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An AIE probe was established for reacting with NO and emitting fluorescence in arthritic joints/chondrocytes. This AIE probe is appropriate for detecting the progression of osteoarthritis.

By using a fluorescent glucose-linked tetraphenylethylene polymer gel, the macroscopic and fluorescence detection of ROS in vitro and in cells was successfully realized via selective gel collapse and remarkable fluorescence quenching.

A series of naphthalimide (NI)-phenothiazine (PTZ) electron donor-acceptor dyads were prepared to study the thermally activated delayed fluorescence (TADF) property of the dyads, from a point of view of detection of the various transient species. The photophysical properties of the dyads were tuned by changing the electron donating and the electron withdrawal capability of the PTZ and NI moieties, respectively, by oxidation of the PTZ unit, or by using different arylamines to attach with the NI unit. This tuning effect was manifested in the UV-vis absorption and fluorescence emission spectra, e.g., the change of the charge transfer absorption bands. TADF was observed for the dyads containing native PTZ unit, and the prompt and delayed fluorescence lifetimes changed when different arylamine was used. In polar solvent, no TADF was observed. For the dyads with the PTZ unit oxidized, no TADF was observed as while. Femtosecond transient absorption spectra show that the charge separation takes ca. 0.6 ps, and admixture of locally excited (3LE) state and charge separated (1CS/3CS) states formed (in n-hexane). The subsequent charge recombination from the 1CS state takes ca. 7.92 ns. Upon oxidation of the PTZ unit, the beginning of charge separation is at 178 fs, and formation of 3LE state takes 4.53 ns. Nanosecond transient absorption (ns-TA) spectra show that both 3CS and 3LE states were observed for the dyads showing TADF, whereas only 3LE or 3CS state was observed for the systems lacking of TADF. This is a rare but unambiguous experimental evidence that the spin-vibronic coupling of 3CS/ 3LE states is crucial for TADF. Without the mediating effect of the 3LE state, no TADF is resulted, even the long-lived 3CS state is populated (lifetime τCS ≈ 140 ns). This experimental result confirms the 3CS → 1CS reverse intersystem crossing (rISC) is slow, without coupling with an approximate 3LE state. These studies are useful for in-depth understanding of the photophysical mechanisms of the TADF emitters, as well as for molecular structure design of new electron donor-acceptor TADF emitters.

Oxidative stress occurs when the intracellular redox homeostasis is disrupted, which is considered to be one of the important factors leading to aging and disease. Antioxidants of non-enzymatic reactive chalcogenide species play an important role in redox homeostasis, among which sulfane sulfur species and reactive selenium species are particularly indispensable. As a class of antioxidants with potential clinical biomarker value, the intracellular levels and distribution of sulfane sulfur and reactive selenium species can directly prove the dynamic state of oxidative stress, which may reveal the difference between physiological and pathological processes. Fluorescence bioimaging technology has the advantages of high temporal and spatial resolution, low invasiveness and fast response, and has become a powerful tool for intracellular detection. Herein, we have summarized the design strategy and development of fluorescent probes for the detection of sulfane sulfur and reactive selenium species. We have also highlighted the important physiological and pathological roles and mechanisms of these reactive species. We expect to point out a path centred on fluorescence imaging for the detection of representative biological reactive species in living systems.

The therapy of non-small lung cancer (NSCLC) is limited by wide metastasis and chemotherapy resistance, herein, we present a new cancer-targeting prodrug PBG with the integration of real-time fluorescence visualization. The potent anticancer drug Gefitinib conjugates a biotin recognition ligand yielding the prodrug PBG via a GSH-activatable disulfide bond linker. Once coupling a near-infrared azo-BODIPY fluorophore into the molecular structure of PBG, we obtain its fluorescent theranostic TBG. The prodrug PBG can sustain Gefitinib release by the high level of GSH in the pathophysiological milieu. We evaluate the drug delivery of the prodrug PBG using fluorescent TBG in PC9 cancer bearing nude mice models, which indicate that TBG can be utilized to monitor the in vivo drug release process. Prodrug PBG can be targeted to accumulate in the cancer lesion with a better and efficaciously therapeutic result compared with the single Gefitinib treatment in cells and in vivo. The fluorescence images also reveal that the targeting accumulation and longitudinal retention of anticancer drug in cancer lesions will contribute to the superior therapeutic effects. The above applications of our new prodrug PBG and its fluorescent theranostic TBG have the potential contribution to the research in biology and the clinical medicine.

