A novel fluorescent probe based on coumarin derivatives-grafted cellulose for specific detection of Fe3+ and its application.

Fe3+ is one of the most important ions for maintaining the normal growth of plants and animals. However, imbalance and accumulation of Fe3+ can lead to serious damage to the environmental system. Hence, it is considerably crucial to monitor the concentration of Fe3+. In this paper, a high-performance fluorescent probe CA-NCC for specifically detecting Fe3+ was obtained by grafting cellulose acetate (CA) with coumarin derivative (NCC). The resulted probe displayed a bright blue fluorescence in THF solution and showed a distinct "turn-off" fluorescence response to Fe3+, while the small molecule compound NCC could not realize the detection of Fe3+. CA-NCC displayed excellent response performance to Fe3+ including excellent selectivity and sensitivity, rapid reaction time (2.5 min), wide pH detection range (6-11), and low detection limit (0.178 µM). More importantly, CA-NCC was successfully fabricated into fluorescent film based on the good processability of cellulose acetate, and achieved highly selective recognition of Fe3+ from various metal ions.

Development of a ratiometric fluorescent probe based on caffeic acid for hydrazine detection and its applications in water samples and living cells.

Hydrazine (N2H4) has been extensively utilized as a highly reactive chemical reagent. However, it is also seriously harmful to human beings and ecosystem. Thus, the development of an efficient detecting method for hydrazine is desirable. Here, caffeic acid was chose as starting material to synthesize a new ratiometric fluorescent probe HPA for detecting hydrazine. This probe possessed the specific recognition ability for hydrazine over other analytes with low detection limit (0.106 µM) and extremely short time (60 s). The sensing mechanism of probe HPA for hydrazine was proved by 1H NMR titration and theoretical calculations. In addition, the probe HPA was loaded on paper strip for rapid quantitative detection of hydrazine with the aid of a software (Image J). The effective detecting performances of probe HPA for hydrazine were verified in environmental water samples as well as in living cells. Thus, HPA has great potential for detection and analysis of hydrazine in health supervision and environmental protection.

A novel fluorescent probe for fast detection of sulfur dioxide derivatives in water, soil, food samples and its applications in biological imaging.

Sulfur dioxide (SO2) has a wide range of applications in food additives and industrial production, and it is one of the main substances that form acid rain, causing serious harm to ecosystems and human health. Hence, it is necessary to construct an effective tool to quickly and accurately detect SO2 derivatives in environmental, food, and biological samples. In this study, fluorescent probe NPMQ was built to detect SO2 derivatives from nopinone with the merits of superior water solubility, high sensitivity (12 nM), excellent specificity, large Stokes shift (180 nm), and rapid response time (within 5 s). NPMQ was used to qualitatively and quantitatively detect SO2 derivatives in environmental water, soil and food samples. In addition, an electrospinning film was prepared with the probe NPMQ to image SO2 derivatives, and test strips are capable of rapidly, sensitively, and selectively detecting SO2 derivatives with the naked eye. Moreover, the probe NPMQ was used to visualize endogenous SO2 derivatives in Arabidopsis thaliana under Cd2+ stress. Furthermore, the probe NPMQ was employed to image exogenous and endogenous SO2 derivatives in living Hela, HepG-2 cells, and zebrafish. This study develops an effective tool for monitoring SO2 derivatives in the environmental, food, and biological systems.

A novel dialdehyde cellulose-based colorimetric and turn-on fluorescent probe for H2S detection and its application in red wine.

Hydrogen sulfide (H2S) is considered one of the most important gaseous transmitters in the metabolic system, and the abnormal concentration of H2S is associated with a variety of diseases. Up to now, it is still a challenge to develop a portable assay for H2S even though the research about the detection of H2S is booming. Herein, a novel bifunctional dialdehyde-cellulose fluorescent probe DAC-DPD was prepared with high selectivity and sensitivity to H2S with colorimetric and fluorescent "turn-on" characteristics, and the limit of detection (LOD) of DAC-DPD for H2S was 0.831 µM. The sensing mechanism of DAC-DPD's to H2S was a Michael addition reaction confirmed by HRMS, 1H NMR and density-functional theory (DFT) calculations. DAC-DPD can be used to detect H2S in red wine samples. In Addition, the prepared DAC-DPD embedded fluorescent membrane can be used as a reliable sensing platform for rapid detection of H2S. It provided a convenient and rapid detection material, simplifying the detection process of H2S, which is of great significance for the development of cellulose-based fluorescent smart material.

