Point-of-Care Testing of Whole Blood for Liver Injury Auxiliary Diagnosis with Biothiols Activable Chemiluminescent Probe.

Liver injury significantly affects a patient's health and quality of life. However, timely and convenient diagnosis of this disease via whole blood detection remains challenging due to the lack of user-friendly and fast readout blood test methods. Herein, we developed such a method for the swift auxiliary diagnosis of liver injury via whole blood detection using a customed point-of-care testing (POCT) system consisting of a biothiols-activatable chemiluminescent probe and a hand-held POCT device. Biothiols served as the target to build the activable chemiluminescence probe due to their abnormal level in liver injury. Compared with fluorescent and electrical POCTs, this method is more convenient and has strong universality. By incorporating cyclodextrin via host-guest chemistry, we intensified chemiluminescence while mitigating chemical hemolysis caused by the dissolution of organic molecules, making this system suitable for whole blood analysis. Preliminary assessments in aqueous solutions, living cells, and mouse models confirmed its sensitivity, reliability, and feasibility. Simply mixing blood with the probe for 30 min yielded a clear signal readout within 15 s on the POCT device. Utilizing this portable detector, the reduced biothiol level was tested in 18 liver injury patient blood samples, and the results were similar to those measured by a commercial kit and in vivo imaging system. Thus, this work provides a universal platform for the fast and convenient detection of other biomarkers in whole blood samples and opens up possibilities for the rapid clinical diagnosis of diseases, enabling patients to conduct home self-examinations with ease.

NIR Fluorescent/Photoacoustic Bimodal Imaging of Ferroptosis in Pancreatic Cancer Using Biothiols-Activable Probes.

Ferroptosis modulation is a powerful therapeutic option for pancreatic ductal adenocarcinoma (PDAC) with a low 5-year survival rate and lack of effective treatment methods. However, due to the dual role of ferroptosis in promoting and inhibiting pancreatic tumorigenesis, regulating the degree of ferroptosis is very important to obtain the best therapeutic effect of PDAC. Biothiols are suitable as biomarkers of imaging ferroptosis due to the dramatic decreases of biothiol levels in ferroptosis caused by the inhibited synthesis pathway of glutathione (GSH) and the depletion of biothiol by reactive oxygen species. Moreover, a very recent study reported that cysteine (Cys) depletion can lead to pancreatic tumor ferroptosis in mice and may be employed as an effective therapeutic strategy for PDAC. Therefore, visualization of biothiols in ferroptosis of PDAC will be helpful for regulating the degree of ferroptosis, understanding the mechanism of Cys depletion-induced pancreatic tumor ferroptosis, and further promoting the study and treatment of PDAC. Herein, two biothiol-activable near-infrared (NIR) fluorescent/photoacoustic bimodal imaging probes (HYD-BX and HYD-DX) for imaging of pancreatic tumor ferroptosis were reported. These two probes show excellent bimodal response performances for biothiols in solution, cells, and tumors. Subsequently, they have been employed successfully for real-time visualization of changes in concentration levels of biothiols during the ferroptosis process in PDAC cells and HepG2 cells. Most importantly, they have been further applied for bimodal imaging of ferroptosis in pancreatic cancer in mice, with satisfactory results. The development of these two probes provides new tools for monitoring changes in concentration levels of biothiols in ferroptosis and will have a positive impact on understanding the mechanism of Cys depletion-induced pancreatic tumor ferroptosis and further promoting the study and treatment of PDAC.

JS-K Combined with a Melanin-Based Theranostic Agent: A Novel Sequential Delivery Strategy to Enhance the Near-Infrared Fluorescence Imaging of Pancreatic Ductal Adenocarcinoma.

