Rational Design of a Dual-Reactivity-Based Fluorescent Probe for Visualizing Intracellular HSNO

Sulfur-based fluorescent probes for biological analysis: A review

The widespread adoption of small-molecule fluorescence detection methodologies in scientific research and industrial contexts can be ascribed to their inherent merits, including elevated sensitivity, exceptional selectivity, real-time detection capabilities, and non-destructive characteristics. In recent years, there has been a growing focus on small-molecule fluorescent probes engineered with sulfur elements, aiming to detect a diverse array of biologically active species. This review presents a comprehensive survey of sulfur-based fluorescent probes published from 2017 to 2023. The diverse repertoire of recognition sites, including but not limited to N, N-dimethylthiocarbamyl, disulfides, thioether, sulfonyls and sulfoxides, thiourea, thioester, thioacetal and thioketal, sulfhydryl, phenothiazine, thioamide, and others, inherent in these sulfur-based probes markedly amplifies their capacity for detecting a broad spectrum of analytes, such as metal ions, reactive oxygen species, reactive sulfur species, reactive nitrogen species, proteins, and beyond. Owing to the individual disparities in the molecular structures of the probes, analogous recognition units may be employed to discern diverse substrates. Subsequent to this classification, the review provides a concise summary and introduction to the design and biological applications of these probe molecules. Lastly, drawing upon a synthesis of published works, the review engages in a discussion regarding the merits and drawbacks of these fluorescent probes, offering guidance for future endeavors.

Reversible Fluorescent Probes for Dynamic Imaging of Liver Ischemia-Reperfusion Injury

ConspectusHepatic ischemia-reperfusion injury (HIRI) is an inevitable complication of clinical surgeries such as liver resection or transplantation, often resulting in postoperative liver dysfunction, hepatic failure in up to 13% of postresection patients, and early graft failure in 11-18% of liver transplantation patients. HIRI involves a series of biochemical events triggered by abnormal alterations in multiple biomarkers, characterized by short lifespans, dynamic changes, subcellular regional distribution, and multicollaborative regulation. However, traditional diagnosis, including serology, imaging, and liver puncture biopsy, suffers from low sensitivity, poor resolution, and hysteresis, which hinder effective monitoring of HIRI markers. Thus, to address the unique properties of HIRI markers, there is a pressing demand for developing novel detection strategies that are highly selective, transiently responsive, dynamically reversible, subcellular organelle-targeted, and capable of simultaneous multicomponent analysis.Optical probe-based fluorescence imaging is a powerful tool for real-time monitoring of biomarkers with the advantages of high sensitivity, noninvasiveness, rapid analysis, and high-fidelity acquisition of spatiotemporal information on signaling molecules compared with conventional methods. Moreover, with the growing demand for continuous monitoring of biomarkers, probes with reversible detection features are receiving more and more attention. Importantly, reversible probes can not only monitor fluctuations in marker concentrations but also distinguish between transient bursts of markers during physiological events and long-term sustained increases in pathological marker levels. This can effectively avoid false-positive test results, and in addition, reversible probes can be reutilized with green and economical features. Therefore, our team has employed various effective methods to design reversible optical probes for HIRI. We proposed reversible recognition strategies based on specific reactions or interactions to detect dynamic changes in markers. Given the biomarkers' unique signaling in subcellular organelles and the synergistic regulatory properties of multiple markers for HIRI, bifunctional reversible detection strategies are exploited, including organelle-targeted reversible and multicomponent simultaneous detection. With these strategies, we have tailored a variety of high-fidelity fluorescent probes for a series of HIRI markers, including reactive oxygen/nitrogen species (O2•- and ONOO-), ATP, protein (Keap1), mitochondrial DNA, etc. Utilizing the probes, the in situ dynamic imaging detection of the HIRI markers was successfully achieved. While performing the precise examination of the earlier occurrence of HIRI disease and visualizing the real-time monitoring of the disease process, we have also further elucidated the HIRI-associated signaling pathways. It is envisioned that our summarized work will inspire the design of future reversible fluorescent probes and help to improve the clinical diagnosis and therapeutic efficiency of these diseases.

