A structural optimized fluorescent probe for monitoring hydrogen sulfide in cells and zebrafish.

In this work, we reported a fluorescent probe Fur-SH, a derivative of benzofuranone, which was used to detect H2S in living cells and zebrafish. Based on the three structural characteristics of the probe, the effects of different structural modifications on the optical properties of the fluorophore were compared. Then, the fluorophore Fur-OH was synthesized by modifying diethylamino group with benzofuranone as the main skeleton. With 2,4-dinitrofluorobenzene as the recognition group and diethylamino as the electron donor, the push-pull electron effect occurred with nitro group, which led to fluorescence quenching, and an openable fluorescent probe Fur-SH was formed. The probe Fur-SH (λex = 510 nm; λem = 570 nm) had the advantages of smaller full width at half maxima, rapid response (5 min) and wide pH window. The quantitative properties of the probe were excellent, reaching saturation at 50 equivalents of substrate. The probe Fur-SH showed high sensitivity to H2S, with LOD of 48.9 nM and LOQ of 50 nM. At present, the probe Fur-SH had been applied to fluorescence imaging of MCF-7 cells and zebrafish. By comparing the effects of different structures on the optical properties of fluorophores, this work was expected to be helpful to the development of fluorescent probes in the future.

Near-infrared imaging of hepatocellular carcinoma and its medicinal treatment with a γ-glutamyl transpeptidase-monitoring fluorescence probe.

Herein, the Near-infrared imaging of hepatocellular carcinoma (HCC) and its medicinal treatment was achieved with a γ-glutamyl transpeptidase (GGT)-monitoring fluorescence probe KYZ-GGT which consisted of the typical recognition group γ-glutamyl and the structurally modified signal reporting group hemicyanine-thioxanthene. Compared with the recently reported probes, KYZ-GGT suggested practical and steady capability for monitoring the GGT level in the cellular, xenograft, induced as well as medicinal treatment HCC models. It realized the mitochondrial targeting intracellular imaging to reflect the GGT dynamics in the induction or medicinal treatment of HCC. In the xenograft and induced model mice with multiple factors, KYZ-GGT showed stable performance for visualizing the HCC status. In the medicinal treatment of the long-period-induced HCC model mice verified by the serum indexes and histopathological analysis, KYZ-GGT successfully imaged the medicinal treatment process of HCC with two marketed drugs (Sorafenib and Lenvatinib) respectively, with an applicative penetration depth. The information here was meaningful for investigating effective medicinal strategies for overcoming HCC.

Imaging Investigation of Hepatocellular Carcinoma Progress via Monitoring γ-Glutamyltranspeptidase Level with a Near-Infrared Fluorescence/Photoacoustic Bimodal Probe.

Hepatocellular carcinoma (HCC) is one of the main principal causes of cancer death, and the late definite diagnosis limits therapeutic approaches in time. The early diagnosis of HCC is essential, and the previous investigations on the biomarkers inferred that the γ-glutamyltranspeptidase (GGT) level could indicate the HCC process. Herein, a near-infrared fluorescence/photoacoustic (NIRF/PA) bimodal probe, CySO3-GGT, was developed for monitoring the GGT level and thus to image the HCC process. After the in-solution tests, the bimodal response was convinced. The various HCC processes were imaged by CySO3-GGT at the cellular level. Then, the CCl4-induced HCC (both induction and treatment) and the subcutaneous and orthotopic xenograft mice models were selected. All throughout the tests, CySO3-GGT achieved NIRF and PA bimodal imaging of the HCC process. In particular, CySO3-GGT could effectively realize 3D imaging of the HCC nodule by visualizing the boundary between the tumor and the normal tissue. The information here might offer significant guidance for the dynamic monitoring of HCC in the near future.

Discovery of the cysteine dynamics during the development and treatment of diabetic process by fluorescent imaging.

