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This tutorial review provides a general overview for the design of prodrugs and activatable phototherapeutics which enables the development of improved therapies.

A turn-on isatin receptor based naphthalimide fluorescent probe encapsulated in PEG was used to rapidly detect peroxynitrite in cells.

We report the synthesis of hydroxyl-radical (˙OH) responsive fluorescent probes that utilise the 3,5-dihydroxybenzyl (DHB) functionality. 4-Methylumbeliferone-DHB (Umb-DHB) and resorufin-DHB (Res-DHB) in the presence of ˙OH radicals resulted in significant increases in their respective fluorescent emission intensities at 460 nm and 585 nm. The incubation of Res-DHB in HeLa cells followed by therapeutic ultrasound (1 MHz) resulted in a significant increase in fluorescence emission intensity thus permitting the ability to monitor ultrasound-induced ˙OH production in live cells.

Due to their simplicity in preparation, sensitivity and selectivity, fluorescent probes have become the analytical tool of choice in a wide range of research and industrial fields, facilitating the rapid detection of chemical substances of interest as well as the study of important physiological and pathological processes at the cellular level. In addition, many long-wavelength fluorescent probes developed have also proven applicable for in vivo biomedical applications including fluorescence-guided disease diagnosis and theranostics (e.g., fluorogenic prodrugs). Impressive progresses have been made in the development of sensing agents and materials for the detection of ions, organic small molecules, and biomacromolecules including enzymes, DNAs/RNAs, lipids, and carbohydrates that play crucial roles in biological and disease-relevant events. Here, we highlight examples of fluorescent probes and functional materials for biological applications selected from the special issues “Fluorescent Probes” and “Molecular Sensors and Logic Gates” recently published in this journal, offering insights into the future development of powerful fluorescence-based chemical tools for basic biological studies and clinical translation.

Luminogens characteristic of aggregation-induced emission (AIEgens) have been extensively exploited for the development of imaging-guided photodynamic therapeutic (PDT) agents. However, intramolecular rotation of donor-acceptor (D-A) type AIEgens favors non-radiative decay of photonic energy which results in unsatisfactory fluorescence quantum and singlet oxygen yields. To address this issue, we developed several molecularly engineered AIEgens with partially "locked" molecular structures enhancing both fluorescence emission and the production of triplet excitons. A triphenylphosphine group was introduced to form a D-A conjugate, improving water solubility and the capacity for mitochondrial localization of the resulting probes. Experimental and theoretical analyses suggest that the much higher quantum and singlet oxygen yield of a structurally "significantly-locked" probe (LOCK-2) than its "partially locked" (LOCK-1) and "unlocked" equivalent (LOCK-0) is a result of suppressed AIE and twisted intramolecular charge transfer. LOCK-2 was also used for the mitochondrial-targeting, fluorescence image-guided PDT of liver cancer cells.

A two-dimensional (2D) glycomaterial for targeted delivery of maytansine to liver cancer cells was developed.

Changes in adenosine triphosphate (ATP) and peroxynitrite (ONOO–) concentrations have been correlated in a number of diseases including ischemia-reperfusion injury and drug-induced liver injury. Herein, we report the development of a fluorescent probe ATP-LW, which enables the simultaneous detection of ONOO– and ATP. ONOO– selectively oxidizes 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). In contrast, 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 allows ONOO– levels to be monitored in the green channel (λex = 488 nm, λem = 500–575 nm) and ATP concentrations in the red channel (λex = 514 nm, λem = 575–650 nm). The use of ATP-LW as a combined ONOO– and ATP probe was demonstrated using hepatocytes (HL-7702 cells) in cellular imaging experiments. Treatment of HL-7702 cells with oligomycin A (an inhibitor of ATP synthase) resulted in a reduction of signal intensity in the red channel and an increase in that of the green channel as expected for a reduction in ATP concentrations. Similar fluorescence changes were seen in the presence of SIN-1 (an exogenous ONOO– donor).

We report here strategic functionalization of the FDA approved chelator deferasirox (1) in an effort to produce organelle-targeting iron chelators with enhanced activity against A549 lung cancer cells. Derivative 8 was found to have improved antiproliferative activity relative to 1. Fluorescent cell imaging revealed that compound 8 preferentially localises within the lysosome.

Fluorescent probes have emerged as indispensable chemical tools to the field of chemical biology and medicine. The ability to detect intracellular species and monitor physiological processes has not only advanced our knowledge in biology but has provided new approaches towards disease diagnosis. In this review, we detail the design criteria and strategies for some recently reported fluorescent probes that can detect a wide range of biologically important species in cells and in vivo. In doing so, we highlight the importance of each biological species and their role in biological systems and for disease progression. We then discuss the current problems and challenges of existing technologies and provide our perspective on the future directions of the research area. Overall, we hope this review will provide inspiration for researchers and prove as useful guide for the development of the next generation of fluorescent probes.

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.

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.

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.

