Exogenous ClO Research Articles

A ratiometric fluorescent probe based on phenothiazine and quinazolinone for rapid detection of ClO− and its application

A novel fluorescent probe (BPQ-1) with large conjugated system (phenothiazine was conjugated with quinazolinone) was synthesized. BPQ-1 showed a remarkable ratiometric fluorescence response to ClO− within 10 s, and achieved large stokes shift (168 nm), high sensitivity (LOD = 16.7 nM) and excellent selectivity. Among the analytes to be detected, there is a significant change from bright yellow fluorescence to cyan fluorescence only when ClO− is added to BPQ-1. Through density functional theory calculation and mass spectrometry experiments, the fluorescence response mechanisms of the BPQ-1 are given. In addition, BPQ-1 has been successfully applied to the detection of ClO− in real water samples and test strips for detecting ClO− with different concentrations have been prepared. In particular, the probe has been successfully applied to the fluorescence imaging of exogenous ClO− in living cells.

Water-Soluble Photoluminescent Ag Nanoclusters Stabilized by Amphiphilic Copolymers as Nanoprobe for Hypochlorite Detection

Luminescent Ag nanoclusters (Ag NCs) are a promising probe material for sensing and bioimaging applications. However, the intrinsic obstacle of poor water stability and photostability greatly restrict their practical application in biological systems. Herein, we report the intracellular hypochlorite (ClO−) detection with amphiphilic copolymer-modified luminescent Ag NCs with good biocompatibility and photostability. The Ag NCs were synthesized by using chemically inert hydrophobic ligands and then modified with an amphiphilic (1,2-distearoyl-sn-glycero-3-phosphoethanolamine-N-[methoxy(poly(ethylene glycol))-2000]) (DSPE-PEG-2000) and sodium dodecyl sulfonate (SDS) for phase transfer. It was found that the approach of the removal of organic solvents during the phase transfer has remarkable influences on the properties of the Ag NCs, including their size, luminescence property, and aqueous stability. Furthermore, the silver core of Ag NCs could be oxidatively damaged by ClO−, thereby causing photoluminescence (PL) quenching. The ClO−-induced PL quenching was specific over the other common reactive oxygen species (ROS) as well as some common interferences. Finally, they have been successfully applied as a fluorescent nanoprobe for detecting exogenous and endogenous ClO− in living cells.

Self-ratiometric photoluminescence carbonized polymer dots with Junas structure for hypochlorite selective sensing

The Janus structure of carbonized polymer dots (CPDs) is characterized by an independent yet interdependent core and shell structure, potentially enabling them to function as a self-ratiometric photoluminescence (PL) sensor. However, to our best knowledge, the current lacking understanding and development of the Janus structure of CPDs lead to the unfortunate loss of its position as PL sensors that could have supported life analysis to some extent. Therefore, it is crucial to comprehensively explore the structural characteristics of CPDs and furtherly develop its potential as self-ratiometric sensors. Herein, green and red double-emitting CPDs has been rationally designed and synthesized, incorporating a distinct core-shell structure to create a self-ratiometric sensor for hypochlorite (ClO−). Leveraging the low toxicity and high-water solubility of CPDs, we have successfully achieved exogenous and endogenous ClO− sensing in cells. This approach offers a novel strategy for developing CPDs-based sensors and sets the stage for a more in-depth exploration of the Janus structure of CPDs.

Ratiometric fluorescent probe with AIE characteristics for hypochlorite detection and biological imaging

It is very important and highly valuable to detect ClO− in samples and living cells with accuracy and speed. In this work, a novel fluorescent probe NA was prepared from 4-bromo-1,8-naphthalic anhydride by acylation reaction and Suzuki coupling reaction and used for the detection of ClO−. Thiomethyl serves as the recognition group for probe NA, while naphthalimide serves as fluorescent chromophore. The probe exhibited an extremely pronounced blue shift from yellow to blue fluorescence within 1 min after the addition of hypochlorite (ClO−). The probe demonstrates high sensitivity to ClO− with a limit of detection (LOD) of 1.22 µM. Also, probe NA demonstrates excellent selectivity and immunity to interference. Additionally, simple fluorescent test strips containing probe NA were prepared in this study, enabling rapid detection of ClO− in water samples. And NA had been effectively used to image endogenous and exogenous ClO−fluorescence in living cells. The results suggest that probe NA has significant potential for portable detection and biological applications.

