Electrocatalytic activity of cobalt phthalocyanine CoPc adsorbed on a graphite electrode for the oxidation of reduced l-glutathione (GSH) and the reduction of its disulfide (GSSG) at physiological pH

Unveiling thiol biomarkers: Glutathione and cysteamine

The physiological and clinical importance of Glutathione and Cysteamine is emphasized by their participation in a range of conditions, such as diabetes, cancer, renal failure, Parkinson's disease, and hypothyroidism. This necessitates the requirement for accessible, expedited, and cost-efficient testing that can facilitate clinical diagnosis and treatment options. This article examines numerous techniques used to detect both glutathione and cysteamine. The discussed methods include electroanalytical techniques such as voltammetry and amperometry, which are examined for their sensitivity and ability to provide real-time analysis. Furthermore, this study investigates the accuracy of gas chromatography-mass spectrometry (GC-MS) and high-performance liquid chromatography (HPLC) in measuring the concentrations of glutathione and cysteamine. Additionally, the potential of new nanotechnology-based methods, such as plasmonic nanoparticles and quantum dots, to improve the sensitivity of detecting glutathione and cysteamine is emphasized.

Magnesium(II) Porphyrazine with Thiophenylmethylene Groups-Synthesis, Electrochemical Characterization, UV-Visible Titration with Palladium Ions, and Density Functional Theory Calculations

The presented studies aimed to evaluate the peripheral coordinating properties of a novel porphyrinoid family representative preceded by its synthesis for potential sensing purposes. Two synthetic pathways were employed to a obtain maleonitrile derivative, further used as a starting material in the cyclotetramerization reaction. In the first one, DAMN was used in sequential double-reductive alkylation with 2-thiophene-carboxyaldehyde and sodium borohydride. In the second, DAMN was used in a one-pot reaction with 2-thiophene-carboxyaldehyde in the presence of a 5-ethyl-2-methylpyridine borane complex in methanol and acetic acid. Following the Linstead approach, the cyclization reaction led to a novel symmetrical magnesium(II) octaaminoporphyrazine with methyl(2-thiophenylmethylene) substituents. The macrocycle's electrochemical properties were assessed by cyclic and differential pulse voltammetries revealing one reduction and two oxidation peak potentials. The additional spectroelectrochemical measurements showed formation of a cationic form of the macrocycle at an applied potential of 0.6 V. The coordinating properties due to the palladium ion of novel porphyrazines were measured with the use of titration combined with UV-vis spectrometry. The titration of Pd2+ revealed the good sensing activity of porphyrazine in the range of 0.1 to 5 palladium molar equivalents. In addition, Pd2+ ions coordination was also assessed by electrochemical studies, indicating the peak potential shift of 0.1 V in the presence of metal cations. DFT calculations showed the good agreement between theoretical and experimental data in the UV-vis and 1H NMR studies.

Electrochemical detection of arsenic (III) hazardous chemicals using cubic CsPbBr3 single crystals: Structural insights from DFT study

Long-term exposure to the highly toxic heavy metal arsenic can harm ecological systems and pose serious health risks to humans. Arsenic pollutant in water and the food chain must be addressed, and active prompt detection of As(III) is essential. The development of an effective detection method for As(III) ions is urgently needed to slow the alarming growth of arsenic pollution in the environment and safeguard the well-being of future generations. This study presents the results of our exhaustive investigation into cubic CsPbBr₃ single crystals, the glassy carbon (GC) electrode modification with CsPbBr₃ single crystals prepared by direct solvent evaporation, as well as our observations of the material's remarkable electrocatalytic properties and exceptional anti-interference sensing of As(III) ions in neutral pH media. The developed CsPbBr₃/GC is exceptionally useful for the ultra-sensitive and specific identification of arsenic in water, exhibiting a detection limit of 0.381 μmol/L, a rapid response across a defined range of 0.1-25 μmol/L, and an ultra-sensitivity of 0.296 μA/μmolL^-1. CsPbBr₃/GCE (prepared without a specific reagent) is superior to other modified electrodes used as sensors in electrocatalytic activity, detection limit, analytical sensitivity, and stability response.

