Dual-Channel/Localization Single-Molecule Fluorescence Probe for Monitoring ATP and HOCl in Early Diagnosis and Therapy of Rheumatoid Arthritis.

Rheumatoid arthritis (RA), a common chronic inflammatory illness, is still incurable, reducing the sufferers' quality of life significantly. Adenosine 5'-triphosphate (ATP) and hypochlorous acid (HOCl) are key indicators in RA, but their precise mechanisms in RA pathophysiology are unknown. As a result, in order to detect ATP and HOCl simultaneously, we created two new dual-channel/localization single-molecule fluorescence probes, RhTNMB and RhFNMB. Furthermore, RhFNMB outperformed RhTNMB in terms of detection performance. ATP and HOCl produce independent fluorescence responses in the light red channel (λex = 520 nm, λem = 586 nm) and deep red channel (λex = 620 nm, λem = 688 nm), respectively, without spectral crosstalk. It should be noted that the probe RhFNMB successfully imaged ATP in mitochondria and HOCl in cells. Surprisingly, the probe RhFNMB demonstrated remarkable detection ability in the diagnosis and treatment of Pseudomonas aeruginosa-induced abdominal inflammation in mice. We continued to apply the probe RhFNMB to track ATP and HOCl in RA and discovered that ATP and HOCl concentrations were considerably greater in RA joints than in normal joints. We also confirmed the therapeutic effect of methotrexate on RA. This study is the first to achieve dual-channel imaging of ATP and HOCl, which is of great value for the early diagnosis and therapy of RA.

Mitochondrial-Targeted AIE-Active Fluorescent Probe Based on Tetraphenylethylene Fluorophore with Dual Positive Charge Recognition Sites for Monitoring ATP in Cells.

Adenosine triphosphate (ATP), as an important intracellular energy currency produced in mitochondria, is closely related to various diseases in living organisms. Currently, the biological application of AIE fluorophore as a fluorescent probe for ATP detection in mitochondria is rarely reported. Herein, D-π-A and D-A structure-based tetraphenylethylene (TPE) fluorophores were employed to synthesize six different ATP probes (P1-P6), and the phenylboronic acid groups and dual positive charge sites of probes could interact with the vicinal diol of ribose and negatively charged triphosphate structure of ATP, respectively. However, P1 and P4 with a boronic acid group and a positive charge site had poor selectivity for ATP detection. In contrast, P2, P3, P5, and P6 with dual positive charge sites exhibited better selectivity than P1 and P4. In particular, P2 had more advantages of high sensitivity, selectivity, and good time stability for ATP detection than P3, P5, and P6, which was ascribed to its D-π-A structure, linker 1 (1,4-bis(bromomethyl)benzene), and dual positive charge recognition sites. Then, P2 was employed to detect ATP, and it exhibited a low detection limit of 3.62 µM. Moreover, P2 showed utility in the monitoring of mitochondrial ATP level fluctuations.

A dual-response mitochondria-targeted NIR fluorescent probe with large Stokes shift for monitoring viscosity and HOCl in living cells and zebrafish.

Mitochondria are important subcellular organelles involved in many cellular activities. Therefore, it is very important to monitor the concentration of various substances in mitochondria. In this work, we constructed a dual-response mitochondria-targeted fluorescent probe HBTN for the detection of viscosity and HOCl in vitro and in vivo. HBTN not only has a long emission wavelength with an emission peak of 680 nm, but also has a large Stokes shift of 278 nm. The fluorescence intensity of probe HBTN at 680 nm has a good linear relationship with solution viscosity, which can be used for quantitative detection of viscosity. In addition, the probe HBTN enables ratiometric detection of HOCl with a low detection limit (DL = 24.5 nM) and rapid response (<20 min). More importantly, the probe HBTN has been successfully applied to the detection of viscosity and exogenous/endogenous HOCl in the mitochondria of MCF-7 cells. Furthermore, the probe HBTN has been implemented in imaging viscosity and HOCl in zebrafish. HBTN is expected to be a practical tool for monitoring viscosity and HOCl in vivo.

Tracking HOCl by an incredibly simple fluorescent probe with AIE plus ESIPT in vitro and in vivo.