Levonorgestrel protected Au10 cluster for hypochlorite sensing in living organisms

BackgroundHighly reactive oxygen species (ROS) could lead to serious damage in living cells and are associated with many diseases like cancers. Metal cluster with strong fluorescence has great potential in biosensing and many thiolate ligands-protected clusters have been applied in ROS sensing. ResultsIn this work, we synthesized levonorgestrel protected Au10 cluster with specific sensing ability for highly ROS via crystal transformation from Au8 cluster, demonstrating the significance of inner core structure on detecting performance. The detection limit of Au10 cluster for ClO− could reach as low as 0.1 μM. This fluorescent probe not only achieving detection of exogenous ClO− in living cells and zebrafish, but also successful imaging of endogenous ClO− in HeLa and HepG2 cells. SignificanceIn comparison to previously reported cluster-based sensors for ROS, this work proposes a different reaction mechanism of metal nanoclusters for ROS detection (breakage of gold-alkynyl bond and oxidation of alkynyl group). This provides new directions for designing specific ROS probes and broadens the applications of metal clusters in disease diagnostics.

A Ratiometric Fluorescent Detection Platform Using G‐CDs@[Ru(bpy)3]2+ for the Specific Detection of Hypochlorite and Live Cell Imaging

AbstractHypochlorite (ClO−), an essential reactive oxygen species (ROS) in physiological processes, is identified to be closely connected with oxidative stress and related diseases. Meanwhile, ClO− is a commonly‐used disinfector for water treatment, and in public places, under acidic conditions, it's easily decomposed into hypertoxic chlorine gas. Since the strong oxidizing property of ClO−, many oxidizing agents may disturb the ClO− detection. Specific and accurate detection of ClO− with superior sensitivity is a challenge. In this work, a sensing platform for rapid, sensitive, and specific ClO− detection is constructed using green fluorescent carbon dots (G‐CDs), with a linear detection range of 0.5–11 µm and a detection limit of 0.233 µm. Moreover, introducing a red fluorescent tripyridinium ruthenium ([Ru(bpy)3]2+) as a reference, a ratiometric fluorescence nanoprobe G‐CDs@[Ru(bpy)3]2+ is prepared and shows favorable intracellular imaging of exogenous and endogenous ClO−. With G‐CDs@[Ru(bpy)3]2+‐based test paper microarrays and a color recognition APP, a smartphone‐based sensing system for point‐of‐care testing of ClO− is also fabricated. In summary, this work proposed a versatile and economical smartphone‐based sensing system that featured reliability and simplicity, and suggested its potential applications in environmental water quality monitoring and live cell imaging.

A dual-emission fluorescent probe for simultaneous detection of singlet oxygen and hypochlorous acid in lipid droplets

Singlet oxygen (1O2) and hypochlorite (ClO-) are two important reactive oxygen species. They coexist in living systems and can be interconverted in organisms, being involved in a variety of pathophysiological processes. Lipid droplets (LDs) are organelles that transport and store lipids, and 1O2 and ClO- tend to destroy unsaturated lipids, leading to lipid oxidation and causing a range of diseases. Here we proposed the first dual-response fluorescent probe DBCC that can simultaneously distinguish 1O2 and ClO- within LDs. The probe is almost non-fluorescent, while significant fluorescence enhancement can be observed in the blue and green channels after treatment with 1O2 and ClO-, respectively. With the excellent properties of high sensitivity, good selectivity and wide tolerance range, the probe DBCC has been successfully used to detect 1O2 and ClO- in HepG2 cells and zebrafish, and faultlessly realized endogenous and exogenous 1O2 and ClO- imaging in LDs. This work provides a powerful analytical tool for further investigating the levels of 1O2 and ClO- in LDs and associated diseases.

