excess ATP in the tumor cells competitively binds ZIF-67, causing the FAM reporter to shed and restore fluorescence. The shed FAM reporter was specifically bound to the overexpressed miRNA-21 in breast cancer cells to achieve fluorescence imaging and therapy of breast cancer. The results of specific imaging and apoptosis experiments of breast cancer cells indicate that bilayer MOF nanomachine provides an effective nanotherapy platform for accurate fluorescence imaging. [ABSTRACT FROM AUTHOR]

We have accomplished concentration-controlled fluorescence and room-temperature phosphorescence color-changing emitters with excellent luminescence performance. [Display omitted] • The concentration dependent CNDs realized a spectral shift from blue to yellow regions. • The effect of self-assembly behavior on fluorescence color and excitation wavelength dependence of CNDs were further studied. • The concentration-dependent RTP CNDs@Urea materials were achieved. • The CNDs and CNDs@Urea materials can be used cell imaging, fingerprint recognition and anti-counterfeiting applications. Carbon nanodots (CNDs) exhibiting concentration dependent properties have been synthesized through a one-pot hydrothermal reaction process utilizing diethylenetriamine and l -aspartic acid. At solid-state or high concentrations, the CNDs display excitation-wavelength independent fluorescence (FL) emissions, while at low concentrations, they exhibit excitation-wavelength dependent FL emissions. Detailed characterization of the structure and optical properties reveals that the concentration dependent FL properties can be ascribed to the intrinsic-state luminescence of the CNDs at low concentrations and the assembled-state luminescence at solid-state/high concentrations. With the increase of concentration, the self-assembly behavior of CNDs may cause the transition from intrinsic-state dominant luminescence to assembled-state dominant luminescence, and finally lead to the red-shift of FL color. Furthermore, the CNDs@Urea composites possess adjustable room-temperature phosphorescence (RTP) from turquoise to yellow by controlling the CNDs doping concentration. CNDs with concentration dependent optical properties have shown certain potentials in the fields of cell imaging, fingerprint recognition and anti-counterfeiting applications. [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.

Fluorescence lifetime imaging microscopy (FLIM) opens new dimensions for highly multiplexed imaging in live cells and organisms using differences in fluorescence lifetime to distinguish spectrally identical fluorescent probes. Here, a set of fluorescence‐activating and absorption‐shifting tags (FASTs) capable of modulating the fluorescence lifetime of embedded fluorogenic 4‐hydroxybenzylidene rhodanine (HBR) derivatives is described. It is shown that changes in the FAST protein sequence can vary the local environment of the chromophore and lead to significant changes in fluorescence lifetime. These fluorescence lifetime‐modulating tags enable multiplexed imaging of up to three targets in one spectral channel using a single HBR derivative in live cells and live zebrafish larvae. The combination of fluorescence lifetime multiplexing with spectral multiplexing allows to successfully image six targets in live cells, opening great prospects for multicolor fluorescence lifetime multiplexing. [ABSTRACT FROM AUTHOR]

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]

Synthesis and photophysical properties of a fluorescent probe HBD is described. Probe upon interaction with metal ions, anions and nucleoside pyrophosphates (NPPs) showed fluorescence quenching with Cu2+ due to chelation enhanced quenching effect (CHEQ). Moreover, interaction of ensemble HBD.Cu2+ with anions and NPPs showed fluorescence "turn‐On" response with ATP selectively. "On‐Off‐On" responses observed with Cu2+ and ATP is attributed to an interplay between ESIPT and TICT processes. Cyclic voltammogram of probe exhibited quasi‐reversible redox behaviour with three oxidation and two reduction potentials and the change in band gaps of probe suggested the interaction with Cu2+ and ATP. The 2 : 1 and 1 : 1 binding stoichiometry for an interaction between probe and Cu2+ (LOD, 62 nM) and ensemble, HBD.Cu2+ with ATP (LOD, 0.4 μM) respectively are realised by Job's plot and HRMS data. Cell imaging studies carried out to detect Cu2+ and ATP in HeLa cells. Also, the output emission observed with Cu2+ and ATP is utilized to construct an implication (IMP) logic gate. Test paper strips showed naked‐eye visible color responses to detect Cu2+ and ATP. In real water samples probe successfully detected copper (0.03 μM) between 5–6.5 ppb level (ICP‐MS method). [ABSTRACT FROM AUTHOR]

