Search

Deferasirox, an FDA-approved iron chelator, has gained increasing attention for use in anticancer and antimicrobial applications. Recent efforts by our group led to the identification of this core as an easy-to-visualize aggregation-induced emission platform, or AIEgen, that provides a therapeutic effect equivalent to deferasirox (

The ester functionality is commonly seen in the areas of chemical biology and medicinal chemistry for the design of cell‐permeable active molecules. Ester‐based pro‐drug/pro‐sensor strategies are employed to mask polar functional groups (i. e. carboxylic acids) and improve the overall cell permeability of these functional molecules. However, their use as reactive units for sensing applications, including bacterial detection, has not been fully explored. Herein, we synthesised two TCF‐based fluorescent probes, TCF‐OAc and TCF‐OBu. As expected, both TCF‐OAc and TCF‐OBu demonstrated a significant fluorescence (22‐ and 43‐fold, respectively) and colorimetric response (yellow to purple) towards porcine liver esterase (PLE) with a limit of detection of 1.18 mU/mL and 0.45 mU/mL, respectively. With these results in hand, the ability of these probes to detect planktonic suspensions of gram‐positive Staphylococcus aureus (S. aureus) and gram‐negative Pseudomonas aeruginosa (P. aeruginosa), and Escherichia coli (E. coli) were evaluated. Different fluorescence responses for gram‐positive and gram‐negative bacteria were observed between TCF‐OAc and TCF‐OBu. After 1 h incubation, TCF‐OAc proved more sensitive towards S. aureus, demonstrating a significant fluorescence “turn on” response (16‐fold); whereas, TCF‐OBu was more selective towards P. aeruginosa, with a 22‐fold increase in the fluorescence response observed. These results demonstrate the influence of the ester chain length on the selectivity for bacterial species.

Here, we report a β-galactosidase (β-Gal)-responsive photochromic fluorescent probe, NpG, that was designed to prebind to human serum albumin (HSA) to form the probe/protein hybrid, NpG@HSA. The formation of NpG@HSA led to an increase in fluorescence emission (520 nm) corresponding to the binding of the fluorescent naphthalimide unit with HSA. In addition, this enabled visualization of the spiropyran fluorescence emission in aqueous media. Our probe/protein hybrid approach afforded a unique imaging platform with enhanced cell permeability and solubility that was capable of visualizing the cellular uptake of NpG@HSA before its activation by β-Gal. The β-Gal-mediated cleavage of the galactose unit within the NpG@HSA hybrid resulted in the formation of NpM@HSA and an increase in red fluorescence emission (620 nm). The resultant merocyanine unit was then able to undergo photoisomerization (merocyanine ↔ spiropyran) to facilitate STORM (i.e., stochastic optical reconstruction microscopy) imaging with minimal phototoxicity and excellent photostability/reversibility. Using STORM, NpG@HSA was able to determine the subcellular distribution of β-Gal activity between cell lines with nanoscale precision. We believe that this system represents a versatile imaging platform for the design of photochromic fluorescent probes suitable for illuminating the precise location of disease-specific biomarkers in various cellular processes.

Reaction-based fluorescent-probes have proven successful for the visualisation of biological species in various cellular processes. Unfortunately, in order to tailor the design of a fluorescent probe to a specific application (i.e. organelle targeting, material and theranostic applications) often requires extensive synthetic efforts and the synthetic screening of a range of fluorophores to match the required synthetic needs. In this work, we have identified Pinkment-OH as a unique “plug-and-play” synthetic platform that can be used to develop a range of ONOO− responsive fluorescent probes for a variety of applications. These include theranostic-based applications and potential material-based/bioconjugation applications. The as prepared probes displayed an excellent sensitivity and selectivity for ONOO− over other ROS. In vitro studies using HeLa cells and RAW 264.7 macrophages demonstrated their ability to detect exogenously and endogenously produced ONOO−. Evaluation in an LPS-induced inflammation mouse model illustrated the ability to monitor ONOO− production in acute inflammation. Lastly, theranostic-based probes enabled the simultaneous evaluation of indomethacin-based therapeutic effects combined with the visualisation of an inflammation biomarker in RAW 264.7 cells., Pinkment, a resorufin based ONOO− selective and sensitive ‘plug and play’ fluorescence-based platform for in vitro and in vivo use, enables facile functionalisation for various imaging and theranostic applications.

