Fluorescent Organic Compounds Research Articles

Luminescent Probe Based on Terbium-Carbon Quantum Dots for the Quantification of Imidacloprid in Caneberries.

We propose a modification of terbium-sensitized luminescence (TSL) by means of the introduction of nanoparticles to improve the sensitivity and selectivity of the analytical methods. TSL detection is usually based on the complexation between fluorescent organic compounds (the analytes) and terbium. The organic compound is then excited, and, after an energy transfer towards terbium, the latter emits the luminescence signal. Here, the modification consists of the introduction of nanoparticles (carbon quantum dots, CQDs) into the system. The carboxylic groups of CQDs react with terbium, providing an interesting time-resolved luminescence probe. We applied this system for the determination of the neonicotinoid imidacloprid (IMID). When IMID was introduced in the terbium-CQDs system, the luminescent signal (λexc/λem of 256/545 nm) was quenched, proportionally to IMID concentration in the range of 100-2500 ng·mL-1, obtaining a limit of detection of 30 ng·mL-1. A method detection limit of 0.9 mg·kg-1 was reached in caneberries, thus complying with the maximum residue level of 5 mg·kg-1 established by Codex Alimentarius. We performed recovery experiments in caneberries (blackberries, blueberries, raspberries, and mulberries), obtaining recovery yields close to 100% in all cases. These results show that the use of terbium ions-nanoparticles luminescence probes can be useful for screening purposes in quality control laboratories.

Photocatalytic membrane coated with α-Fe2O3/Fe3O4 for enhanced filtration performance and antifouling property in surface water treatment

A photocatalytic membrane coated with α-Fe2O3/Fe3O4 nanoparticles has been developed to address the challenges of membrane fouling and organic removal in the treatment of natural surface water. The photocatalytic and filtration properties of the membranes were investigated through a variety of methods. The successful preparation of iron oxide was confirmed by UV–vis diffuse reflectance spectra and X-ray diffractometry, with α-Fe2O3 identified as the primary photocatalytic agent. A commercial ultrafiltration (UF) membrane was employed as a comparison to evaluate the photocatalytic performance and filtration properties of the modified membrane. Results showed that the photocatalytic membrane achieved better removal rates for UV254 (22.0%) and specific fluorescent organic compounds, such as component 2 (19.38%) and component 3 (16.89%), compared to the control group. Furthermore, both irreversible and reversible fouling resistances of the prepared membranes were significantly lower than that of the control group, with reductions of 39.4% and 50.2%, respectively. The membrane coated with α-Fe2O3/Fe3O4 nanoparticles exhibited moderate removal of protein-like and terrestrially derived humic-like fluorescent organics while controlling membrane fouling. Although the α-Fe2O3/Fe3O4 nanoparticles-coated photocatalytic membrane demonstrated good anti-fouling properties, the removals of organic matters were not as effective as anticipated due to the shorter hydraulic retention time. This study provides valuable insights for enhancing pollutant degradation and anti-fouling properties of membranes through the utilization of solar photocatalytic α-Fe2O3/Fe3O4 surface-modified membranes in the treatment of natural surface water.

Data-driven machine learning models for quick prediction of the Stokes shift of organic fluorescent materials

Organic fluorescent materials are widely used in various fields, including OLEDs, organic solar cells, and bio-imaging. However, designing and synthesizing new fluorescent organic materials with desirable properties for specific applications require knowledge of the chemical and physical properties of previously studied molecules. One critical property of fluorescent organic compounds is the Stokes shift, which is usually measured experimentally and is known to be time-consuming. Time-dependent density functional theory (TD-DFT) has been used to predict Stokes shifts, but its computational costs restrict the screening of fluorescent organic materials. To address this challenge, we propose a machine learning model based on an ensemble learning approach called LightGBM algorithm, to predict the Stokes shift of organic fluorescent compounds. Based on 15,987 sets of Stokes shift data processed with molecular fingerprints, our ML models show satisfactory results. The squared correlation coefficient (R2), mean absolute error (MAE), and root mean square error (RMSE) of the independent test set for the optimal model are 0.86, 12.27 nm, and 19.16 nm, respectively. Unseen cases confirmed the prediction performance of our ML model. Finally, we applied the ML prediction model to enable rapid screening of organic fluorescent compound with desired Stokes shift. Our study presents a rapid and accurate method for predicting the Stokes shift of organic fluorescent compounds, which accelerate the design of organic fluorescent materials with desired Stokes shift. All source codes and dataset are freely available at https://github.com/Yihuan-Zhao93/Stocks-shiftsML.

