A BODIPY-based two-photon fluorescent probe validates tyrosinase activity in live cells

Delineating a Tailor-Made Fluorescent Probe Designed for the Selective Detection of Tyrosinase

A dicyanoisophorone based fluorescent probe (E)-2-(3-(4-hydroxystyryl)-5,5-dimethylcyclohex-2-en-1-ylidene)malononitrile (DCIP-OH) was developed for the selective sensing of tyrosinase in apple extract and live cells. The probe was obtained by the condensation of 2-(3,5,5-trimethylcyclohex-2-en-1-ylidene)malononitrile with 4-hydroxybenzaldehyde. Upon interaction with tyrosinase, the probe exhibited absorbance switching from 417 nm to 357 nm, accompanied by a slight increase in absorption value and an isosbestic point observed at 373 nm. Additionally, a reduction in emission intensity at 592 nm was observed. Furthermore, we successfully employed the probe for sensing of tyrosinase in apple extract and conducted inhibition studies by using kojic acid. LOD was determined to be ~0.4 nM. Moreover, the biocompatible nature of DCIP-OH enabled its effective localization in epithelial-like melanoma cells, B16F10, where it demonstrated successful fluorescent probing of intracellular tyrosinase.

Photoinduced electron transfer (PeT) based fluorescent probes for cellular imaging and disease therapy

Typical PeT-based fluorescent probes are multi-component systems where a fluorophore is connected to a recognition/activating group by an unconjugated linker. PeT-based fluorescent probes are powerful tools for cell imaging and disease diagnosis due to their low fluorescence background and significant fluorescence enhancement towards the target. This review provides research progress towards PeT-based fluorescent probes that target cell polarity, pH and biological species (reactive oxygen species, biothiols, biomacromolecules, etc.) over the last five years. In particular, we emphasise the molecular design strategies, mechanisms, and application of these probes. As such, this review aims to provide guidance and to enable researchers to develop new and improved PeT-based fluorescent probes, as well as promoting the use of PeT-based systems for sensing, imaging, and disease therapy.

Boron-containing compounds on neurons: Actions and potential applications for treating neurodegenerative diseases

Boron-containing compounds (BCC) exert effects on neurons. After the expanding of both the identification and synthesis of new BCC, novel effects in living systems have been reported, many of these involving neuronal action. In this review, the actions of BCC on neurons are described; the effects have been inferred by boron deprivation or addition. Also, the effects can be related to those mediated by interaction on ionic channels, G-protein coupled receptors, or other receptors exerting modification on neuronal behavior. Additionally, BCC have exhibited effects by the modulation of inflammation or oxidative processes. BCC are expanding as drugs. Deprivation of boron sources from the diet shows the role of some natural BCC. However, the observations of several new synthesized compounds suggest their ability to act with attractive potency, efficacy, and long-term action on neuronal receptors or processes related with the origin and evolution of neurodegenerative processes. The details of BCC-target interactions are currently being elucidated in progress, as those observed from BCC-protein crystal complexes. Taking all of the above into account, the expansion is presumably near to having studies on the application of BCC as drugs on specific targets for treating neurodegenerative diseases.

Modulation of the lipophilicity and molecular size of thiosemicarbazone inhibitors to regulate tyrosinase activity

A group of 5-methylsalicylaldehyde thiosemicarbazone derivatives (HMTs) bearing different lipophilic and steric substituents attached at the 3-position of cresol ring were synthesized and investigated as mushroom tyrosinase (TYR) inhibitors. The ability of HMTs to inhibit the diphenolase activity of TYR was evaluated with L-DOPA as substrate by determining IC₅₀ values in relation to their structure modifications. HMTs displayed distinct inhibitory competencies towards TYR activity with IC₅₀ values in the range of 1.02-143.56 μM. A close correlation between their inhibition potency and both lipophilicity and molecular size was observed. The inhibitory effect of the hydroxyethyl-containing derivatives was much higher than the hydroxyethyl-free ones overall. Among them, HMT-NBO exhibited the most potent effect with IC₅₀ of 5.85 μM, which was nearly 25-fold and 3.8-fold lower than its parent HMT-NBE and the control kojic acid, respectively. The hydroxyethyl clearly benefited the improvement of the inhibitory competences and acted as a regulating group of lipophilicity of the inhibitors. The kinetic analyses showed that HMTs were reversible and mixed type inhibitors against mushroom TYR. The inhibition mechanism was studied by means of fluorescence spectroscopy, FT-IR, ESI-MS and molecular docking analysis. The results indicated that the observed inhibitory effect of HMTs was accomplished by acting on the amino acid residues rather than by chelating the centre copper ions of TYR. Each of HMTs can insert the hydrophobic pocket and interact with the residues of TYR through Van der Waals forces and hydrogen bonds, with additional electrostatic interactions for HMT-NEE and HMT-NEO further strengthening the affinity. Meanwhile, the inhibitors were observed to bind with L-DOPA or/and L-DOPAquinone forming 1:1 stoichiometric complexes, probably exerting indirect inhibition against TYR activity.