In Situ Electrochemical Formation of Oxo-Functionalized Graphene on Glassy Carbon Electrode with Chemical Fouling Recovery and Antibiofouling Properties for Electrochemical Sensing of Reduced Glutathione

Electrochemical detection can be used to achieve intracellular or in vivo analysis of reduced glutathione (GSH) in tissues such as brain by using a microelectrode, which can help to better understand the complex biochemical processes of this molecule in the human body. The main challenges associated with electrochemical GSH detection are the chemical fouling of electrodes, caused by the oxidation product of GSSG, and biofouling due to the non-specific absorption of biological macromolecules. Oxo-functionalized graphene was generated in situ on the surface of a glassy carbon electrode using a green electrochemical method without using any other modifiers or materials in a mild water solution. The fabricated oxo-functionalized graphene interface was characterized by Raman spectroscopy, X-ray photoelectron spectroscopy, electrochemistry, electrochemical impedance spectroscopy, and contact angle measurements. The interface showed high electrocatalytic activity towards the oxidation of GSH, and a simple and efficient GSH sensor was developed. Interestingly, the electrode is reusable and could be recovered from the chemical fouling via electrochemical oxidation and reduction treatment. The electrode also exhibited good antibiofouling properties. The presented method could be a promising method used to treat carbon materials, especially carbon-based microelectrodes for electrochemical monitoring of intracellular glutathione or in vivo analysis.

Highly sensitive and selective detection of glutathione using ultrasonic aided synthesis of graphene quantum dots embedded over amine-functionalized silica nanoparticles

Glutathione (GSH) is the most abundant antioxidant in the majority of cells and tissues; and its use as a biomarker has been known for decades. In this study, a facile electrochemical method was developed for glutathione sensing using voltammetry and amperometry analyses. In this study, a novel glassy carbon electrode composed of graphene quantum dots (GQDs) embedded on amine-functionalized silica nanoparticles (SiNPs) was synthesized. GQDs embedded on amine-functionalized SiNPs were physical-chemically characterized by different techniques that included high resolution-transmission electron microscopy (HR-TEM), X-ray diffraction spectroscopy (XRD), UV-visible spectroscopy, Fourier-transform infrared spectroscopy(FTIR), and Raman spectroscopy. The newly developed electrode exhibits a good response to glutathione with a wide linear range (0.5-7 µM) and a low detection limit (0.5 µM) with high sensitivity(2.64 µA µM-1). The fabricated GQDs-SiNPs/GC electrode shows highly attractive electrocatalytic activity towards glutathione detection in the neutral media at low potential due to a synergistic surface effect caused by the incorporation of GQDs over SiNPs. It leads to higher surface area and conductivity, improving electron transfer and promoting redox reactions. Besides, it provides outstanding selectivity, reproducibility, long-term stability, and can be used in the presence of interferences typically found in real sample analysis.

Azaporphyrins Embedded on Carbon-Based Nanomaterials for Potential Use in Electrochemical Sensing-A Review

Phthalocyanines and porphyrazines as macrocyclic aza-analogues of well-known porphyrins were deposited on diverse carbon-based nanomaterials and investigated as sensing devices. The extended π-conjugated electron system of these macrocycles influences their ability to create stable hybrid systems with graphene or carbon nanotubes commonly based on π-π stacking interactions. During a 15-year period, the electrodes modified by deposition of these systems have been applied for the determination of diverse analytes, such as food pollutants, heavy metals, catecholamines, thiols, glucose, peroxides, some active pharmaceutical ingredients, and poisonous gases. These procedures have also taken place, on occasion, in the presence of various polymers, ionic liquids, and other moieties. In the review, studies are presented that were performed for sensing purposes, involving azaporphyrins embedded on graphene, graphene oxide or carbon nanotubes (both single and multi-walled ones). Moreover, possible methods of electrode fabrication, limits of detection of each analyte, as well as examples of macrocyclic compounds applied as sensing materials, are critically discussed.

A reliable alternative approach for the ultra-sensitive detection ofl-glutathione with wet chemically synthesized Co3O4-doped SnO2nanoparticles decorated on a glassy carbon electrode

An electrochemical sensor was developed for the non-enzymatic detection ofl-glutathione based on wet-chemically prepared Co₃O₄-doped SnO₂nanoparticles decorated on a glassy carbon electrode sensor-probe.

