Search

The human gut microbiota plays an integral role in the management of human health. Effective detection of gut-derived bacteria and their metabolites, as well as assessing antibiotic susceptibility, are crucial for the treatment of intestinal bacteria-related diseases. Herein, we designed and developed a dual-site (nitrophenyl sulfide group and aldehyde group) fluorescent probe DNO-HC, which could rapidly (∼1 min) respond to glutathione (GSH) with low background fluorescence, high selectivity, and low detection limits (45 nM). Moreover, the probe can be used to evaluate the metabolic levels (GSH) in different gut-derived bacteria and discriminate their Gram status. Remarkably, the assessment of antimicrobial susceptibility to a variety of antibiotics has been successfully accomplished utilizing this probe. It offers a promising strategy for the treatment of diseases associated with bacterial infections., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier B.V. All rights reserved.)

Studying numerous biologically important species simultaneously is crucial to understanding cellular functions and the root causes of related diseases. Direct visualization of endogenous biothiols in biological systems is of great value to understanding their biological roles. Herein, a novel multi-signal fluorescent probe was rationally designed and exploited for the simultaneous sensing of homocysteine (Hcy), cysteine (Cys), and glutathione (GSH) using different emission channels. This probe was successfully applied to the simultaneous discrimination between and visualization of endogenous Hcy, Cys, GSH, and their transformation in living cells., (© 2019 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.)

In this paper, the colorimetric sensing of H 2 O 2 related molecules and biothiols based on etching and anti-etching strategy was firstly proposed. Ag/carbon nanocomposite (Ag/C NC) was served as the sensing nanoprobe, which was synthesized via carbon dots (C-dots) as the reductant and stabilizer. The characteristic surface plasmon resonance (SPR) absorbance of Ag nanoparticles (AgNPs) was sensitive to the amount of hydrogen peroxide (H 2 O 2 ). It exhibited strong optical responses to H 2 O 2 with the solution colour changing from yellow to nearly colourless, which is resulted from the etching of Ag by H 2 O 2 . The sensing platform was further extended to detect H 2 O 2 related molecules such as lactate in coupling with the specific catalysis oxidation of L-lactate by lactate oxidase (LOx) and formation of H 2 O 2 . It provides wide linear range for detecting H 2 O 2 in 0.1-80μM and 80-220μM with the detection limit as low as 0.03μM (S/N=3). In the presence of biothiols, the etching from the H 2 O 2 can be hampered. Other biothiols exhibit anti-etching effects well. The strategy works well in detecting of typical biothiols including cysteine (Cys), homocysteine (Hcy) and glutathione (GSH). Thus, a simple colorimetric strategy for sensitive detection of H 2 O 2 and biothiols is proposed. It is believed that the colorimetric sensor based on etching and anti-etching strategy can be applied in other systems in chemical and biosensing areas., (Copyright © 2017 Elsevier B.V. All rights reserved.)

The graphitic carbon nitride nanodots (g-C 3 N 4 -dots) were synthesized by a simple electrochemical "tailoring" process from bulk graphitic carbon nitride (g-C 3 N 4 ) under alkaline solution for the first time. Compared with the bulk g-C 3 N 4 , the novel g-C 3 N 4 -dots not only exhibit enhanced fluorescence and excellent dispersion stability in water but also show the reducibility for the reduction of Ag + to AgNPs at 60°C. The biothiols can bound with Ag + through formation of biothiol-Ag + complex to consume the Ag + and act as capping agent to prevent the growth of AgNPs, which cause the decrease of the absorption peak of the AgNPs. Therefore, an optical sensor was developed for the detection of biothiols based on the change of the plasmon resonance absorption peak of the AgNPs. The proposed method exhibits excellent sensitivity and selectivity to biothiols with low detection limit for cysteine (Cys), homocysteine (Hcy), and glutathione (GSH) with 11.5, 16.1, and 15.5nM, respectively. This method also has been successfully applied for the detection of biothiols in human serum with satisfactory results., (Copyright © 2016 Elsevier B.V. All rights reserved.)