Taking advantage of the excellent host–guest complexation ability between an auxochrome (adamantane group) and CB[7], the fluorescence emission performance of dyes in water was effectively improved with the addition of two equivalents of CB[7], which provided an efficient method for increasing fluorescence intensity in aqueous environments. Furthermore, these dyes with the host were successfully used in cell imaging. [ABSTRACT FROM AUTHOR]

In this paper, we propose a fluorescence-lifetime imaging microscopy (FLIM) multiplexing system based on the fluorogen-activating protein FAST. This genetically encoded fluorescent labeling platform employs FAST mutants that activate the same fluorogen but provide different fluorescence lifetimes for each specific protein-dye pair. All the proposed probes with varying lifetimes possess nearly identical and the smallest-in-class size, along with quite similar steady-state optical properties. In live mammalian cells, we target these chemogenetic tags to two intracellular structures simultaneously, where their fluorescence signals are clearly distinguished by FLIM. Due to the unique structure of certain fluorogens under study, their complexes with FAST mutants display a monophasic fluorescence decay, which may facilitate enhanced multiplexing efficiency by reducing signal cross-talks and providing optimal prerequisites for signal separation upon co-localized and/or spatially overlapped labeling. A genetically encoded labeling system uses smallest-in-class fluorogen-activating protein tags for time-resolved fluorescence multiplexed cellular imaging, offering monoexponential decay and potential for sophisticated fluorescence lifetime analysis. [ABSTRACT FROM AUTHOR]

Standing wave (SW) microscopy is a method that uses an interference pattern to excite fluorescence from labelled cellular structures and produces high‐resolution images of three‐dimensional objects in a two‐dimensional dataset. SW microscopy is performed with high‐magnification, high‐numerical aperture objective lenses, and while this results in high‐resolution images, the field of view is very small. Here we report upscaling of this interference imaging method from the microscale to the mesoscale using the Mesolens, which has the unusual combination of a low‐magnification and high‐numerical aperture. With this method, we produce SW images within a field of view of 4.4 mm × 3.0 mm that can readily accommodate over 16,000 cells in a single dataset. We demonstrate the method using both single‐wavelength excitation and the multi‐wavelength SW method TartanSW. We show application of the method for imaging of fixed and living cells specimens, with the first application of SW imaging to study cells under flow conditions. LAY DESCRIPTION: With a standard microscope, it is possible to interfere two or more beams of light and produce a contour map of cell structures using a technique known as standing wave microscopy. This method is usually applied with high power objective lenses, and only a tiny area can be studied, usually showing structural detail from one or two cells at most. The Mesolens is a unique objective lens that has been designed and manufactured to image large populations of cells in a single image. Two‐dimensional images of cells can be obtained with the Mesolens using regular illumination methods, but the cell topography is lost. Here we have combined standing wave illumination with the Mesolens to perform topographical imaging of large numbers of cells in a single image. We first proved the method with a non‐biological specimen comprised of a glass lens, and then we applied the technique to imaging of fixed and living cells: in the case of red blood cells, we showed that we can study the topography of more than 16,000 cells in a single image. With the much larger area of study afforded by the Mesolens, we also used standing wave illumination for the first time monitor red blood cell topography when the cells are subject to flow environment. This new application of standing wave imaging at unusually large spatial scales may prove useful for studying behaviour in the circulatory system. [ABSTRACT FROM AUTHOR]

Here, we report a novel kind of protein nanoparticles of 11 nm in size, which have a central protein core surrounded by two layers of lipid. One layer of the lipid was covalently attached to the protein, while the other layer has been physically assembled around the protein core. Particle synthesis is highly modular, while both the size and charge of the protein nanoparticles are controlled in a predictable manner. Circular dichroism studies of the conjugate showed that the protein secondary structure is retained, while biophysical characterizations indicated the particle purity, size, and charge. The conjugate had a high thermal stability to steam sterilization conditions at 121°C (17 psi). After labeling the protein core with few different fluorescent dyes, they were strongly fluorescent with the corresponding colors independent of their size, unlike quantum dots. They are readily digested by proteases, and these water‐soluble, non‐toxic, highly stable, biocompatible, and biodegradable conjugates are suitable for cell imaging and drug delivery applications. [ABSTRACT FROM AUTHOR]