A novel hepatocyte-targeting fluorescent probe of rhodamine analogues to detect hypochlorite in lysosomes: Design, synthesis and evaluation

A novel hepatocyte-targeting and lysosomal-targeting fluorescent probe of rhodamine analogues MOR-HOCl-Gal was designed and synthesized. MOR-HOCl-Gal exhibited good sensitivity and selectivity towards ClO−, without interference from other reactive oxygen species, representative anions, and representative cations. MOR-HOCl-Gal could be oxidized by ClO− to generate an instantaneous dicarbonyl diimide, and then hydrolyzed and ring-opened to a conjugated structure with high fluorescence property, which is confirmed by MS, 1HNMR and DFT calculations. Low toxic MOR-HOCl-Gal could distinguish hepatoma cells from other tissue cells, and selectively monitor endogenous and exogenous ClO− in liver lysosomes. The success of MOR-HOCl-Gal imaging in the zebrafish suggests that the aimed probe has the potential to visually monitor the presence of ClO− in vivo, and is expected to become a new effective diagnostic tool for liver related diseases.

A novel fluorescent probe based on carbazole-thiophene for the recognition of hypochlorite and its applications

A carbazole thiophene-aldehyde and 4-methylbenzenesulfonhydrazide conjugate CSH was synthesized by introducing 5-thiophene aldehyde at the 3-position of the carbazole group as the precursor and then condensing it with 4-methylbenzenesulfonhydrazide. CSH has high selectivity and sensitivity towards ClO−, which can specifically identify ClO− by UV–Vis and fluorescence spectroscopy. CSH can rapidly respond to ClO− in the physiological pH range through a fluorescence quenching pattern, accompanied by the color of CSH changing markedly from turquoise to yellowish green under the 365 nm UV light. Probe CSH exhibits a quantitative response to ClO− (0–11 μM) with a low detection limit (1.16 × 10−6 M). Cell imaging experiments have shown that CSH can capture fluorescent signals in the cyan and yellow channels of HeLa cells through fluorescence confocal microscopy, and can successfully identify exogenous ClO− in HeLa cells. In addition, probe CSH can also be used to detect ClO− in environmental water samples. These results indicate that CSH has potential application prospects in the environmental analysis and biological aspects.

Fluorescent Biomass-Based Platform for Detection of ClO- in Cells and Water-Soluble Systems.

The generation and presence of excessive hypochlorous acid derivative ionic form (ClO-) could cause various diseases, such as arteriosclerosis, DNA damage, and cardiovascular illness. It is a critical need to develop a highly sensitive sensor for reliable detection of ClO- in cells and water-soluble systems. In this work, a hydroxyl group has been introduced into the compound 2-amino-3-(((E)-4-(2-(2-(2-hydroxyethoxy)ethyl)-1,3-dioxo-2,3-dihydro-1H-benzo[de]isoquinolin-6-yl)benzylidene)amino)maleonitrile (NDC) to increase its solubility in water, at the same time, the hydrazone unit was designed as a specific recognition group for the "off-on" fluorescence probe of ClO-. The probe NDC presents high selectivity, sensitivity, anti-interference, and low detection limit (67 nM) for ClO-. The recognition mechanism that ClO- breaks the C=N bond and forms the fluorescent compound 4-(2-(2-(2-hydroxyethoxy)ethyl)-1,3-dioxo-2,3-dihydro-1H-benzo[de]isoquinolin-6-yl)benzaldehyde (ND-3) has been confirmed by time-of-flight mass spectrometry. The probe NDC presents a good performance in the actual test of water samples and can be designed as the test papers for the quick and convenient detection of ClO- range from 0 to 1 μM. Moreover, the practical application was demonstrated by the successful imaging of endogenous and exogenous ClO- in HeLa cells. Our fluorescent biomass-based platform opens vast possibilities for repeatability, sensitivity, and selectivity detection of ClO- in cells and water-soluble systems.