Considering the pivotal role of biomarkers in plasma, the development of biomarker specific sensing platforms is of great significance to achieve accurate diagnosis and monitor the occurrence and progress in acute kidney injury (AKI). In this paper, we develop a promising surface-enhanced Raman scattering-based aptasensor for duplex detection of two protein biomarkers in AKI. Exploiting the base-pairing specificity of nucleic acids to form a Y-shaped self-assembled aptasensor, the MGITC labelled gold nanoparticles will be attached to the surface of magnetic beads. In the presence of specific AKI-related biomarkers, the gold nanoparticles will detach from magnetic beads into the supernatant, thus leading to a SERS signal increase, which can be used for the highly sensitive analysis of target biomarkers. In addition, the limit of detection calculated for each biomarker indicates that the SERS-based aptasensor can well meet the detection requirements in clinical applications. Finally, the generality of this sensor in the early diagnosis of AKI is confirmed by using a rat model and spiked plasma samples. This sensing platform provides a facile and general route for sensitive SERS detection of AKI-related biomarkers, which offers great promising utility for

Bacterial infection seriously restricts the wound healing process due to the severe inflammations and delayed wound healing. Unfortunately, the over or improper use of antibiotics leads to the advent of...

Intersystem crossing was observed for diaminoanthraquinone via transient absorption spectroscopy and the compounds were used as novel initiators for photopolymerization.

Reliable biomarkers is crucial for early diagnosis of diseases and precise therapy. Biological thiols (represented with glutathione, GSH) play vital roles in the antioxidant defense system for maintaining intracellular redox...

We provide comprehensive highlights of the state-of-the-art studies on fluorescent labelling of EVs, covering the various labelling strategies, the biomedical application in vitro, and the study on EV biology in vivo based on bioimaging tools.

Early specific detection through indicative biomarkers and precise visualization of lesion sites are urgent requirements for clinical disease diagnosis. However, current detection and optical imaging methods are insufficient for these demands. Molecular imaging technologies are being intensely studied for reliable medical diagnosis. In the past several decades, molecular imaging with surface-enhanced Raman scattering (SERS) has significant advances from analytical chemistry to medical science. SERS is the inelastic scattering generated from the interaction between photons and substances, presenting molecular structure information. The outstanding SERS virtues of high sensitivity, high specificity, and resistance to biointerference are highly advantageous for biomarker detection in a complex biological matrix. In this work, we review recent progress on the applications of SERS imaging in clinical diagnostics. With the assistance of SERS imaging, the detection of disease-related proteins, nucleic acids, small molecules, and pH of the cellular microenvironment can be implemented for adjuvant medical diagnosis. Moreover, multimodal imaging integrates the high penetration and high speed of other imaging modalities and imaging precision of SERS imaging, resulting in final complete and accurate imaging outcomes and exhibiting robust potential in the discrimination of pathological tissues and surgical navigation. As a promising molecular imaging technology, SERS imaging has achieved remarkable performance in clinical diagnostics and the biomedical realm. It is expected that this review will provide insights for further development of SERS imaging and promote the rapid progress and successful translation of advanced molecular imaging with clinical diagnostics.

Living-cell imaging demands high specificity, sensitivity, and minimal background interference to the targets of interest. However, developing a desirable imaging probe that can possess all the above features is still challenging. The bioorthogonal surface-enhanced Raman scattering (SERS) imaging has been recently emerged through utilizing Raman reporters with characteristic peaks in Raman-silent region of cells (1800−2800 cm−1), which opens a revolutionary avenue for living-cell imaging with multiplexing capability. In this review, we focus on the recent advances in the technology development and the biological and biomedical applications of the living-cell bioorthogonal SERS imaging technique. After introduction of fundamental principles for bioorthogonal tag or label, we present applications for visualization of various intracellular components and environment including proteins, nucleic acids, lipids, pH and hypoxia, even for cancer diagnosis in tissue samples. Then, various bioorthogonal SERS imaging-guided therapy strategies have been discussed such as phototherapy and surgery. In conclusion, this strategy has great potential to be a flexible and robust tool for visualization detection and diseases diagnosis.

Epilepsy is a chronic neurodegenerative disease that has seriously threatened human health. Accumulating evidence reveals that the pathological progression of epilepsy is closely related to peroxynitrite (ONOO-). Unfortunately, understanding the physiological roles of ONOO- in epilepsy is still challenging due to the lack of powerful imaging probes for the determination of the level of fluctuations of ONOO- in the epileptic brain. Herein, a near-infrared (NIR) two-photon (TP) fluorescent probe [dicyanomethylene-4H-pyran (DCM)-ONOO] is presented to trace ONOO- in living cells and in kainate (KA)-induced rat epilepsy models with satisfactory sensitivity and selectivity. The probe is composed of a NIR TP DCM fluorophore and a recognition moiety diphenylphosphinamide. The phosphoramide bond of the probe is interrupted after reacting with ONOO- for 10 min, and then, the released amino groups emit strong fluorescence due to the restoration of the intramolecular charge transfer process. The probe can effectively detect the changes of endogenous ONOO- with excellent temporal and spatial resolution in living cells and in rat epileptic brain. The imaging results demonstrate that the increasing level of ONOO- is closely associated with epilepsy and severe neuronal damage in the brain under KA stimulation. In addition, the low-dose resveratrol can effectively inhibit ONOO- overexpression and further relieve neuronal damage. With the assistance of TP fluorescence imaging in the epileptic brain tissue, we hypothesize that the abnormal levels of ONOO- may serve as a potential indicator for the diagnosis of epilepsy. The TP fluorescence imaging based on DCM-ONOO provides a great potential approach for understanding the epilepsy pathology and diagnosis.