A highly effective curcumin-based fluorescent probe with single-wavelength excitation for simultaneous detection and bioimaging of Cys, Hcy and GSH.

Cysteine (Cys), homocysteine (Hcy) and glutathione (GSH) act as significant roles in many physiological processes, and their abnormal proliferation will cause multiple diseases including Alzheimer's disease, Parkinson's disease, Cardiovascular disease, atherosclerosis, and soft tissue damage. However, It is challenging work to develop a efficient method for differentiating and detecting GSH, Cys and Hcy because of their significant similarity in structures and functions. In this work, a smart fluorescent probe FBCN based on curcumin was rationally devised and developed by etherifying the phenol hydroxyl group on FBC with NBD-Cl, which emitted strong green at 516 nm. FBCN distinguished Hcy from Cys/GSH with naked eyes based on the color variation of probe solution in sunlight. Meanwhile, GSH induced the powerful fluorescence quenching of probe solution, but the fluorescence color of FBCN solution transformed from green to luminous yellow accompanied with emission wavelength redshifted from 516 nm to 540 nm or 553 nm in the existence of Hcy and Cys, respectively. Probe FBCN had outstanding sensitivity and anti-interference, low detection limit (56.5 nM, 77.7 nM, and 288 nM corresponded to Cys, Hcy, and GSH, respectively), short response time (the response time of FBCN to Cys, Hcy and GSH was 1 min, 2 min and 5 min, respectively). The DFT calculation and HRMS had verified the sensing mechanism of FBCN to biothiols. In addition, the probe was successfully utilized to detect three biothiols levels in living cell and zebrafish.

Rational design of a highly effective cellulose-based macromolecular fluorescent probe for real-time recognition of palladium ion in environmental samples and its applications in plant and zebrafish.

Palladium ion (Pd2+) plays an important role in our daily life, but poses a great threat to the environment and human health. Thus, it is desirable to exploit a rapid and sensitive approach to realize the detection of Pd2+. In this study, a cellulose acetate-based macromolecular fluorescent probe CA-NA-PA was successfully prepared for tracking amounts of Pd2+. CA-NA-PA showed an obvious "on-off" fluorescence response to Pd2+, accompanied by the fluorescence color changed from bright yellow to colorless. CA-NA-PA had some outstanding detection performances such as low detection limit (26 nM), extremely short response time (1 min), good selectivity and anti-interference ability. Based on the advantages of probe mentioned above, CA-NA-PA could realize recognition of Pd2+ concentration in environmental water and soil samples. What's more, the probe CA-NA-PA was applied to image Pd2+ in zebrafish as well as in live onion tissue due to the good biocompatibility and cell membrane permeability of cellulose, suggesting its wide application prospect in biosystems.

Phenanthroimidazole-based fluorescence probe for discriminative detecting of hydrazine and bisulfite and its applications in environmental samples.

Hydrazine (N2H4) and bisulfite (HSO3-) detection methods are urgently needed due to its harmful to the human health and environment safety. Herein, we reported a dual-response fluorescence probe EPC, which is capable of sequential detection of N2H4 and HSO3- by two different fluorescence signals. The probe EPC itself showed yellow florescence. In presence of N2H4, probe EPC exhibited an obviously fluorescence change (from yellow to green). However, a new addition product came into being after probe EPC mixed with HSO3-, followed with weak yellow emission. More important, probe EPC exhibited excellent fluorescence response properties for N2H4 and HSO3-, such as high sensitivity (0.182 µM for N2H4, 0.093 µM for HSO3-), rapid response (55 s for N2H4, 45 s for HSO3-), excellent selectivity and anti-interference performance. The sensing mechanisms for N2H4 and HSO3- were proved by 1H NMR and MS spectra. Practical applications were studied. EPC based test paper can be utilized for quantitative detecting N2H4 in actual water samples. And, probe EPC has been successfully applied to recognize N2H4 contaminant in soil samples. Moreover, EPC has great potential to be used to detect HSO3- in real food samples.