Activity-Based Fluorescent Probes for Hydrogen Sulfide and Related Reactive Sulfur Species

Hydrogen sulfide (H2S) is not only a well-established toxic gas but also an important small molecule bioregulator in all kingdoms of life. In contemporary biology, H2S is often classified as a "gasotransmitter," meaning that it is an endogenously produced membrane permeable gas that carries out essential cellular processes. Fluorescent probes for H2S and related reactive sulfur species (RSS) detection provide an important cornerstone for investigating the multifaceted roles of these important small molecules in complex biological systems. A now common approach to develop such tools is to develop "activity-based probes" that couple a specific H2S-mediated chemical reaction to a fluorescent output. This Review covers the different types of such probes and also highlights the chemical mechanisms by which each probe type is activated by specific RSS. Common examples include reduction of oxidized nitrogen motifs, disulfide exchange, electrophilic reactions, metal precipitation, and metal coordination. In addition, we also outline complementary activity-based probes for imaging reductant-labile and sulfane sulfur species, including persulfides and polysulfides. For probes highlighted in this Review, we focus on small molecule systems with demonstrated compatibility in cellular systems or related applications. Building from breadth of reported activity-based strategies and application, we also highlight key unmet challenges and future opportunities for advancing activity-based probes for H2S and related RSS.

A nitric oxide and hydrogen sulfide dual-donating nanosystem for highly synergistic gas-radiotherapy against hepatocellular carcinoma

A drug delivery system (DDS) based on gold-capped mesoporous silica nanoparticles (MSN) is fabricated for loading NOSH-aspirin, a nitric oxide (NO) and hydrogen sulfide (H₂S) dual-donating cytotoxic molecule. The liver targeting and tumor microenvironment responsive properties of the nanosystem enable, for the first time, the concurrent delivery of NO and H₂S from a DDS into hepatocellular carcinoma (HCC) cells. Combined gas-radiotherapy (GT-RT) from drug-loaded DDS (NOSH@MSN-Au-Gal) and X-ray irradiation shows highly synergistic anti-cancer activity against both normoxic and hypoxic HCC cells. Further studies revealed that the combined GT-RT not only retains the well-known anticancer mechanism of NO, H₂S, and X-ray individually, but also alleviates HCC hypoxia via NO- and H₂S- involved unique pathways. In mice, the GT-RT greatly slows the growth of both subcutaneous and orthotopic HCC tumors and shows high biocompatibility. The current work is expected to promote the clinical application of combined GT-RT as an effective cancer treatment.

Evaluation of nitroreductase activity in nasopharyngeal carcinoma progression by an activatable two-photon fluorescent probe

Nasopharyngeal carcinoma (NPC) originating from the epithelium cells is the most common malignant tumor of the head and neck. Small-molecule fluorescent probes for early diagnosis of NPC can effectively improve the 5-year survival rate of patients, which makes it become a research hotspot in recent years. Previous studies have suggested the expression levels of NTR in hypoxic tissues or cells and tumors increased relative to the normal state and were positively correlated with the degree of hypoxia. Regarding the mentioned above, we designed a two-photon fluorescent probe NaT-NTR for the detection of NTR in nasopharyngeal cell lines and tissues at different hypoxia levels. NaT-NTR showed high selectivity and sensitivity toward NTR in a complex physiological environment. Furthermore, imaging NTR in different cell lines revealed that the level of intracellular NTR might be positively correlated with the malignancy of nasopharyngeal carcinoma. More importantly, NaT-NTR was successfully applied to detect and image NTR in human nasopharyngeal carcinoma with a penetration depth of 100 µm. On this basis, NaT-NTR might be a powerful chemical tool for the early diagnosis of nasopharyngeal carcinoma.

Thiol-based Oxidative Posttranslational Modifications (OxiPTMs) of Plant Proteins

The thiol group of cysteine (Cys) residues, often present in the active center of the protein, is of particular importance to protein function, which is significantly determined by the redox state of a protein's environment. Our knowledge of different thiol-based oxidative posttranslational modifications (oxiPTMs), which compete for specific protein thiol groups, has increased over the last 10 years. The principal oxiPTMs include S-sulfenylation, S-glutathionylation, S-nitrosation, persulfidation, S-cyanylation and S-acylation. The role of each oxiPTM depends on the redox cellular state, which in turn depends on cellular homeostasis under either optimal or stressful conditions. Under such conditions, the metabolism of molecules such as glutathione, NADPH (reduced nicotinamide adenine dinucleotide phosphate), nitric oxide, hydrogen sulfide and hydrogen peroxide can be altered, exacerbated and, consequently, outside the cell's control. This review provides a broad overview of these oxiPTMs under physiological and unfavorable conditions, which can regulate the function of target proteins.