Persistent and Efficient Multimodal Imaging for Tyrosinase Based on Two-Photon Excited Fluorescent and Room-Temperature Phosphorescent Probes

Tyrosinase is crucial to regulate the metabolism of phenol derivatives, playing an important role in the biosynthesis of melanin pigments, whereas an abnormal level of tyrosinase would lead to severe diseases. It is rather necessary to develop a sensitive and selective imaging tool to assess the level of tyrosinase in vivo. We thoroughly researched the luminous mechanism of the existing TPTYR probe and provided design strategies to improve its two-photon excited fluorescence properties. The designed probes benza2-TPTYR and product benza2-TPTYR-coumarin have large two-photon absorption cross sections at the NIR spectral region (41 GM/706 nm, 71 GM/852 nm), while benza2-TPTYR-coumarin possesses easily distinguishable spectrum in the visible region and a high fluorescence efficiency (Φ_F = 0.27). What is more, novel two-photon excited multimodal imaging based on the pure organic small molecule benza1-TPTYR-coumarin (61 GM/936 nm) is proposed first, simultaneously possessing strong instantaneous fluorescent (563.79 nm) and persistent room-temperature phosphorescent emissions (767.68 nm, 0.54 ms).

A self-ratiometric and selective electrochemical sensor for the detection of tyrosinase in mouse brain homogenate

An electrochemical method for selectively sensing and accurately quantifying tyrosinase in mouse brain homogenate is reported.

One-pot synthesis of a peroxidase-like nanozyme and its application in visual assay for tyrosinase activity

Both single-atom nanozymes (SAzymes) and protein-template metal nanoparticles have attracted comprehensive attention in several respects owing to their excellent catalytic performance, green facile synthesis process, and robustness. Herein, the peroxidase-like activity of single-atom copper anchored on bovine hemoglobin-template gadolinium nanoparticles (Cu,Gd@BHb^FITC NPs) were successfully synthesized and two sensitive turn-on fluorescence strategies for tyrosinase (TYR) activity sensing were proposed for the first time. For strategy Ⅰ, TYR sensing was carried out from 1.00 to 7.80 U/mL with the detection limit (LOD) of 0.20 U/mL based on the fluorescence resonance energy transfer (FRET) between the fluorescein isothiocyanate (FITC) and the in situ generated polydopamine dots (PDA-dots). For strategy Ⅱ, The LOD of TYR was 0.05 U/mL with the linear range of 0.40-19.70 U/mL based on the elimination of inner-filter effect (IEF) between FITC and the reaction product (RC) of phenol and 4-Aminoantipyrine (AAP). The smartphone-assisted sensing platform was applied to construct the on-site detection of TYR with both strategies. The developed probe possessed good selectivity and was successfully utilized to TYR detection in serum samples.

Fluorescent probes for visualizing ROS-associated proteins in disease

Abnormal expression of proteins, including catalytic and expression dysfunction, is directly related to the development of various diseases in living organisms. Reactive oxygen species (ROS) could regulate protein expression by redox modification or cellular signal pathway and thus influence the development of disease. Determining the expression level and activity of these ROS-associated proteins is of considerable importance in early-stage disease diagnosis and the identification of new drug targets. Fluorescence imaging technology has emerged as a powerful tool for specific in situ imaging of target proteins by virtue of its non-invasiveness, high sensitivity and good spatiotemporal resolution. In this review, we summarize advances made in the past decade for the design of fluorescent probes that have contributed to tracking ROS-associated proteins in disease. We envision that this review will attract significant attention from a wide range of researchers in their utilization of fluorescent probes for in situ investigation of pathological processes synergistically regulated by both ROS and proteins.

Highly selective two-photon fluorescent off-on probes for imaging tyrosinase activity in living cells and tissues

A coumarin-based two-photon (TP) fluorescent off-on probe has been developed for detecting tyrosinase activity. High selectivity, sensitivity and biocompatibility enable the probes to successfully image tyrosinase activity in live cells and tissues using TP microscopy.