Pancreatic ductal adenocarcinoma (PDAC) is an aggressive malignancy with a 5 year survival rate less than 12%. This malignancy is closely related to the unique tumor microenvironment (TME), which is characterized by a hypovascular and hyperdense extracellular matrix, making it difficult for drugs to permeate the tumor center. Near-infrared fluorescence (NIRF) imaging, which has high sensitivity and resolution, may improve the survival rate of PDAC patients. In this study, we first used JS-K (O2-(2,4-dinitrophenyl) 1-[(4-ethoxycarbonyl) piperazine-1-yl] diazene-1-ium-1,2-diolate) to specifically dilate blood vessels within the TME of PDAC patients and subsequently injected IR820-PEG-MNPs (IPM NPs) to diagnose and treat orthotopic PDAC. We found that JS-K promoted the accumulation of IPM NPs in orthotopic Pan02 tumor-bearing mice and was able to increase the tumor signal-to-background ratio (SBR) in the orthotopic PDAC area by 41.5%. In addition, surgical navigation in orthotopic Pan02 tumor-bearing mice and complete tumor resection based on fluorescence imaging were achieved with a detection sensitivity of 81.0%. Moreover, we verified the feasibility of the combination of laparoscopy and photothermal ablation (PTA) for the treatment of PDAC. Finally, we demonstrated that IPM NPs had greater affinity for human PDAC tissues than for normal pancreatic tissues ex vivo, preliminarily highlighting the potential for clinical translation of these NPs. In conclusion, we developed and validated a novel sequential delivery strategy that promotes the accumulation of nanoagents in the tumor area and can be used for the diagnosis and treatment of PDAC.

IL-17 signaling pathway: A potential therapeutic target for reducing skeletal muscle inflammation.

BACKGROUND: The interleukin-17 (IL-17) signaling pathway is intricately linked with immunity and inflammation; however, the association between the IL-17 signaling pathway and skeletal muscle inflammation remains poorly understood. The study aims to investigate the role of the IL-17 signaling pathway in skeletal muscle inflammation and to evaluate the therapeutic potential of anti-IL-17 antibodies in reducing muscle inflammation. METHODS: A skeletal muscle inflammation model was induced by cardiotoxin (CTX) injection in C57BL6/J mice. Following treatment with an anti-IL-17 antibody, we conducted a comprehensive analysis integrating single-cell RNA sequencing (scRNA-seq), bioinformatics, enzyme-linked immunosorbent assay (ELISA), immunofluorescence, and Western blot techniques to elucidate underlying mechanisms. RESULTS: scRNA-seq analysis revealed a significant increase in neutrophil numbers and activity in inflamed skeletal muscle compared to other cell types, including macrophages, T cells, B cells, endothelial cells, fast muscle cells, fibroblasts, and skeletal muscle satellite cells. The top 30 differentially expressed genes within neutrophils, along with 55 chemokines, were predominantly enriched in the IL-17 signaling pathway. Moreover, the IL-17 signaling pathway exhibited heightened expression in inflamed skeletal muscle, particularly within neutrophils. Treatment with anti-IL-17 antibody resulted in the suppression of IL-17 signaling pathway expression, accompanied by reduced levels of pro-inflammatory cytokines IL-1ß, IL-6, and TNF-α, as well as decreased numbers and activity of Ly6g+/Mpo+ neutrophils compared to CTX-induced skeletal muscle inflammation. CONCLUSION: Our findings suggest that the IL-17 signaling pathway plays a crucial role in promoting inflammation within skeletal muscle. Targeting this pathway may hold promise as a therapeutic strategy for ameliorating the inflammatory micro-environment and reducing cytokine production.

A de novo strategy to develop NIR precipitating fluorochrome for long-term in situ cell membrane bioimaging.