As a result of their high specificity for their corresponding biological targets, peptides have shown significant potential in a range of diagnostic and therapeutic applications. However, their widespread use has been limited by their minimal cell permeability and stability in biological milieus. We describe here a hepta-dicyanomethylene-4H-pyran appended β-cyclodextrin (DCM(7)-β-CD) that acts as a delivery enhancing “host” for 1-bromonaphthalene-modified peptides, as demonstrated with peptide probes P1–P4. Interaction between the fluorescent peptides P1–P3 and DCM(7)-β-CD results in the hierarchical formation of unique supramolecular architectures, which we term supramolecular-peptide-dots (Spds). Each Spd (Spd-1, Spd-2, and Spd-3) was found to facilitate the intracellular delivery of the constituent fluorescent probes (P1–P3), thus allowing spatiotemporal imaging of an apoptosis biomarker (caspase-3) and mitosis. Spd-4, incorporating the antimicrobial peptide P4, was found to provide an enhanced therapeutic benefit against both Gram-positive and Gram-negative bacteria relative to P4 alone. In addition, a fluorescent Spd-4 was prepared, which revealed greater bacterial cellular uptake compared to the peptide alone (P4-FITC) in E. coli. (ATCC 25922) and S. aureus (ATCC 25923). This latter observation supports the suggestion that the Spd platform reported here has the ability to facilitate the delivery of a therapeutic peptide and provides an easy-to-implement strategy for enhancing the antimicrobial efficacy of known therapeutic peptides. The present findings thus serve to highlight a new and effective supramolecular delivery approach that is potentially generalizable to overcome limitations associated with functional peptides.

Infection and dissemination of influenza viruses (IVs) causes serious health concerns worldwide. However, effective tools for the accurate detection and blocking of IVs remain elusive. Here, we develop a new sialyllactosyl probe with self-assembled core-shell structure for the ratiometric detection and blocking of IVs. N,N′-diaryl-dihydrodibenzo[a,c]phenazines were used to form the core structure by hydrophobic assembly in an aqueous solution with an aggregation-enhanced blue fluorescence mission. Subsequently, dicyanomethylene-4H-pyran-based sialyllactosides were used for self-assembly with the core structure, producing the sialyllactosyl probe that emits a red fluorescence due to Forster resonance energy transfer. The probe developed has been proven to be available for (1) the fluorescence ratiometric detection of IVs through selective interaction with the sialyllactosyl-binding proteins on the virus surface, and (2) effectively blocking the invasion of human-infecting IVs towards host cells as accentuated by the sialyllactosides on the surface of the probes.

With this research, we have developed two long-wavelength theranostic probes (DCMT and DCMC) with aggregation-induced emission (AIE)-based properties for image-guided photodynamic therapy (PDT) of hepatoma cells. Introduction of a triphenylamine or carbazole group to a dicyanomethylene-4H-pyran dye with long-wavelength fluorescence emission produces the AIE-based probes, which were subsequently modified with triphenyl-phosphonium cation for actively targeting the mitochondria of hepatoma cells. Solution-based experiments show that the probes exhibit a mixed photophysical mechanism of twisted-intramolecular charge transfer and AIE at different aggregation states. The molecular aggregation of the probes also leads to an enhanced ability for oxygen photosensitization, suggesting their potential for PDT of cancer cells. Our subsequent cell-based assays show that the probes localize in the mitochondria of hepatoma cells and the use of light leads to cell death through the intracellular production of reactive oxygen species.

Correction for ‘Fluorescent glycoconjugates and their applications’ by Baptiste Thomas et al., Chem. Soc. Rev., 2020, 49, 593–641, DOI: 10.1039/C8CS00118A.

The concentrations of ATP and ONOO− have been correlated with the progression a number of diseases including ischemia-reperfusion injury and drug-induced liver injury. Here, we report the development of fluorescent probe, ATP-LW, which enables the simultaneous detection of ONOO− and ATP. ONOO− selectively oxidises the boronate pinacol ester of ATP-LW, to afford the fluorescent 4-hydroxy-1,8-naphthalimide product NA-OH (λex = 450 nm, λem = 562 nm or λex = 488 nm, λem = 568 nm). While, the binding of ATP to ATP-LW induces the spirolactam ring opening of rhodamine to afford a highly emissive product (λex = 520 nm, λem = 587 nm). Due to the differences in emission between the ONOO− and ATP products, ATP-LW exhibits the unique ability to image ONOO− levels in the green channel (λex = 488 nm, λem = 500-575 nm) and ATP concentrations using the red channel (λex = 514 nm, λem = 575-650 nm). This was demonstrated using hepatocytes (HL-7702 cells) in cellular imaging experiments. The treatment of HL-7702 cell line with oligomycin A (an inhibitor of ATP synthase) resulted in a reduction of ATP in the red channel and increase in ONOO− green channel. While, the presence of SIN-1 (an exogenous ONOO− donor) results in an increase of ONOO−, and decrease in ATP. Significantly, when HL-7702 cells were treated with acetaminophen as a biological model for drug-induced liver injury, an increase in ONOO− green and decrease in ATP red channel fluorescence was observed. These results illustrate the utility of ATP-LW as a chemical tool to simultaneously monitor ATP and ONOO− concentrations in cellular-based applications.