Organic Fluorescent Compounds Based on Phenanthroimidazole: A Review on Highlights Studies.

Organic compounds containing phenanthroimidazole; Its optical, thermal, chemical, and high fluorescence have drawn the interest of numerous researchers. Phenanthroimidazole derivatives are appealing for various applications owing to these characteristics. This research provides a summary of the general information contained in studies on the synthesis, characterisation, photophysical characteristics, and possible applications of phenanthroimidazole derivative compounds. The focus of this study revolves around these topics' utilization in technological fields such sensors, solar cells, optical brighteners, and OLED, which covers significant studies on mentioned topics. We anticipate that this study is meant to provide an outline for researchers aiming to further examine fluorescent organic compounds for technological innovations. Furthermore, we anticipate that this research will be crucial in developing long term high organic compounds for optoelectronic devices.

Degradation characteristics of refractory organic matter in naproxen pharmaceutical secondary effluent using vacuum ultraviolet–ozone treatment

Vacuum ultraviolet–ozone (VUV-O3) treatment was found to be superior to ultraviolet–ozone (UV-O3) treatment in terms of ozone utilization and hydroxyl radicals (·OH) generation when used to treat the secondary effluent (SE) from a naproxen pharmaceutical plant. VUV-O3 treatment was beneficial in terms of decolorization (100%), chemical oxygen demand removal (43.29%), and total organic carbon removal (54.81%). The VUV-O3 process was applicable over a wide pH range, and the presence of various anions had no significant influence on the oxidation efficiency. After treatment, the genotoxicity, unsaturation degree, and polarity of the SE decreased. In addition, the oxidation sensitivities of the fluorescent organic compounds were ranked as follows: humic acid-like > tyrosine-like > fulvic acid-like > tryptophan-like Moreover, the VUV-O3 process effectively converted refractory organic matter (molecular weights, MW > 2000 Da) into short-chain molecules with low MWs. The removal efficiency of dissolved organic matter (DOM) was 63.27%, and 77.27% of the DOM was found to be reactive to VUV-O3 oxidation. The unsaturation, polarity, and compositional complexity of the DOM decreased after VUV-O3 treatment. Finally, it was deduced that the direct O3 oxidation,·OH, O2·− and 1O2 played a role in the VUV-O3 oxidation process.

Multifunctional carbon aerogel granules designed for column reactor for efficient treatment of shale gas flowback and produced water

Shale gas flowback and produced water (SGFPW) greatly hinders sustainable shale gas development and can cause severe environmental threats without proper treatment. Aerogel is an advanced adsorption material for treating SGFPW with complex components; nevertheless, there is little investigation on the aerogel adsorbent designed for SGFPW treatment on-site. Herein, we report a facile and green method for preparing carbon aerogel granules (CAGs) with porous biochar aerogel (PBA) incorporated on physically cross-linked chitosan matrix for high-performance treatment of SGFPW. CAGs exhibit good elasticity with Young’s modulus of 49 kPa for practical use and ultra-high water adsorption ratio of 1936.7 % for fast liquid-phase mass transfer of pollutants from SGFPW to CAGs. CAGs show high removal rates for various organic pollutants in SGFPW, including ≥ 36.6 % of dissolved organic carbon (DOC), ≥ 72.2 % of UV254, and ≥ 92.2 % of total fluorescent organic compounds within 60 min. Meanwhile, CAGs allow steady adsorption of heavy metals such as Zn (18.8–21.7 %), Co (20.1–23.7 %), Cu (18.4–29.8 %), Pb (32.5–62.1 %), and Al (54.8–58.1 %) in SGFPW. The adsorption of dissolved organic pollutants in SGFPW by CAGs is mainly based on their π-π electron-donor–acceptor (EDA) interaction with the PBA carbon skeleton, while the adsorption of heavy metals based on their complexation with the N and O atoms of PBA. CAGs are suitable for the fixed bed to treat SGFPW, which displays good binary functions of filtration and adsorption, showing high potential for treating SGFPW on-site.

Cucurbit[n]uril-based fluorescent indicator-displacement assays for sensing organic compounds.