Cell membrane-targeted bioimaging is a prerequisite for studying the roles of membrane-associated biomolecules in various physiological and pathological processes. However, long-term in situ bioimaging on the cell membrane with conventional fluorescent probes leads to diffusion into cells from the membrane surface. Therefore, we herein proposed a de novo strategy to construct an antidiffusion probe by integrating a fluorochrome characterized by strong hydrophobicity and low lipophilicity, with an enzyme substrate to meet this challenge. This precipitating fluorochrome HYPQ was designed by conjugating the traditionally strong hydrophobic solid-state fluorochrome 6-chloro-2-(2-hydroxyphenyl) quinazolin-4(3H)-one (HPQ) with a 2-(2-methyl-4H-chromen-4-ylidene) malononitrile group to obtain closer stacking to lower lipophilicity and elongate emission to the far-red to near-infrared wavelength. As proof-of-concept, the membrane-associated enzyme γ-glutamyltranspeptidase (GGT) was selected as a model enzyme to design the antidiffusion probe HYPQG. Then, benefiting from the precipitating and stable signal properties of HYPQ, in situ imaging of GGT on the membrane was successfully realized. Moreover, after HYPQG was activated by GGT, the fluorescence signal on the cell membrane remained unchanged, with incubation time even extending to 6 h, which is significant for in situ monitoring of enzymatic activity. In vivo testing subsequently showed that the tumor region could be accurately defined by this probe after long-term in situ imaging of tumor-bearing mice. The excellent performance of HYPQ indicates that it may be an ideal alternative for constructing universal antidiffusion fluorescent probes, potentially providing an efficient tool for accurate imaging-guided surgery in the future.

A review of metallurgical slags as catalysts in advanced oxidation processes for removal of refractory organic pollutants in wastewater.

With the rapid growth of the metallurgical industry, there is a significant increase in the production of metallurgical slags. The waste slags pose significant challenges for their disposal because of complex compositions, low utilization rates, and environmental toxicity. One promising approach is to utilize metallurgical slags as catalysts for treatment of refractory organic pollutants in wastewater through advanced oxidation processes (AOPs), achieving the objective of "treating waste with waste". This work provides a literature review of the source, production, and chemical composition of metallurgical slags, including steel slag, copper slag, electrolytic manganese residue, and red mud. It emphasizes the modification methods of metallurgical slags as catalysts and the application in AOPs for degradation of refractory organic pollutants. The reaction conditions, catalytic performance, and degradation mechanisms of organic pollutants using metallurgical slags are summarized. Studies have proved the feasibility of using metallurgical slags as catalysts for removing various pollutants by AOPs. The catalytic performance was significantly influenced by slags-derived catalysts, catalyst modification, and process factors. Future research should focus on addressing the safety and stability of catalysts, developing green and efficient modification methods, enhancing degradation efficiency, and implementing large-scale treatment of real wastewater. This work offers insights into the resource utilization of metallurgical slags and pollutant degradation in wastewater.

Reaction-Activated Disassembly of the NIR-II Probe Enables Fast Detection and Ratiometric Photoacoustic Imaging of Glutathione In Vivo.

Glutathione (GSH), the most abundant nonprotein biothiol, is a significant endogenous molecule that plays a key role in redox equilibrium in vivo and is regarded as a critical biomarker of cancer. Currently, various fluorescent probes have been designed and synthesized for imaging GSH at the cellular level in the visible range and the first near-infrared window (NIR-I, 750-900 nm). However, the application of these fluorescent probes for bioimaging and biosensing in vivo has been extremely hindered by the high biobackground and low tissue penetration. Herein, based on the self-assembly and disassembly of J-aggregation, we designed and synthesized a GSH-activatable probe MC-PSE for second near-infrared window (NIR-II) fluorescence and ratiometric photoacoustic imaging of GSH in vivo. The anionic cyanine-based MC-PSE tends to form stable J-aggregates in an aqueous solution. Upon the reaction with GSH, the J-aggregates of MC-PSE disassembled, the emission peak intensity of MC-PSE at 940 nm significantly increased by about 20 times, and the PA900/PA980 ratio increased by 4 times within 15 min in vitro. Notably, we used MC-PSE to visualize GSH in tumor-bearing mice and to distinguish normal and tumor areas successfully by virtue of NIR-II FL and PA dual-modal imaging. The design strategy of MC-PSE provides a novel method for ratiometric photoacoustic imaging, and MC-PSE is expected to be a powerful tool for the accurate detection of GSH in cancer diagnosis.