Peroxynitrite (ONOO

Following the wisdom of nature to assemble functional candidates into exquisite nanoarchitectures is emerging as a promising field of research and has been widely applied in biomedical sciences. Owing to their excellent properties of structural controllability, functional diversity, dynamic adjustability, and prominent biocompatibility, the self-assembled nanoarchitectures come to play a pivotal role in fighting against cancer. This review outlines the most up-to-date developments in constructing phototherapeutic nanomaterials for photodynamic and photothermal therapy (PDT and PTT) of tumors, with emphasis on design ideas, building blocks, and advantageous characteristics of self-assembly. The prominent activities of cancer therapy obtained by these photoinduced nanotheranostics are also explored in-depth, together with the connections between the specific nanostructures and unique features, providing a comprehensive understanding of the self-assembled nanomaterials in improving the outcomes of PDT and PTT. This review aims to highlight the significance of self-assembled nanomaterials in enhancing phototherapeutic efficacy and to promote its development in various research interests ranging from material science and nanoscience to biomedicine and clinical medicine.

Over the past decades, microfluidic devices based on many advanced techniques have aroused widespread attention in the fields of chemical, biological, and analytical applications. Integration of microdevices with a variety of chip designs will facilitate promising functionality. Notably, the combination of microfluidics with functional nanomaterials may provide creative ideas to achieve rapid and sensitive detection of various biospecies. In this review, focused on the microfluids and microdevices in terms of their fabrication, integration, and functions, we summarize the up-to-date developments in microfluidics-based analysis of biospecies, where biomarkers, small molecules, cells, and pathogens as representative biospecies have been explored in-depth. The promising applications of microfluidic biosensors including clinical diagnosis, food safety control, and environmental monitoring are also discussed. This review aims to highlight the importance of microfluidics-based biosensors in achieving high throughput, highly sensitive, and low-cost analysis and to promote microfluidics toward a wider range of applications.

Chronic hypoxic stress disrupts the intracellular redox homeostasis, leads to a series of physiological dysfunction, and finally results in many diseases including cancer and inflammatory and cardiovascular diseases. The intracellular redox status is related to the homeostasis between reactive oxygen species (ROS) and cellular antioxidant species. Superoxide anion (O2•-) is considered to be a precursor of ROS. As a member of reactive sulfur species, hydrogen polysulfides (H2S n) are a class of antioxidants in cells, which act as an important regulator for the intracellular redox state. Therefore, trapping the cross-talk of O2•- and H2S n is a benefit for further understanding the physiological and pathological effects. Herein, we conceive a fluorescent probe HCy-ONO for sequential detection of O2•- and H2Sn in cells and in mouse models. Based on a tandem reaction, the probe HCy-ONO can be used to detect O2•- and H2S n in different fluorescence collection windows without spectral overlap interference with limits of detection 90 and 100 nM, respectively. The strategy affords high sensitivity and selectivity for our detection in living cell models under continuous hypoxic and intermittent hypoxic conditions, revealing the reason for ischemia-reperfusion injury. Moreover, the probe can distinguish the inflamed tissue from normal tissue in acute peritonitis mouse model. Finally, our probe is successfully applied for imaging of O2•- and H2S n in the SH-SY5Y tumor-bearing mouse model, which is helpful to elucidate the physiological and pathological processes. These data demonstrated that different hypoxic status lead to different concentrations between H2S n and O2•-.

