Selective Detection Of GSH Research Articles

Multifunctional Eu-doped carbon dots nanoprobe for highly sensitive and selective determination of glutathione in biological fluid and cell imaging

Glutathione (GSH) holds a vital role in biological systems, serving diverse cellular functions. Selective determination of GSH over cysteine (Cys) and homocysteine (Hcy) stays challenging due to the shared functional groups among these biothiols. In this study, a versatile Eu-doped carbon dots (Eu-CDs) nanoprobe has been developed for the exceptionally sensitive and selective detection of GSH in biological fluids. The synthesized Eu-CDs exhibited high solubility in water, stability to salt and pH variations, and consistent fluorescence emission, boasting a quantum yield of 40.67 %. Following the optimization of detection parameters, a robust linear relationship for GSH was established in the concentration range of 0.0–50 μM, with a detection limit of 0.03 μM. The viability of the technique in actual samples was evaluated by successfully measuring the GSH in urine and human serum samples with a range recovery from 90.6 % to 98.5 %. Furthermore, Eu-CDs proved to be exceptionally suitable for imaging Hela cells owing to their low cytotoxicity and remarkable biocompatibility. As a result, the developed fluorescent biosensor demonstrated significant potential for widespread application in clinical diagnostic analyses.

ZnS/MnO2 metal organic framework based conductive hydrogel for highly selective and sensitive detection of glutathione in serum samples

Glutathione (GSH) is a vital natural antioxidant that plays a central role in protecting cells from toxins and free radicals. This work reports the synthesis of a novel ZnS/MnO2 – metal organic framework hydrogel (MOF-HG) via a lyophilization process for the highly sensitive and selective detection of GSH in stimulated blood serum. The hydrogel is synthesized by crosslinking ZnS/MnO2 – MOF with polyvinyl alcohol (PVA) and nafion (5 % solution). The hydrogel exhibits high porosity, resulting in a large surface area for enhanced electron transport, excellent electrical conductivity, sample absorption, and oxygen and sulphur vacancies that offer electro-oxidation of glutathione (GSH). Morphological and structural analysis of the hydrogel shows uniform porosity and a cubic structure for the ZnS/MnO2 - MOF, which are evenly distributed on the hydrogel surface. For the detection of glutathione (GSH), the differential pulse voltammetry (DPV) technique is used, showcasing a linear detection range of 10 nM to 10 mM, high sensitivity of 8.45 µA.nM−1.cm−2 and a low limit of detection (LOD) of 6.88 nM (=3S/m), making it highly effective for physiological GSH sensing. One of the key advantages of the substrate is its exceptional selectivity for GSH, even in the presence of a 2-fold concentration of interfering substances such as ascorbic acid (AA), uric acid (UA), Na+, Cl-, Ca2+, K+, bovine serum albumin (BSA), and glucose (GLU). In real samples, the sensor displays significant recovery percentages of 92.59 %, 101.00 %, and 120.22 %, further confirming the reliability and effectiveness of the developed sensor in detecting glutathione.

Silver nanoparticles combined with amino-functionalized UiO-66 for sensitive detection of glutathione

Herein, a fluorescent nanosensor has been constructed for detection of glutathione (GSH) based on NH2-UiO-66 and AgNPs. The NH2-UiO-66 was synthesized where 2-amino-terephthalic acid as the organic ligand and Zr4+ as the center metal ions. The AgNPs can enhance the fluorescence of NH2-UiO-66 based on metal enhanced fluorescence (MEF) effect. Moreover, in the present of GSH, the fluorescence of NH2-UiO-66@AgNPs was quenched via electrostatic interaction and Ag-S reaction. The present sensing strategy shows good linear relation with the concentration of GSH in the range of 0.2–1.0 μM and 1.0–30 μM, and the limit of detection is 79 nM. Furthermore, our fluorescent nanosensor was utilized to detect GSH in human serum with a recovery of 96.8–102.5%. The results indicated that NH2-UiO-66@AgNPs is successfully applied for high sensitive and selective detection of GSH in human serum.