A simple, efficient, and reversible fluorescent sensor probe, PBA (2,6-dimethyl pyrone barbituric acid conjugate), comprised of a pro-aromatic donor conjugated with a barbituric acid, was developed for the detection of highly toxic mercuric ions. The probe showed high selectivity and "Turn-On" fluorescence response towards Hg2+ among various metal cations such as Na+, Mg2+, Ca2+, Mn2+, Fe2+, Co2+, Ni2+, Cu2+, Zn2+, Cd2+, Ba2+, Hg2+, and Pb2+, in both homogeneous and microheterogeneous micelle medium sodium dodecyl sulphate (SDS). The binding stoichiometry, limit of detection (LOD), and binding constant for the PBA-Hg complex were determined. The mechanism of binding was ascertained using the N,N'-dimethylbarbituric acid conjugate of 2,6-dimethylpyran (PDMBA), where no binding interaction by deprotonation is possible. In the presence of cysteamine hydrochloride and trifluoroacetic acid (TFA), the complexation of Hg2+ with PBA was demonstrated to be reversible, indicating its potential for the development of reusable sensors. Moreover, the practical applicability of PBA in monitoring Hg2+ in living cells was also evaluated. [ABSTRACT FROM AUTHOR]

Due to its high toxicity, long durability, easy absorption by aquatic organisms, and significant bioaccumulation, Hg2+ has caused substantial environmental damage and posed serious threats to human health. Therefore, effective detection of Hg2+ is of utmost importance. In this study, a turn-on fluorescent probe based on dicyanoisoflurone was developed for the detection of Hg2+. The probe exhibited near-infrared fluorescence signal at 660 nm upon excitation by 440 nm UV light in a mixture of CH3CN and HEPES buffer (4:1, v/v, 10 mM, pH = 7.5), with selective binding to Hg2+ in a molar ratio of 1:1. This binding event was accompanied by a visible color change from light yellow to orange. By utilizing the enhanced fluorescence signal change, this probe enables highly sensitive analysis and detection of Hg2+ with excellent selectivity (association constant = 1.63 × 104 M− 1), large Stokes shift (220 nm), high sensitivity (detection limit as low as 5.6 nM), short reaction time (30 s), and a physiological pH range of 7.5–9.5. The probe was successfully employed for detecting of Hg2+ in real water and living cells. [ABSTRACT FROM AUTHOR]

Due to its high toxicity, long durability, easy absorption by aquatic organisms, and significant bioaccumulation, Hg2+ has caused substantial environmental damage and posed serious threats to human health. Therefore, effective detection of Hg2+ is of utmost importance. In this study, a turn-on fluorescent probe based on dicyanoisoflurone was developed for the detection of Hg2+. The probe exhibited near-infrared fluorescence signal at 660 nm upon excitation by 440 nm UV light in a mixture of CH3CN and HEPES buffer (4:1, v/v, 10 mM, pH = 7.5), with selective binding to Hg2+ in a molar ratio of 1:1. This binding event was accompanied by a visible color change from light yellow to orange. By utilizing the enhanced fluorescence signal change, this probe enables highly sensitive analysis and detection of Hg2+ with excellent selectivity (association constant = 1.63 × 104 M− 1), large Stokes shift (220 nm), high sensitivity (detection limit as low as 5.6 nM), short reaction time (30 s), and a physiological pH range of 7.5–9.5. The probe was successfully employed for detecting of Hg2+ in real water and living cells. [ABSTRACT FROM AUTHOR]

Visualization of the spatiotemporal organization and dynamics of the genome in the nucleus is essential to elucidate how chromatin structure and nuclear function are intertwined. In the past, such studies were limited by the lack of appropriate tools. However, various imaging techniques now allow direct visualization of genomic loci in living cells. One of the main drivers behind this progress is the clustered regularly interspaced short palindromic repeats (CRISPR)/CRISPR-associated proteins (Cas) technology. Initially used as an efficient and specific genome editing tool, the versatility of the CRISPR/Cas system has rapidly expanded its application range to include diagnostics, therapeutics, and, more recently, live cell imaging. In contrast to traditional fluorescent in situ hybridization, CRISPR/Cas-based imaging systems enable real-time dynamic tracking of genomic sequences down to the level of single cells and even a single locus. Recognizing the vital role played by CRISPR/Cas-based imaging systems in advancing our understanding of genome function in relation to its spatiotemporal organization, this review aimed to depict the current landscape of CRISPR/Cas-based technologies in genomic imaging. It discusses the principles, notable features, advantages, and limitations of these CRISPR/Cas-based imaging systems and concludes with a brief outlook into the future. [ABSTRACT FROM AUTHOR]