Fluorescent imaging and smartphone detection of ClO- using sensors based on trifluoromethylquinoline-substituted pyranonitrile

In the field of novel fluorescent sensors, achieving rapid and sensitive tracking of target substances has become an urgent imperative. Applying this technology to the detection of biomarkers for biological diseases holds profound practical significance. Hypochlorous acid (HClO) is a significant reactive oxygen species (ROS) within biological systems. Aberrant metabolism of HClO can result in disruptions of physiological functions and oxidative stress, consequently influencing the development of various diseases. In this context, our study has successfully developed a novel fluorescent probe named W-4a, which employs trifluoromethyl quinoline as a substitute for traditional pyranonitrile compounds, enabling the rapid (<40 s) and highly sensitive (UV limit of detection: 1.62 μM; fluorescence limit of detection: 0.14 μM) detection of ClO-, during the detection process, ClO- effectively activated the fluorescent probe and showed a distinct red fluorescent signal at 687 nm. Furthermore, the W-4a probe exhibits excellent biocompatibility and excels in both exogenous and endogenous ClO- detection imaging within cells, Co-localization experiments indicate that probe W-4a effectively targets the Golgi apparatus. Additionally, in conjunction with the W-4a probe, we have devised a portable smart detection method for hypochlorous acid in environmental settings, which holds the potential to serve as a flexible and potent tool for monitoring environmental toxicity.

Construction of optical dual-mode sensing platform based on green emissive carbon quantum dots for effective detection of ClO- and cellular imaging

Hypochlorite (ClO-) is an important redox regulator in reactive oxygen species, which play a considerable role in oxidative stress and related diseases. Hence, accurate and sensitive monitoring of ClO- concentration was urgently needed in the fields of life sciences, food and environment. Bright green fluorescent carbon quantum dots (G-CQDs) were synthesized utilizing one-step hydrothermal method with citric acid and acriflavine precursors. Through TEM, FTIR, XPS and zeta potential characterization procedures, G-CQDs illustrated uniformly dispersed and significant number of –NH2 and –OH on the surface. Meanwhile, the fluorescence and colorimetric analysis exhibited wide linear range and low detection limit response to ClO-. The fluorescence changes of G-CQDs were identified via smartphone to realize mobile sensing of ClO-. Subsequently, G-CQDs was applied for visualization and quantitative detection of ClO- in drinking water samples with satisfactory recovery rate. More importantly, G-CQDs demonstrated good water solubility, optical stability and excellent biocompatibility, which offered a promising analysis approach in cell imaging and exogenous ClO- detection in living cells. G-CQDs illustrated bright prospect and great potential in practical application of ClO- associated disease prevention and early clinical diagnosis.

Synthesis and application of hypochlorite mediated acylhydrazone fluorescence probes.

Hypochlorous acid (HClO/ClO- ) is one of the important reactive oxygen species (ROS). It acts as a second signaling molecule within and between cells and is an indispensable active molecule in living organisms to regulate physiological and pathological processes. In this article, two fluorescent probes (PTF and PTA) for highly selective fluorescent recognition of ClO- were successfully synthesized based on the ICT mechanism by condensing phenothiazines with two hydrazides via the hydrazide structure (). PTF can identify different concentrations of ClO- in two steps. Due to its ClO- two site recognition, the probe exhibited good selectivity (specific recognition of ClO- over a wide concentration range), a fast time response (rapid recognition in seconds), a sufficiently low detection limit (3.6 and 11.0nM), and large Stokes shifts (180 and 145 nm). Furthermore, the recognition of ClO- by contrasting probes with different substituents exhibited different fluorescence changes of ratiometric type and turn-off. PTF successfully achieves the detection of exogenous and endogenous ClO- in aqueous solution and living cells.