The widespread conversion of synthetic receptors into luminescent sensors has been achieved via the use of fluorescent-indicator displacement assays (F-IDAs). Due to their rigid structures and efficient binding affinities, cucurbit[n]urils, combined with a variety of fluorescent guests, have gained extensive utilization in fluorescent-indicator displacement assays for sensing non-fluorescent or weakly fluorescent organic compounds (analytes) in a selective and specific manner. This mini-review summarizes recent advances in the design of cucurbit[n]uril-based fluorescent-indicator displacement assays and discusses the current challenges and future prospects in this area.

Novel Antitumor Agents Based on Fluorescent Benzofurazan Derivatives and Mesoporous Silica

Two novel fluorescent mesoporous silica-based hybrid materials were obtained through the covalent grafting of [4-hydrazinyl-7-nitrobenz-[2,1,3-d]-oxadiazole (NBDH) and N1-(7-nitrobenzo[c][1,2,5]-oxadiazol-4-yl) benzene-1,2-diamine (NBD-PD), respectively, inside the channels of mesoporous silica SBA-15. The presence of fluorescent organic compounds (nitrobenzofurazan derivatives) was confirmed by infrared spectroscopy (IR), X-ray photoelectron spectroscopy (XPS), thermal analysis (TG), and fluorescence spectroscopy. The nitrogen physisorption analysis showed that the nitrobenzofurazan derivatives were distributed uniformly on the internal surface of SBA-15, the immobilization process having a negligible effect on the structure of the support. Their antioxidant activity was studied by measuring the ability to reduce free radicals DPPH (free radical scavenging activity), in order to formulate potential applications of the materials obtained. Cytotoxicity of the newly synthesized materials, SBA-NBDH and SBA-NBD-PD, was evaluated on human B16 melanoma cells. The morphology of these cells, internalization and localization of the investigated materials in melanoma and fibroblast cells were examined through fluorescence imaging. The viability of B16 (3D) spheroids after treatment with SBA-NBDH and SBA-NBD-PD was evaluated using MTS assay. The results showed that both materials induced a selective antiproliferative effect, reducing to various degrees the viability of melanoma cells. The observed effect was enhanced with increasing concentration. SBA-NBD-PD exhibited a higher antitumor effect compared to SBA-NBDH starting with a concentration of 125 µg/mL. In both cases, a significantly more pronounced antiproliferative effect on tumor cells compared to normal cells was observed. The viability of B16 spheroids dropped by 40% after treatment with SBA-NBDH and SBA-NBD-PD at 500 µg/mL concentration, indicating a clear cytotoxic effect of the tested compounds. These results suggest that both newly synthesized biomaterials could be promising antitumor agents for applications in cancer therapy.

Fluorescent and Phosphorescent Nitrogen-Containing Heterocycles and Crown Ethers: Biological and Pharmaceutical Applications.

Fluorescent molecules absorb photons of specific wavelengths and emit a longer wavelength photon within nanoseconds. Recently, fluorescent materials have been widely used in the life and material sciences. Fluorescently labelled heterocyclic compounds are useful in bioanalytical applications, including in vivo imaging, high throughput screening, diagnostics, and light-emitting diodes. These compounds have various therapeutic properties, including antifungal, antitumor, antimalarial, anti-inflammatory, and analgesic activities. Different neutral fluorescent markers containing nitrogen heterocycles (quinolones, azafluoranthenes, pyrazoloquinolines, etc.) have several electrochemical, biological, and nonlinear optic applications. Photodynamic therapy (PDT), which destroys tumors and keeps normal tissues safe, works in the presence of molecular oxygen with light and a photosensitizing drugs (dye) to obtain a therapeutic effect. These compounds can potentially be effective templates for producing devices used in biological research. Blending crown compounds with fluorescent residues to create sensors has been frequently investigated. Florescent heterocyclic compounds (crown ether) increase metal solubility in non-aqueous fluids, broadening the application window. Fluorescent supramolecular polymers have widespread use in fluorescent materials, fluorescence probing, data storage, bio-imaging, drug administration, reproduction, biocatalysis, and cancer treatment. The employment of fluorophores, including organic chromophores and crown ethers, which have high selectivity, sensitivity, and stability constants, opens up new avenues for research. Fluorescent organic compounds are gaining importance in the biological world daily because of their diverse functionality with remarkable structural features and positive properties in the fields of medicine, photochemistry, and spectroscopy.