Hydrazine (N2H4) has been listed as a possible human carcinogen. It can cause severe damage to various organs through respiratory tract, skin and digestive tract. Although some fluorescent probes have been developed for imaging of N2H4, there is very few entry of application in vivo, probably limited by the short fluorescence emission wavelengths. Moreover, the sensitivity also needs to be improved to meet the requirement of detection in vivo. Hence, we design and synthesize a new NIR ratiometric fluorescent probe Cy-OAc based on cyanine derivatives for the sensitive detection of N2H4 in cells and in mice models. Cy-OAc consists of a large π-conjugated system and a masking unit for both regulating the π-system and tracing N2H4. Cy-OAc holds the emission profile centered at 825 nm under the excitation of 730 nm, and upon reaction with N2H4, it shifts the emission profile centered at 662 nm with an excitation at 540 nm, resulting in the NIR ratiometric emission response, as well as a distinct color change that can be distinguished by the naked eye. Cy-OAc has been successfully applied to imaging the N2H4 in apoptotic cells. The results reveal that N2H4 can lead to the apoptosis of HeLa cells via the damage of mitochondrial membrane potential. Taking advantage of the NIR emissions, Cy-OAc exhibits the deep tissue penetration of 700 μm in kidney tissue. Our probe Cy-OAc is further utilized to visually detect N2H4-metabolism and estimate kidney damage in mice models. We envision that the probe Cy-OAc can be an attractive chemical tool for exploring N2H4 in bio-specimen.

Peroxynitrite (ONOO-) is an important reactive oxygen species (ROS), which can react with a variety of biologically active species and cause many diseases, such as cancer, neurodegenerative disorders. Herein, we develop a novel far-red fluorescent probe DCM-KA, which is equipping with α-ketoamide moiety caged DCM-NH2. The probe exhibits fluorescence off-on response to ONOO- over other biological interfering analytes by ONOO--induced α-ketoamide deprotection reaction. More importantly, the probe is biocompatible and has been successfully utilized to visualize endogenous ONOO- production in macrophage cell line J774A.1.

Idiopathic pulmonary fibrosis (IPF) is a lung-limited and progressive fibrotic disease. The early diagnosis and therapies of IPF are still full of clinical challenges. Glutathione S-transferase (GSTs) plays significant roles in promoting the formation of pulmonary fibrosis. Herein, we report a fluorescent probe (Cy-GST) for the detection of GSTs concentration fluctuations in cells and in mice models. The probe can selectively and sensitively respond to GSTs with an "off-on" type fluorescence switch. Our results demonstrated that the level of intracellular GSTs increase in the pulmonary fibrosis cells and mice models. And the IPF patients hold high levels of GSTs concentrations. Thus, GSTs are likely to play important roles in pulmonary fibrosis. The inhibitor of GSTs TLK117 can reduce the severity of pulmonary fibrosis. The synergistic treatment of TLK117 and pirfenidone have better therapeutic effects than only using pirfenidone in pulmonary fibrosis mice models. The level of GSTs in IPF may be a new potential marker for IPF diagnosis. And the inhibition of GSTs may be a new therapeutic strategy for IPF treatment.

Cysteine (Cys) plays significant roles in many physiological processes, although its normal concentration is maintained at the micromole level. Abnormally high levels of intracellular Cys can lead to many diseases including cancer. Recent years, many effective fluorescent probes have been developed for the selective detection of Cys against other biological thiols. Herein, we synthesized a ratiometric near-infrared (NIR) fluorescent probe Cy-OAcr for selective imaging of intracellular Cys. Cy-OAcr has a lipophilic iminium cation unit as the mitochondrial guider and an acrylate group as the Cys recognition unit as well as a fluorescence modulator for rearranging the conjugated π-electron system of cyanine fluorophore. Upon detection of Cys, there occurs a significant absorption and fluorescence spectral shift, which are desirably beneficial for ratiometric detection. This probe has high sensitivity and selectivity for Cys detection over glutathione (GSH), homocysteine (Hcy), and other biomolecules with a low limit of detection at 0.09 μM. Probe Cy-OAcr is capable to detect and image Cys in three living cancer cell lines and their corresponding tumor-bearing mice models. More importantly, we successfully apply this fluorescent probe to evaluate the level of Cys in orthotopic lung cancer model. Imaging analyses reveal that the probe can discriminate tumor lesions from normal tissues, indicating its significant potential applications for clinical auxiliary diagnosis of cancer.

Selective fluorescence imaging of biomarkers in vivo and in situ for evaluating orthotopic hepatocellular carcinoma (HCC) chemotherapy remains a great challenge due to current imaging agents suffering from the potential interferences of other hydrolases. Herein, we observed that carbamate unit showed a high selectivity toward the HCC-related biomarker carboxylesterase (CE) for evaluation of treatment. A near-infrared two-photon fluorescent probe was developed to not only specially image CE activity in vivo and in situ but also target orthotopic liver tumor after systemic administration. The in vivo signals of the probe correlate well with tumor apoptosis, making it possible to evaluate the status of treatment. The probe enables the imaging of CE activity in situ with a high-resolution three-dimensional view for the first time. This study may promote advances in optical imaging approaches for precise imaging-guided diagnosis of HCC in situ and its evaluation of treatment.