Herein, we report a protein-based hybridization strategy that exploits the host-guest chemistry of HSA (human serum albumin) to solubilize the otherwise cell impermeable ONOO− fluorescent probe Pinkment-OAc. Formation of a HSA/Pinkment-OAc supramolecular hybrid was confirmed by SAXS and solution-state analyses. This HSA/Pinkment-OAc hybrid provided an enhanced fluorescence response towards ONOO−versusPinkment-OAc alone, as determined by in vitro experiments. The HSA/Pinkment-OAc hybrid was also evaluated in RAW 264.7 macrophages and HeLa cancer cell lines, which displayed an enhanced cell permeability enabling the detection of SIN-1 and LPS generated ONOO− and the in vivo imaging of acute inflammation in LPS-treated mice. A remarkable 5.6 fold (RAW 264.7), 8.7-fold (HeLa) and 2.7-fold increased response was seen relative to Pinkment-OAc alone at the cellular level and in vivo, respectively. We anticipate that HSA/fluorescent probe hybrids will soon become ubiquitous and routinely applied to overcome solubility issues associated with hydrophobic fluorescent imaging agents designed to detect disease related biomarkers., Herein, we report a protein-based hybridization strategy that exploits the host–guest chemistry of HSA (human serum albumin) to solubilize the otherwise cell impermeable ONOO− fluorescent probe Pinkment-OAc.

Herein, we report the evaluation and synthesis of a reaction based fluorescent probe DCM‐Bpin for the detection of Peroxynitrite (ONOO−). DCM‐Bpin exhibits selective fluorescence off‐on response for ONOO− over other reactive oxygen species, including H2O2. Moreover, DCM‐Bpin is biocompatible and has been used to visualize exogenous ONOO− in HeLa cells., Turn on the light: A 50‐fold “turn‐on” fluorescence response at 667 nm was observed for DCM‐Bpin upon the addition of ONOO− (0–27 equiv.) using an excitation wavelength of 560 nm.

The development of photochromic fluorescence sensors with dynamic and multiple-signaling is beneficial to the improvement of biosensing/imaging precision. However, elaborate designs with complicated molecular structures are always required to integrate these functions into one molecule. By taking advantages of both redox-active/high loading features of two-dimensional (2D) manganese dioxide (MnO2) and dynamic fluorescence photoswitching of photochromic sensors, we here design a hybrid photochromic MnO2 glycosheet (Glyco-DTE@MnO2) to achieve the photoswitchable imaging of intracellular glutathione (GSH). The photochromic glycosheet manifests significantly turn-on fluorescence and dynamic ON/OFF fluorescence signals in response to GSH, which makes it favorable for intracellular GSH double-check in targeted human hepatoma cell line (HepG2) through the recognition between β-D-galactoside and asialoglycoprotein receptor (ASGPr) on cell membranes. The dynamic fluorescence signals and excellent selectivity for detection and imaging of GSH ensure the precise determination of cell states, promoting its potential applications in future disease diagnosis and therapy.