Iron Phthalocyanine Decorated Nitrogen-Doped Graphene Biosensing Platform for Real-Time Detection of Nitric Oxide Released from Living Cells

Nitric oxide (NO) is a transcellular messenger involved in many physiological and pathological processes, but the real-time detection of NO in biological systems is still challenging due to its rapid diffusion, low concentration, and short half-life. A novel electrochemical sensing platform based on iron phthalocyanine (FePc) functionalized nitrogen-doped graphene (N-G) nanocomposites was constructed to achieve in situ monitoring of NO released from living cells on the sensing layer. By taking advantage of the synergetic effect of N-G and FePc nanocomposites, the N-G/FePc sensor displays excellent electrocatalytic activity toward NO with a high sensitivity of 0.21 μA μM^-1 cm^-2 and a low detection limit of 180 nmol L^-1. The following layer-by-layer assembly of poly-l-lysine (PLL) and Nafion further improved the capacity of resisting disturbance as well as the biocompatibility of the sensing interface. The flexible design of the ITO substrate based electrode provides a more controlled cellular biosensing system which could capture molecular signals immediately after NO released from human umbilical vein endothelial cells (HUVECs). The exhibited additional features of high sensitivity, rapid response, and ease of operation implies that the proposed N-G/FePc/Nafion/PLL ITO biosensor is a promising powerful platform in various complex biological systems.

Fabrication of a cobalt phthalocyanine free-standing film on an ionic liquid surface for memory device applications

The fabrication of a metal phthalocyanine (MPc) film with good transferability and exploitation of its properties are very important for further application. In this study, a continuous free-standing film of CoPc was obtained on an ionic liquid (IL) surface via a physical vapor deposition (PVD) method. The as-obtained film has a β-phase structure and is constructed with one dimensional CoPc to form a network structure. The morphology of the film could be easily tuned by tunning the flow rate of the carrier gas. More importantly, the device based on these films shows obvious electrical switching and negative differential resistance (NDR) characteristics. The maximum ON/OFF current ratio of two distinctive conductivity states is ∼100 at a reading voltage of +30 V. The conductivity and conductive switching behavior of the NW constructed device are better than the device constructed with NRs. The NDR effect and electrical switching conduction mechanism can be explained by the charge trap elements of the Co^II/Co^I redox couples. The above results open up the possibility of CoPc as a memory medium for information storage and logic circuits applications.

The fabrication of a metal phthalocyanine (MPc) film with good transferability and exploitation of its properties are very important for further application.

Sonochemical synthesis of silver nanoparticles anchored reduced graphene oxide nanosheets for selective and sensitive detection of glutathione

Developed here an eco-friendly, one-pot approach toward rapid synthesis of silver nanoparticles anchored reduced graphene oxide (AgNPs_(TMSPED)-rGO) nanosheets via sonochemical irradiation method, using an aqueous solution mixture of GO and AgNO₃ in the presence of N-[3(trimethoxysilyl)propyl] ethylenediamine (TMSPED) without any reducing agent. As synthesized decorated nanosheets was thoroughly characterized by transmission electron microscopy (TEM), atomic force microscopy (AFM), Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD) spectroscopy, Raman spectroscopy and X-ray photoelectron spectroscopy (XPS). Pristine AgNPs_(TMSPED), pristine rGO_(TMSPED) and as prepared AgNPs_(TMSPED)-rGO materials were employed to modify the glassy carbon (GC) electrode and demonstrated its excellent electrocatalytic activities towards glutathione (GSH). Voltammetry and amperometry measurements were utilized to assess the electrochemical properties towards the glutathione detection. When the Ag nanoparticles were anchored onto the rGO surface, the observed results illustrated that the electrocatalytic properties of rGO might be enhanced. The resulting sensor exhibits excellent repeatability and long-term stability. Furthermore, AgNPs_(TMSPED)-rGO/GC electrode able to be employed for the selective determination of GSH in amperometric analysis in the presence of ascorbic acid (AA), dopamine (DA), uric acid (UA) and glucose. Finally, this modified electrode was effectively applied to determine glutathione in real samples with good recoveries.