A dual-functional platform for the sensing of acetylcholinesterase (AChE) activity and cadmium ions (Cd 2+ ) was developed based on the fluorescence resonance energy transfer (FRET) between NaYF 4 :Yb,Er upconversion nanoparticles (UCNPs) and gold nanoparticles (AuNPs) via glutathione regulation. The detection mechanism is based on the fact that AuNPs can quench the fluorescence of UCNPs. AChE catalyzes the hydrolysis of acetylthiocholine (ATC) into thiocholine which reacts with AuNPs by S-Au conjunction and results the aggregation of AuNPs and change in fluorescence of UCNPs. Therefore, the AChE activity can be detected through the changes of the color of solution and fluorescence recovery of UCNPs. However, the presence of glutathione (GSH) can protect AuNPs from aggregation and enlarge the inter-particle distance between AuNPs and UCNPs. When Cd 2+ is added into the stable mixture of AuNPs, GSH and AChE/ATC, Cd 2+ could interact with GSH to form a spherical shaped (GSH) 4 Cd complex, which decreases the free GSH on the surface of AuNPs to weaken the stability of AuNPs and lead to the easily aggregation of them in the system. The aggregated-AuNPs are released from the surface of UCNPs, which results in the fluorescence of UCNPs gradually recovered. Under the optimized conditions, the detection limits of AChE activity and Cd 2+ are estimated to be 0.015mU/mL and 0.2µM, respectively. The small molecules regulated dual-functional platform based on UCNPs/AuNPs is a simple, label-free method and can be applied for the turn-on fluorescence detection of AChE activity in human serum and Cd 2+ in real water samples. The present work demonstrates a general strategy for the design of small molecules regulated multifunctional platform and will be expanded for different areas in the future., (Copyright © 2016 Elsevier B.V. All rights reserved.)

A fluorescent probe (N-(4-methyl-2-oxo-2H-chromen-7-yl)-2,4-dinitrobenzenesulfonamide), which exhibits high selectivity to glutathione and cysteine among amino acids including sulphur-containing methionine and metal ions, was synthesized. The experiments demonstrate that the fluorescent probe is a reliable and specific probe for glutathione and cysteine in living cells.

The variations of the microenvironment in cells are always associated with changes in the concentrations of some active species. However, visual detection of these species is still a challenge. In this work, near-infrared (NIR)-emitting fluorescent Ag2S quantum dots (Ag2S QDs) were synthesized via a rapid microwave reaction under normoxic conditions, which were utilized as sensitive fluorescent nanoprobes in sensing and bioimaging of glutathione (GSH) combined with CoOOH nanosheets (CoOOH NSs). The negatively charged Ag2S QDs can easily and effectively attach to the surface of CoOOH NSs to form the Ag2S QD/CoOOH nanoprobe through electrostatic interactions, accompanied by the quenching of the fluorescence of Ag2S QDs at 685 nm via the inner-filter effect (IFE). However, upon the addition of GSH, the fluorescence of Ag2S QDs was recovered due to the reduction of CoOOH NSs into Co2+ by GSH. Meanwhile, the fluorescent emission wavelength shifts slightly, which may result from the ligand exchange reaction between GSH and d-penicillamine (DPA) to form comodified Ag2S QDs. Based on the low toxicity and high tissue penetration depth of the NIR fluorescence of the Ag2S QDs and the good biocompatibility of CoOOH NSs, the nanoprobe composed of Ag2S QDs and CoOOH NSs was successfully applied in bioimaging, which can distinguish the normal cells and cancer cells, the semiquantitative content of endogenous and exogenous GSH. The as-developed strategy not only provides a simple, convenient, cost-effective, and rapid platform for the diagnosis of clinical diseases related to GSH but shows great prospects in fluorescence-assisted surgery. [ABSTRACT FROM AUTHOR]