Synthesis, Reactivity, and Properties of a Class of π-Extended BODIPY Derivatives.

A new family of π-extended BODIPY derivatives were obtained through the condensation of aldehyde and pyrrole in aqueous solution in the presence of HCl. The new rigid π-framework extends beyond the dipyrromethene unit, which is significantly different from classical BODIPYs in the electronic configuration. Both π-extended BODIPYs displayed intense absorption and moderate emission with maxima around 565 and 620 nm, respectively, and showed interesting reactivity toward various nucleophiles. Moreover, these π-extended BODIPYs were developed as fluorescent probes for rapid and selective detection of GSH and were successfully applied for live-cell imaging.

Biomass carbon dots derived from Wedelia trilobata for the direct detection of glutathione and their imaging application in living cells.

The development of long-wavelength emission carbon dots as a label-free sensing platform for the direct detection of glutathione (GSH) is still of great challenge. Herein, novel rose-red fluorescence carbon dots (wCDs) with a long-wavelength emission of 654 nm were successfully synthesized by a one-step microwave-solvothermal treatment of biomass Wedelia trilobata. The biomass-based wCDs could sensitively respond to copper ions (Cu2+) with a limit of detection (LOD) of 0.22 μM, which could be utilized as the fluorescence turn off-on sensor for the detection of GSH through recovering their fluorescence quenched by Cu2+. Moreover, the label-free wCDs with abundant active functional groups could be used to construct a direct quenching platform for the sensitive and selective detection of GSH by the dynamic quenching effect within 20 s without further modification, displaying a good linear range of 0-3.0 mM with a LOD of 35 μM that fits well with the GSH content in living cells (0.5-10 mM). Additionally, confocal imaging of living cells indicates that as-prepared wCDs with high photobleaching resistance and favorable biocompatibility possess the capacity for real-time monitoring of the variations of intracellular Cu2+ and GSH levels, and distinguishing cancerous cells from normal cells owing to the overexpression of GSH in cancerous cells. This study opens a new vision for developing an efficient and sensitive fluorescent sensor for the detection of GSH, and demonstrates the great prospects for wCDs in ion/molecule tracking, bioimaging and cancer diagnosis.

Highly uniform self-assembled monolayers of silver nanospheres for the sensitive and quantitative detection of glutathione by SERS.

The homeostasis and imbalance of glutathione (GSH), an important antioxidant in organisms, are one of the key signals that reflect the health of organisms. In this paper, a novel SERS sensing platform based on Ag film@Si that self-assembled using silver nanospheres was proposed, which was used for the highly sensitive and selective detection of GSH. With the aid of an oil/water/oil three-phase system, the nano-silver film was self-assembled and finally deposited on silicon wafers. The heterobifunctional crosslinking agent N-succinimidyl-3-(2-pyridyldithio)propionate (SPDP), which contains pyridine rings and disulfide bonds, was involved in the exchange reaction between the sulfhydryl groups and disulfide bonds. With the addition of GSH, the breakage of disulfide bonds was promoted, thereby enhancing the SERS signal of SPDP. GSH can be detected sensitively by detecting the changes in the SPDP signal. The detection limit of GSH is 10 nM, and the method is still highly stable when the external environment is serum or other more complex environments.

Selective detection of glutathione based on the recovered fluorescence of BSA‐AuNCs/Cu 2+ system

A bovine serum albumin-stabilised gold nanoclusters/Cu2+ (BSA-Au NCs/Cu2+) system was constructed as a fluorescent sensor for the ‘off–on’ detection of glutathione (GSH). The fluorescence of BSA-Au NCs could be effectively quenched by Cu2+ due to the strong affinity between BSA-Au NCs and Cu2+. Then, coordination of Cu2+ to GSH enabled the recovery of the fluorescence of BSA-Au NCs. To assess the selectivity of the BSA-Au NCs/Cu2+ for GSH, K+, Mg2+, Ca2+, glucose, cysteine, tryptophan, and phenylalanine were examined under identical conditions, and all of them did not induce noticeable responses to BSA-Au NCs/Cu2+ except for Cys. There was a good linear dependence of fluorescence intensity on the concentration of GSH in the range of 0.4–20.0 μM with the detection limit of 0.36 μM. The proposed sensor showed excellent performance in the selective detection of GSH.

