Fluorescent Probe For Hypochlorous Acid Research Articles

A TICT-based fluorescent probe for hypochlorous acid and its application to cellular and zebrafish imaging

Hypochlorous acid (HOCl) is a crucial reactive oxygen species in biological systems, and its abnormal metabolism is associated with various diseases. Therefore, it is essential to accurately detect HOCl to understand its biological function and develop related therapeutic strategies for diseases. In this work, we developed a novel fluorescence probe, BCy-S, based on the twisted intramolecular charge transfer (TICT) mechanism for rapid and sensitive detection of HOCl in an aqueous solution. The probe exhibited a significant turn-on fluorescence response to HOCl, with high selectivity, rapid kinetics (less than 40 s), large Stokes shift (about 170 nm), and low detection limit (35.2 nM), based on the specific oxidation reaction of HOCl with sulfur atoms. Additionally, the outcomes of the bioimaging experiment showed that BCy-S was capable of real-time fluorescence visualization of HOCl in living HeLa cells and zebrafish. The development of BCy-S presents a new tool for investigating the physiological function of HOCl and its pathological role in diseases.

A Highly Selective Fluorescent Probe for Hypochlorous Acid in Living Cells Based on a Naphthalene Derivative.

Hypochlorous acid (HOCl) was crucial for maintaining the homeostasis in cells and plays vital roles in many physiological and pathological processes. In this work, a highly selective fluorescent probe for hypochlorous acid in living cells was constructed and prepared based on a naphthalene derivative. A naphthalene derivative was utilized as the fluorescent group, and N,N-dimethylthiocarbamate was applied as the selective recognition site for HOCl. Before adding HOCl, the fluorescent probe exhibited weak fluorescence. Upon adding HOCl, the fluorescent probe displayed remarkable fluorescence enhancement. The fluorescence intensity at 502 nm showed a linear response to the concentration of HOCl from 3.0 × 10−7 to 1.0 × 10−5 mol·L−1. The detection limit was estimated to be 1.5 × 10−7 mol·L−1 for HOCl. The fluorescent probe showed fast response and outstanding selectivity toward HOCl. It owned good biocompatibility and had also been successfully applied in the confocal imaging of exogenous and endogenous HOCl in living cells.

Hydrogen bond-induced planarity and ESPT Process: A theoretical insight into the sensing mechanism of a fluorescent probe for hypochlorous acid

A time-dependent density functional theory is used to study photochemical properties and endogenous hypochlorous acid (HClO) recognition mechanism of a reported fluorescent probe (Chem. Sci. 2019, 10, 3715). Upon the addition of HClO, an intramolecular hydrogen bond in the oxidation product of the probe flattens the molecular geometry and leads to an excited-state proton transfer (ESPT) process, which increases the fluorescence wavelength. Frontier orbital analysis verifies that intramolecular charge transfer is the primary driving force for the ESPT process of the oxidation product. An excited-state potential energy scan further confirmed that ESPT is a spontaneous process without an energy barrier.

A New Fluorescent Probe for Hypochlorous Acid Based on Chlorinium Ions Recognition Mechanism and Its Bioimaging Research in Living Cells

A New Fluorescent Probe for Hypochlorous Acid Based on Chlorinium Ions Recognition Mechanism and Its Bioimaging Research in Living Cells

A highly sensitive, fast responsive and reversible naphthalimide-based fluorescent probe for hypochlorous acid and ascorbic acid in aqueous solution and living cells.

It is very important to exploit real-time, ultrasensitive and specific visualization detection methods for hypochlorous acid/hypochlorite (HOCl/ClO-) in biological systems as they are the guardians of the human immune system against pathogens invasion. In our work, we designed a novel reversible naphthalimide-based fluorescent probe NAP-OH to recognize HClO/ClO- with a unique selective colorimetric and fluorescent response, a short response time (<8 s) and a high sensitivity (10.3nM). In addition, NAP-OH exhibits a novel on-off-on fluorescence response to ClO-/ascorbic acid (AA) with good cycle stability. The fluorescence signal is quenched because HClO/ClO- oxidizes the subunit of NAP-OH to the segment 2,2,6,6-tetramethyl-1-oxo-piperidinium in NAP-O, which can be reduced by AA with the recovery of fluorescence. Finally, the confocal fluorescence imaging has been performed, which proves that NAP-OH can satisfactorily monitor intracellular endogenous and exogenous HClO/AA redox cycles.