A colormetric and ratiometric AIE probe for imaging endogenous and exogenous hypochlorite

Herein, we designed a potent ClO− probe named ETMC, which exhibited aggregation-induced emission (AIE) characteristic in solid state and water/EtOH binary solvent. Probe ETMC exhibited an colormetric from yellow to blue and ratiometric response to ClO− with high selectivity and sensitivity, and a low detection limit of 3.66 × 10−7 M. Moreover, probe ETMC could be applied to visibly and quantitatively detect the different concentraction of ClO− in test paper. Importantly, probe ETMC could effectively detect endogenous and exogenous ClO− in living A549 cells by an outstanding ratio signal change. Also, the sensing mechanism of probe ETMC for ClO− was confirmed by FT-IR, 1H NMR, HRMS, DLS, TEM and DFT calculation.

A new phenoxazine-based turn-on fluorescent probe for monitoring hypochlorite in food/urine/water/beverage samples and bioimaging in zebrafish

High level of hypochlorite (ClO−) can lead to oxidative stress responses and cell damage, thus, it is of the utmost importance to monitor ClO− in real-world samples and live systems. In this work, a new phenoxazine-based turn-on fluorescent probe (PB) was reported for detecting ClO− with high specificity and strong anti-interference effect, along with the naked-eye fluorescence color changed from dark to green. Probe PB responded to ClO− with high sensitivity (detection limit: 0.11 µM), broad pH working range (5–9) and fast response (<5 min). The detecting mechanism was verified by the corresponding spectra of 1H NMR/HRMS and DFT calculations. With the favorable sensing performances, the probe PB-coated test strips were fabricated for easy, convenient, fast and colorimetric identification of ClO− with sensitive responses. Meanwhile, probe PB was applied to detect ClO− in urine/food/water/beverage samples, sprouting potatoes and living soybean sprouts, showing its diverse practical applicability. Furthermore, PB probe was also used to monitor exogenous ClO− in zebrafish owing to its good biocompatibility, indicating its great bioimaging potential for micro-level detection of ClO− in vivo. All the investigated results demonstrated that there exist promising possibilities of PB for practical applications in bioimaging system and urine/food/water/beverage monitoring.

A Simple ICT-Based Fluorescent Probe for HOCl and Bioimaging Applications.

Over the past few decades, drug-induced liver damage (DILI) has become a serious public health problem due to drug abuse. Among multifarious reactive oxygen species, mounting evidence attests that ClO- has been used as a potential biomarker in DILI. In this work, a new "turn-on" fluorescent probe 1 was designed and synthesized by modifying 4'-hydroxybiphenyl-4-carbonitrile (dye 2) with N, N-dimethylthiocarbamate as a response site for detecting ClO-. Probe 1 displayed a low detection limit (72 nM), fast response time (30 s), wide pH operating range (6-8), great tissue penetration, large Stokes shift (125 nm) and 291-fold fluorescence enhancement at 475 nm in the mapping of ClO-. Probe 1 could trace amounts of exogenous and endogenous ClO- with high sensitivity in MCF-7 cells and HeLa cells. Expectantly, the fluoxetine-induced liver injury model is successfully established, and probe 1 has been used for detecting the fluctuation of ClO- levels in the mouse model of fluoxetine-induced liver injury. All in all, probe 1 with its high specificity, good biological compatibility and liver tissue penetration ability is expected to assist with the early diagnosis of DILI and the clinical screening of various new drugs. We expect that probe 1 could be efficiently used as a powerful molecular tool to predict clinical DILI and explore molecular mechanisms between molecules and disease.