Biochar/layered double hydroxides composites as catalysts for treatment of organic wastewater by advanced oxidation processes: A review.

Heterogeneous advanced oxidation process has been widely studied as an effective method for removing organic pollutants in wastewater, but the development of efficient catalysts is still challenging. This review summaries the present status of researches on biochar/layered double hydroxides composites (BLDHCs) as catalysts for treatment of organic wastewater. The synthesis methods of layered double hydroxides, the characterizations of BLDHCs, the impacts of process factors influencing catalytic performance, and research advances in various advanced oxidation processes are discussed in this work. The integration of layered double hydroxides and biochar provides synthetic effects for improving pollutant removal. The enhanced pollutant degradation in heterogeneous Fenton, sulfate radical-based, sono-assisted, and photo-assisted processes using BLDHCs have been verified. Pollutant degradation in heterogeneous advanced oxidation processes using BLDHCs is influenced by process factors such as catalyst dosage, oxidant addition, solution pH, reaction time, temperature, and co-existing substances. BLDHCs are promising catalysts due to the unique features including easy preparation, distinct structure, adjustable metal ions, and high stability. Currently, catalytic degradation of organic pollutants using BLDHCs is still in its infancy. More researches should be conducted on the controllable synthesis of BLDHCs, the in-depth understanding of catalytic mechanism, the improvement of catalytic performance, and large-scale application of treating real wastewater.

A Quencher-Based Blood-Autofluorescence-Suppression Strategy Enables the Quantification of Trace Analytes in Whole Blood.

Precise quantification of trace components in whole blood via fluorescence is of great significance. However, the applicability of current fluorescent probes in whole blood is largely hindered by the strong blood autofluorescence. Here, we proposed a blood autofluorescence-suppressed sensing strategy to develop an activable fluorescent probe for quantification of trace analyte in whole blood. Based on inner filter effect, by screening fluorophores whose absorption overlapped with the emission of blood, a redshift BODIPY quencher with an absorption wavelength ranging from 600-700 nm was selected for its superior quenching efficiency and high brightness. Two 7-nitrobenzo[c] [1,2,5] oxadiazole ether groups were introduced onto the BODIPY skeleton for quenching its fluorescence and the response of H2 S, a gas signal molecule that can hardly be quantified because of its low concentration in whole blood. Such detection system shows a pretty low background signal and high signal-to-back ratio, the probe thus achieved the accurate quantification of endogenous H2 S in 20-fold dilution of whole blood samples, which is the first attempt of quantifying endogenous H2 S in whole blood. Moreover, this autofluorescence-suppressed sensing strategy could be expanded to other trace analytes detection in whole blood, which may accelerate the application of fluorescent probes in clinical blood test.

Precipitated Fluorophore-Based Molecular Probe for In Situ Imaging of Aminopeptidase N in Living Cells and Tumors.

Aminopeptidase N (APN) is capable of cleaving N-terminal amino acids from peptides with alanine in the N-terminal position and plays a key role in the growth, migration, and metastasis of cancer. However, reliable in situ information is hard to be obtained with the current APN-responsive molecular probes because the released fluorophores are cytoplasmic soluble and thus rapidly depart from the enzymatic reaction sites and spread out all over the cytoplasm. Here, we report a de novo precipitated fluorophore, HBPQ, which is completely insoluble in water and shows strong yellow solid emission when excited with a 405 nm laser. Owing to the controllable solid fluorescence of HBPQ by the protection-deprotection of phenolic hydroxyl, we further utilized HBPQ to design an APN-responsive fluorogenic probe (HBPQ-A) for the imaging of intracellular APN. Importantly, HBPQ-A can not only perform in situ imaging of APN in different organelles (e.g., lysosomes, mitochondria, endoplasmic reticula, and so forth) but also display a stable and indiffusible fluorescent signal for reliable mapping of the distribution of APN in living cells. In addition, through real-time imaging of APN in 4T1 tumors, we found that the fluorescent signal with high fidelity generated by HBPQ-A could remain constant even after 12 h, which further confirmed its diffusion-resistant ability and long-term reliable imaging ability. We believe that the precipitated fluorophore may have great potential for long-term in situ imaging.