Intracellular Imaging of Glutathione with MnO2 Nanosheet@Ru(bpy)32+-UiO-66 Nanocomposites.

Fluorescent detection of glutathione (GSH) in the living system has attracted much attention, but current fluorescent probes are usually exposed to the exterior environment, leading to photobleaching and premature leakage and subsequently limiting the sensitivity and photostability. Herein, luminescent metal-organic frameworks [Ru(bpy)32+ encapsulated in UiO-66] coated with manganese dioxide nanosheets [MnO2 NS@Ru(bpy)32+-UiO-66] were prepared by an in situ growth method and further explored to construct a GSH-switched fluorescent sensing platform. Because of the splendid fluorescence quenching ability, special probe leakage blocking role and distinguished recognition of the MnO2 NS, and the improved fluorescence of Ru(bpy)32+ by UiO-66, a low background, highly sensitive and selective detection of GSH with a low limit of detection as 0.28 μM was realized. At the same time, the preparation of MnO2 NS@Ru(bpy)32+-UiO-66 nanocomposites is simple and less toxic, and there was no notable loss of cell survivability after being exposed to MnO2 NS@Ru(bpy)32+-UiO-66 below the concentrations of 120 μg mL-1 for 24 h. Consequently, the results coming from this effort suggest that the new sensing platform will have a great potential in the detection of GSH in living cells.

A turn-on MOF-based luminescent sensor for highly selective detection of glutathione

Glutathione (GSH), as a key regulator for the redox balance of biological processes, was detected with a metal-organic framework (MOF) (UiO-67-sbdc) fluorescence sensor. The fluorescence of UiO-67-sbdc could be effectively enhanced by GSH via an electronic effect between GSH and the ligand of MOF, thus achieving the recognition of GSH. It is the first attempt to design a MOF-based fluorescent sensor to distinguish GSH from cysteine (Cys). This sensor exhibited short response time (<120 s), suitable linear range, and high selectivity towards GSH. Further research conducted in serum also showed a quantitative and selective detection of GSH. Thus, the reported UiO-67-sbdc in this work has its application prospect in clinically judging antioxidant capacity of the body.

Silver-Nanoparticle-Embedded Porous Silicon Disks Enabled SERS Signal Amplification for Selective Glutathione Detection.

As the major redox couple and nonprotein thiol source in human tissues, the level of glutathione (GSH) has been a concern for its relation with many diseases. However, the similar physical and chemical properties of interference molecules such as cysteine (Cys) and homocysteine (Hcy) make discriminative detection of GSH in complex biological fluids challenging. Here we report a novel surface-enhanced Raman scattering (SERS) platform, based on silver-nanoparticle-embedded porous silicon disks (PSDs/Ag) substrates for highly sensitive and selective detection of GSH in biofluids. Silver nanoparticles (AgNPs) were reductively synthesized and aggregated directly into pores of PSDs, achieving a SERS enhancement factor (EF) up to 2.59 × 107. Ellman's reagent 5,5'-ditho-bis (2-nitrobenzoic acid) (DTNB) was selected as the Raman reactive reporting agent, and the GSH quantification was determined using enzymatic recycling method, and allowed the detection limit of GSH to be down to 74.9 nM using a portable Raman spectrometer. Moreover, the significantly overwhelmed enhancement ratio of GSH over other substances enables the discrimination of GSH detection in complex biofluids.