Spectrophotometric Assays for Sensing Tyrosinase Activity and Their Applications

Tyrosinase (TYR, E.C. 1.14.18.1), a critical enzyme participating in melanogenesis, catalyzes the first two steps in melanin biosynthesis including the ortho-hydroxylation of L-tyrosine and the oxidation of L-DOPA. Previous pharmacological investigations have revealed that an abnormal level of TYR is tightly associated with various dermatoses, including albinism, age spots, and malignant melanoma. TYR inhibitors can partially block the formation of pigment, which are always used for improving skin tone and treating dermatoses. The practical and reliable assays for monitoring TYR activity levels are very useful for both disease diagnosis and drug discovery. This review comprehensively summarizes structural and enzymatic characteristics, catalytic mechanism and substrate preference of TYR, as well as the recent advances in biochemical assays for sensing TYR activity and their biomedical applications. The design strategies of various TYR substrates, alongside with several lists of all reported biochemical assays for sensing TYR including analytical conditions and kinetic parameters, are presented for the first time. Additionally, the biomedical applications and future perspectives of these optical assays are also highlighted. The information and knowledge presented in this review offer a group of practical and reliable assays and imaging tools for sensing TYR activities in complex biological systems, which strongly facilitates high-throughput screening TYR inhibitors and further investigations on the relevance of TYR to human diseases.

Mitochondrial H2Sn-Mediated Anti-Inflammatory Theranostics

The insistent demand for space-controllable delivery, which reduces the side effects of non-steroidal anti-inflammatory drugs (NSAIDs), has led to the development of a new theranostics-based approach for anti-inflammatory therapy. The current anti-inflammatory treatments can be improved by designing a drug delivery system responsive to the inflammatory site biomarker, hydrogen polysulfide (H₂S_n). Here, we report a novel theranostic agent 1 (TA1), consisting of three parts: H₂S_n-mediated triggering part, a two-photon fluorophore bearing mitochondria targeting unit (Rhodol-TPP), and anti-inflammatory COX inhibitor (indomethacin). In vitro experiments showed that TA1 selectively reacts with H₂S_n to concomitantly release both Rhodol-TPP and indomethacin. Confocal-microscopy imaging of inflammation-induced live cells suggested that TA1 is localized in the mitochondria where the H₂S_n is overexpressed. The TA1 reacted with H₂S_n in the endogenous and exogenous H₂S_n environments and in lipopolysaccharide treated inflammatory cells. Moreover, TA1 suppressed COX-2 level in the inflammatory-induced cells and prostaglandin E₂ (PGE₂) level in blood serum from inflammation-induced mouse models. In vivo experiments with inflammation-induced mouse models suggested that TA1 exhibits inflammation-site-elective drug release followed by significant therapeutic effects, showing its function as a theranostic agent, capable of both anti-inflammatory therapy and precise diagnosis. Theranostic behavior of TA1 is highly applicable in vivo model therapeutics for the inflammatory disease.

Review on the recent progress in the development of fluorescent probes targeting enzymes

Enzymes are very important for biological processes in a living being, performing similar or multiple tasks in and out of cells, tissues and other organisms at a particular location. The abnormal activity of particular enzyme usually caused serious diseases such as Alzheimer's disease, Parkinson's disease, cancers, diabetes, cardiovascular diseases, arthritis etc. Hence, nondestructive and real-time visualization for certain enzyme is very important for understanding the biological issues, as well as the drug administration and drug metabolism. Fluorescent cellular probe-based enzyme detectionin vitroandin vivohas become broad interest for human disease diagnostics and therapeutics. This review highlights the recent findings and designs of highly sensitive and selective fluorescent cellular probes targeting enzymes for quantitative analysis and bioimaging.

Increase of tyrosinase activity at the wound site in zebrafish imaged by a new fluorescent probe

Tyrosinase plays a pivotal role in the hyperpigmentation of wounds. Here, we develop a new fluorescent probe and with it, we reveal an increase of tyrosinase activity at the wound site in zebrafish.