Herein, a novel fluorescent probe RhoDCM was developed for monitoring the cysteine (Cys) dynamics. For the first time, the Cys-triggered implement was applied in relatively complete diabetic mice models. The response of RhoDCM towards Cys suggested advantages including practical sensitivity, high selectivity, rapid reaction, and steadiness in various pH and temperature conditions. RhoDCM could basically monitor the intracellular Cys level, both exogenous and endogenous. It could further monitor the glucose level via detecting consumed Cys. Furthermore, the diabetic mice models including the no diabetic control group, the induced model groups by streptozocin (STZ) or alloxan, and the treatment groups induced by STZ and treated with vildagliptin (Vil), dapagliflozin (DA), or metformin (Metf) were constructed. The models were checked by oral glucose tolerance test and significant liver-related serum indexes. Based on the models, the in vivo imaging and penetrating depth fluorescence imaging both indicated that RhoDCM could characterize the status of the development and treatment in the diabetic process via monitoring the Cys dynamics. Consequently, RhoDCM seemed beneficial for inferring the order of severity in the diabetic process and evaluating the potency of therapeutic schedules, which might be informatic for correlated investigations.

Discovery of coumaric acid derivatives hinted by coastal marine source to seek for uric acid lowering agents.

In this work, a series of novel compounds Spartinin C1-C24 were screened, synthesised and evaluated for inhibiting xanthine oxidase thus lowering serum uric acid level. The backbones were derived from the components of coastal marine source Spartina alterniflora and marketed drugs. The top hits Spartinin C10 & C22 suggested high inhibition percentages (78.54 and 93.74) at 10 µM dosage, which were higher than the positive control Allopurinol. They were low cytotoxic onto human normal hepatocyte cells. Treatment with Spartinin C10 could lower the serum uric acid level to 440.0 µM in the hyperuricemic model mice (723.0 µM), comparable with Allopurinol (325.8 µM). Spartinin C10 was more appreciated than Allopurinol on other serum indexes. The preliminary pharmacokinetics evaluation indicated that the rapid absorption, metabolism and elimination of Spartinin C10 should be further improved. The discovery of pharmaceutical molecules from coastal marine source here might inspire the inter-disciplinary investigations on public health.

Discovery of derivatives from Spartina alterniflora-sourced moiety as xanthine oxidase inhibitors to lower uric acid.

In this work, hit compounds Spartinin F1-F20 sharing the Spartina alterniflora-sourced ferulic acid backbone were synthesized and evaluated on inhibiting xanthine oxidase and lowering uric acid level. The top hit Spartinin F2 exhibited inhibition percentages at 10 µM dosage as high as 84.48 (higher than that of the positive control allopurinol) and low cyto-toxicity. Spartinin F2 inferred potential efficiency in lowering the serum UA level (from 631.6 µM to 295.0 µM), which was comparable with allopurinol (to 309.2 µM). Spartinin F2 was also beneficial for other serum indexes. The bioavailability of Spartinin F2 was 63.71% from the preliminary pharmacokinetics test and the molecular docking simulation indicated that except for retaining the hydrogen bonds with the key residues such as THR 1010 and LYS 771, the introduction of the π-sulfur interactions via the sulfonate might also be beneficial for developing more potent XO inhibitors.

A fluorescent probe for monitoring sulfite in living cells with large Stokes shift and rapid response.

Sulfite (SO32-) is considered as a monitor of a wide range of physiological processes. However, cells and tissues are adversely affected when the body ingests high level of sulfite. Here, we designed and synthesized a "turn on" fluorescent probe ImiSft-1 with 2-cyano-N-methylacetamide as the specific recognition site of SO32-. This probe predominantly achieved high response intensity to SO32- and desirable properties such as large Stokes shift (∼180 nm), fast response time (within 15 s), and high sensitivity (LOD = 0.12 µM). Importantly, the probe was highly selective for sulfite from other bio-species including biological thiols. Other functional properties included broad pH adaptability (5.0-10.0) and low cytotoxicity. Given these advantages and the fluorescence imaging in living MCF-7 cells, it was demonstrated that probe ImiSft-1 could monitor the changes of sulfite concentration in living cells.