Pulmonary fibrosis is a fatal chronic lung disease, leading to poor prognosis and high mortality. Accumulating evidence suggests that oxidative stress characterized by excessive production of hydrogen peroxide (H2O2) is an important molecular mechanism causing pulmonary fibrosis. We conceive a new type of mitochondria-targeted near-infrared fluorescent probe Mito-Bor to investigate changes in the level of endogenous H2O2 in living cells and mice models with pulmonary fibrosis. In the design strategy of the Mito-Bor probe, we selected azo-BODIPY as the fluorophore owing to its near-infrared fluorescence, strong photochemical stability, and low biological toxicity. Under physiological conditions, the response moiety 4-bromomethylphenylboronic acid pinacol ester could easily detect H2O2, and turn the fluorescence switch on. The modification of the lipophilic triphenylphosphine cation on the fluorophore would allow the probe to easily pass through the phospholipid bilayer of cells, and the internal positive charge could contribute to the selectivity of the mitochondria accumulation. The Mito-Bor probe provides high selectivity, low limit of detection, high biocompatibility, and excellent photostability. It can be used to detect changes in the level of H2O2 in living cells and in vivo. Therefore, the probe is applied to investigate the fluctuation of the H2O2 level during the process of inducing pulmonary fibrosis in cells, with changes in its fluorescence intensity correlating with the concentration of H2O2 and indicating the level of oxidative stress in fibroblasts. Conversely, pulmonary fibrosis can be modulated by adjusting the level of H2O2 in cells. A further study in mice models of bleomycin-induced pulmonary fibrosis confirms that NADPH oxidase 4 (NOX4) acts as a "button" to regulate H2O2 levels. The direct inhibition of NOX4 can significantly reduce the level of H2O2, which can delay the progression of lung fibrosis. These results provide an innovative way for the clinical treatment of pulmonary fibrosis.

In recent years, considerable achievements have been made to motivate the construction of tumor microenvironment (TME)-specific functional nanomaterials, which can effectively respond to the inherent pathological and physicochemical conditions in diseased regions to improve the specificity of imaging and drug delivery. Until now, various nanoarchitectures have been designed to combat cancer effectively and specifically. This review summarizes the latest developments in TME-specific theranostic nanoplatforms based on multifunctional nanomaterials that hold potential for achieving the targeted recognition at tumor sites. Recent progress and achievements have also been summarized for nanosystems that can specifically respond to the TME with various stimulus-responsive strategies and their applications for drug delivery, diagnosis, treatment, and synergistic theranostics of cancer. This review emphasizes the significance of functional nanomaterials in response to tumor stimuli to enhance anticancer treatment efficiency and facilitate development in extensive research fields, including nanoscience, biomedicine, and clinical applications.

Hydrogen polysulfides (H2Sn, n ≥ 2) is recently regarded as a potential signaling molecule which shows a higher efficiency than hydrogen sulfides (H2S) in regulating enzymes and ion channels. However, the development of specific fluorescent probes for H2Sn with long-wavelength emission (>600 nm) are still rare. In this work, a semi-naphthorhodafluor-based red-emitting fluorescent probe SNARF-H2Sn containing a phenyl 2-(benzoylthio) benzoate responsive unit was constructed. SNARF-H2Sn was capable of selectively detecting H2Sn over other reactive sulfur species. Treatment with H2Sn would result in a > 1000-fold fluorescence enhancement within 10 min. SNARF-H2Sn showed a low limit of detection down to 6.7 nM, and further enabled to visualize exogenous/endogenous H2Sn in living A549 cells and zebrafish.

The early diagnosis of osteoarthritis (OA) can halt or delay the progression of the disease, and it is essentially beneficial to its treatment. However, biomarkers with sufficient sensitivity for dynamically identifying early OA are still yet to be determined. The overproduced hypochlorous acid (HOCl) has been proposed as an obvious symptom in early OA. Herein, based on the oxidation reaction of the sulfur atom in phenothiazine into sulfoxide, we design and synthesize a phenothiazine-derived coumarin fluorescent probe PDC for the detection of ClO- in cells and in an OA mouse model. The probe PDC exhibits excellent selectivity and sensitivity for ClO- detection with a limit of detection as low as 16.1 nM. Taking advantage of the probe PDC, we visualize and evaluate the level changes of ClO- in macrophage cells, which is stimulated by various inflammatory factors. The anti-inflammatory and therapeutic effects of selenocysteine and methotrexate in inflamed cells are also confirmed. Finally, with in vivo imaging of ClO- concentration changes in OA BALB/c mouse models, we successfully inspected the relationship between OA phenotypes and the burst of ClO-. We suggest that abnormal changes in HOCl concentration may be considered as a new biomarker for the early OA diagnosis.