In-situ evaluation the fluctuation of hypochlorous acid in acute liver injury mice models with a mitochondria-targeted NIR ratiometric fluorescent probe.

Acute liver injury (ALI) is a frequent and devastating liver disease that has been made more prevalent by the excessive use of chemicals, drugs, and alcohol in modern life. Hypochlorous acid (HClO), an important biomarker of oxidative stress originating mainly from the mitochondria, has been shown to be intimately connected to the development and course of ALI. Herein, a novel BODIPY-based NIR ratiometric fluorescent probe Mito-BS was constructed for the specific recognition of mitochondrial HClO. The probe Mito-BS can rapidly respond to HClO within 20 s with a ratiometric fluorescence response (from 680 nm to 645 nm), 24-fold fluorescence intensity ratio enhancement (I645/I680), a wide pH adaptation range (5-9) and the low detection limit (31 nM). The probe Mito-BS has been effectively applied to visualize endogenous and exogenous HClO fluctuations in living zebrafish and cells based on its low cytotoxicity and prominent mitochondria-targeting ability. Furthermore, the fluorescent probe Mito-BS makes it possible to achieve the non-invasive in-situ diagnosis of ALI through in mice, and provides a feasible strategy for early diagnosis and drug therapy of ALI and its complications.

A ratiometric fluorescent probe with a large Stokes shift for rapid and sensitive detection of Hg2+ in environmental water samples and its applications in living cells and zebrafish.

Detection of highly toxic mercury ions (Hg2+) in actual environmental and biological samples is of significant importance for protecting environment and human health. In this paper, a new ratiometric fluorescent probe BTIA was designed and synthesized from 3-pinone based on Internal Charge Transfer (ICT) mechanism. BTIA could selectively recognize Hg2+ over other competitive analytes with short reaction time (5 s), distinct ratiometric response, strong anti-interference ability, large Stokes shift (200 nm), and low detection limit (2.36 × 10-7 M). Furthermore, BTIA was applicable for detecting Hg2+ in actual water samples and it also performed an excellent imaging capability in living RAW264.7 cells, zebrafish and onion tissue.

Comprehensive investigations of four ratiometric fluorescent chemosensors based on 4-(1H-imidazol-2-yl)benzaldehyde skeleton for malononitrile detection.

Malononitrile is a very important chemical material and has wide application fields in production of medicines, pesticides, and extraction of gold. However, its nonnegligible hypertoxicity inspired researchers to develop more efficient analysis techniques to sensitively and selectively detect malononitrile. Nopinone derivatives initiated by our research group have been developed as a class of organic fluorescent chemosensors for identifying multiple analytes in recent years. Different heterocyclic compounds based on nopinone were designed and synthesized to be applied in the fields of environmental analysis, food detection and bioimaging. Nevertheless, the comparison research on the optical properties of fluorescent compounds containing the nopinyl matrix with other structural analogs including alkyl, cyclohexyl and phenyl groups was deficient. Herein, four 4-(1H-imidazol-2-yl)benzaldehyde-based ratiometric fluorescent chemosensors based on o-dimethyl cyclohexyl, phenyl and nopinyl units for recognizing malononitrile were designed and developed, and their differences in the optical properties and detection performances were investigated by using spectral analysis combined with theoretical calculations. Moreover, the nopinone-based 4-(1H-imidazol-2-yl)benzaldehyde fluorescent chemosensor NMZQ was successfully applied in the dual channel fluorescence bioimaging of malononitrile in living HeLa cells and zebrafish, which attributed to its outstanding spectral property and detection performance.

Study on the biodynamic characteristics and internal vibration behaviors of a seated human body under biomechanical characteristics.