Multifunctional Fluorescent Probe for Simultaneously Detecting Microviscosity, Micropolarity, and Carboxylesterases and Its Application in Bioimaging.

Based on OR logic gate, we proposed a smart near-infrared (NIR) fluorescent probe, named VPCPP, for simultaneously monitoring local microviscosity, micropolarity, and carboxylesterases (CEs) in living cells through blue and red channels. This proposed probe was capable of distinguishing cancer cells from normal cells and had good potential for identifying living liver cell lines. Furthermore, the fluctuations of the three analytes of interest in different cell status was successfully explored. Particularly, facilitated with high-content analysis (HCA) and VPCPP, a simple and efficient high-throughput screening (HTS) platform was first constructed for screening antitumor drugs and studying their effect on the analytes. For the first time, we found that sorafenib-induced ferroptosis led to an increase in the microviscosity and up-regulation of CEs at the same time. Additionally, the procedure that aristolochic acid (AA) induced the overexpression of CEs was verified. Besides, VPCPP was utilized for imaging the variations of the two microenvironment parameters and CEs in the inflammation model. Finally, VPCPP was able to image the tumor ex vivo and in vivo through two channels and one channel separately, as well as to visualize the kidneys and liver ex vivo with dual emissions, which indicated that the probe had great potential for imaging applications such as medical diagnosis, preclinical research, and imaging-guided surgery.

Detection Methods and Research Progress of Human Serum Albumin.

Human serum albumin (HSA) is a biological macromolecule with important physiological functions; abnormal HSA levels are associated with coronary heart disease, multiple myeloma, diabetes, nephropathy, neurometabolic disorders, liver cirrhosis and other diseases. Therefore, accurate and quantitative detection of HAS have extremely important research and application value in biological science, molecular biology, clinical medicine and other fields. As for the detection method of HSA, dye-binding method and immune method are the first to be used, and have been applied in clinical detection. In recent years, many new detection technologies have emerged, such as fluorescent probe detection method, nano-materials for HSA detection, biosensor and so on. Although there are many methods developed recently to detect HSA, comprehensive reviews for HSA detection methods are still rare. Thus, writing this review to fill in the blank is in need. In order to highlight the recent progress in the field of HSA detection, in this review, the methods used to detect HSA are summarized and sorted, the advantages and disadvantages of these detection methods are also listed, then the research progress of small molecular fluorescence probe method is emphatically introduced in this paper. Then, we briefly discussed the challenges and future development directions in this field.

A fluorescent Rhodol-derived probe for rapid and selective detection of hydrogen sulfide and its application.

H2S has been reported to play essential roles in a variety of physiological and pathological procedures. In this work, a novel fluorescent probe, Rho-HS, for detecting H2S was developed by introducing the ortho-halogen to activate the least reactive recognition group 2,4-dinitrophenyl moiety. In combination of the structures from both Rhodamine B and fluorescein, Rho-HS could generate both the colorimetric and fluorescent responses. This feature was not frequently achieved and could lead to the quantitative and convenient for the end-user. In comparison with recent probes for H2S, the major advantages of Rho-HS included suiting wide pH range (6.0-10.0), relatively rapid response (within 15 min) and the high selectivity among the competing species including the biothiols. With low cytoxicity, Rho-HS was further applied in the biological imaging in living MCF-7 cells and Caenorhabditis elegans. We hope that the designing strategy in this work might provide useful information for more preferable implements in this field.

A novel selective probe for detecting glutathione from other biothiols based on the concept of Fluorescence Fusion.