A novel fluorescent probe for real-time imaging of thionitrous acid under inflammatory and oxidative conditions

Thionitrous acid (HSNO), a crosstalk intermediate of two crucial gasotransmitters nitric oxide and hydrogen sulfide, plays a critical role in redox regulation of cellular signaling and functions. However, real-time and facile detection of HSNO with high selectivity and sensitivity remains highly challenging. Herein we report a novel fluorescent probe (SNP-1) for HSNO detection. SNP-1 has a simple molecular structure, but showing strong fluorescence, a low detection limit, a broad linear detection range (from nanomolar to micromolar concentrations), ultrasensitivity, and high selectivity for HSNO in both aqueous media and cells. Benefiting from these unique features, SNP-1 could effectively visualize changes of HSNO levels in mouse models of acute ulcerative colitis and renal ischemia/reperfusion injury. Moreover, the good correlation between colonic HSNO levels and disease activity index demonstrated that HSNO is a promising new diagnostic agent for acute ulcerative colitis. Therefore, SNP-1 can serve as a useful fluorescent probe for precision detection of HSNO in various biological systems, thereby facilitating mechanistic studies, therapeutic assessment, and high-content drug screening for corresponding diseases.

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HSNO was the preferred intermediate to study crosstalk between H₂S and NO.

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HSNO displayed translational potential for diagnosis and assessment of diseases.

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SNP-1 displayed excellent fluorescence performance for HSNO detection.

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SNP-1 could effectively image HSNO in cells and mouse models.

Fluorescent probes for the detection of disease-associated biomarkers

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.

Biocompatible perovskite quantum dots with superior water resistance enable long-term monitoring of the H2S level in vivo

The application of perovskite quantum dots (PQDs) in biomedical fields such as bioimaging and biosensing has been limited owing to their instability in the physiological environment. Herein, PQDs are innovatively encapsulated into nano-micelles composed of a polyethylene glycol-polycaprolactone (PEG-PCL) block copolymer, which allows the preparation of biocompatible PQDs (bio-PQDs) with excellent water resistance. Due to the benefits of extraordinary water resistance and biocompatibility, these bio-PQDs are capable of real-time and long-term quantitatively monitoring the H₂S level in living cells as well as in zebrafish.

A modular template for the design of thiol-triggered sensors and prodrugs

A unique reaction between thiols (RSH) and alkyl sulfonylbenzothiazole was discovered. This reaction was specific for thiols and produced a sulfinic acid (RSO₂H) as the intermediate, which further triggered an intramolecular cyclization to release a -OH containing payload. This reaction was used to develop thiol-triggered fluorescent sensors and prodrugs. The modular design of this template provides tunability of the release profiles of the payloads.

Mitochondria and lysosome-targetable fluorescent probes for hydrogen peroxide

Hydrogen peroxide (H₂O₂), as a key member of the reactive oxygen species (ROS), has a certain regulatory effect on many physiological processes, such as cell proliferation, differentiation and migration. However, abnormal production of H₂O₂ can cause diseases including cancer, Alzheimer's disease, cardiovascular disease, and so on. Therefore, it is important to detect changes in H₂O₂ at the subcellular level. In recent years, many fluorescent probes for H₂O₂ have been developed and used in living cells. In this review, we introduce some typical fluorescent probes for H₂O₂ with mitochondrial and lysosomal targeting. This review contains targeting strategies, detection mechanisms, optical characteristics and cell imaging of these probes.

A novel fluorescent probe with dual-sites for simultaneously monitoring metabolisms of cysteine in living cells and zebrafishes

Understanding cellular metabolism holds immense potential for developing new drugs that regulate metabolic pathways. Two gas signal molecules, SO₂ and H₂S, are the main metabolites from cysteine (Cys) via oxidation and desulfurization pathways, respectively. However, a few fluorescent probes for real-time monitor of the metabolic pathways of cysteine have been reported. To understand metabolic alterations of cysteine, we have rationally designed and prepared a dual-signal fluorescent probe HN, which could differentiate SO₂ and H₂S through two different fluorescence channels simultaneously, along with similar reaction kinetics and both "off-on" fluorescence responses. Probe HN exhibits the potential to monitor the metabolism pathways of cysteine, and the distinguishment of cancer cells from normal cells could be realized. This methodology will promote further understanding of the physiological and pathological roles of cysteine.