To provide reference and theoretical guidance for establishing human body dynamics models and studying biomechanical vibration behavior, this study aimed to develop and verify a computational model of a three-dimensional seated human body with detailed anatomical structure under complex biomechanical characteristics to investigate dynamic characteristics and internal vibration behaviors of the human body. Fifty modes of a seated human body were extracted by modal method. The intervertebral disc and head motions under uniaxial white noise excitation (between 0 and 20 Hz at 1.0, 0.5 and 0.5 m/s2 r.m.s. for vertical, fore-aft and lateral direction, respectively) were computed by random response analysis method. It was found that there were many modes of the seated human body in the low-frequency range, and the modes that had a great impact on seated human vibration were mainly distributed below 13 Hz. The responses of different positions of the spine varied greatly under the fore-aft and lateral excitation, but the maximum stress was distributed in the lumbar under different excitations, which could explain why drivers were prone to lower back pain after prolonged driving. Moreover, there was a large vibration coupling between the vertical and fore-aft direction of an upright seated human body, while the vibration couplings between the lateral and other directions were very small. Overall, the study could provide new insights into not only the overall dynamic characteristics of the human body, but also the internal local motion and biomechanical characteristics under different excitations.

A novel colormetric and light-up fluorescent sensor from flavonol derivative grafted cellulose for rapid and sensitive detection of Hg2+ and its applications in biological and environmental system.

Mercury ion (Hg2+) is one of harmful heavy metal ions that can accumulate inside the human organism and cause some health problems. In the article, a highly effective fluorescent probe named EC-T-PCBM was prepared by grafting flavonol derivatives onto ethyl cellulose for the specific recognition of Hg2+. EC-T-PCBM exhibited a remarkable fluorescence light-up response toward Hg2+ with excellent sensitivity. EC-T-PCBM possessed several prominent sensing properties for Hg2+, such as low detection limit (43.9 nM), short response time (5 min), and wide detection pH range (6-9). The response mechanism of EC-T-PCBM to Hg2+ has been verified through 1H NMR titration and DFT computation. Additionally, EC-T-PCBM not only can be used for accurately determining trace amount of Hg2+ in actual environmental water samples, but also can serve as a portable and rapid device by loading it on test strips for sensitive and selective visualization of Hg2+. More importantly, the confocal fluorescence imaging of onion cells suggested the favorable cell membrane permeability of EC-T-PCBM and its prominent ability to continuously monitor the enrichment from Hg2+ within fresh plant tissues.

A ratiometric fluorescent probe with a large Stokes shift for the detection of Hg2+ and its applications in environmental sample and living system analysis.

Toxic mercury ions (Hg2+) can cause serious environmental pollution and accumulate in living organisms via the food chain. Therefore, monitoring Hg2+ is crucial in ensuring the safety of ecosystems and organisms. In this work, a novel ratiometric fluorescent probe CMT (5-(4-(diphenylamino)phenyl)-1-(7-hydroxy-coumarin-3-yl)-4-pentene-1,3-dione) based on coumarin was developed for detecting Hg2+, which displayed obvious fluorescence changes, a low detection limit (2.24 × 10-7 M), good selectivity, and a large Stokes shift (255 nm). The CMT probe could detect Hg2+ in real environmental soil and water samples. Furthermore, the CMT probe enabled the naked-eye detection of Hg2+ using test paper experiments. CMT was also applied for fluorescence imaging in living zebrafish and plants. This work provides a highly efficient tool for monitoring Hg2+ in environmental samples and biological systems.

A novel dual-responsive colorimetric/fluorescent probe for the detection of N2H4 and ClO- and its application in environmental analysis and bioimaging.