Computational modeling for the design of new fluorescent organic compounds based on both diketopyrrolopyrrole and nitrobenzofurazan moieties

• Design of new fluorescent organic compounds based on both diketopyrrolopyrrole and nitrobenzofurazan moieties. • Planar geometry stabilized by intra-molecular non-covalent interactions (NCIs). • Excellent optoelectronic properties of the studied compounds. • Push-pull effects on the geometrical, optical and charge transfer properties of the designed molecules have been examined. • Potential applications of the designed materials for their use in OSCs and NLO devices. Three examples of organic π-conjugated systems, based on both diketopyrrolopyrrole (DPP) and nitrobenzofurazan (NBD) were theoretically designed as host fluorescent materials that all of them emitted intense infrared fluorescence and the maximum emission bands ranged from 841 nm to 868 nm. Theoretical analysis by utilizing density function theory (DFT) and its extension of TD-DFT methods with B3LYP functional at the 6–311 g(d,p) calculation level, in acetonitrile, have been reported on the geometry, optoelectronic, absorption/emission characteristics of the studied materials. The furan-, thiophene-, or selenophene-flanked-DPP and coupled to NBD, named after M1 (X = O), M2 (X = S) and M3 (X = Se), have a great impact on optoelectronic properties to design lower optical band gap materials with excellent nonlinear optical (NLO) properties and efficient intra-molecular charge transfer (ICT). The studied molecular structures adopt a planar geometry stabilized by intra-molecular non-covalent interactions (NCIs). The reduced density gradient (RDG) has been further developed to analyze and understand the typical NCIs and their characteristics. The analysis of electron density and its reduced density gradient (RDG), NCIs, the topological analyses from MEP, ELF and LOL, QTAIM were carried out to evaluate the charge transfer within the investigated compounds.

EFFECT OF HYDROGEN BONDING ON FLUORESCENCE QUENCHING OF QUINOLIN-8-OL - ANALYSIS USING NEGATIVE STERN-VOLMER PLOTS

Photophysics of fluorescent organic compounds give a better knowledge of the excited state properties which in turn will help in the design of newer molecules and understanding their performance in specific applications. Here we present the fluorescence quenching study of a Quinolin-8-ol (QO) in toluene and butanol solvents by steady state fluorescence measurements. Anilineis the quencher. Negative deviation in the Stern – Volmer (S-V) plots has been observed with moderate quencher concentration. The downward curvature in the S-V plot is interpreted in terms of existence of different conformers of the solute in the ground state. The formation of intermolecular and intra molecular hydrogen bonding is found to be responsible for the conformational changes in the ground state of the solute. Quenching data is analyzed by modified Stern-Volmer equation or Lehrer equation.

Development of Optical Biosensor for the Detection of Glutamine in Human Biofluids Using Merocyanine Dye.

Merocyanine dye based fluorescent organic compound has been synthesized for the detection of glutamine. The probe showed remarkable fluorescent intensity with glutamine through ICT (Intermolecular Charge Transfer Mechanism). Hence, it is tested for the detection of glutamine using colorimetric and fluorimetric techniques in physiological and neutral pH (7.2). Under optimized experimental conditions, the probe detects glutamine selectively among other interfering biomolecules. The probe has showed a LOD (lower limit of detection) of 9.6 × 10-8mol/L at the linear range 0-180µM towards glutamine. The practical application of the probe is successfully tested in human biofluids.

Organic fluorescent compounds with twisted D-π-A molecular structure and acidochromic properties

Organic fluorescent compounds with acidochromic properties are fluorescent materials whose spectra show a significant change when exposed to acid and alkaline gases. These properties confer the advantages of high sensitivity, improved stability, and adjustable performance. Herein, we designed and synthesized a new acid stimuli-responsive molecule, namely TPA-F-PD, incorporating a twisted donor-π-acceptor (D-π-A) structure. Based on the photoelectric physical properties of TPA-F-PD, combined with experimental analysis and theoretical calculation, this thesis discusses the detailed acidochromic mechanism and explores its potential application in white-light organic light-emitting diodes (WOLEDs). TPA-F-PD exhibited a remarkable solvatochromic effect. As presented in the PL spectra, the emission peak of TPA-F-PD red-shifted by approximately 102 nm with an increase in the polarity of the solvent. When trifluoroacetic acid (TFA) was dropped into the TPA-F-PD solution, its photoluminescence (PL) spectra exhibited double emission peaks, located at 460 and 650 nm. Based on the emission-layer TPA-F-PD films treated with TFA, a WOLED was fabricated by controlling the content of TFA and expressed color coordinates of (0.31, 0.32) and a maximum external quantum efficiency of 2.1%.