Employing a fluorescent and colorimetric picolyl-functionalized rhodamine for the detection of glyphosate pesticide

The ongoing poisoning of agricultural products has pushed the security problem to become an important issue. Among them, exceeding the standard rate of pesticide residues is the main factor influencing the quality and security of agricultural products. Monitoring pesticide residues and developing simple, yet ultrasensitive detection systems for pesticide residues are urgently needed. In this study, we successfully developed a novel rhodamine derivative as fluorescent and colorimetric chemosensor R-G for the rapid, selective and ultrasensitive detection of glyphosate pesticide residue in aqueous solution. Through a Cu²⁺-indicator displacement strategy, glyphosate can displace an indicator (R-G) from a Cu²⁺-indicator complex due to its strong affinity to bind with Cu²⁺ to give a turn-on fluorescence and distinct color change. Moreover, a test strip was also fabricated to achieve a facile detection of glyphosate pesticide. To demonstrate the possibility of practical applications, glyphosate was detected on the surface of cabbage and in a spiked soil sample. The detection limit of 4.1 nM and the response time of 2 min indicate that the method is enough sensitive and rapid to detect the glyphosate residue at or below levels that pose a health risk.

Recent advances in probe design to detect reactive sulfur species and in the chemical reactions employed for fluorescence switching

Reactive sulfur species, including hydrogen sulfide, hydropersulfide, and polysulfide, have many roles in biological systems. For example, hydrogen sulfide is involved in the relaxation of vascular smooth muscles and mediation of neurotransmission, while sulfane sulfur, which exists in cysteine persulfide/polysulfide, and glutathione persulfide/polysulfide, is involved in physiological antioxidation and cytoprotection mechanisms. Fluorescence imaging is well suited for real-time monitoring of reactive sulfur species in living cells, and many fluorescent probes for reactive sulfur species have been reported. In such probes, the choice of detection chemistry is extremely important, not only to achieve effective fluorescence switching and high selectivity, but also because the reactions may be applicable to develop other chemical tools, such as reactive sulfur species donors/scavengers. Here, we present an overview of both widely used and recently developed fluorescent probes for reactive sulfur species, focusing especially on the chemical reactions employed in them for fluorescence switching. We also briefly introduce some applications of fluorescent probes for hydrogen sulfide and sulfane sulfur.

Specific Reactions of RSNO, HSNO, and HNO and Their Applications in the Design of Fluorescent Probes

Nitric oxide (NO)-derived species play essential roles in regulating cellular responses. Among these species, S-nitrosothiols (including RSNO and HSNO) and nitroxyl (HNO) are especially interesting. Owing to their high reactivity and short survival time, the detection of these molecules in biological settings can be challenging. In this regard, much effort has been invested in exploring novel reactions of RSNO/HSNO/HNO and applying these reactions to develop fluorescence probes. Herein, reported specific reactions of RSNO/HSNO/HNO are summarized and strategies used in the design of fluorescent probes are illustrated. The properties and potential problems of representative probes are also discussed.

Aggregation Enhanced Responsiveness of Rationally Designed Probes to Hydrogen Sulfide for Targeted Cancer Imaging

Activatable molecular probes hold great promise for targeted cancer imaging. However, the hydrophobic nature of most conventional probes makes them generate precipitated agglomerate in aqueous media, thereby annihilating their responsiveness to analytes and precluding their practical applications for bioimaging. This study reports the development of two small molecular probes with unprecedented aggregation enhanced responsiveness to H₂S for in vivo imaging of H₂S-rich cancers. The subtle modulation of the equilibrium between hydrophilicity and lipophilicity by N-methylpyridinium endows these designed probes with the capability of spontaneously self-assembling into nanoprobes under physiological conditions. Such probes in an aggregated state, rather than a molecular dissolved state, show NIR fluorescence light up and photoacoustic signals turn on upon H₂S specific activation, allowing in vivo visualization and differentiation of cancers based on differences in H₂S content. Thus, our study presents an effective design strategy which should pave the way to molecular design of optimized probes for precision cancer diagnostics.