Known as a new member of the reactive sulphur species (RSS), endogenous sulfur dioxide (SO

Hypoxia is a significant global issue affecting the health of organisms. Oxygen homeostasis is critical for mammalian cell survival and cellular activities. Hypoxic stress can lead to cell injury and death, which contributes to many diseases. Sulfane sulfur is involved in crucial roles in physiological processes of maintaining intracellular redox state and ameliorating oxidative damage. Therefore, real-time imaging of changes in sulfane sulfur levels is important for understanding their biofunctions in cells. In this study, we develop a new near-infrared (NIR) fluorescent probe BD-diSeH for imaging of sulfane sulfur changes in cells and in vivo under hypoxic stress. The probe includes two moieties: an NIR azo-BODIPY fluorophore equipped with a strong nucleophilic phenylselenol group (-SeH). The probe is capable of tracing dynamic changes of endogenous sulfane sulfur based on a fast and spontaneous intramolecular cyclization reaction. The probe has been successfully used for imaging sulfane sulfur in 3D-multicellular spheroid and mouse hippocampus under hypoxic stress. The overall levels of sulfane sulfur are affected by the degree and length of hypoxic stress. The results reveal a close relationship between sulfane sulfur and hypoxia in living cells and in vivo, allowing better understanding of physiological and pathological processes involving sulfane sulfur. Moreover, to investigate the effects of environmental hypoxia on aquatic animals, this probe has been applied for sulfane sulfur detection in hypoxic zebrafish.

Nitroxyl (HNO) plays a crucial role in anti-inflammatory effects via the inhibition of inflammatory pathways, but the details of the endogenous generation of HNO still remain challenging owing to the complex biosynthetic pathways, in which the interaction between H2S and NO simultaneously generates HNO and polysulfides (H2Sn) in mitochondria. Moreover, nearly all the available fluorescent probes for HNO are utilized for imaging HNO in cells and tissues, instead of the in situ real-time detection of the simultaneous formation of HNO and H2Sn in mitochondria and animals. Here, we have developed a mitochondria-targeting near-infrared fluorescent probe, namely, Mito-JN, to detect the generation of HNO in cells and a rat model. The probe consists of three moieties: Aza-BODIPY as a fluorescent signal transducer, a triphenylphosphonium cation as a mitochondria-targeting agent, and a diphenylphosphinobenzoyl group as an HNO-responsive unit. The response mechanism is based on an aza-ylide intramolecular ester aminolysis reaction with fluorescence emissions on. Mito-JN displays high selectivity and sensitivity for HNO over various other biologically relevant species. Mito-JN was successfully used for the detection of the endogenous generation of HNO, which is derived from the crosstalk between H2S and NO in living cells. The additional generation of H2Sn was also confirmed using our previous probe Cy-Mito. The anti-inflammatory effect of HNO was examined in a cell model of LPS-induced inflammation and a rat model of gouty arthritis. The results imply that our probe is a good candidate for the assessment of the protective effects of HNO in inflammatory processes.

We establish a near-infrared two-photon fluorescent probe for the detection of CE2 with high selectivity and sensitivity. This probe exhibits low cytotoxicity and superior tissue penetration ability for evaluating the real-time activity of CE2 in living cells, in cancer tissues, and in a colon carcinoma mice model.

Hydrogen sulfide (H2S) is an important endogenous gasotransmitter and has been implicated with a variety of biological processes. The development of an efficient method for monitor H2S fluctuations in biological systems is of great significance to understand its roles in physiological and pathological conditions. In this work, two red-emitting fluorescent probes SNARF-SSPy and SNARF-SeSPy for H2S detection with turn-on fluorescence signals were reported. Interestingly, SNARF-SeSPy exhibited excellent anti-interference via dual selenium-sulfur exchange reaction even in the presence of high concentrations of thiols, whereas SNARF-SSPy did not sense H2S in the same condition. Additionally, in the present of H2S, SNARF-SeSPy showed a rapid response and excellent sensitivity with a detection limit of 34 nM. Most importantly, SNARF-SeSPy featured low cytotoxicity and could be employed to detect and image exogenous/endogenous H2S in living cells and zebrafish.