Rational Design of a Two-Photon Ratiometric Fluorescent Probe for Hypochlorous Acid with a Large Stokes Shift.

By introducing the tetrahydroquinoxaline group as the electron donor to enhance intramolecular charge transfer effect, we deliberately designed a coumarin derivative, TQC-HClO, to serve as a two-photon ratiometric fluorescent probe for imaging hypochlorous acid in cells and zebra fish with good sensitivity and high selectivity. TQC-HClO displayed an obvious two-photon absorbance cross-section (over 100 GM in 800-840 nm), large Stokes shifts (159 to 173 nm), and a ratiometric fluorescence change from orange (λmaxem = 583 nm) to red (λmaxem = 650 nm) in response to hypochlorous acid.

An endoplasmic reticulum-targeting and ratiometric fluorescent probe for hypochlorous acid in living cells based on a 1,8-naphthalimide derivative

A novel reticulum-targeting and ratiometric fluorescent probe for determining hypochlorous acid has been developed.

Sulfonyl-semicarbazide group as a recognition site: A novel ratiometric fluorescent probe for hypochlorous acid and imaging in living cells

In this work a sulfonyl-semicarbazide moiety was developed initially to be a selective recognition site for the design of HClO fluorescent probe. The 1,8-naphthalimide fluorophore platform was chosen to construct the probe by making use of its intramolecular charge transfer (ICT) nature. By modifying the electron-donating 4-amino group on the 1,8-naphthalimide molecular with the more electron-deficient sulfonyl-semicarbazide group, probe 1 was synthesized and showed ratiometric fluorescent responses towards HClO exclusively. This was ascribed to the specific cleavage of HClO towards the substituent resulting in the release of 4-amino-1,8-naphthalimide. Also, the probe showed excellent performance in high sensitivity and good selectivity towards HClO over other reactive oxygen species and a wide variety of coexist species in biological pH condition. The probe was successfully applied to detect hypochlorous acid in real water samples and image HClO in living U-373MG cells.

A lysosome-targetable and ratiometric fluorescent probe for hypochlorous acid in living cells based on a 1,8-naphthalimide derivative.

Hypochlorous acid (HClO) is an important reactive oxygen species (ROS) and plays a significant role in living organisms. Highly selective and lysosome-targetable probes for sensing hypochlorous acid are rare. In this article, we designed and prepared a new lysosome-targeting and ratiometric fluorescent probe for monitoring the levels of hypochlorous acid. 4-Aminonaphthalimide was chosen as the fluorescent group and (2-aminoethyl) thiourea group was used as a specific recognition group for HClO. A morpholine unit was employed as a lysosome-targeting group. In the absence of HClO the probe underwent intramolecular charge transfer (ICT) and showed a green emission. When excess HClO is present, the ICT process was interrupted which caused a 57 nm blue-shift of fluorescence emission from 533 nm to 476 nm. The ratiometric fluorescent probe showed outstanding selectivity toward HClO over other various bioactive species. Furthermore, the ratiometric fluorescent probe exhibited rapid response time and ability of working in a wide pH range. The linear response of I476nm/I533nm toward HClO was obtained in a concentration range of HClO from 1.0 × 10-6 to 1.0 × 10-4 mol·L-1. The detection limit was estimated to be 8.0 × 10-7 mol·L-1 for HClO. Moreover, the probe showed a perfect lysosome-targeting ability, and has been successfully used to the confocal imaging of HClO in lysosomes of HepG2 cells with little cell toxicity. All of such good properties illustrated that it could be applied to determine HClO at lysosomes in living cells.