Biological thiols importantly regulate the intracellular redox activity and metabolic level, but many of the developed probes for biothiols are facing difficulty in effectively distinguishing GSH from Cys/Hcy due to the similarity in mechanism. In this work, despite the previous pattern of "Logic Gate", we reported the concept of "Fluorescence Fusion" for the first time to achieve only one excitation-emission process. The exploited the probe, MZ-NBD, could quickly measure GSH in 10 min with a large Stokes shift (130 nm). Though the reacting mechanism was similar, only GSH could cause the "Fluorescence Fusion" with only one strong fluorescence response while Cys/Hcy caused two peaks. Adjusting the excitation wavelength could hardly split the fused peak into two. Though image recognition by artificial intelligence could easily distinguish the patterns of peaks, here we used the signal-treating method to realize the high selectivity towards GSH. Moreover, MZ-NBD could be utilized for rapid detection of GSH in living MCF-7 cells, which was more suitable for GSH than using the "Logic Gate" strategy. More than introducing a novel probe with the new concept, this work was meaningful as the linker of traditional reaction-based fluorescent probes and potential image recognition by artificial intelligence, thus led to various future researches in inter-disciplines.

A NIR-triggered multifunctional nanoplatform mediated by Hsp70 siRNA for chemo-hypothermal photothermal synergistic therapy.

Recently, hypothermal photothermal therapy (HPTT) seemed essential for the future clinical transformation of cancer optical therapies. However, at a lower working temperature, heat shock proteins (HSPs) seriously affect the anti-tumor effect of HPTT. This work reports a reasonable design of a dual-responsive nanoplatform for the synergistic treatment of chemotherapy and HPTT. We adopted a one-step method to wrap indocyanine green (ICG) into imidazole skeleton-8 (ZIF-8) and further loaded it with the chemotherapy drug doxorubicin (DOX). Furthermore, we introduced Hsp-70 siRNA to block the affection of HSPs at an upstream node, thereby avoiding the side effects of traditional heat shock protein inhibitors. The prepared ZIF-8@ICG@DOX@siRNA nanoparticles (ZID-Si NPs) could significantly improve the stability of siRNA to effectively down-regulate the expression of HSP70 protein during the photothermal therapy, thus realizing the pH-controlled and NIR-triggered release of the chemotherapeutical drug DOX. Moreover, tumors were also imaged accurately by ICG wrapped in ZID-Si nanoparticles. After the evaluation of the in vitro and in vivo photothermal effect as well as the anti-tumor activity, we found that the added Hsp-70 siRNA enhanced the synergistic anti-cancer activity of HPTT and chemotherapy. In summary, this work holds great potential in cancer treatment, and suggests better efficacy of synergistic chemo/HPTT than the single-agent therapy.

A DNA-based nanocarrier for efficient cancer therapy.

The study aimed to achieve enhanced targeted cytotoxicity and cell-internalization of cisplatin-loaded deoxyribonucleic acid-nanothread (CPT-DNA-NT), mediated by scavenger receptors into HeLa cells. DNA-NT was developed with stiff-topology utilizing circular-scaffold to encapsulate CPT. Atomic force microscopy (AFM) characterization of the DNA-NT showed uniformity in the structure with a diameter of 50-150 nm and length of 300-600 nm. The successful fabrication of the DNA-NT was confirmed through native-polyacrylamide gel electrophoresis analysis, as large the molecular-weight (polymeric) DNA-NT did not split into constituting strands under applied current and voltage. The results of cell viability confirmed that blank DNA-NT had the least cytotoxicity at the highest concentration (512 nM) with a viability of 92% as evidence of its biocompatibility for drug delivery. MTT assay showed superior cytotoxicity of CPT-DNA-NT than that of the free CPT due to the depot release of CPT after DNA-NT internalization. The DNA-NT exhibited targeted cell internalizations with the controlled intracellular release of CPT (from DNA-NT), as illustrated in confocal images. Therefore, in vitro cytotoxicity assessment through flow cytometry showed enhanced apoptosis (72.7%) with CPT-DNA-NT (compared to free CPT; 64.4%). CPT-DNA-NT, being poly-anionic, showed enhanced endocytosis via scavenger receptors.