Learning from Artemisinin: Bioinspired Design of a Reaction-Based Fluorescent Probe for the Selective Sensing of Labile Heme in Complex Biosystems.

Labile heme (LH) is an important signaling molecule in virtually all organisms. However, specifically detecting LH remains an outstanding challenge. Herein, by learning from the bioactivation mechanism of artemisinin, we have developed the first LH-responsive small-molecule fluorescent probe, HNG, based on a 4-amino-1,8-naphthalimide (NG) fluorophore. HNG showed high selectivity for LH without interference from hemin, protein-interacting heme, and zinc protoporphyrin. Using HNG, the changes of LH levels in live cells were imaged, and a positive correlation of LH level with the degree of hemolysis was uncovered in hemolytic mice. Our study not only presents the first molecular probe for specific LH detection but also provides a strategy to construct probes with high specificity through a bioinspired approach.

Naked-Eye Readout of Analyte-Induced NIR Fluorescence Responses by an Initiation-Input-Transduction Nanoplatform.

Fluorescence visualization (FV) in the near-infrared (NIR) window promises to break through the signal-to-background ratio (SBR) bottleneck of traditional visible-light-driven FV methods. However, straightforward NIR-FV has not been realized, owing to the lack of methods to readily transduce NIR responses into instrument-free, naked eye-recognizable outputs. Now, an initiation-input-transduction platform comprising a well-designed NIR fluorophore as the signal initiator and lanthanide-doped nanocrystals as the transducer for facile NIR-FV is presented. The analyte-induced off-on NIR signal serves as a sensitizing switch of transducer visible luminescence for naked-eye readout. The design is demonstrated for portable, quantitative detection of phosgene with significantly improved SBR and sensitivity. By further exploration of initiators, this strategy holds promise to create advanced NIR-FV probes for broad sensing applications.

Fabricating Dual-Atom Iron Catalysts for Efficient Oxygen Evolution Reaction: A Heteroatom Modulator Approach.

Understanding the thermal aggregation behavior of metal atoms is important for the synthesis of supported metal clusters. Here, derived from a metal-organic framework encapsulating a trinuclear FeIII 2 FeII complex (denoted as Fe3 ) within the channels, a well-defined nitrogen-doped carbon layer is fabricated as an ideal support for stabilizing the generated iron nanoclusters. Atomic replacement of FeII by other metal(II) ions (e.g., ZnII /CoII ) via synthesizing isostructural trinuclear-complex precursors (Fe2 Zn/Fe2 Co), namely the "heteroatom modulator approach", is inhibiting the aggregation of Fe atoms toward nanoclusters with formation of a stable iron dimer in an optimal metal-nitrogen moiety, clearly identified by direct transmission electron microscopy and X-ray absorption fine structure analysis. The supported iron dimer, serving as cooperative metal-metal site, acts as efficient oxygen evolution catalyst. Our findings offer an atomic insight to guide the future design of ultrasmall metal clusters bearing outstanding catalytic capabilities.

Fluorescence-Guided Cancer Diagnosis and Surgery by a Zero Cross-Talk Ratiometric Near-Infrared γ-Glutamyltranspeptidase Fluorescent Probe.