Conspectus This Account describes a range of strategies for the development of fluorescent probes for detecting reactive oxygen species (ROS), reactive nitrogen species (RNS), and reactive (redox-active) sulfur species (RSS). Many ROS/RNS have been implicated in pathological processes such as Alzheimer’s disease, cancer, diabetes mellitus, cardiovascular disease, and aging, while many RSS play important roles in maintaining redox homeostasis, serving as antioxidants and acting as free radical scavengers. Fluorescence-based systems have emerged as one of the best ways to monitor the concentrations and locations of these often very short lived species. Because of the high levels of sensitivity and in particular their ability to be used for temporal and spatial sampling for in vivo imaging applications. As a direct result, there has been a huge surge in the development of fluorescent probes for sensitive and selective detection of ROS, RNS, and RSS within cellular environments. However, cellular environments are extremely complex, often with more than one species involved in a given biochemical process. As a result, there has been a rise in the development of dual-responsive fluorescent probes (AND-logic probes) that can monitor the presence of more than one species in a biological environment. Our aim with this Account is to introduce the fluorescent probes that we have developed for in vitro and in vivo measurement of ROS, RNS, and RSS. Fluorescence-based sensing mechanisms used in the construction of the probes include photoinduced electron transfer, intramolecular charge transfer, excited-state intramolecular proton transfer (ESIPT), and fluorescence resonance energy transfer. In particular, probes for hydrogen peroxide, hypochlorous acid, superoxide, peroxynitrite, glutathione, cysteine, homocysteine, and hydrogen sulfide are discussed. In addition, we describe the development of AND-logic-based systems capable of detecting two species, such as peroxynitrite and glutathione. One of the most interesting advances contained in this Account is our extension of indicator displacement assays (IDAs) to reaction-based indicator displacement assays (RIAs). In an IDA system, an indicator is allowed to bind reversibly to a receptor. Then a competitive analyte is introduced into the system, resulting in displacement of the indicator from the host, which in turn modulates the optical signal. With an RIA-based system, the indicator is cleaved from a preformed receptor–indicator complex rather than being displaced by the analyte. Nevertheless, without a doubt the most significant result contained in this Account is the use of an ESIPT-based probe for the simultaneous sensing of fibrous proteins/peptides AND environmental ROS/RNS.

A simple dual analyte fluorescein-based probe (PF3-Glc) was synthesised containing β-glucosidase (β-glc) and hydrogen peroxide (H2O2) trigger units. The presence of β-glc, resulted in fragmentation of the parent molecule releasing glucose and the slightly fluorescent mono-boronate fluorescein (PF3). Subsequently, in the presence of glucose oxidase (GOx), the released glucose was catalytically converted to d-glucono-δ-lactone, which produced H2O2 as a by-product. The GOx-produced H2O2, resulted in classic H2O2-mediated boronate oxidation and the release of the highly emissive fluorophore, fluorescein. This unique cascade reaction lead to an 80-fold increase in fluorescence intensity.

With this research we set out to develop a number of coumarin-based ‘AND’ logic fluorescence probes that were capable of detecting a chosen analyte in the presence of HCys. Probe JEG-CAB was constructed by attaching the ONOO� reactive unit, benzyl boronate ester, to a HCys/Cys reactive fluorescent probe, CAH. Similarly, the core unit CAH was functionalised with the nitroreductase (NTR) reactive p-nitrobenzyl unit to produce probe JEG-CAN. Both, JEG-CAB and JEG-CAN exhibited a significant fluorescence increase when exposed to either HCys and ONOO� (JEG-CAB) or HCys and NTR (JEG-CAN) thus demonstrating their effectiveness to function as AND logic gates for HCys and a chosen analyte.

Deferasirox, ExJade, is an FDA-approved iron chelator used for the treatment of iron overload. In this work, we report several fluorescent deferasirox derivatives that display unique photophysical properties, i.e., aggregation-induced emission (AIE), excited state intramolecular proton transfer, charge transfer, and through-bond and through-space conjugation characteristics in aqueous media. Functionalization of the phenol units on the deferasirox scaffold afforded the fluorescent responsive pro-chelator ExPhos, which enabled the detection of the disease-based biomarker alkaline phosphatase (ALP). The diagnostic potential of these deferasirox derivatives was supported by bacterial biofilm studies.

In this tutorial review, we will explore recent advances in the construction and application of Forster resonance energy transfer (FRET)-based small-molecule fluorescent probes. The advantages of FRET-based fluorescent probes include: a large Stokes shift, ratiometric sensing and dual/multi-analyte responsive systems. We discuss the underlying energy donor–acceptor dye combinations and emphasise their applications for the detection or imaging of cations, anions, small neutral molecules, biomacromolecules, cellular microenvionments and dual/multi-analyte responsive systems.

A post-synthetic strategy is reported that allows for functionalisation of Au(i)-bis NHCs via carbonate formation. The scope of this methodology was explored using both aromatic and aliphatic alcohols. As a demonstration of potential utility, the fluorescent Au(i)-bis NHC conjugate 5 was prepared; it was found to have enhanced stability when formulated with bovine serum albumin, localise within the mitochondria of A549 cells and do so without compromising the high cytotoxicity seen for the parent Au(i)-bis NHC system.