18F-labelled BODIPY dye as a dual imaging agent: Radiofluorination and applications in PET and optical imaging

Dual Positron emission tomography (PET)/optical imaging techniques have captured scientific interest for clinical applications due to their potential as an effective tool for visualizing in vivo information such as disease processes. 4,4'-Difluoro-4-bora-3a,4a-diaza-s-indacene (BODIPY) dye has been considered an ideal platform strategy to achieve dual PET/optical imaging due to its photochemical nature and chemical structure. Various radiofluorination methods to prepare [18F]BODIPY dye have been developed and established, ranging from nucleophilic substitution reactions to isotope exchange reactions. In addition, 18F-labelled BODIPY dyes for biologically important targets have been used for in vivo and ex vivo studies. These studies proved the practicality of [18F]BODIPY dyes as a hybrid PET/optical imaging probe. In this review, recent advances in the synthesis and biological evaluation of 18F-labelled BODIPY dyes are described.

Selective bioimaging of cancer cells and detection of HSA with indomethacin-based fluorescent probes

Two fluorescent probes were designed by connecting indomethacin to coumarin through different linkers. The introduction of indomethacin quenched the fluorescence of coumarin-based probes with apparent red-shifts in the absorption and emission maxima, probably due to the photoinduced electron transfer (PET) from the indomethacin to the fluorophore and the formation of folding conformation. The addition of human serum albumin (HSA) triggered about 40-fold fluorescence enhancements of ADC-IMC-2 and ADC-IMC-6 with 85 nm blue-shifts. The probe with longer spacer ADC-IMC-6 exhibited ratiometric fluorescent response toward HSA, and that with shorter linker showed "off-on" fluorescence response to HSA. However, insignificant spectral changes of the reference compounds (ADC-6 and ADC-2) initiated by HSA implied that indomethacin played critical role in the identification of HSA. The competitive assays and molecular docking results reveal that the indomethacin in ADC-IMC-6 could tightly combine at drug site I of HSA. Fluorescence bio-imaging experiments show that both probes could distinguish cancer cells from normal cells.

Advances in nanomedicines for diagnosis of central nervous system disorders

In spite of a great improvement in medical health services and an increase in lifespan, we have witnessed a skyrocket increase in the incidence of central nervous system (CNS) disorders including brain tumors, neurodegenerative diseases (Alzheimer's disease, Parkinson's disease, amyotrophic lateral sclerosis, Huntington's disease), ischemic stroke, and epilepsy, which have seriously undermined the quality of life and substantially increased economic and societal burdens. Development of diagnostic methods for CNS disorders is still in the early stage, and the clinical outcomes suggest these methods are not ready for the challenges associated with diagnosis of CNS disorders, such as early detection, specific binding, sharp contrast, and continuous monitoring of therapeutic interventions. Another challenge is to overcome various barrier structures during delivery of diagnostic agents, especially the blood-brain barrier (BBB). Fortunately, utilization of nanomaterials has been pursued as a potential and promising strategy to address these challenges. This review will discuss anatomical and functional structures of BBB and transport mechanisms of nanomaterials across the BBB, and special emphases will be placed on the state-of-the-art advances in the development of nanomedicines from a variety of nanomaterials for diagnosis of CNS disorders. Meanwhile, current challenges and future perspectives in this field are also highlighted.

Biocompatible fluorescent probe for detecting mitochondrial alkaline phosphatase activity in live cells

Alkaline phosphatase (ALP) is an enzyme that actively plays a significant role in the various metabolic processes by transferring a phosphate group to the protein, nucleic acid, etc. The elevated level of ALP in blood plasma is the hallmark of inflammation/cancer. The hyperactive mitochondria in cancer cells produce an excess of ATP to fulfill the high energy demand. Thus, we have developed a fluorescent probe Mito-Phos for ALP, which can detect phosphatase expression in mitochondria in live cells. The probe Mito-Phos has shown ~15-fold fluorescence intensity increments at 450 nm in the presence of 500 ng/mL of ALP. It takes about 60 min to consume the whole amount of ALP (500 ng/mL) in physiological buffer saline. It can selectively react with ALP even in the presence of other probable cellular reactive components. It is highly biocompatible and nontoxic to the live cells. It has shown ALP expression in a dose-dependent manner by providing concomitant fluorescence images in the blue-channel region. It has localized exclusively in the mitochondria in live cells. The probe Mito-Phos is highly biocompatible with the ability to assess ALP expression in mitochondria in live cells.