6‐Mercaptopurine‐Induced Fluorescence Quenching of Monolayer MoS2 Nanodots: Applications to Glutathione Sensing, Cellular Imaging, and Glutathione‐Stimulated Drug Delivery

AbstractMolybdenum disulfide (MoS2) nanodots (NDs) with sulfur vacancies have been demonstrated to be suitable to conjugate thiolated molecules. However, thiol‐induced fluorescence quenching of MoS2 NDs has been rarely explored. In this study, 6‐mercaptopurine (6‐MP) serves as an efficient quencher for the fluorescence of monolayer MoS2 (M‐MoS2) NDs. 6‐MP molecules are chemically adsorbed at the sulfur vacancy sites of the M‐MoS2 NDs. The formed complexes trigger the efficient fluorescence quenching of the M‐MoS2 NDs due to acceptor‐excited photoinduced electron transfer. The presence of glutathione (GSH) efficiently triggers the release of 6‐MP from the M‐MoS2 NDs, thereby switching on the fluorescence of the M‐MoS2 NDs. Thus, the 6‐MP‐M‐MoS2 NDs are implemented as a platform for the sensitive and selective detection of GSH in erythrocytes and live cells. Additionally, thiolated doxorubicin (DOX‐SH)‐loaded M‐MoS2 NDs (DOX‐SH/M‐MoS2 NDs) serve as GSH‐responsive nanocarriers for DOX‐SH delivery. In vitro studies reveal that the DOX‐SH/M‐MoS2 NDs exhibit efficient uptake by HeLa cells and greater cytotoxicity than free DOX‐SH and DOX. In vivo study shows that GSH is capable of triggering the release of DOX‐SH from M‐MoS2 ND‐based nanomaterials in mice. It is revealed that the DOX‐SH/M‐MoS2 NDs can be implemented for simultaneous drug delivery and fluorescence imaging.

Introducing Ratiometric Fluorescence to MnO2 Nanosheet-Based Biosensing: A Simple, Label-Free Ratiometric Fluorescent Sensor Programmed by Cascade Logic Circuit for Ultrasensitive GSH Detection.

Glutathione (GSH) plays crucial roles in various biological functions, the level alterations of which have been linked to varieties of diseases. Herein, we for the first time expanded the application of oxidase-like property of MnO2 nanosheet (MnO2 NS) to fluorescent substrates of peroxidase. Different from previously reported fluorescent quenching phenomena, we found that MnO2 NS could not only largely quench the fluorescence of highly fluorescent Scopoletin (SC) but also surprisingly enhance that of nonfluorescent Amplex Red (AR) via oxidation reaction. If MnO2 NS is premixed with GSH, it will be reduced to Mn2+ and lose the oxidase-like property, accompanied by subsequent increase in SC's fluorescence and decrease in AR's. On the basis of the above mechanism, we construct the first MnO2 NS-based ratiometric fluorescent sensor for ultrasensitive and selective detection of GSH. Notably, this ratiometric sensor is programmed by the cascade logic circuit (an INHIBIT gate cascade with a 1 to 2 decoder). And a linear relationship between ratiometric fluorescent intensities of the two substrates and logarithmic values of GSH's concentrations is obtained. The detection limit of GSH is as low as 6.7 nM, which is much lower than previous ratiometric fluorescent sensors, and the lowest MnO2 NS-based fluorescent GSH sensor reported so far. Furthermore, this sensor is simple, label-free, and low-cost; it also presents excellent applicability in human serum samples.

A mitochondria-targeting fluorescent probe for the selective detection of glutathione in living cells.

We report a fluorescent probe for the selective detection of mitochondrial glutathione (GSH). The probe, containing triphenylphosphine as a mitochondrial targeting group, exhibited ratiometric and selective detection of GSH over Cys/Hcy. The probe was used for imaging mitochondrial GSH in living HeLa cells.