Organic and polymer fluorescent nanomaterials are a frontier research focus. Here in this work, a series of fluorinated zwitterionic random copolymers end‐attached with a quasi‐chromophoric group of pyrene or tetraphenylethylene (TPE) are well synthesized via atom transfer radical polymerization with activators regenerated by electron transfer (ARGET ATRP). Those random copolymers with total degree of polymerization 100 or 200 are able to produce fluorescent single‐chain nanoparticles (SCNPs) through intra‐chain self‐folding assembly with quite uniform diameters in the range of 10–20 nm as characterized by dynamic light scattering and transmission electron microscopy. By virtue of the segregation or confinement effect, both SCNPs functionalized with pyrene or TPE group are capable of emitting fluorescence, with pyrene tethered SCNPs exhibiting stronger fluorescence emission reaching the highest quantum yield ≈20%. Moreover, such kind of fluorescent SCNPs manifest low cytotoxicity and good cell imaging performance for Hela cells. The creation of fluorescent SCNPs through covalently attached one quasi‐chromophore to the end of one fluorinated zwitterionic random copolymer provides an alternative strategy for preparing polymeric luminescence nanomaterials, promisingly serving as a new type of fluorescent nanoprobes for biological imaging applications. [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]

This document is a correction notice for an article titled "Upregulation of miR-107 Inhibits Glioma Angiogenesis and VEGF Expression" published in the journal Cellular & Molecular Neurobiology. The original article contained errors in figures, specifically in Fig. 2C and Fig. 3A, which led to inaccuracies in the images. The corrected figures are presented in the correction notice. The article has been corrected, and Springer Nature remains neutral with regard to jurisdictional claims and institutional affiliations. [Extracted from the article]

PEGylated 2-(2-(6-(dimethylamino)benzooxazol-2-yl)vinyl)quinolin-8-ol (BQ-mPEG) was synthesized, which exhibited strong fluorescence at 610 nm (φf = 0.11) and a large Stoke's shift (Δλ = 202 nm) in the aqueous solution. The fluorophore displayed a two-photon absorption characteristic and a strong red emission (λem = 625 nm) was observed with NIR (950 nm) irradiation. The feasibility of using BQ-mPEG as a fluorescent imaging reagent suggested that the fluorophore targets mitochondria, and with 950 nm excitation, bright fluorescence images in HeLa live cells were observed. Furthermore, the fluorophore exhibited some advantages of high photostability and pH stability, as well as low cytotoxicity. [ABSTRACT FROM AUTHOR]

Monitoring hydrogen sulfide (H2S) in living organisms is very important because H2S acts as a regulator in many physiological and pathological processes. Upregulation of endogenous H2S concentration has been shown to be closely related to the occurrence and development of tumors, atherosclerosis, neurodegenerative diseases and diabetes. Herin, a novel fluorescent probe HND with aggregation-induced emission was designed. Impressively, HND exhibited a high selectivity, fast response (1 min) and low detection limit (0.61 μM) for H2S in PBS buffer (10 mM, pH = 7.42). Moreover, the reaction mechanism between HND and H2S was conducted by Job's plot, HR-MS, and DFT. In particular, HND was successfully employed to detect H2S in HeLa cells. [ABSTRACT FROM AUTHOR]

The deployment of small‐molecule fluorescent agents plays an ever‐growing role in medicine and drug development. Herein, we complement the portfolio of powerful fluorophores, reporting the serendipitous discovery and development of a novel class with an imidazo[1,2‐a]pyridinium triflate core, which we term PyrAtes. These fluorophores are synthesized in a single step from readily available materials (>60 examples) and display Stokes shifts as large as 240 nm, while also reaching NIR−I emissions at λmax as long as 720 nm. Computational studies allow the development of a platform for the prediction of λmax and λEm. Furthermore, we demonstrate the compatibility of these novel fluorophores with live cell imaging in HEK293 cells, suggesting PyrAtes as potent intracellular markers. [ABSTRACT FROM AUTHOR]