Hypochlorous acid is an important active substance involved in a variety of physiological processes in living organisms, while abnormal concentrations of HOCl are strongly associated with a variety of diseases such as cancer, inflammation, atherosclerosis, and Alzheimer's disease. As a result, it's crucial to establish a reliable method for tracking HOCl in vivo in order to investigate its physiological consequences. In this work, we developed a fluorescent probe DFSN with both AIE and ESIPT for imaging HOCl in vivo. DFSN not only has a basic structure and is easy to synthesize, but also has superior performance. The probe responds to HOCl in less than 10 s and has good selectivity and sensitivity to HOCl (DL = 6.3 nM), with a 110-fold increase in fluorescence intensity following response. In addition, DFSN can realize the rapid detection of hypochlorous acid with naked eyes. Moreover, DFSN can be used for the detection of exogenous and endogenous HOCl in RAW264.7 cells, and additionally enables the tracking of HOCl in cancer cells (Hela cells and HepG2 cells). More notably, it has been utilized to image hypochlorous acid in zebrafish with great success. The probe DFSN will be useful in determining the physiological significance of HOCl.

Red and Near-Infrared Fluorescent Probe for Distinguishing Cysteine and Homocysteine through Single-Wavelength Excitation with Distinctly Dual Emissions.

Small-molecule biothiols, including cysteine (Cys), homocysteine (Hcy), and glutathione (GSH), participate in various pathological and physiological processes. It is still a challenge to simultaneously distinguish Cys and Hcy because of their similar structures and reactivities, as well as the interference from the high intramolecular concentration of GSH. Herein, a novel fluorescent probe, CySI, based on cyanine and thioester was developed to differentiate Cys and Hcy through a single-wavelength excitation and two distinctly separated emission channels. The probe exhibited a turn-on fluorescence response to Cys at both 625 nm (the red channel) and 740 nm (the near-infrared channel) but only showed fluorescence turn-on to Hcy at 740 nm (the near-infrared channel) and no fluorescent response to GSH. With the aid of built-in self-calibration of single excitation and dual emissions, simultaneous discriminative determinations of Cys and Hcy were realized through red and near-infrared channels. CySI exhibited excellent selectivity toward Cys and Hcy with a fast response. This probe was further exploited to visualize exogenous Cys and Hcy in cells through dual emission channels under one excitation. Moreover, it could efficiently target mitochondria and was applied to monitor the endogenous Cys fluctuations independently in mitochondria through the red emission channel.

Visualizing hydrogen sulfide in living cells and zebrafish using a red-emitting fluorescent probe via selenium-sulfur exchange reaction.

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.

A novel near-infrared fluorescent probe for detection of hypobromous acid and its bioimaging applications.

Hypobromous acid (HOBr) is an important reactive oxygen species and has been recently found to be associated with a variety of diseases. However, owing to a lack of effective analytical tools, there is still limited understanding of its roles in living systems. Here, we present a new type of near-infrared fluorescent probe DCSN for HOBr detection. The designed probe exhibits high sensitivity with a low detection limit, excellent selectivity over other interfering species and low cytotoxicity. More interestingly, the fluorescence response behavior of the probe was different from the previous literatures due to the intramolecular charge transfer process. Moreover, we have successfully monitored HOBr in living cells by utilizing DCSN. This probe has potential to be used as a promising tool for better understanding the physiological functions of HOBr.

Construction of a novel far-red fluorescence light-up probe for visualizing intracellular peroxynitrite.

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.

A colorimetric/fluorescence dual-channel probe for highly discriminating detection of cysteine.

In this work, a novel fluorescence (FL) probe for selective and sensitive detection of Cys with colorimetric and FL dual signal changes was reported. The probe was synthesized by two step of sulfonamide reaction coupling between a sulfonyl benzoxadiazole (SBD) dye and dansyl chloride linked with rigid piperazine group. The probe showed a specific off-on response to Cys in aqueous solution with nanomolar LOD, and without interference by a range of amino acids and several competing analytes. Upon addition of Cys, the probe will undergo sequential substitution and intramolecular rearrangement reactions, yielding a 4-amino SBD derivative, which results in generation of strong yellow fluorescence emission at 575 nm accompanied by a two-step red shift in the absorption spectral. Moreover, it can be used for imaging of endogenous Cys in living cells.