Two red-emitting dicyanomethylene-4H-pyran (DM) based fluorescent probes were designed and used for peroxynitrite (ONOO- ) detection. Nevertheless, the aggregation-caused quenching effect diminished the fluorescence and restricted their further applications. To overcome this problem, tetraphenylethylene (TPE) based glycoclusters were used to self-assemble with these DM probes to obtain supramolecular water-soluble glyco-dots. This self-assembly strategy enhanced the fluorescence intensity, leading to an enhanced selectivity and activity of the resulting glyco-dot comparing to DM probes alone in PBS buffer. The glyco-dots also exhibited better results during fluorescence sensing of intracellular ONOO- than the probes alone, thereby offering scope for the development of other similar supramolecular glyco-systems for chemical biological studies.

Supramolecular assembly between conjugated polymers and fluorescent dyes produces a unique class of fluorogenic “nanogrenades”. These nanomaterials have shown the ability to image as well as irreversibly destruct amyloid β fibril plaques by simple light irradiation.

Deferasirox, ExJade, an FDA-approved treatment for iron overload disorders has been shown to inhibit the growth of both gram-positive and -negative bacteria through iron (Fe(III)) chelation. Modification of the ExJade framework led to the identification of a new fluorescent platform ExPh and ExBT. Functionalization of the phenol moieties on ExBT with phosphate units afforded a ratiometric fluorescent pro-chelator (ExPhos), which was effective in the inhibition of two clinically relevant antibiotic-resistant bacteria, (MRSA (ATCC 43300) and VRE (ATCC 51299)), and allowed the fluorescent imaging of MRSA. Remarkably, this pro-chelation strategy proved selective towards bacteria with no cytotoxicity observed for ExPhos treated A549 cells (72 h incubation). This work represents a new pro-chelator antibiotic strategy that can be modified with a chosen reactive chemical trigger to provide a diagnostic signal in conjunction with a therapeutic response with a potential of minimal off-target toxicities.

Here, we report a new pentafluoropropanamido rhodamine fluorescent probe (ACS-HNE) that allows for the selective detection of neutrophil elastase (NE). ACS-HNE displayed high sensitivity, with a low limit of detection (

A coumarin-based novel ‘AND’ logic fluorescent probe ROS-AHC has been developed for the simultaneous detection of ONOO− and biological thiols. ROS-AHC was shown to exhibit only a very small fluorescence response upon addition of a single GSH or ONOO− analyte. Exposure to both analytes, however, resulted in a significant fluorescence enhancement.

International audience; Glycoconjugates and their applications as lectin ligands in biology has been thoroughly investigated in the past decades. Meanwhile, the intrinsic properties of such multivalent molecules were limited essentially to their ability to bind to their receptors with high selectivity and/or avidity. The present review will focus on multivalent glycoconjugates displaying an additional capability such as fluorescence properties for applications toward imaging of cancer cells, detection of proteins or pathogens but also for drug delivery systems toward targeted cancer therapy. This review is a collection of research articles discussed in the context of the structural features of the fluorescent glycoconjugates organized according to their fluorescent core scaffold and with their representative applications.

Two novel drug-conjugates based on a “coumarin linker” have been designed for the synergic release of a therapeutic agent and fluorescent probe for the potential application of theranostics. The drug conjugates; CC-RNS and CI-RNS were designed to be activated by reactive oxygen species or reactive nitrogen species (ROS/RNS). The fluorescence OFF-ON response was triggered by the peroxynitrite-mediated transformation of a boronic acid pinacol ester to a phenol moiety with simultaneous release of the therapeutic agents (Confirmed by HRMS). The limit of detection for peroxynitrite using CC-RNS and CI-RNS was 0.29 and 37.2 μM, respectively. Both CC-RNS and CI-RNS demonstrated the ability to visualize peroxynitrite production thus demonstrating the effectiveness of these probes for use as tools to monitor peroxynitrite-mediated drug release in cancer cell lines.

Despite the rapid development of imaging techniques, precise probe localization and modulation in living cells is still a challenging task. Here we show that the simple hybridization between a photochromic fluorescent glycoprobe and human serum albumin (HSA) enables a unique fluorescence "double-check" mechanism for precisely localizing and manipulating probe molecules in living cells. Docking of a carbohydrate-modified naphthalimide (Naph)-spiropyran (SP) dyad to a hydrophobic pocket of HSA produces the glycoprobe-protein hybrid, causing the protein conformation to fold as determined by small-angle X-ray scattering. We show that the Naph and merocyanine (the photo isomer of SP) fluorescence of the resulting hybrid can be reversibly switched by light in buffer solution and in target cells overexpressing the carbohydrate receptor.