Rational design of ERα targeting hypoxia turn-on fluorescent probes with antiproliferative activity for breast cancer

The overexpression of estrogen receptor (ER) α is not only closely related to the development of ER⁺ breast cancer, but is also an important biomarker for clinical diagnosis and treatment. Herein, we report several ERα targeting hypoxia turn-on fluorescent probes with antitumor activity for breast cancer cells. Among them, probes 3 and 5 displayed good ERα targeting ability and favorable hypoxia turn-on response in MCF-7 cells. Moreover, the probes 3 and 5 exhibited good antiproliferative activity towards MCF-7 cells (IC₅₀ = 8.5 μM, 10.3 μM) and a much lower cytotoxicity to normal cells compared with the positive control. It is expected that these novel fluorescent probes may provide useful tools for the theranostics of ER⁺ breast cancer.

Highly efficient H2S scavengers via thiolysis of positively-charged NBD amines

H2S is a well-known toxic gas and also a gaseous signaling molecule involved in many biological processes. Advanced chemical tools that can regulate H2S levels in vivo are useful for understanding H2S biology as well as its potential therapeutic effects. To this end, we have developed a series of 7-nitro-1,2,3-benzoxadiazole (NBD) amines as potential H2S scavengers. The kinetic studies of thiolysis reactions revealed that incorporation of positively-charged groups onto the NBD amines greatly increased the rate of the H2S-specific thiolysis reaction. We demonstrate that these reactions proceed effectively, with second order rate constants (k 2) of >116 M-1 s-1 at 37 °C for NBD-S8. Additionally, we demonstrate that NBD-S8 can effectively scavenge enzymatically-produced and endogenous H2S in live cells. Furthering the biological significance, we demonstrate NBD-S8 mediates scavenging of H2S in mice.

Far-red pentamethine cyanine dyes as fluorescent probes for the detection of serum albumins

Benzothiazole based cyanine dyes with bridged groups in the pentamethine chain were studied as potential far-red fluorescent probes for protein detection. Spectral-luminescent properties were characterized for unbound dyes and in the presence of serum albumins (bovine (BSA), human (HSA), equine (ESA)), and globular proteins (β-lactoglobulin, ovalbumin). We have observed that the addition of albumins leads to a significant increase in dyes fluorescence intensity. However, the fluorescent response of dyes in the presence of other globular proteins was notably lower. The value of fluorescence quantum yield for dye bearing a sulfonate group complexed with HSA amounted to 42% compared with 0.2% for the free dye. The detection limit of HSA by this dye was greater than 0.004 mg ml-1 which indicates the high sensitivity of dye to low HSA concentrations. Modelling of structure of the dyes complexes with albumin molecules was performed by molecular docking. According to these data, dyes could bind to up to five sites on the HSA molecule; the most preferable are the haemin-binding site in subdomain IB and the dye-binding site in the pocket between subdomains IA, IIA and IIIA. This work confirms that pentamethine cyanine dyes could be proposed as powerful far-red fluorescent probes applicable for highly sensitive detection of albumins.

Photochemistry of HNSO2 in cryogenic matrices: spectroscopic identification of the intermediates and mechanism

Small molecules solely consisting of H, N, O, and S are highly relevant intermediates in atmospheric chemistry and biology. Even though several isomers of [HNO2S] have been computationally predicted, only the IR spectra for the two lowest-energy isomers HNSO2 and syn-syn HONSO have been previously reported. Herein, the photochemistry (193 nm laser) of HNSO2 in N2-, Ne-, and Ar-matrices (≤15 K) has been studied. Aside from syn-syn HONSO, several new isomers including anti-syn HONSO, gauche-syn HOSNO, syn HOS(O)N, anti HOS(O)N, syn HS(O)NO, anti HN(O)SO, gauche-syn HSONO, and an elusive caged-radical pair HOS˙˙NO have been identified. Additionally, the formation of fragments HONO, HO˙, ˙NO, and ˙NO2 has also been observed. The characterization of these species with matrix-isolation IR and UV/Vis spectroscopy is supported by 15N-labeling and quantum chemical computations at the B3LYP/6-311++G(3df,3pd) level. Furthermore, the photo-induced isomerization reactions, including the conformational conversion of syn-syn HONSO → anti-syn HONSO and reversible isomerization of HOSNO ↔ anti-syn HONSO, syn-syn HONSO ↔ HN(O)SO, HSONO ↔ HS(O)NO, and HOS˙˙NO ↔ HOSNO have also been observed, and the underlying mechanism is discussed.