Hydrazine (N2H4) and hypochlorite (ClO-) are both reactive chemical substances extensively utilized across various industrial domains. Excessive hydrazine (N2H4) and hypochlorite (ClO-) can pose significant risks to the environment, ecosystems, and human health. In order to assess and control the environmental hazard caused by N2H4 and ClO-, there is an imperative need for efficient methods capable of rapid and precise detection of these contaminants. This paper introduces a novel dual-responsive colorimetric/fluorescent probe (MDT) for the detection of N2H4 and ClO- in environmental and biological samples. The probe exhibits turn-on fluorescent responses to N2H4 or ClO- with low detection limits (N2H4: 8 nM; ClO-: 15 nM), large Stokes shifts (N2H4: 175 nm; ClO-: 203 nm), short response time (N2H4: 4 min; ClO-: 5 s) and broad pH range (5-10). In practical applications, MDT has been successfully employed in detecting N2H4 and ClO- in water and soil samples from diverse locations. Test strips loaded with MDT offer a visual and convenient means to track N2H4 vapor and quantify N2H4 and ClO- concentrations in solutions. Finally, MDT has been utilized for sensing N2H4 and ClO- in Arabidopsis thaliana roots and living zebrafish. This study presents a promising tool for monitoring N2H4 and ClO- in the environment and living organisms.

A novel ratiometric fluorescent sensor from modified coumarin-grafted cellulose for precise pH detection in strongly alkaline conditions.

Accurate and convenient monitoring of pH under extreme alkaline conditions is still a challenge. In this work, 4-(3-(7-hydroxy-2-oxo-2H-chromen-3-yl)-3-oxoprop-1-en-1-yl)benzamide (HCB), a coumarin derivative, was grafted onto dialdehyde cellulose (DAC) to obtain a sensor DAC-HCB, which exhibited a ratiometric fluorescent response to the pH of alkaline solutions, resulting in a significant fluorescent color change from yellow to blue (FI459 nm/FI577 nm) at pH 7.5-14. The structure of DAC-HCB was characterized through FT-IR, XRD, XPS, SEM. The pKa of sensor DAC-HCB was 13.16, and the fluorescent intensity ratio FI459 nm/FI577 nm possessed an excellent linear characteristic with pH in the scope of 9.0-13.0. Meanwhile, sensor DAC-HCB showed good selectivity, anti-interference, and fast response time to basic pH, which is an effective fluorescent sensor for examination of pH in alkali circumstance. The recognition mechanism of DAC-HCB to OH- was elucidated with HRMS and density-functional theory (DFT) computational analyses. Sensor DAC-HCB was successfully used for precise detection of environmental water samples pH. This work furnished a new protocol for test strips as a convenient and highly efficient pH detection tool for the high pH environment, and it has great potential for application in environmental monitoring.

An ultrasensitive cellulose-based fluorescent sensor for Al3+ detection and its applications in plant tissue and food samples.

Fluorescent sensors available for metal ions detection have been extensively developed in recent years. However, developing an ultrasensitive fluorescent sensor for highly selectively detecting Al3+ based on cellulose remains a challenge. In this study, an ethylcellulose-based flavonol fluorescent sensor named EC-BHA was synthesized by the esterification of ethylcellulose (EC) with a new flavonol derivative 4-(2-(2,3-bis(ethoxymeothy)phenyl)-3-hydroxy-4-oxo-4-H-chromen-7-yl) benzoic acid (BHA). The fluorescence intensity of EC-BHA exhibited a 180-fold increase at 490 nm after binding with Al3+ and provided an ultralow detection limit of 13.0 nM. The sensor showed some exceptional sensing properties including a broad pH range (4-10), large Stokes shifts (190 nm), and a short response time (3 min). This sensor was successfully applied for determining trace Al3+ in food samples as well as in plant tissue. Moreover, the electrostatic spun film EBP was fabricated by blending EC-BHA with PS (polystyrene) via electrostatic spinning technique and utilized for selective detection of Al3+ as soon as possible.

Rational design and comparison of three curcumin-based fluorescent probes for viscosity detection in living cells and zebrafish.