The ability to detect cancer early in an accurate and rapid fashion is of critical importance for cancer diagnosis and accurate resection in surgery. γ-Glutamyltranspeptidase (GGT) is overexpressed in several human cancers, while maintaining a low expression in normal microenvironments, and thus is recognized as an important cancer biomarker. To date, rational design of a zero cross-talk ratiometric near-infrared (NIR) GGT fluorescent probe for efficient cancer diagnosis in various biological samples is still a big challenge. In this work, a zero cross-talk ratiometric NIR GGT fluorescent probe named Cy-GSH is developed. Cy-GSH shows high sensitivity to GGT, which is desired for early cancer diagnosis. Upon additional GGT, a large emission shift from 805 to 640 nm is observed, which is suitable for visualizing deeply located cancer in vivo. In addition, successful monitoring of GGT activity in blood, cells, tissues, and in vivo makes Cy-GSH possess great potential for the clinical cancer early diagnosis. Furthermore, accurately visualizing tumors and metastases in mouse models illuminates that the probe may be a convenient tool for fluorescence-guided cancer surgery. To our knowledge, this is the first report to describe the strategy of a zero cross-talk ratiometric NIR GGT fluorescent probe for early cancer diagnosis and fluorescence-guided surgery.

Two-Photon Supramolecular Nanoplatform for Ratiometric Bioimaging.

Two-photon fluorescent imaging that utilizes two near-infrared photons as an excitation source affords higher penetration depth of tissue for biomedical research, compared with one-photon fluorescent imaging. However, the high laser power levels of the excitation source may induce photobleaching of two-photon dyes and photodamage to biosamples, which hampers its wide application for in vivo imaging. Inspired by supramolecular chemistry, we have developed a two-photon excited nanoprobe (TPFN) via host-guest interaction with excellent sensitivity, selectivity, biocompatibility, water solubility, and imaging penetration depth. Notably, this supramolecular assembly can significantly amplify the fluorescence intensities of guest molecules (21-fold increase), thereby affording a detection limit of 0.127 µM for sensing H2O2, which is greatly lower than that of free guest molecules (11.98 µM). In particular, ratiometric fluorescent imaging provides more accurate analysis of intracellular H2O2 via the built-in correction of the internal reference. Importantly, TPFN excited by a two-photon laser provides higher penetration depth for visualizing H2O2 in deeper liver tissues, compared with that of one-photon excitation. Thus, TPFN can serve as a powerful nanoplatform for ratiometric imaging of various species via this facile supramolecular self-assembly strategy.

Near-Infrared Fluorescent Furin Probe for Revealing the Role of Furin in Cellular Carcinogenesis and Specific Cancer Imaging.

Furin, an important member in the family of proprotein convertases, is a participant in the activation of various precursor proteins. The expression level of furin stays in a very low range in most normal cells, but elevates with a big margin in many cancer cells. More importantly, furin is closely related to tumor formation and migration. Herein, a furin-activatable near-infrared (NIR) fluorescent probe (HD-F) was first developed that allowed for specific, sensitive detection and imaging of furin both in vitro and in vivo. HD-F consists of a classical NIR fluorophore (HD), a furin-particular polypeptide sequence RVRR, and a self-eliminating linker. Without the interaction with furin, no noticeable fluorescence enhancement was detected, even over 3 days, demonstrating the excellent stability of HD-F. Upon conversion by furin, there was a distinct signal increase around 708 nm. It has achieved assay and visualization of endogenous furin in various cells, tumor tissues, and tumor-bearing mouse models. Importantly, HD-F is well-suited for monitoring the change of furin expression level in the process of hypoxia-inducible factor-1 stabilized by CoCl2. Moreover, HD-F could visualize the divergence in the expression level of furin between normal and cancer cells, indicating its potential in specific cancer imaging. Thus, this novel probe is able to serve as a potential tackle for better understanding of the intrinsic link between a hypoxic physiological environment and cellular carcinogenesis and predicting cancer in preclinical applications.

Multi-walled carbon nanotubes promoted lipid accumulation in human aortic smooth muscle cells.