A facile label-free colorimetric method for highly sensitive glutathione detection by using manganese dioxide nanosheets

Glutathione (GSH) provides essential functions towards metabolism process in biological systems and is related to many diseases such as human immunodeficiency virus, Parkinson, cardiovascular diseases, etc. In this work, a very simple, fast and label-free colorimetric method for highly sensitive GSH quantification is proposed. This strategy is based on the color change of MnO2 nanosheets solution from yellowish-brown to colorless. Without GSH, MnO2 nanosheets exhibit a strong ultraviolet–visible (UV–vis) absorption peak at 376nm with the color showing as yellowish-brown. Once GSH is introduced, MnO2 nanosheets are reduced to Mn2+ ions rapidly, which leads to a yellowish-brown color fading and a remarkable decrease of the absorbance at 376nm. Based on the distinct color change, a method for highly sensitive and selective detection of GSH was realized with bare eyes and UV–vis spectroscopy, respectively. This method has a wide dynamic range from 0.5μM to 100μΜ and shows a good linear relationship from 0.5μM to 10μΜ with a detection limit of 0.1μM. More importantly, this procedure is very simple and the whole assay can be accomplished quickly within 5min. Additionally, this developed assay has also been successfully applied to the detection of GSH in biological fluids with satisfactory results.

Dual emission channels for sensitive discrimination of Cys/Hcy and GSH in plasma and cells.

A new selective fluorescent and colorimetric chemosensor for the detection of GSH was developed. The discrimination of GSH from Cys and Hcy is achieved through two emission channel detection. The detection limit of probe 1 for GSH reached 10 nM (3 ppb). The excellent sensitivity and selectivity of probe 1 allow the selective detection of GSH over Cys and Hcy, which can be visualized colorimetrically and/or fluorescently. The sensitive detection of GSH allowed for convenient measurement of the GSH content in human plasma. The presence of GSH in cells was demonstrated through cell imaging.

A highly sensitive upconverting phosphors-based off–on probe for the detection of glutathione

At present, glutathione (GSH) is a very important biomarker in vivo. However, the sensitive and selective assay for the detection of GSH in biological matrix still keeps challenging due to the high complexity of samples. Lanthanide-doped upconverting phosphors (UCPs) which exhibit unique near-infrared (NIR) excitation nature are able to overcome interferences from complex samples. In this study, a novel probe based on the linkage of UCPs and dopamine-quinone through hydrogen bonding and electrostatic interaction has been designed for rapid, economic, sensitive and selective detection of GSH in aqueous solution and human blood serum. Here, dopamine-quinone served as an efficient quencher for upconverting fluorescence, while GSH as a strong reducing agent chemically reduced the dopamine-quinone turning on the fluorescence. The fluorescence recovery was found to be proportional to GSH concentration within the range from 1 to 75μM. The detection limit of this sensor was 0.29μM, which was quite competitive for GSH detection. The simple, sensitive and selective fluorescence method took full advantages of UCPs properties of low interferences and broadened the application scope of UCPs in complex biological detection.

Size-dependence enhancement in electrocatalytic activity of NiHCF-gold nanocomposite: potential application in electrochemical sensing

A nanocomposite of nickel hexacyanoferrate (NiHCF) was made with gold nanoparticles (AuNPs) of two different sizes (20 and 80 nm as AuNP(red) and AuNP(blue) respectively), synthesized via 3-glycidoxypropyltrimethoxysilane mediated reduction of 3-aminopropyltrimethoxysilane treated gold chloride and characterized by scanning electron microscopy and UV-VIS spectroscopy. The size of AuNPs was found to influence the two pairs of reversible voltammetric peaks of cation rich and cation deficient NiHCF. Such influence was identified from cyclic voltammetry of nanocomposite modified electrodes and applications during electrochemical sensing of two different analytes hydrazine and glutathione (GSH). Electrochemical sensing of hydrazine was based on cyclic voltammetry and differential pulse voltammetry (DPV) found as a function of sodium deficient NiHCF and was greatly amplified with increasing AuNPs nanogeometry. NiHCF alone is not an efficient electrode material for GSH analysis at the level required, however, the presence of AuNPs introduces size dependent sensitive and selective detection of GSH. GSH sensing based on linear sweep voltammetry (LSV) was found to be mediated by the potassium rich form of NiHCF redox couple in the presence of AuNPs. The results justified electrochemical detection of these analytes based on a mediated mechanism and support the role of AuNPs for facilitated electrochemical activity of NiHCF based systems as a function of nanogeometry.