Metalloporphyrin-Based Fluorescent Sensor for the Discrimination of Volatile Organic Compounds Using Density Functional Theory

This spectral property of the fluorescent sensors were investigated using density functional theory (DFT) and time-dependent density functional theory (TD-DFT). The considered silver porphyrin (AgP) was selected as a representative dye for the theoretical study of the fluorescent sensors. The molecular structures of AgP and its complexes were optimized at B3LYP/LANL2DZ basis set. The calculated geometry structures, front-line molecular orbitals, absorption spectra, and electronic structures were analyzed to reveal the molecular reaction between AgP-based fluorescent sensors and volatile organic compounds (VOCs). The energy gaps indicated that the efficient orders of AgP-based fluorescent sensor reacted with volatile organic compounds were shown as O2 < N2 < propane (L3) < propaldehyde (L5) < H2S < propanol (L2) < trimethylamine (L1) < ethyl acetate (L6) < butanone (L4). The calculated results all reveal that the AgP-based fluorescent sensor possesses significant changes (i.e., molecular structure, frontline molecular orbital, and absorption spectra) before and after reacting with volatile organic compounds, which are closely related to the selectivity and sensitivity property of AgP-based fluorescent sensor. Therefore, this study may be useful for the AgP-based fluorescent sensor in a special application region.

Zeolitic imidazolate frameworks as an efficient platform for potential curcumin-based on/off fluorescent chemosensor

Incorporating the fluorescent organic compound on the platform toward the capture of metal ions has become an attractive strategy for chemical sensor. Curcumin-based sensory platforms are fabricated chemo-sensors for the detection of cations and anions. Herein, the homogenous nanoparticle porous zeolitic imidazolate frameworks, ZIF-8 and ZIF-11 with a smaller than 100 nm particle size were used as platform for curcumin loading. The ZIF compounds were characterized by powder X-ray diffraction, N 2 sorption isotherms, and thermal gravimetric analysis to assess their potential for liquid adsorption. According to investigation of liquid adsorption, the curcumin concentration, time, and temperature of adsorption process have been carried out to provide the adsorption properties and adsorption capacity of two materials. The maximum adsorption capacity on both ZIFs was up to 4.5 mg mg −1 , with faster adsorption rates than other adsorbents reported. Compared to ZIF-11, ZIF-8 surprisingly demonstrates higher encapsulation, intraparticle diffusion, and lower kinetic parameters of k 2 . This phenomenon is explained via the crystallographic aperture size, surface area, and affinity of the 2-methylimidazolate linker in ZIF-8 relative to the benzimidazole linker in ZIF-11. The release of curcumin in both pH 5.5 and 7.4 environments below 2% for 24h showed the consistent stability of curcumin in the nanocarrier. In addition, the curcumin-based sensory ZIF-8 and ZIF-11 exhibited efficient fluoride ion sensing performance with a detection limit as low as 100 ppm. The colorimetric fluorescence sensing at ON/OFF mode highlighted the promising potential of Cur-based ZIF materials for the high dose of fluoride ion in water at pH 5.5 and 7.4. • The ZIF-8 and ZIF-11 nanomaterials (<100 nm) were successfully synthesized. • The materials display highly efficient and fast curcumin adsorption. • Kinetics, thermodynamics, and adsorption mechanism were comprehensively examined. • The stronger stability of curcumin in ZIFs at PBS is lower 8% over 10 days. • The curcumin-loaded in ZIFs exhibited efficient fluoride ion sensing performance.

Nano-assembly and optical properties of difluoroboron dibenzoylmethane-polysilane

Aggregation of various fluorophores is a useful approach to build highly sensitive and selective fluorescent sensors. In this work, the ability of oligomeric polydiphenylsilanes to associate with fluorescent low molecular weight organic compound is illustrated by the formation of stable aggregates between poly[diphenyl-co-methyl(H)]silane and dibenzoylmethanatoboron difluoride in solution. The formation of these nano-structures in solution was investigated both experimentally using gel permeation chromatography, σ spectroscopy and fluorescence spectroscopy, and theoretically by molecular modeling. Thin films obtained from this solution have a characteristic morphology in which the nano-aggregates undergo a self-organizing process and form crystalline spherulites. Association between the fluorescent polysilane and the fluorescent diketonato boron complex proceeds with an increase of fluorescence (amplification efficiency up to 90%) through a FRET mechanism as a result of aggregation, a phenomenon that could be used in the development of fluorescent sensors.