It has been shown before that exposure to nanomaterials (NMs) might promote the formation of foam cells, the key cells involved in all stages of atherosclerosis. However, to our best knowledge, previous studies, particularly in vitro studies, only investigated the transformation of macrophages into foam cells, whereas the importance of smooth muscle cells (SMCs) was overlooked. The present study investigated the toxicity of pristine multi-walled carbon nanotubes (MWCNTs; Code XFM19) and carboxylated MWCNTs (Code XFM21) to human aortic smooth muscle cells (HASMCs). The results showed that exposure to both types of MWCNTs significantly reduced mitochondrial activity but might not damage lysosomes. MWCNT exposure had minimal impact on cytokine release but significantly promoted lipid accumulation, which was significantly inhibited when the cells were pre-incubated with ER stress inhibitors or antioxidants. The mRNA levels of ER stress markers DDIT3 and XBP-1 s and protein levels of chop and p-chop were induced particularly by XFM21, accompanying with increased SREBF1 and SREBF2 mRNA as well as FASN protein, the key regulators involved in de novo lipogenesis. In addition, the mRNA levels of KLF4 and KLF5 and protein levels of KLF were induced after exposure to both types of MWCNTs, associated with an increase of CD68 protein levels. We concluded that MWCNTs might promote lipid accumulation in HASMCs through the induction of ER stress leading to de novo lipogenesis, as well as the activation of KLF pathway resulting in SMC transformation.

Fragilides U-W: New 11,20-Epoxybriaranes from the Sea Whip Gorgonian Coral Junceella fragilis.

Three new 11,20-epoxybriaranes-fragilides U-W (1-3), as well as two known metabolites, junceellonoid D (4) and junceellin (5), were obtained from the octocoral Junceella fragilis. The structures of briaranes 1-3 were elucidated by spectroscopic methods and briaranes 3 and 5 displayed inhibition effects on inducible nitric oxide synthase (iNOS) release from RAW264.7.

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

Abnormal enzymatic activities are directly related to the development of cancers. Identifying the location and expression levels of these enzymes in live cancer cells have considerable importance in early-stage cancer diagnoses and monitoring the efficacy of therapies. Small-molecule fluorescent probes have become a powerful tool for the detection and imaging of enzymatic activities in biological systems by virtue of their higher sensitivity, nondestructive fast analysis, and real-time detection abilities. Moreover, due to their structural tailorability, numerous small-molecule enzymatic fluorescent probes have been developed to meet various demands involving real-time tracking and visualizing different enzymes in live cancer cells or in vivo. In this review, we provide an overview of recent advances in small-molecule enzymatic fluorescent probes mainly during the past decade, including the design strategies and applications for various enzymes in live cancer cells. We also highlight the challenges and opportunities in this rapidly developing field of small-molecule fluorescent probes for interventional surgical imaging, as well as cancer diagnosis and therapy.

A Bioluminescent Probe for Imaging Endogenous Peroxynitrite in Living Cells and Mice.

Peroxynitrite (ONOO-), an extremely reactive nitrogen species (RNS), is implicated in diverse pathophysiological conditions, including cancer, neurodegenerative diseases, and inflammation. Sensing and imaging of ONOO- in living systems remains challenging due to the high autofluorescence and the limited light penetration depth. In this work, we developed a bioluminescent probe BP-PN, based on luciferase-luciferin pairs and the ONOO--responded group α-ketoamide, for highly sensitive detection and imaging of endogenous ONOO- in living cells and mice for the first time. Attributed to the BL without external excitation, the probe BP-PN exhibits a high signal-to-noise ratio with relatively low autofluorescence. Furthermore, we examine the application of the probe BP-PN using the mice model of inflammation, and BP-PN shows high sensitivity for imaging endogenous ONOO- in inflamed mice. This newly developed bioluminescent probe would be a potentially useful tool for in vivo imaging of ONOO- in wider physiological and pathological processes.