Glycosidases, which are the enzymes responsible for the removal of residual monosaccharides from glycoconjugates, are involved in many different biological and pathological events. The ability to detect sensitively the activity and spatiotemporal distribution of glycosidases in cells will provide useful tools for disease diagnosis. However, the currently developed fluorogenic probes for glycosidases are generally based on the glycosylation of the phenol group of a donor–acceptor type fluorogen. This molecular scaffold has potential drawbacks in terms of substrate scope, sensitivity because of aggregation-caused quenching (ACQ), and the inability for long-term cell tracking. Here, we developed glycoclusters characterized by aggregation-induced emission (AIE) properties as a general platform for the sensing of a variety of glycosidases. To overcome the low chemical reactivity associated with phenol glycosylation, here we developed an AIE-based scaffold, which is composed of tetraphenylethylene conjugated with dicyanomethylene-4H-pyran (TPE–DCM) with a red fluorescence emission. Subsequently, a pair of dendritic linkages was introduced to both sides of the fluorophore, to which six copies of monosaccharides (d-glucose, d-galactose or l-fucose) were introduced through azide–alkyne click chemistry. The resulting AIE-active glycoclusters were shown to be capable of (1) fluorogenic sensing of a diverse range of glycosidases including β-d-galactosidase, β-d-glucosidase and α-l-fucosidase through the AIE mechanism, (2) fluorescence imaging of the endogenous glycosidase activities in healthy and cancer cells, and during cell senescence, and (3) glycosidase-activated, long-term imaging of cells. The present study provides a general strategy to the functional, in situ imaging of glycosidase activities through the multivalent display of sugar epitopes of interest onto properly designed AIE-active fluorogens., We report a general strategy for the fluorogenic sensing of glycosidases in cells based on aggregation-induced emission of glycoclusters.

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.

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.

Supplemental material, sj-pdf-2-ajs-10.1177_03635465211042014 for Securing Transplanted Meniscal Allografts Using Bone Plugs Results in Lower Risks of Graft Failure and Reoperations: A Meta-analysis by Zachariah Gene Wing Ow, Chin Kai Cheong, Hao Han Hai, Cheng Han Ng, Dean Wang, Aaron J. Krych, Daniel B.F. Saris, Keng Lin Wong and Heng An Lin in The American Journal of Sports Medicine

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.

In this work, a new reversible colorimetric and fluorescent probe for sequential recognition of copper ions and biothiols is synthesized easily. Based on the chelation-enhanced fluorescence quenching (CHEQ) effect, this probe shows high sensitivity and selectivity towards Cu2+, which can be detected by the naked eye. And this experimental phenomenon can also be realised upon addition of biothiols, restoring their initial fluorescence intensity. This probe also features a very high response speed (less than 5 seconds) and a large stokes shift (178 nm) toward Cu2+ and biothiols. Moreover, the detection limit for Cu2+ and biothiols is as low as 7.34 nM and 10.3 nM, respectively. Additionally, this ON–OFF–ON-type fluorescence recognition cycle can be repeated more than 5 times by addition of Cu2+ and biothiols in turn. Particularly, this 1–Cu2+ ensemble is further successfully applied for GSH detection in living cells.

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.

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 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.

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˙−.

Biothiols including cysteine (Cys) and glutathione (GSH) are biological signaling molecules responsible for cell detoxification, cell metabolism and neutralization of reactive oxygen species. Here, we synthesized a long-wavelength fluorescent probe, DCIMA, for lysosome-targeted imaging of Cys and GSH in living cells. DCIMA is consisted of a dicyanoisophorone core modified with an acrylate group for biothiol detection through the Michael addition reaction and a morpholine group as the lysosome-targeting agent. The presence of the electron-donating morpholine group also enhances the intramolecular charge transfer mechanism of the probe, thereby enabling its long-wavelength fluorescence emission (670 nm) and large Stokes shift (180 nm). In concentration range of 0-30 μM, the probe was determined to react quickly with both Cys and GSH with low detection limits (5 min, 35.2 nM for GSH and 34.8 nM for Cys) and achieve the sensitive fluorescence imaging of the biothiols located in the lysosomes of living cells.

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.

Three cationic conjugated polyelectrolytes (CPEs) with a common poly(p-phenylene ethynylene) backbone and different galactose-containing side chains were designed and synthesized. These CPEs were characterized and their application in targeted hepatoma cell imaging was demonstrated.

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

Lipid droplets (LDs) are cellular organelles that are essential for maintaining lipid and energy homeostasis. Once regarded as merely inert fat particles, they are now recognized as highly dynamic, mobile organelles required for preventing lipotoxicity and for interacting and cooperating with various organelles. Despite the progress made in understanding the role of LDs, a number of fundamental questions remain unanswered. Effective imaging agents for observing the morphology and dynamic physiological processes of LDs in cells could help address this knowledge gap. Such probes are expected to aid in our understanding of LDs and facilitate the development of new and effective therapeutics. In this review, we have provided a brief introduction to the formation and physiological functions of LDs in an attempt to highlight the importance of these underappreciated organelles. Recent examples of LD-based fluorescent probes are discussed, including the fluorescence phenomenon used in their design. To date, both intramolecular charge transfer (ICT) and aggregation-induced emission (AIE) fluorescence mechanisms have been exploited to create LD probes. However, alternative strategies can be envisioned. We hope the readers will be enlightened as to the importance of these key organelles, will be poised to exploit existing probes to explore various biological applications, and be inspired to create new LD fluorescent sensors that will further our understanding of LDs and their associated physiology.

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⸱-.

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.