Two birds with one stone: a NIR fluorescent probe for mitochondrial protein imaging and its application in photodynamic therapy.

Mitochondrial proteins, most of which are encoded in the nucleus and the rest of which are regulated by the mitochondrial genome, play pivotal roles in essential cellular functions. However, fluorescent probes that can be used for monitoring mitochondrial proteins have not yet been widely developed, thereby severely limiting the exploration of the functions of proteins in mitochondria. Towards this end, here we propose a near-infrared (NIR) fluorescence probe MPP to effectively illuminate the dynamic changes in mitochondrial proteins in live cells under oxidative stress, with excellent temporal and spatial resolution. Of particular importance, MPP extends the study of the pharmacology involved in apoptosis induced by anti-cancer drugs (hydroxycamptothecin (HCPT), epirubicin (Epi) and cyclophosphamide (CPA)) for the first time. Furthermore, employing a protein-activatable strategy, this probe could serve as an excellent phototherapeutic agent in photodynamic therapy (PDT). Finally, in vivo experiments suggest that this versatile probe can be used to image tumors in HeLa tumor-bearing mice for 24 h, which demonstrates that our probe could play a dual role as a robust phototherapeutic and imaging agent.

A versatile nanoplatform based on multivariate porphyrinic metal-organic frameworks for catalytic cascade-enhanced photodynamic therapy.

In recent years, the antitumor application of photodynamic therapy (PDT) has gained widespread interest in treating solid tumors. Due to the hypoxic environment in tumors, the major limit of PDT seems to be the source of oxygen. In this work, we attempted to relieve hypoxia and enhance photodynamic therapy, and therefore, designed and assembled a catalytic cascade-enhanced PDT multifunctional nanoplatform. The mentioned platform termed UIO@Ca-Pt is based on porphyrinic metal-organic framework (UIO) combination, which is simultaneously loaded by CaO2 NPs with polydopamine (PDA) and then the Pt raw material to further improve biocompatibility and efficiency. In a tumor microenvironment, CaO2 could react with water to generate calcium hydroxide and hydrogen peroxide, which was further decomposed by Pt nanoparticles to form oxygen, thereby facilitating the generation of cytotoxic singlet oxygen by photosensitizer TCPP under laser irradiation. Both in vitro and in vivo experiment results confirmed the excellent oxygen production capacity and enhanced PDT effect of UIO@Ca-Pt. With guaranteed safety in PDT, the oxygen-supplying strategy might stimulate considerable interest in the development of various metal-organic materials with multifunctionality for tumor diagnosis and therapy.

A Novel Fluorescent Probe for Selective Detection of Hydrazine and Its Application in Imaging.

In this work, a novel fluorescent probe with first-time-selected thiazepine backbone, TZPzine-1, was developed for selective detection of hydrazine in water samples and living cells. Chosen from our recent anti-cancer agents, TZPzine-1 inferred structurally based advantages of the optical adjustability and the hydrazine-trapping approach. It also showed applicable properties including high sensitivity (LOD = 50 nM), wide linear range (0-15 equiv.), high selectivity (especially from competing species), rapid response (within 20 min), and practical steadiness in various pH (6.0-11.0) and temperature (15-50 °C) conditions. To satisfy the interdisciplinary requirements in environmental toxicology, TZPzine-1 was successfully applied in water samples and living cells. We hope that the information in this work, as well as the concept of monitoring the nitrogen cycle, may be referable for future research on systematic management.

Design and synthesis of a novel "turn-on" long range measuring fluorescent probe for monitoring endogenous cysteine in living cells and Caenorhabditis elegans.