The ability of chemical tools to effectively detect malignancy in frozen sections removed from patients during surgery is important for the timely determination of the subsequent surgical program. However, current clinical methods for tissue imaging rely on dye-based staining or antibody-based techniques, which are sluggish and complicated. Methods: Here, we have developed a 2D material-based supramolecular imaging probe for the simple, rapid yet precise diagnosis of hepatocellular carcinoma (HCC). The 2D probe is constructed through supramolecular self-assembly between a water soluble, fluorescent peptide ligand that selectively targets glypican-3 (GPC-3, a specific cell-surface biomarker for HCC) and 2D molybdenum disulfide that acts as a fluorescence quencher as well as imaging enhancer. Results: We show that the 2D imaging probe developed with minimal background fluorescence can sensitively and selectively image cells overexpressing GPC-3 over a range of control cells expressing other membrane proteins. Importantly, we demonstrate that the 2D probe is capable of rapidly (signal became readable within 1 min) imaging HCC tissues over para-carcinoma regions in frozen sections derived from HCC patients; the results are in accordance with those obtained using traditional clinical staining methods. Conclusion: Compared to conventional staining methods, which are laborious (e.g., over 30 min is needed for antibody-based immunosorbent assays) and complex (e.g., diagnosis is based on discrimination of the nucleus morphology of cancer cells from that of normal cells), our probe, with its simplicity and quickness, might become a promising candidate for tumor-section staining as well as fluorescence imaging-guided surgery.

We have developed a new series of glycoprobe-polymer dot ensembles for the fluorogenic, homogeneous detection of lectins. Electrostatic self-assembly between positively charged rhodamine-based glycosides and negatively charged poly(3-hexylthiophene-2,5-diyl)/poly(styrene-co-maleic anhydride) polymer dots produces the ensembles with a quenched fluorescence. Fluorescence spectroscopy showed that the ensembles exhibited a concentration-dependent fluorescence enhancement with selective lectins over a range of unselective lectins and proteins. This research provides insight into the development of simple fluorogenic probes for homogeneous lectin analyses based on the supramolecular assembly between polymeric nanoparticles and fluorescent glycoprobes.

We have developed a novel AND logic based fluorescence probe for the simultaneous detection of ONOO− and GSH (GSH-PF3). The GSH-PF3 probe was synthesised over three steps starting from commercially available fluorescein. The probe was constructed by attaching the GSH reactive motif, 2,4-dinitrobenzenesulfonyl, to the previously reported boronate fluorescence based probe, PF3. GSH-PF3 produced only a small fluorescence response towards the addition of GSH or ONOO− separately. However, when the probe was exposed to both analytes, there was a significant (40-fold) fluorescence enhancement. GSH-PF3 demonstrated an excellent selectivity towards both GSH and ONOO−. In cellular imaging experiments the probe was shown to be cell permeable with no ‘turn-on’ response observed for the addition of either GSH or ONOO− separately. However, in the presence of both analytes, a clear fluorescence response was observed in live cells. GSH-PF3 was further able to monitor the co-existence of metabolically produced ONOO− and GSH by exogenous stimulation.

Traditionally, fluorescence probes have focused on the detection of a single biomarker for a specific process. In this work, we set out to develop a number of fluorescence probes that enable the detection of a chosen analyte in the presence of reactive oxygen/nitrogen species (ROS/RNS). These fluorescence probes when activated result in the formation of the highly fluorescent pink dye, resorufin. Therefore, we have labelled these fluorescent probes as ‘Pinkments’. Our first ‘Pinkment’ was shown to detect biologically relevant concentrations of ONOO− and have an excellent selectivity against other ROS/RNS. Pinkment-OH was developed to provide a core unit which could be easily functionalised to produce a range of ‘AND’ based fluorescence probes for the detection of ROS/RNS and a second analyte. For proof of concept, we synthesised Pinkment-OTBS and Pinkment-OAc. These ‘AND’-based probes were successfully shown to detect ROS/RNS and F− or esterase, respectively.