3-Aminophenyl Boronic Acid Functionalized Quantum-Dot-Based Ratiometric Fluorescence Sensor for the Highly Sensitive Detection of Tyrosinase Activity

Using the commercially available and economical 6-hydroxycoumarin (6-HC) as the substrate, a dual-emission ratiometric fluorescence sensor was developed to detect tyrosinase (TYR) activity based on 3-aminophenyl boronic acid functionalized quantum dots (APBA-QDs). TYR can catalyze 6-HC, a monohydroxy compound, to form a fluorescence-enhancing o-hydroxy compound, 6,7-dihydroxycoumarin. Owing to the special covalent binding between the o-hydroxyl and boric acid groups, APBA-QDs react with 6,7-dihydroxycoumarin to form a five-membered ring ester dual-emission fluorescence probe for TYR. With an increase in TYR activity, the fluorescence at 675 nm originating from the QDs is gradually quenched, whereas that at 465 nm owing to 6,7-dihydroxycoumarin increases. Referencing the decreasing signal of the dual-emission probe at 675 nm to measure the increasing signal at 465 nm, a ratiometric fluorescence method was established to detect the TYR activity with high sensitivity and selectivity. Under the conditions optimized via response surface methodology, a linear range of 0-0.05 U/mL was obtained for the TYR activity. The detection limit was as low as 0.003 U/mL. This sensing strategy can also be adopted for the rapid screening of the TYR inhibitors.

Fast tyrosinase detection in early stage melanoma with nanomolar sensitivity using a naphthalimide-based fluorescent read-out probe

We report an expeditious approach for selective tyrosinase detection in early stage melanoma with nanomolar sensitivity using a napthalimide-based fluorescent probe.

Far-red/near-infrared emitting, two-photon absorbing, and bio-stable amino-Si-pyronin dyes

Organic fluorophores emitting in the far-red/near-infrared (NIR) wavelength region are in great demand for minimal autofluorescence and reduced light scattering in deep tissue or whole body imaging. Currently, only a few classes of far-red/NIR fluorophores are available including widely used cyanine dyes, which are susceptible to photobleaching and form nonfluorescent aggregates. Even rare are those far-red/NIR emitting dyes that have two-photon imaging capability. Here we report a new class of far-red/NIR-emitting dyes that are photo-stable, very bright, biocompatible, and also two-photon absorbing. The introduction of an electron-withdrawing group such as N-acyl or N-alkoxycarbonyl groups on the C-10-amino substituent of the new julolidine-derived amino-Si-pyronin dyes (ASiPj), which emit in the far-red region, causes large bathochromic shifts, leading to NIR-emitting amino-Si-pyronin dyes (NIR-ASiPj) having high cellular stability. Furthermore, the ASiPj-NIR-ASiPj couple offers a novel ratiometric bioimaging platform with a large spectral gap, as demonstrated here with a boronate-containing NIR-ASiPj derivative that is converted to the corresponding ASiPj dye upon reaction with hydrogen peroxide.

Excellent benzocoumarin-based ratiometric two-photon fluorescent probe for H2O2 detection

The level of hydrogen peroxide (H2O2) plays an essential role in regulating biological processes. The in vivo or in vitro detection of H2O2 in deep tissues by utilizing two-photon (TP) fluorescent probes can significantly alleviate the detection damage inflicted onto living organisms as well as facilitate high-resolution imaging when compared with one-photon (OP) fluorescent probes. However, few TP fluorescent probes possess both high fluorescence efficiency and easily distinguishable spectra for measuring H2O2. Therefore, an in-depth understanding of the relationship between the electronic structure and TP fluorescent properties and fabricating probes with excellent performance are still challenging. Consequently, we designed a series of benzocoumarin-based ratiometric TP fluorescent probes and corresponding product molecules for H2O2 detection. Thereafter, we theoretically evaluated the TP recognition performance of these compounds and studied the relationship between their molecular structure and TP performance by means of time-dependent density functional theory and quadratic response theory. Moreover, we determined their spectral properties and fluorescence efficiencies. Fortunately, in this study, we were able to propose an excellent TP probe BC-3 and the corresponding product molecule DCCA-3, which exhibit large TPA cross-sections in the NIR region (3420 GM/988 nm; 316 GM/939 nm) and large Stokes (116 nm; 60 nm) and emission (225 nm) shifts. Therefore, this probe enables the simultaneous NIR and TP imaging of H2O2, which is a unique ability and has never been previously reported. Moreover, we comprehensively investigated the effect of the benzene-fused position in the coumarin backbone on the transition dipole moment and nonradiative decay channels, explaining the fluorescence near-quenching mechanism of benzo[f]coumarin derivative DCCA-4 for the first time.