Cysteine (Cys) is an indispensable small organic molecule containing sulfhydryl groups, which has essential regulatory effects on the physiological process of human body. In this work, a red emission fluorescent probe TCFQ-Cys was designed and exploited based on 2-(3-cyano-4,5,5-trimethylfuran-2(5H)-ylidene) malononitrile-derivatives. The probe could effectively monitor Cys through the typical acrylate cleavage. The detecting system showed a red emission at 633 nm and the fluorescence was stable within the pH range of 6-9. The detection could be completed in 30 min. TCFQ-Cys presented high sensitivity with a detection limit of 0.133 µM and high selectivity towards Cys from other biological mercaptans. The most important feature was that the system had a wide linear range of 0-300 µM, which covered the physiological requirements of Cys detection. Subsequently, we conducted the biological imaging of Cys in MCF-7 cells and Caenorhabditis elegans (C. elegans). Therefore, TCFQ-Cys had a practical application prospect for further investigating the physiological function of Cys.

A novel series of benzothiazepine derivatives as tubulin polymerization inhibitors with anti-tumor potency.

In this work, a series of diaryl benzo[b][1,4]thiazepine derivatives D1-D36 were synthesized and screened as tubulin polymerization inhibitors with anti-tumor potency. They were designed by introducing the seven-member ring benzothiazepine as the linker for CA-4 modification for the first time. Among them, the hit compound D8 showed potential on inhibiting the growth of several cancer cell lines (IC50 values: 1.48 µM for HeLa, 1.47 µM for MCF-7, 1.52 µM for HT29 and 1.94 µM for A549), being comparable with the positive controls Colchicine and CA-4P. The calculated IC50 value of D8 as an tubulin polymerization inhibitor was 1.20 µM. The results of the flow cytometry assay revealed that D8 could induce the mitotic catastrophe and the death of living cancer cells. D8 also indicated the anti-vascular activity. The possible binding pattern was implied by docking simulation, inferring the possibility of introducing interactions with the nearby tubulin chain. Since the novel structural trial has been conducted with preliminary discussion, this work might stimulate new ideas in further modification of tubulin-related anti-cancer agents and therapeutic approaches.

A curcumin-analogous fluorescent sensor for cysteine detection with a bilateral-response click-like mechanism.

A novel curcumin-analogous fluorescent sensor, DNP, was developed for cysteine detection with a bilateral-response click-like mechanism. DNP indicated high selectivity and practical sensitivity. It could recognize Cys from other biologically relevant molecules, especially, from GSH and Hcy. The most interesting point was that, with typical azide groups for sensing, DNP indicated a covalent binding procedure with Cys instead of a presupposed simple reduction for reductive sulfide. Moreover, the recognition occurred at both sides of the sensor. DNP could be utilized into the detection of endogenous and exogenous Cys in living cells. Though the specific optical performances of DNP still need optimization, this work supplied novel information for broadening the vision on fluorophores and mechanisms, for the monitoring of Cys and even other sulfur-containing species.

A fluorescent sensor for selective detection of hypochlorite and its application in Arabidopsis thaliana.

Hypochlorite, as one of reactive oxygen species, has drawn much attention due to its essential roles in special biological events and disorders. The exogenous hypochlorite remains a risk for human, animals and plants. In this work, a novel water soluble quinolin-containing nitrone derivative T has been developed for fluorometric sensing hypochlorite. The response mechanism of T towards ClO- was reported for the first time. In comparison with the reported sensors for ClO-, the sensor T in this work exhibited advantages including high selectivity (80 fold over other analytes), rapid response (within 5 s) and lipid-water distribution transformation (LogP from 2.979 to 6.131). Further biological applications suggested that T was capable of monitoring both exogenous and endogenous ClO- in living cells. The imaging in Arabidopsis thaliana indicated that the absorption and transmission of ClO- in plant could be monitored by this sensor through the chlorine-related mechanism. This work might raise referable information for further investigations in the physiological and pathological events in both tumor and plants.