Viscosity is a crucial indicator of the cellular microenvironment, which can affect the normal level of cellular metabolism. Aberrant levels of viscosity can result in the emergence of a variety of physiological problems including diabetes, Parkinson's disease, inflammation, etc. Therefore, it is crucial to exploit effective assays that can detect viscosity levels in living cells and organisms. Three new nitrogen-containing heterocyclic fluorescent probes, CNO, CNN and CNNB, were designed and prepared by coupling curcumin with isoxazole, pyrazole, and phenylpyrazole rings, respectively. The fluorescence response properties of these probes to the viscosity level were analyzed in parallel. All the probes, CNO, CNN and CNNB, exhibited a significantly enhanced fluorescence response to viscosity in a broad pH range with excellent photostability, sensitivity and anti-interference ability. The sensing mechanisms of these probes for viscosity were verified by DFT calculations. In addition, these probes were successfully employed for detecting viscosity levels in living HeLa cells and zebrafish. This research compares the viscosity-responsive capabilities of curcumin-based fluorescent probes containing different nitrogen-containing heterocyclic structures, and provides a new design strategy and guidance for developing curcumin-based fluorescent probes for viscosity analysis.

A highly specific chalcone derivative grafted ethylcellulose fluorescent probe for rapid and sensitive detection of Al3+ in actual environmental and food samples.

Al3+ is commonly utilized in daily life, however, the excessive accumulation of Al3+ within organisms can result in severe health problems. Herein, a highly efficient fluorescent probe EC-HTC for Al3+ was synthesized through chemical modification of ethyl cellulose. This probe exhibited a significant fluorescence enhancement response to Al3+, and it interestingly also possessed an obvious aggregation-induced emission (AIE) effect. The detection limit of probe EC-HTC for Al3+ was as low as 0.23 µM, and its pH usage range was as wide as 5-10. The complexation ratio of EC-HTC with Al3+ was determined to be 1:1 based on Job's plot, which was further confirmed by 1H NMR titration and HRMS analysis. Moreover, the probe EC-HTC was successfully employed for the determination of Al3+ in environmental and food samples. In addition, the probe EC-HTC compositing PS (polystyrene) electrostatic spun fiber membranes EHP with high specific surface area were prepared to achieve the rapid and portable detection of Al3+.

Fluorescent probe for sensitive discrimination of GSH and Hcy/Cys with single-wavelength excitation in biological systems via different emission.

Biothiols (GSH, Hcy, Cys) are important active sulfur substances in biological systems and widely participate in various physiological processes. The three kinds of biothiols have similar chemical structures, including the sulfhydryl group (-SH) and an amino group (-NH2), so distinguishing two or more of them simultaneously is an important challenge. Herein, a nopinone-based fluorescent probe 3-(3-((4-nitrobenzoxadiazole vinyl) nopinyl difluoride (NF-NBD) was designed to distinguish GSH and Hcy/Cys by generating different fluorescence channels with a single excitation wavelength. The nitrobenzodioxazole (NBD) was introduced in the fluorescent probe by ether bounds that can quench fluorescence and selectively discriminate GSH and Hcy/Cys. After reacting with GSH and Hcy/Cys, NF-NBD exhibited strong fluorescence (green for GSH and yellow for Hcy/Cys). NF-NBD displayed a wide linear range, low detection limit, a rapid response time, and superior selectivity for biothiols. Furthermore, NF-NBD was applied to image and distinguish different biothiols in living cells and zebrafish via different fluorescence signals at a single excitation wavelength.

An efficient chitosan-naphthalimide fluorescent probe for simultaneous detection and adsorption of Hg2+ and its application in seafood, water and soil environments.

As a virulent heavy metal ion, Hg2+ will lead to a serious threat to ecosystem and human health. In this work, we reported a chitosan-naphthalimide fluorescent probe CS-NA-ITC for specific recognition and efficient adsorption of Hg2+. CS-NA-ITC showed no fluorescence in solution state, while the fluorescence intensity increased obviously at the presence of Hg2+, accompanied by the fluorescence color becomes from colorless to bright yellow. It displayed favorable properties like low detection limit (73 nM), extensive pH detection range (5-10) and excellent anti-interference ability. The binding pattern of CS-NA-ITC to Hg2+ was verified by Job's plot, XPS analysis and FT-IR test. In addition, CS-NA-ITC was utilized to recognition of Hg2+ in actual water and soil samples and seafood products. Furthermore, the CS-NA-ITC hydrogel could be employed as an efficient Hg2+ adsorbent with good reusability, which adsorption ability was enhanced compared to chitosan hydrogel.