A ratiometric fluorescent probe for hypochlorous acid and its biological applications

We present a lysosome-targetable and ratiometric fluorescent probe, TJ2, for visually monitoring exogenous and endogenous HOCl in living cells by using a built-in S atom within the π-extended rhodamine fluorophore as a pH-independent recognition site. Based on the oxidation-promoted intramolecular charge transfer processes, TJ2 demonstrates fast ratiometric fluorescence response, excellent selectivity, and high sensitivity (2.3 nM) toward HOCl. Furthermore, TJ2 is highly lysosome-targetable, which could be used for ratiometric monitoring of the levels of HOCl in lysosomes.

A highly selective and sensitive fluorescent probe for hypochlorous acid and its lysosome-targetable biological applications

A novel lysosome-targetable fluorescence probe PT-1 based on a photoinduced electron transfer (PET) mechanism has been designed and synthesized. For comparison, the probe PT-2 without morpholine moiety as a lysosome-directing group was also synthesized and investigated. Probes PT-1 and PT-2 exhibited high selectivity, high sensitivity (with the detection limits down to the 10−10M range) and response in real time (within 10s) toward HOCl over other reactive oxygen species (ROS). Both PT-1 and PT-2 were cell permeable and enabled them to be used for monitoring of HOCl in living cells. Meanwhile, the probe PT-1 demonstrated an accurately lysosome-targeting ability, and was successfully applied to image of exogenous, endogenous produced HOCl in living cells. The success of subcellular imaging suggested that the probe PT-1 could be used in further applications for the investigation of biological functions and pathological roles of HOCl at organelle levels.

A phenanthroimidazole-based fluorescent probe for hypochlorous acid with high selectivity and its bio-imaging in living cells

In this study, a new compound 2-amino-3-[(4-(1H-phenanthro [9,10-d] imidazol-2-yl) phenyl methylene) amino]-2-butenedinitrile (probe 1) as a simple fluorescent probe for hypochlorous acid has been synthesized and characterized. It exhibited high selectivity and sensitivity as hypochlorite sensor in mixed aqueous medium. NMR and mass spectral analysis showed that the probe reacted with the hypochlorite ion through de-diaminomaleonitrile reaction which disrupted the ICT mechanism by breaking the donor and acceptor linkage resulting in a remarkable enhancement of the emission intensity. In addition, the probe worked excellently within a wide pH range of 4 to 10 and the detection limit was found to be 1.4×10−2μM. The cell experiments showed the good cell-membrane permeability of probe, and it could be used to image exogenous HOCl.

A solvent depend on ratiometric fluorescent probe for hypochlorous acid and its application in living cells

Hypochlorous acid (HOCl)/hypochlorite (OCl−) plays an important role in immune system, while as a major reactive oxygen species (ROS) in living systems, HOCl/OCl− is responsible for some human diseases. Thus it is critical to monitor the change of HOCl in the living cells. In this study, we prepared a novel fluorescent probe BDP-OX based on BODIPY-Dialdoxime for HOCl/OCl− determination, which displayed a remarkable “ratio” fluorescence response towards HOCl/OCl− with a fast response (completed within 15 s). The ratios of emission intensities at 538–589 nm (I538/I589) displayed a large increase from 0.015 to 2.88 with this probe. More importantly, confocal fluorescence imaging with BDP-OX showed separated signals in the presence of HOCl/OCl− in living A549 cells, that indicating BDP-OX have potential biological application prospects.

Development of a BODIPY-based ratiometric fluorescent probe for hypochlorous acid and its application in living cells

A BODIPY-based ratiometric fluorescent probe for HOCl has been designed based on the transduction of thioether to sulfoxide function. This probe features a marked absorption and emission blue-shift upon the HOCl-promoted rapid transduction, enabling the highly selective and ratiometric detection. In addition, the probe works excellently within a wide pH range of 4–10, addressing the existing pH dependency issue. Living cells studies demonstrate that the probe is cell membrane permeable and can be employed successfully to image endogenous HOCl generation in macrophage cells.