Studying numerous biologically important species simultaneously is crucial to understanding cellular functions and the root causes of related diseases. Direct visualization of endogenous biothiols in biological systems is of great value to understanding their biological roles. Herein, a novel multi‐signal fluorescent probe was rationally designed and exploited for the simultaneous sensing of homocysteine (Hcy), cysteine (Cys), and glutathione (GSH) using different emission channels. This probe was successfully applied to the simultaneous discrimination between and visualization of endogenous Hcy, Cys, GSH, and their transformation in living cells. Multitasking: A multi‐signal fluorescent probe was exploited for simultaneously differentiating between and sensing of endogenous homocysteine, cysteine, glutathione, and their transformation in living cells. [ABSTRACT FROM AUTHOR]

A fluorimetric and colorimetric method is described for the determination of glutathione (GSH) and silver (I). It is based on the use of MnO2 nanosheets that were prepared by solution mixing and exfoliation. They display oxidase-mimicking activity and can catalyze the oxidation of o-phenylenediamine (OPD) to form yellow 2,3-diaminophenazine (DAP) with an absorption maximum at 410 nm. DAP also has a yellow fluorescence (with a peak at 560 nm). The MnO2 nanosheets can be rapidly reduced to Mn2+ by GSH. This reduces the efficiency of the oxidase mimic MnO2 and causes a decrease in fluorescence and absorbance intensity. However, on addition of Ag+, a complex is formed with GSH. It prevents the destruction of MnO2 nanosheets so that the enzyme mimicking activity is retained. A dual-method for the determination of GSH and Ag(I) was developed. It has excellent sensitivity for GSH with lower detection limits of 62 nM (fluorimetric) and 0.94 μM (colorimetric). The respective data for Ag(I) are 70 nM and 1.15 μM. The assay was successfully applied to the determination of GSH and Ag(I) in spiked serum samples. [ABSTRACT FROM AUTHOR]

Schematic representation for the synthesis of Fc-Cu-MOF and the detection of GSH. [Display omitted] Chemical biosensing techniques are essential for food analysis and disease diagnosis. Nanomaterials with redox activity show great potential in electrochemical analysis, acting as signal labels or signal amplification unit, which can reflect the targets concentration in foods and biological samples. Here, an ultra-sensitive dual-signal intrinsic self-calibration electrochemical platform for GSH was firstly fabricated based on the novel electroactive nanomaterial of ferrocene-functionalized copper metal–organic framework (Fc-Cu-MOF). Due to the solid-state electrochemical property of cuprous chloride (CuCl), a sharp characteristic peak with an increased signal appears with the coexistence of chloride ions in solution. The stronger specific affinity between Cu+ and GSH than that of Cu+ and Cl- triggers a "crowding effect" that causes the current signal of CuCl decrease greatly. Meanwhile, the peak current of ferrocene keeps unchanged as an internal reference. Based on the ratio of the peak current variation (Δ I Cu /Δ I Fc) as the signal output, Fc-Cu-MOF modified electrode showed wider linear range in 0.1 nM −1 μM for GSH with the detection limit as low as 0.025 nM. And the sensor was successfully applied in the determination of GSH with excellent recoveries in various real samples such as food and serum samples, providing good prospect in application of bioanalysis and food screening. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • A new fluorescence nanoplatform for sensitive detection of Cd2+ was developed based on AuNCs and HRGO. • The FL of AuCNs were quenched by HRGO owing to the FRET between them. • FL was recovered when adding Cd2+ in the system owing to the formation of Cd-GSH complex. • The HRGO-AuNCs FL-OFF-ON nanoplatform has larger FL quench efficiency than that of GO. • Improved detection sensitivity for Cd2+ was obtained compared with using GO-AuNCs or AuNCs nanoplatform. Abstract Heavy metal contamination is a widely focused topic in environmental analysis and health care in recent years. Herein, a new fluorescence (FL) nanoplatform for sensitive detection of Cd2+ was developed based on AuNCs and holey reduced graphene oxide (HRGO). HRGO was obtained by hydrothermal method using graphene oxide (GO) as the precursor, H 2 O 2 as an etchant and ascorbic acid (AA) as a reducing agent. GSH-AuNCs were synthesized by using glutathione (GSH) as the template and reducing agent. The FL of AuCNs were quenched by HRGO, which may result from fluorescence resonance energy transfer (FRET) between AuNCs and HRGO and then the FL was recovered when adding Cd2+ in the system owing to the formation of Cd-GSH complex. In the presence of the holey, inter-crossing and open structure of the HRGO, the HRGO-AuNCs FL-OFF-ON nanoplatform has larger FL quench efficiency than that of GO. At the same time, the nanoplatform can further provide a more convenient environment for Cd2+ detection with improved detection sensitivity compared with those in the presence of GO or direct detection of Cd2+ using AuNCs. At the optimized concentration of HRGO, the fluorescence intensity of HRGO-AuNCs increased with the concentration of Cd2+ and the linear range was 0.1-100 μM with the detection limit of 42.0 nM. Moreover, the nanoplatform can be used for Cd2+ in real samples with good accuracy and excellent recovery. Therefore, the attempt of HRGO in fluorescence nanoplatform may be expanded to other optical sensing areas or medicine delivery and has great prospective. [ABSTRACT FROM AUTHOR]