A novel colorimetric fluorescence probe for the sensitive and selective detection of hypochlorite and its bioimaging in living cells

Hypochlorite (ClO−) is a well-known redox regulator among reactive oxygen species and plays a crucial role in bacterial disinfection and body immunity. Therefore, there is a high demand for an analytical technique to monitor ClO− under physiological conditions. Herein, a novel fluorescence probe, RES-DPPT, was developed for detecting ClO−. This probe employs diphenylphosphinothioyl unit as the recognition group and resorufin as the fluorescent platform. RES-DPPT has high sensitivity and specificity, rapid response, and wide pH tolerance for monitoring ClO−. Additionally, RES-DPPT undergoes colorimetric and fluorescence color changes in the solution, which can be observed by the “naked eye.” Furthermore, RES-DPPT is successfully able to detect exogenous and endogenous ClO− in living cells.

An endoplasmic reticulum-targeted ratiometric fluorescent probe for hypochlorite bioimaging based on aggregation-induced ratiometric emission

A novel pyrene-based fluorescent probe was synthesized, with an aggregation-induced ratiometric emission (AIRE) at 525 nm in 99% H2O solution (containing 1% DMSO). This AIRE was quenched, and a new blue emission at 470 nm was detected after adding hypochlorite (ClO−), according to a fast (within 20 s) and sensitive (detection limit of 269 nM) ratiometric fluorescent response to ClO−. The sensing mechanism of the probe to ClO− was assessed by ESI-MS, transmission electron microscopy, time-resolved fluorescence measurements, and density functional theory. In addition, the probe is equipped with p-toluenesulfonamide as the endoplasmic reticulum (ER) localization group, and has been applied to the imaging of endogenous and exogenous ClO− in both living cells and zebrafish.

A fluorescent probe based on phenothiazine for detection of ClO− with naked-eye color change properties

Hypochlorite (ClO−) plays a key role in life systems and it is necessary to develop an effective detection method. In view of the significant advantages of the fluorescent probe, we have synthesized a naked-eye recognition fluorescent probe NNCF for the detection of ClO− based on phenothiazine and naphthalimide. The probe NNCF is sensitive (LOD = 9.5 nM) and fast for ClO− (within 30 s), and its Stokes shift is as large as 161 nm. In addition, the probe NNCF has been successfully used for imaging detection of exogenous ClO− in MCF-7 cells with low toxicity.

A ratiometric hypochlorite-specific nanoprobe constructed by rationally designed AIE luminogen for fluorescence imaging of alcoholic liver disease

There is a lack of effective and friendly diagnostic technique for alcoholic liver disease (ALD). Fluorescence imaging, which has been widely applied in disease diagnostic ascribed to the merits of high sensitivity, excellent temporal resolution and minimal invasiveness, is probably a good candidate for ALD studying. Herein, by precise molecular optimization, an aggregation-induced emission (AIE) probe of TCPQ was designed to show bright near-infrared (NIR) emission centered at 680 nm, and selective response towards ClO− for ALD diagnosis. In comparison with PNQ, the started fluorophore constructed with ClO− oxidizable donor phenothiazine (PZ) and AIE active acceptor quinoline-malononitrile (QM), the emission wavelength and fluorescence quantum yield of TCPQ were 63 nm red-shifted and 2.3-fold enhanced after structural optimization. Once exposed to ClO−, the S atom in PZ donor of TCPQ could be oxidized to sulfoxide, leading to blue-shifted emission, which made TCPQ be suitable for ratiometirc imaging with high accuracy, while the such weak emissions of the other probes here in presence of ClO− made the ratiometric imaging impossible. After forming nanoparticles (NPs) with amphiphilic F-127, TCPQ NPs have successfully imaged the exogenous and endogenous ClO− fluctuations through the ratio between brightness of green channel and red channel, and have been further utilized to quantitatively evaluate the ClO− levels in four types of cells. The possibility of ClO− as a biomarker for ALD was confirmed in the cellular ALD model. Subsequently, TCPQ NPs were further applied in ALD diagnosis and pharmacodynamic evaluation of an anti-ALD drug in the mouse model.