Alkaline phosphatase (ALP) is a class of enzymes that are widely found in various tissues of the human body. It plays important roles in regulating diverse cellular functions. The aberrant levels of serum ALP are implicated in diseases. The development of sensitive and accurate detection tool for evaluating the level changes of ALP in living organisms will be very helpful in the fields of biochemistry, cytology and clinical medicine. Herein, we develop a near-infrared probe (QcyP) for the specific detection of different ALP levels both in different cell lines and in tumor-bearing mice models. The probe is composed of two moieties: a unique heptamethine cyanine fluorophore and a phosphate monoester. ALP can trigger an off-on fluorescence switch via an enzyme-catalyzed cleavage of the phosphate group. The fluorescence regulation mechanism is based on the rearrangement of the conjugated π-electron system. The probe exhibits high selectivity and good sensitivity towards ALP. The results demonstrate that the probe QcyP not only can be applied to discriminate the levels of ALP in different cell lines, but also can distinguish the ALP level changes between hepatic tumor mice model and normal mice.

As important active sites of oxidoreductase in mitochondria, selenocysteine (Sec) takes the responsibility for cytoprotective effect and intracellular redox homeostasis. Carbon disulfide (CS2) is a common solvent in industry, which can inhibit the activities of oxidoreductase and induce oxidative stress. It is necessary to investigate the cytoprotective effect of Sec against CS2 exposure. After integrated, the response moiety 2,4-dinitrobenzenesulfonamide and mitochondrial targeting moiety into the near-infrared heptamethine cyanine fluorophore, we develop a mitochondrial targeting near-infrared ratiometric fluorescent probe Mito-diNO2 for the selective and sensitive analysis of Sec concentration fluctuations in living cells and in mice models under the stimulation of CS2. The probe can effectively accumulate in mitochondria and selectively detect the endogenous Sec concentrations in BRL 3A, RH-35, HL-7702, HepG2, and SMMC-7721 cell lines. The results indicate that CS2 exposure can lead to a decrease of Sec level and result in mitochondrial related acute inflammation. The exogenous supplement of Sec can protect cells from oxidative damage and reduce the symptoms of inflammation. We also establish CS2 induced acute and chronic hepatitis mice models to examine the tissue toxicity of CS2 and cytoprotection of Sec in liver. The organism can increase the concentration of Sec to deal with the damage caused by CS2 in acute hepatitis mice model. Also the exogenous supplement of Sec for the two mice models can effectively defend the CS2 induced liver damage. The real-time imaging of Sec concentrations in liver can be used to assess the degrees of liver injury during CS2 poisoning. The above applications make our probe a potential candidate for the clinical accurate diagnosis and treatment of CS2 poisoning.

This paper describes a novel rotational paper-based analytical device (RPAD) to implement multi-step electrochemiluminescence (ECL) immunoassays. The integrated paper-based rotational valves can be easily controlled by rotating paper discs manually and this advantage makes it user-friendly to untrained users to carry out the multi-step assays. In addition, the rotational valves are reusable and the response time can be shortened to several seconds, which promotes the rotational paper-based device to have great advantages in multi-step operations. Under the control of rotational valves, multi-step ECL immunoassays were conducted on the rotational device for the multiplexed detection of carcinoembryonic antigen (CEA) and prostate specific antigen (PSA). The rotational device exhibited excellent analytical performance for CEA and PSA, and they could be detected in the linear ranges of 0.1–100 ng mL−1 and 0.1–50 ng mL−1 with detection limits down to 0.07 ng mL−1 and 0.03 ng mL−1, respectively, which were within the ranges of clinical concentrations. We hope this technique will open a new avenue for the fabrication of paper-based valves and provide potential application in clinical diagnostics.

The therapy of non-small-cell lung cancer (NSCLC) is challenging because of poor prognosis. There are urgent demands for targeting anti-tumor drugs with reliable efficacy and clear pharmacokinetics. Methods: We designed and synthesized an active tumor-targeting prodrug for the precision therapy of NSCLC. The prodrug polyamine analog Gefitinib (PPG) was derived from the conjugation between a tumor-targeting ligand polyamine analog (PA) and an epidermal growth factor receptor tyrosine kinase inhibitor Gefitinib via a cleavable disulfide linker. Furthermore, the integration of the near-infrared azo-BODIPY fluorophore into the structure of the prodrug PPG yielded an activatable fluorescent theranostics (TPG), which could be used to monitor the in real-time delivery of prodrug PPG and initiate precise medicine in vivo. Results: PPG efficiently delivered the anti-tumor drug to cancer cells and reduced the serious side effects of the drug to normal cells, thereby increasing the potent of the anti-tumor drug. PPG was not only efficacious for killing Gefitinib-sensitive PC9 cells, but also for inhibiting the growth of Gefitinib-resistant H1650 cells. We provided a new evidence that the tumor-targeting PA ligand could inhibit the Akt pathway in H1650 cells, and had a synergistic effect with Gefitinib for anticancer efficacy. The in vivo results on nude mice bearing tumors of NSCLC cell lines demonstrated that PPG could target tumor lesions and had the expected therapeutic effects. Finally, we used TPG for fluorescent labeling of transbronchial lung biopsy (TBLB) specimens. The results indicated that TPG could provide rapid diagnosis for lung cancer within 4 h. Conclusion: Our work had identified that PPG could be effectively used for the treatment of Gefitinib-resistance NSCLC in cells and in mice models. The theranostic TPG emerged as a promising fluorescent imaging tool for the application in the therapy and diagnosis of NSCLC.