A simple benzothiazole fluorescent chemosensor was developed for the fast sequential detection of Cu 2 + and biothiols through modulating the excited-state intramolecular proton transfer (ESIPT) process. The compound 1 exhibits highly selective and sensitive fluorescence “ on - off ” recognition to Cu 2 + with a 1:1 binding stoichiometry by ESIPT hinder. The in situ generated 1 -Cu 2 + complex can serve as an “ on - off ” fluorescent probe for high selectivity toward biothiols via Cu 2 + displacement approach, which exerts ESIPT recovery. It is worth pointing out that the 1 -Cu 2 + complex shows faster for cysteins (within 1 min) than other biothiols such as homocysteine (25 min) and glutathione (25 min). Moreover, the compound 1 displays 160 nm Stoke-shift for reversibly monitoring Cu 2 + and biothiols. In addition, the probe is successfully used for fluorescent cellular imaging. This strategy via modulation the ESIPT state has been used for determination of Cu 2 + and Cys with satisfactory results, which further demonstrates its value of practical applications. [ABSTRACT FROM AUTHOR]

A sensitive dual-signal intrinsic self-calibration electrochemical sensor for glutathione (GSH) was developed based on the in situ electrodeposited silver nanoparticles modified nickel and iron contained Prussian Blue analog (Ag/NiFe PBA). Two different oxidation peaks ascribed to species of Ag and Fe with wide peak-to-peak potential can be found on the Ag/NiFe PBA modified electrode. In the presence of chloride ions, owing to the solid-state electrochemistry of silver chloride (AgCl), a sharp characteristic peak appeared with largely enhanced current intensity. After adding GSH, sensitive decline in the peak current of AgCl can be found for the specific interaction of Ag-GSH accompany with the "crowding-out effect", while the peak current of NiFe PBA remains unchanged. Using the ratio of the peak currents (I AgCl / I Fe) as the signal output, Ag/NiFe PBA modified electrode showed wide linear range of 0.5 nM-5 μM for the quantitative of GSH with an extremely low detection limit of 0.12 nM, showing superior performance compared with previous electrochemical methods. The sensor can be utilized for the determination of GSH in various vegetable and serum samples. The ultrasensitive solid-state electrochemistry of AgCl promoted signal amplification strategy as well as the specific recognition and competitive reaction increasing the selectivity make the ratiometric sensor great potential in bioanalysis, food analysis and early diagnosis of cancer in clinics. [ABSTRACT FROM AUTHOR]