A simple ESIPT-based fluorescence probe (HMBT-LW) was developed for the detection of superoxide (O2˙−). HMBT-LW was synthesised over two steps and was shown to rapidly detect low concentrations of O2˙− (limit of detection = 7.4 μM), fully reacting within two minutes. Furthermore, HMBT-LW demonstrated excellent selectivity and sensitivity towards O2˙−.

The seasonal outbreak of influenza causes significant morbidity and mortality worldwide because a number of influenza virus (IV) strains have been shown to infect and circulate in humans. Development of effective means to timely monitor as well as block IVs is still a challenging task. Whereas conventional fluorescence probes rely on a fluorimetric change upon recognizing IVs, here we developed simple "Supra-dots" that are formed through the aqueous supramolecular assembly between a blue-emitting polymer dot and red-emitting sialylglycan probes for the ratiometric detection of IVs. Tuning the Förster resonance energy transfer from polymer dots to glycan probes by selective sialylglycan-virus recognition enables the fluorescence ratiometric determination of IVs, whereas the presence of unselective, control viruses quenched the fluorescence of the Supra-dots. Meanwhile, we show that the Supra-dots can effectively inhibit the invasion of a human-infecting IV toward a human cell line, thereby making possible a unique bifunctional, supramolecular probe for influenza theranostics.

As a common environmental pollutant, the sulfide anion (S2−) is toxic to the human body. We report here the simple preparation of a selective fluorogenic glycoprobe–metal complex for the rapid analysis of S2− in full aqueous solution and real water samples. The probe was synthesized by “clicking” a dipropargyl naphthalimide dye with a water-soluble azido β- d -galactoside. Fluorescence spectroscopic analyses showed that the probe had an on–off response to Cu2+, forming a fluorogenic probe–Cu2+ complex. The subsequent addition of S2− selectively recovered the fluorescence of the complex over other anions tested, probably because of the high-affinity association between Cu2+ and S2−. The complex showed a good linear range and a nanomolar limit of detection with S2− in full aqueous solution, and has also proven to be suitable for accurate recovery of spiked S2− in real water samples.

The development of small-molecule fluorescent probes for the detection of ions and biomacromolecules and for cellular and in vivo imaging has been a very active research area. Nevertheless, many problems exist for traditional probes including their poor water solubility, toxicity and the inability to target specific tissues. Because of the enhanced water solubility, biocompatibility and targeting ability for specific cells, there has been an emerging movement to use carbohydrates as either the backbone or as a warhead to decorate conventional fluorescent probes, producing "glycoprobes" with enhanced properties. This feature article provides an overview of recently developed glycoprobes for ion and protein detection as well as targeted (receptor targeting) cellular imaging and theranostics. Here, we summarise the tactics for preparing small molecular glycoprobes and their supramolecular 2D material composites.

A novel dual-function fluorescent probe (ATP-LW) was developed for the detection of ONOO- and ATP.

International audience; We describe a novel green-emitting tetraphenylethylene-dicyanomethylene-4H-pyran (TPE-DCM) based fluorescent probe (TD-1). Conjugating TPE and DCM moieties allowed TD-1 to display high selectivity for thiophenol with excellent AIE properties in aqueous solution. Nevertheless, the poor water-solubility from the hydrophobic structure resulted in the weak and unstable emission intensity. Non-covalent self-assembly of TD-1 with TPE glycocluster (TPE2S) led to a largely improved water solubility producing a reliable and stable sensing system. The corresponding glyco-probe could detect sensitively exogenous thiophenol concentrations in PBS buffer or environmental water samples.

A 2D "glycosheet" based on supramolecular self-assembly between 2D MoS2 and fluorescent glycoligands is developed. The composite 2D material is proven suitable for targeted intracellular production of reactive oxygen species (singlet oxygen) by the sequential control of a receptor endocytosis and light irradiation.

We have developed a theranostic nanocomposite of metallic nanoparticles that uses two distinct fluorescence mechanisms: Forster Resonance Energy Transfer (FRET) and Metal-Enhanced Fluorescence (MEF) controlled by ligand-receptor interaction. Supramolecular assembly of the fluorophore-labeled glycoligands to cyclodextrin-capped gold nanoparticles produces a nanocomposite with a quenched fluorescence due to FRET from the fluorophore to the proximal particle. Subsequently, interaction with a selective protein receptor leads to an aggregation of the composite, reactivating the fluorescence by MEF from the distal metallic particles to fluorophores encapsulated in the aggregates. The aggregation also causes a red-shift in absorbance of the composite, thereby enhancing the production of reactive oxygen species (ROS) on red-light irradiation. Our nanocomposite has proven suitable for targeted cancer cell imaging as well as multimode therapy using both the photodynamic and drug delivery properties of the composite.