Owing to their high significance in fundamental study and diverse applications, stimuli-responsive and fluorescent polymers, particularly those with cluster-triggered emission (CTE) featured by non-conjugated chromophores, have drawn tremendous attention in recent years. In this work, fluorescent and multi-responsive polysiloxane (FRPS) was synthesized by hydrolytic condensation polymerization of 3-aminopropyl methyl diethoxysilane (APMS) with 3-(N-isopropyl propionamide) iminopropyl methyl diethoxysilane (APMS-NIP), which was formed in situ through aza-Michael addition between APMS and N-isopropyl acrylamide. FRPS was not only highly sensitive to temperature, pH and CO2 in water, but also showed an enhanced and stimuli-adjustable fluorescence emission. The effects of monomer feeding, pH and CO2 on its lower critical solution temperature and fluorescent property were investigated. FRPS fluorescence emission was ascribed to CTE mechanism. In addition, FRPS was shown to be highly potential as physiological indicator for cell imaging, and for controlled release and trace detection of doxorubicin. This study provides therefore a type of stimuli-responsive and fluorescent material for potential applications in biomedical fields, and it is also of great significance for understanding of the fluorescence mechanism of polysiloxane-based stimuli-responsive polymers. [ABSTRACT FROM AUTHOR]

[Display omitted] • A responsive probe EHDI for ratiometric fluorescence analysis of bisulfite (HSO 3 -) and sulfite (SO 3 2-) is developed. • The probe EHDI exhibits blue shifts in both the UV–Vis and emission spectra upon responding to HSO 3 -. • The probe EHDI features high sensitivity and selectivity for HSO 3 - detection in buffer and imaging in live cells. • Detection of HSO 3 - in beef samples by probe EHDI is validated by HPLC. The development of reliable probe technology for the detection of bisulfite (HSO 3 -) in situ in food and biological samples is contributing significantly to food quality and safety assurance as well as community health. In this work, a responsive probe, EHDI, is developed for ratiometric fluorescence detection of HSO 3 - in aqueous solution, meat samples, and living cells. The probe is designed based on the HSO 3 - triggered 1,4-addition of electron deficit C = C bond of EHDI. As a result of this specific 1,4-addition, the π-conjugation system was destructed, resulting in blue shifts of the emission from 687 to 440 nm and absorption from 577 to 355 nm. The probe has good water solubility, high sensitivity and selectivity, allowing it to be used for imaging of HSO 3 - internalization and production endogenously. The capability of probe EHDI for HSO 3 - was then validated by traditional HPLC technology, enabling accurately detect HSO 3 - in beef samples. The successful development of this probe thus offers a new tool for investigating HSO 3 - in situ in food and biological conditions. [ABSTRACT FROM AUTHOR]

In this paper, nitrogen-doped carbon dots (NCDs) were synthesized via a facile hydrothermal method using gum arabic (GA) and tris(hydroxymethyl)methyl aminomethane (tris) as precursors. The resultant NCDs show uniform size distribution and stable optical performance. Then a fluorescent signal quenching probe based on NCDs was proposed for the quantitative detection of mercury ions (Hg2+). The developed fluorescent nanoprobe based on NCDs demonstrated a good linear relationship in the range of 10 to 120 μM (R² = 0.99265) for toxic mercury(II), with a detection limit of 4.87 μM. Additionally, the present assay system could be efficiently used for the detection of Hg2+ in real water samples with a satisfactory recovery rate (96.11-104.04%). The metal-free NCDs, which exhibited little cytotoxicity, were successfully applied to in vitro fluorescence imaging of human triple negative breast cancer (TNBC) cells, achieving visualization of Hg2+ in cells. With good water solubility and biocompatibility, the nitrogen-doped carbon dots synthesized by this economical and ecologically friendly process are suitable for use in analytical testing and biological research. [ABSTRACT FROM AUTHOR]