A ratiometric fluorescent probe for visualization of thiophenol and its applications

Thiophenol has a broad application in agriculture and industry. However, thiophenol can harm to the environment and health for its high toxicity. Developing an effective method for detection of thiophenol in the field of environmental and biology is valuable. In this work, we construct a reaction-based ratiometric fluorescent probe (E)-4-(2-(7-(diethylamino)-2-oxo-2H-chromen-3-yl)vinyl)-1-(4-(2,4-dinitrophenoxy)benzyl)pyridin-1-ium bromide (DCVP-DNP) for probing thiophenol in environment and cells by employing (E)-7-(diethylamino)-3-(2-(pyridin-4-yl)vinyl)-2H-chromen-2-one (DCVP) as the fluorophore and 2,4-dinitrophenyl (DNP) ether as the recognition group for the first time. The probe has high selectivity for thiophenol though thiophenol-triggered nucleophilic substitution reaction. In addition, the ratio of emission intensities of the probe has linearly with thiophenol concentration in the range of 0-65 μM and the detection limit of thiophenol is as low as 4.8 × 10^-8 M. Moreover, the probe can not only be applied for detection of thiophenol in water samples, but also image thiophenol in living cells, suggesting its potential application in environment and biological system.

A large-Stokes-shift fluorescent probe for Zn2+ based on AIE, and application in live cell imaging

A fluorescence-enhanced sensor based on aggregation-induced emission (AIE) was synthesized using a di(2-picolyl)amine (DPA) group as a highly selective metal chelating agent for Zn²⁺. The combination of the probe and Zn²⁺ was achieved in an environment where the volume fraction of water was 90%, giving the probe good biocompatibility, and a large Stokes shift (100 nm) occurred after Zn²⁺ was combined with the probe. The obvious color change makes the probe visible to the naked eye, and gives it a high signal-to-noise ratio, and high contrast, and minimizes self-absorption. Because of the high selectivity of the DPA group to Zn²⁺, the sensitivity of the probe to detect Zn²⁺ has been improved. The mechanism of the formation of complexes between the probe and Zn²⁺ was confirmed by nuclear magnetic resonance spectroscopy (NMR), high-resolution mass spectrometry (HRMS), and particle size distribution. Under the optimal experimental conditions, the linear fluorescence reaction of Zn²⁺ was good, between 0.2 and 18 μM, and the detection limit was 1.3 × 10^-7 M. The low toxicity and excellent membrane permeability of the probe in living cells enable it to be efficiently applied for Zn²⁺ imaging in cells. Graphical abstract.

A highly selective and sensitive fluorescent probe based on the chromone fluorophore for imaging hydrogen sulfide in living cells

A fluorescent probe that was designed based on the 6-amino chromone fluorophore for detecting H₂S can distinguish H₂S from Cys/GSH under acidic conditions.

Loss of thioredoxin reductase function in a mouse stroke model disclosed by a two-photon fluorescent probe

The first two-photon fluorescent probe (TP-TRFS) is reported, and it was successfully used in vivo.

Defining a standardized methodology for the determination of the antioxidant capacity: case study of Pistacia atlantica leaves

Antioxidant activity can be measured by a variety of methods, that include hydrogen atom transfer (HAT) and single electron transfer (ET) methods.

Near-infrared ratiometric self-assembled theranostic nanoprobe: imaging and tracking cancer chemotherapy

A novel near-infrared ratiometric fluorescent theranostic nanoprobe is applied for real-time fluorescence tracking and imaging cancer therapy in vivo and in situ.

Stepwise elucidation of fluorescence based sensing mechanisms considering picric acid as a model analyte

The precise study of fluorescence-based sensing mechanisms and a step-by-step design experiment for the elucidation of the mechanism of sensing for newly designed sensing systems can be ascertained using the presented tutorial review.

A paper-based chemosensor for highly specific, ultrasensitive, and instantaneous visual detection of toxic phosgene

A chemosensor containing an o-hydroxyaniline unit as the reaction site was developed for colorimetric and fluorimetric detection of phosgene, which showed fast response (15 s), high specificity, and an extremely low detection limit.