Aminoluciferin 4-hydroxyphenyl amide enables bioluminescence detection of endogenous tyrosinase

Tyrosinase, a copper-containing enzyme existing widely in plants, animals and microorganisms, usually serves as an important biomarker in melanoma, and is also related to hyperpigmentation of the skin, melasma, age spots and albinism. At present, only one bioluminescent probe has been applied to image tyrosinase in cells. Thus, it's of great significance to develop a new bioluminescent probe that can detect tyrosinase in living cells and in live animals. In the current work, we report a new BL probe, TyrBP-3, which not detect tyrosinase in vitro and in living cells, but can also visualize the level of tyrosinase activity in tumors of living animals. In summary, TyrBP-3 is the first bioluminescent probe that can image tyrosinase on a cellular level. Hence, we anticipate that TyrBP-3 can be a good tool to monitor tyrosinase in complex biosystems in the future.

Easy-to-Use Colorimetric Cyanine Probe for the Detection of Cu2+ in Wilson's Disease

Copper(II) is one of the essential metal elements in human body, which can accumulate in many organs and finally excrete in urine. Excessive load of Cu²⁺ can cause liver cirrhosis, kidney dysfunction, and many neurological symptoms in the case of Wilson's disease (WD). Therefore, the selective and efficient detection of Cu²⁺ is of great importance. Although various fluorescent probes have been reported for the detection of Cu²⁺, an efficient and capable probe is still rare for patients' self-use on a routine basis. In this study, we developed an easy-to-use probe CY1 based on UV-vis-near-infrared absorption changes with excellent sensitivity and selectivity for Cu²⁺. The mechanism of oxidation of CY1 by Cu²⁺ was first explored. We demonstrated the role of the probe in the quantitative detection of Cu²⁺ in urine from WD patients and showed that it has great potential for clinical applications.

Melanosome-Targeting Near-Infrared Fluorescent Probe with Large Stokes Shift for in Situ Quantification of Tyrosinase Activity and Assessing Drug Effects on Differently Invasive Melanoma Cells

Tyrosinase (TYR) plays a vital role in melanin biosynthesis and is widely regarded as a relatively specific marker for melanocytic lesions which involve vitiligo, malignant cutaneous melanoma, Parkinson's disease (PD), etc. However, the detection of TYR in living cells with fluorescent probes is usually interfered by diverse endogenous reactive oxygen species (ROS) and reactive nitrogen species (RNS). Herein, we synthesized a melanosome-targeting near-infrared (NIR) fluorescent probe (HB-NP) with a large Stokes shift (195 nm), achieving a highly sensitive and selective in situ detection for intracellular TYR, by incorporating a m-hydroxybenzyl moiety that recognizes TYR specifically and the morpholine unit which facilitates the probe accumulating in the melanosome into a salicyladazine skeleton. When treated with TYR, the probe itself with weak fluorescence is lit up via an inhibited photoinduced electron-transfer (PET) effect and HB-NP shows a strong fluorescence signal (nearly 48-fold enhancement) with a low detection limit of 0.5 U mL^-1. HB-NP has been successfully applied in visualizing and in situ quantification of the intracellular TYR activity. Moreover, owing to the different expression levels of TYR, two human uveal melanoma cells with different invasive behaviors are distinguished by means of bioimaging and the effects of the inhibitor, kojic acid, and the up-regulating treatment, psoralen/ultraviolet A, on TYR activity of the two melanoma cells are evaluated. HB-NP is expected to be a useful tool to monitor diseases associated with the abnormal level of melanin and screen medicines for TYR disorder more effectively.

NIR two-photon fluorescent probe for biothiol detection and imaging of living cells in vivo

A fluorescence probe, Cz-BDP-NBD, for detecting biothiols with two photon excited fluorescence has been designed and used under irradiation from sapphire pulsed lasers at 800 nm.

A conjugated BODIPY–triphenylamine multi-aldoxime: Sonogashira coupling, ratiometric chemodosimeter and rapid detection of hypochlorite with two-photon excited fluorescence

The chemodosimeter is an off–on TPEF probe for detecting NaOCl selectively with red emission.

A hydrogen sulfide triggered self-immolative fluorescent probe for lysosome labeling in live cells

We developed a naphthalimide-based, lysosome-targeting, and self-immolative fluorescent probe for H₂S detection.

FRET and PET paired dual mechanistic carbon dots approach for tyrosinase sensing

In the presence of tyrosinase, the probe shows a ratiometric fluorescence response owing to a dual mechanistic FRET and PET approach.

Recent progresses in small-molecule enzymatic fluorescent probes for cancer imaging

An overview of recent advances in small-molecule enzymatic fluorescent probes for cancer imaging, including design strategies and cancer imaging applications.