The precise release and characterization of nitroxyl (HNO) gas signaling molecule remain a challenge due to its short lifetime to date. To solve this issue, an azobenzene-based HNO donor (Azo-D1) was proposed as a colorimetric and fluorometric chemosensor for HNO releasing, to release both HNO and an azobenzene fluorescent reporter together. Specifically, the Azo-D1 has an HNO release half-life of ∼68 min under physiological conditions. The characteristic color change from the original orange to the yellow color indicated the decomposition of the donor molecule. In addition, the stoichiometry release of HNO was qualitatively and quantitatively verified through the classical phosphine compound trap. As compared with the donor molecule by itself, the decomposed product demonstrates a maximum fluorescence emission at 424 nm, where the increase of fluorescence intensity by 6.8 times can be applied to infer the real-time concentration of HNO. Moreover, cellular imaging can also be achieved using this Azo-D1 HNO donor through photoexcitation at 405 and 488 nm, where the real-time monitoring of HNO release was achieved without consuming the HNO source. Finally, the Azo-D1 HNO donor would open a new platform in the exploration of the biochemistry and the biology of HNO. [Display omitted] • The first azobenzene-based HNO donor (Azo-D1) was developed. • Azo-D1 can release HNO (t 1/2 –68 min) under physiological conditions. • HNO release can be monitored by colorimetric and fluorometric changes. • Cell imagines were successfully obtained using Azo-D1 donor. [ABSTRACT FROM AUTHOR]

A new structurally simple fluorescent CP probe based on chromone was designed and synthesized, and its structure was fully characterized using various analytical techniques. The CP probe displays a high selectivity and sensitivity for sensing Fe3+ with a "turn-off" fluorescence response over other metal ions in a DMSO/H2O (4:1, v/v) solution. The experiment results show that the CP probe is stable over a wide pH range of 2.0–12.0. The detection limit for Fe3+ was calculated to be 0.044 μmol•L−1. The molar ratio method indicated that the binding mode between the CP probe and Fe3+ is a 1:1 complex formation. HR-MS and density functional theory (DFT) calculations were also performed to further confirm the recognition mechanism. Both fluorescence imaging experiments and the MTT assay demonstrated that the CP probe was suitable for detecting intracellular Fe3+ and no significant cytotoxicity in living cells. [ABSTRACT FROM AUTHOR]

Live-cell imaging of fluorescent biosensors has demonstrated that space-time correlations in signalling of cell collectives play an important organisational role in morphogenesis, wound healing, regeneration, and maintaining epithelial homeostasis. Here, we demonstrate how to quantify one such phenomenon, namely apoptosis-induced ERK activity waves in the MCF10A epithelium. We present a protocol that starts from raw time-lapse fluorescence microscopy images and, through a sequence of image manipulations, ends with ARCOS, our computational method to detect and quantify collective signalling. We also describe the same workflow in the interactive napari image viewer to quantify collective phenomena for users without prior programming experience. Our approach can be applied to space-time correlations in cells, cell collectives, or communities of multicellular organisms, in 2D and 3D geometries. [ABSTRACT FROM AUTHOR]

Biologically‐active near‐ultraviolet emitting spirooxindole‐pyrrolidine/pyrrolothiazole‐β‐ketothiolester have been synthesised via Chemo‐/regio‐/stereoselective manner. Excited‐state intramolecular proton transfer (ESIPT) of β‐ketothiolester exhibits excitation‐dependent emission with intermolecular hydrogen bonding ability with solvents. The emission could be tunable between 330 nm to 460 nm. Selected fluorescent compounds 4{4,2,1}, 4{12,2,2}, 5{4,2,1} and 5{12,2,2} shows cytotoxicity effect on PC3 cells, where the highest IC50 value (6 μM) was found for the probe 5{12,2,2}. The fluorescent behavior of 5{4,2,1} and 5{12,2,2} acted as an imaging molecule against cancer cells. [ABSTRACT FROM AUTHOR]

Organic fluorophores with dual-state emission (DSE) are rare or difficult to observe because most of them display either aggregation-induced emission (AIE) or aggregation-caused quenching (ACQ). Amazing works have been accomplished, yet most of the DSE compounds were excited by UV light which limits their wide application in bioimaging. In this work, we achieved a visible-light excited DSE fluorophore and realized its imaging in SKOV-3 cells and zebrafish. The naphtho[2',3':4,5]imidazo[1,2-a]pyridine (NIP) core ensures its emission in dilute solution. Meanwhile, the twisted phenyl ring blocks fluorescence quenching induced by the π-π stacking and leads to the emission of the solid. The fluorescence intensity is steady even after 6 h of continuous intense sunlight. More importantly, photostability of NIP in cells is much better than commercial dye (mitochondrial green). [ABSTRACT FROM AUTHOR]