The outburst of superoxide anion (O 2 − ) in mitochondrial during ischemia/reperfusion (I/R) process will cause a series of oxidative damage including polarity loss of mitochondrial membrane potential, overload of secondary cellular calcium, and cascade apoptosis. To monitor the O 2 − level fluctuations as well as to evaluate the relationship between O 2 − concentration and the degree of cell apoptosis during I/R process, we propose a ratiometric near-infrared mitochondrial targeting fluorescent probe Mito-Cy-Tfs for the detection of level changes of O 2 − in cells and in vivo . The probe Mito-Cy-Tfs is composed of three moieties: near-infrared heptamethine cyanine as fluorescence signal transducer, trifluoromethanesulfonamide as fluorescence modulator, and lipophilic triphenylphosphonium cation as mitochondrial guider. The probe can well locate in mitochondria and respond the concentration changes of endogenous O 2 − selectively and sensitively. The probe has been successfully utilized to image the endogenous O 2 − fluctuations in four kinds of cell I/R models (glucose deprivation/reperfusion, serum deprivation/reperfusion, oxygen deprivation/reperfusion and glucose-serum-oxygen deprivation/reperfusion). The probe also exhibits deep tissue penetration for real-time imaging of O 2 − concentration in liver of I/R mice model. We confirm that the adoption of ischemic preconditioning (IPC) and postconditioning (IPTC) can protect liver from I/R injury. The probe can be employed to accurately indicate and evaluate the mutual relationship between the levels of O 2 − and the degrees of organ damage during I/R, IPC and IPTC processes. The above applications make our new probe a potential candidate for the clinical surgery assessment.

Formaldehyde (FA) is an endogenously produced reactive carbonyl species (RCS) through biological metabolic processes whose concentration is closely related to human health and disease. Noninvasive and real-time detection of FA concentration in organisms is very important for revealing the physiological and pathological functions of FA. Herein, we design and synthesize a reversible fluorescent probe BOD-NH2 for the detection of FA in living cells and in vivo. The probe is composed of two moieties: the BODIPY fluorophore and the primary amino group response unit. The probe undergoes an intracellular aldimine condensation reaction with FA and forms imine (C[double bond, length as m-dash]N) which will result in C[double bond, length as m-dash]N isomerization and rotation to turn-off the fluorescence of the probe. It is important that the probe can show a reversible response to FA. The probe BOD-NH2 has been successfully applied for detecting and imaging FA in the cytoplasm of living cells. BOD-NH2 is capable of detecting fluctuations in the levels of endogenous and exogenous FA in different types of living cells. The probe can be used to visualize the FA concentration in fresh hippocampus and the probe can further qualitatively evaluate the FA concentrations in ex vivo-dissected organs. Moreover, BOD-NH2 can also be used for imaging in mice. The above applications make our new probe a potential chemical tool for the study of physiological and pathological functions of FA in cells and in vivo.

Sulfane sulfur refers to ionized sulfur that is reversibly attached to other sulfur atoms in the form of 6-valence electrons (S0). Sulfane sulfur possesses stronger nucleophilicity and reducibility than hydrogen sulfide in a series of physiological reactions, which probably makes sulfane sulfur the actual signal molecule in cells. Herein, we designed and synthesized a near-infrared (NIR) fluorescent probe BD-diSH for sensitive detection and imaging of sulfane sulfur in living cells and in vivo. The probe BD-diSH is composed of two moieties: the fluorophore azo-BODIPY and the sulfane sulfur recognition unit, viz., 2-mercapto benzoate. BD-diSH displayed high sensitivity and selectivity towards sulfane sulfur. The mercapto group (–SH) of 2-mercapto benzoic acid can nucleophilically capture the sulfur atom of thiosulfoxide tautomers in sulfane sulfur to form –SSH. The group –SSH will immediately induce intramolecular cyclization reaction and release the azo-BODIPY fluorophore to emit NIR fluorescence. The probe BD-diSH was successfully applied to detect and image sulfane sulfur in the cytoplasm of the living cells. The results illustrated that the endogenous and exogenous sulfane sulfur level changed depending on different cell lines. BD-diSH was also capable of imaging the level changes of sulfane sulfur in mice. The above applications make our new probe a potential chemical tool for the study of physiological and pathological functions of sulfur sulfide in living cells and in vivo.