Small-molecular probes capable of monitoring and interfering with the activity of biomacromolecules – such as polysaccharides, nucleotides and proteins – are of paramount importance to the advancement of life science. However, such probes that can detect and simultaneously modulate the construction of biomacromolecules are elusive. Here we report a fluorogenic, foldable glycoprobe that can recognize and assemble a protein receptor in a synchronous fashion. The glycoprobe synthesized by introducing a glycoligand (for protein recognition) to a bola-type bis-fluorophore conjugate shows a “self-shielded” fluorescence in the folded state. Association with a receptor protein rapidly unfolds the probe, releasing a fluorophore capable of crosslinking the proteins – as determined using small-angle X-ray scattering – thereby producing a unique fluorescent supramolecular construct. We have demonstrated the use of the foldable glycoprobe in order to track the endocytic cycle of a transmembrane receptor.

International audience; Tetraphenylethylene (TPE) is fluorescent through aggregation induced emission (AIE) in water. Herein, TPE was used as the core of glycoclusters that target the bacterial lectins LecA and LecB of Pseudomonas aeruginosa. Synthesis of these TPE-based glycoclusters was accomplished by using azide-alkyne "click" chemistry. The AIE properties of the resulting glycoclusters could be readily verified, but imaging could not be pursued due to the overlap of the fluorescence signals from cells and bacteria. Nonetheless, the glycoclusters displayed nanomolar affinities toward LecA and LecB. Further evaluation in a cell-based anti-adhesive assay highlighted a limited decrease in adhesion (20%) for the fucosylated glycocluster. This confirmed that these TPE-based glycoclusters are indeed LecA and LecB high-affinity ligands. Nevertheless, the hypotheses involving their application in imaging or anti-adhesive therapy could not be verified.

In this review we will explore recent advances in the design and application of excited-state intramolecular proton-transfer (ESIPT) based fluorescent probes. Fluorescence based sensors and imaging agents (probes) are important in biology, physiology, pharmacology, and environmental science for the selective detection of biologically and/or environmentally important species. The development of ESIPT-based fluorescence probes is particularly attractive due to their unique properties, which include a large Stokes shift, environmental sensitivity and potential for ratiometric sensing.

An ESIPT-based 'AND' logic fluorescence probe (GSH-ABAH) was developed for the simultaneous detection of ONOO- and biological thiols. GSH-ABAH was shown to have good cell permeability and with the addition of just SIN-1 (ONOO- donor) or GSH, no fluorescence response was observed in live cells. However, in the presence of both analytes GSH-ABAH could be used to image exogenous ONOO- 'AND' GSH added to RAW264.7 cells.

The sensitive imaging of amyloid-β (Aβ) peptides is important for the timely detection of neurodegenerative diseases, such as Alzheimer's disease (AD). Although clinically the diagnosis of AD relies on the use of radiolabeled imaging reagents, herein we report the simple construction of a "flat ensemble" formed between a quinoline-malononitrile AIEgen (EDS) and thin-layer molybdenum disulfide (2D MoS2 ) for the sensitive detection of Aβ by means of fluorescence-based techniques. Self-assembly between EDS and 2D MoS2 in aqueous buffer solution produces the flat ensemble, and the subsequent interaction of the material ensemble with oligomeric and aggregated Aβ peptides leads to up to 19-fold enhanced fluorescence of EDS. The ensemble is also applicable for staining Aβ aggregates in vivo.

We have developed a supramoleuclar imaging probe based on thin-layer manganese dioxide functionalized with a fluorescent, multivalent glyco-poly-cycolodextrin for the targeted, stimulus-responsive bioimaging of cancer cells.

Although being widely used in organic synthesis, thiophenol (Tp) is toxic to the human body. We report here the preparation of a ratiometric fluorescence probe for the selective, transient determination of Tp in full aqueous solution. The probe was synthesized by a click reaction coupling between an alkynyl naphthalimide-dansyl dyad and an azido galactoside which increases the water solubility. Fluorescence spectroscopic analyses showed that the probe had a specific ratiometric response to Tp transiently in a full aqueous solution, over a range of other species. The probe has also proven suitable for the quantification of Tp in environmental water samples, and possesses superior properties to previous Tp fluorescence probes in terms of water solubility and sensitivity.