Chiral liquid crystalline networks demonstrating reversible optical texture and reversible fluorescence towards dynamic anti-counterfeiting

A dynamic surface pattern with tunable liquid crystalline texture and fluorescence in response to external stimulus can enable information recording and reading. Therefore, such patterns are widely used in the field of information security and anti-counterfeiting. A higher level of security in anti-counterfeiting is extremely desirable but challenging, herein, the chiral liquid crystalline networks (CLCN) used for anti-counterfeiting displaying both dynamic reversible Grandjean textures and fluorescence were dexterously designed and prepared by graft copolymerization of polymethylhydrosiloxane (PMHS), nematic liquid crystal M1, chiral crosslinker M2 and organic fluorescent pyrene compounds M3. The CLCN can emit blue-fluorescence when irradiating with ultraviolet light. More importantly, the Grandjean textures and fluorescence can be simultaneously and precisely adjusted by temperature. The as-prepared CLCN display reversible Grandjean textures during the heating and cooling process from the intrinsic chiral arrangement of CLCN. The discrete pyrene chromogenic segments in CLCN matrix enable the tunable photoluminescence by temperature, furthermore, the CLCN present highly sensitive photoluminescence evolution. The dynamic reversible Grandjean textures and fluorescence make the smart materials promising candidates in anticounterfeiting, providing a versatile strategy to fabricate intelligent optical anti-counterfeiting materials.

Fluorescent chiral liquid-crystalline networks with dual-mode temperature response

ABSTRACT Due to the excellent optical properties and great application prospects in the optical field, both pyrene compounds (PCs) and chiral liquid crystal have attracted extensive attention in theoretical research and practical applications. Fluorescent chiral liquid-crystalline networks (FCLCN) with good liquid-crystalline properties and tunable fluorescence properties as a response to temperature were prepared using Poly(methylhydrogeno)siloxane (PMHS), chiral liquid-crystalline monomer (M1), chiral crosslinker (M2) and organic fluorescent pyrene compounds (M3). The as-prepared FCLCN display reversible chiral Grandjean texture during the heating and cooling process from the intrinsic chiral arrangement of FCLCN. The discrete pyrene chromogenic segments in FCLCN matrix endowed the networks with excellent fluorescence properties when irradiating with ultraviolet light and the fluorescence can be precisely adjusted by temperature, furthermore, the FCLCN presents highly sensitive fluorescence evolution with a high response sensitivity of 3.4% K−1. The FCLCN can be manufactured into temperature-driven dynamic fluorescence patterns with a fast and reversible response.

Imaging Analysis of Photoswitching Fluorophores Using Single-Imaging Analysis of Photoswitching Fluorophores Using Single-Molecule Microscopy Molecule Microsco

Single-molecule localization microscopy (SMLM) is a developing field of biological imaging that employs the use of photoswitching fluorophores to image sub-cellular biological structures at a higher resolution than was previously possible. These fluorophores are used for protein labeling, so that the sample can be imaged under fluorescence microscopy. This type of microscopy requires the use of many different types of fluorophores, which are fluorescent organic compounds that blink stochastically on and off. Thus, it is critical for developers in the field to have easy access to statistical models of the behaviors of different fluorophores. Here, we take AlexaFluor 647 and analyze it using a fluorescence microscope, taking data on its blinking behaviors and discerning its properties when immersed in a fluorescence-dampening buffer solution. We find that the compound behaves best in buffer solution, and we forge a new methodology for evaluating new fluorophores in a systematic fashion using readily available computer software.

Covalent-Assembly Based Fluorescent Probes for Detection of hNQO1 and Imaging in Living Cells.

Human NAD(P)H: quinone oxidoreductase (hNQO1) is an important biomarker for human malignant tumors. Detection of NQO1 accurately is of great significance to improve the early diagnosis of cancer and prognosis of cancer patients. In this study, based on the covalent assembly strategy, hNQO1-activated fluorescent probes 1 and 2 are constructed by introducing coumarin precursor 2-cyano-3-(4-(diethylamino)-2-hydroxyphenyl) acrylic acid and self-immolative linkers. Under reaction with hNQO1 and NADH, turn-on fluorescence appears due to in-situ formation of the organic fluorescent compound 7-diethylamino-3-cyanocoumarin, and fluorescent intensity changes significantly. Probe 1 and 2 for detection of hNQO1 are not interfered by other substances and have low toxicity in cells. In addition to quantitative detection of hNQO1 in vitro, they have also been successfully applied to fluorescent imaging in living cells.