A highly selective turn-on fluorescent probe for hypochlorous acid based on hypochlorous acid-induced oxidative intramolecular cyclization of boron dipyrromethene-hydrazone

A BODIPY-based fluorescent probe, HBP, was developed for the detection of hypochlorous acid based on the specific hypochlorous acid-promoted oxidative intramolecular cyclization of heterocyclic hydrazone in response to the amount of HOCl. The reaction is accompanied by a 41-fold increase in the fluorescent quantum yield (from 0.004 to 0.164). The fluorescence intensity of the reaction between HOCl and HBP is linear in the HOCl concentration range of 1–8μM with a detection limit of 2.4nM (S/N=3). Confocal fluorescence microscopy imaging using RAW264.7 cells showed that the new probe HBP could be used as an effective fluorescent probe for detecting HOCl in living cells.

A turn-on fluorescent probe for hypochlorous acid based on HOCl-promoted removal of the CN bond in BODIPY-hydrazone

A boron dipyrromethene-based fluorescent probe was developed for sensing HOCl.

Development of a selenide-based fluorescent probe for imaging hypochlorous acid in lysosomes

Abstract The development of fluorescent probes for hypochlorous acid (HOCl) has received intense attention because of the biological significance of HOCl. In this work, a novel fluorescent probe based on a selenide switch for the detection of HOCl in lysosomes has been designed and synthesized on a 1,8-naphthalimide scaffold. The probe exhibited a high selectivity for HOCl over various reactive oxygen species (ROS) with a fast response and a large fluorescence enhancement in aqueous media. Confocal microscopy imaging of living cells indicated that the probe was able to accumulate in lysosomes and was successfully applied to imaging exogenous HOCl in living cells. Attempts of using Lyso-NI-Se to image HOCl in stimulated RAW264.7 cells failed, probably due to the absence of endogenous HOCl in lysosomes or the undesirable detection limit.

A sensitive and selective turn-on fluorescent probe for hypochlorous acid based on a thiorhodamine 6G amide, and its application in cellular imaging

We report that a previously found fluorescent chemodosimeter for Hg(II) ions can also be used as a fluorescent probe for hypochlorous acid (HClO) in that its fluorescence intensity (excited at 520 nm and measured at 563 nm) is linearly proportional to the concentration of HClO in the 1–100 μM range and with a 0.1 μM detection limit. The probe can detect HClO with virtually no interference by Hg(II) and other metal ions. The mechanism for the high selectivity for HClO has been studied. The probe was applied to image hypochlorite in E. coli cells.

A Highly Specific Fluorescent Probe for Hypochlorous Acid and Its Application in Imaging Microbe-Induced HOCl Production

Oxidative stress induced by reactive oxygen species (ROS) plays crucial roles in a wide range of physiological processes and is also implicated in various diseases, including cancer, chronic inflammatory diseases, and neurodegenerative disorders. Among the various ROS, hypochlorous acid (HOCl) plays as a powerful microbicidal agent in the innate immune system. The regulated production of microbicidal HOCl is required for the host to control the invading microbes. However, as a result of the highly reactive and diffusible nature of HOCl, its uncontrolled production may lead to an adverse effect on host physiology. Because of its biological importance, many efforts have been focused on developing selective fluorescent probes to image ROS. However, it is still challenging to design a fluorescent probe with exclusive selectivity toward a particular member of ROS. In the current work, we designed FBS as a new fluorescent HOCl probe which has high selectivity, sensitivity, and short response time in a broad range of pH. Compared with other sensors, the "dual-lock" structure of FBS has an advantage of eliminating interferences from other ROS/RNS. Importantly, we further showed that our HOCl probe could be applied for the in vivo imaging of physiological HOCl production in the mucosa of live animals. This probe provides a promising tool for the study of HOCl production.

A “turn-on” fluorescent probe for hypochlorous acid: convenient synthesis, good sensing performance, and a new design strategy by the removal of CN isomerization

A new design strategy for the development of fluorescent turn-on chemodosimeters toward OCl(-) was proposed by the removal, but not the general inhibition, of the C=N isomerization. Accordingly, Flu-1 was prepared, which, as shown in the fluorescent picture, exhibited the off-on response for OCl(-), sensitively and selectively.