Glassy carbon electrode modified with 7,7,8,8-tetracyanoquinodimethane and graphene oxide triggered a synergistic effect: Low-potential amperometric detection of reduced glutathione

A sensitive electrochemical sensor based on the synergistic effect of 7,7,8,8-tetracyanoquinodimethane (TCNQ) and graphene oxide (GO) for low-potential amperometric detection of reduced glutathione (GSH) in pH 7.2 phosphate buffer solution (PBS) has been reported. This is the first time that the combination of GO and TCNQ have been successfully employed to construct an electrochemical sensor for the detection of glutathione. The surface of the glassy carbon electrode (GCE) was modified by a drop casting using TCNQ and GO. Cyclic voltammetric measurements showed that TCNQ and GO triggered a synergistic effect and exhibited an unexpected electrocatalytic activity towards GSH oxidation, compared to GCE modified with only GO, TCNQ or TCNQ/electrochemically reduced GO. Three oxidation waves for GSH were found at -0.05, 0.1 and 0.5V, respectively. Amperometric techniques were employed to detect GSH sensitively using a GCE modified with TCNQ/GO at -0.05V. The electrochemical sensor showed a wide linear range from 0.25 to 124.3μM and 124.3μM to 1.67mM with a limit of detection of 0.15μM. The electroanalytical sensor was successfully applied towards the detection of GSH in an eye drop solution.

Evaluation of the reactivity of exhaust from various biodiesel blends as a measure of possible oxidative effects: A concern for human exposure

Diesel exhaust particles (DEP) are a major constituent of ambient air pollution and are associated with various adverse health effects, posing a major safety and public health concern in ambient and occupational environments. The effects of DEP from various biodiesel blends on biological systems was investigated using glutathione (GSH) as a marker of possible oxidative effects, based on the decrease in the concentration of GSH at physiological pH. The fluorophoric agent 2,3-naphthalenedicarboxaldehyde (NDA) was used as a selective probe of GSH in the presence of any likely interferents via fluorescence detection. Three different polar solvents (acetonitrile, methanol and water) were used to extract DEP generated during the combustion of different biodiesel blends (5%-99%). Oxidation of GSH to the disulfide (GSSG) was confirmed using electrospray ionization mass spectrometry. A decrease in the concentration of GSH was observed in the presence of DEP extracts from all of the biodiesel blends studied, with reaction rates that depend on the biodiesel blend. Interestingly the reactivity peaked at 50% biodiesel (B50) rather than decreasing monotonically with increased biodiesel content, as was expected. Organic solvent DEP extracts showed wider variations in reactivity with GSH, with methanol extracts giving the largest decrease in GSH concentrations. This may imply a more organic nature of the oxidants in the biodiesel exhaust. It is therefore important to consider ways of reducing concentrations of organic components in biodiesel exhaust that can cause different toxic activity before any blend is offered as a preferred alternative to petroleum diesel fuel.

Magnesium(ii) 1-(1-adamantylsulfanyl)phthalocyanine – synthesis, photochemical and electrochemical properties

Phthalocyanine with moderate fluorescence and singlet oxygen quantum yield was obtained and its electrochemical properties were assessed.

Computational Study of the Cation-Modified GSH Peptide Interactions With Perovskite-Type BFO-(111) Membranes Under Aqueous Conditions

We elucidated a number of facets regarding glutathione (GSH)-bismuth ferrite (BiFeO3, BFO) interactions and reactivity that have previously remained unexplored on a molecular level. In this approach, the cation-modified reduced GSH (or oxidised glutathione (GS·)) formed on the (111)-oriented BiFeO3 membrane (namely BFO-(111)) can serve as an efficient quencher, and the luminescence mechanism is explained in aqueous conditions. Notably, we suggest the use of Fe(2+)↓ ion as an electron donor and K(+) ion as an electron acceptor to exert a "gluing" effect on the glutamic acid (Glu) and glycine (Gly) side chains, producing an exposed sulfhydryl (-SH) configuration. This method may enable the rational design of a convenient platform for biosensors.

Glutathione

Glutathione is an endogenous peptide with antioxidant and other metabolic functions. The nomenclature, formulae, elemental composition, and appearance and uses of the drug are included. The methods used for the synthesis and biosynthesis of glutathione are described. This profile contains the physical characteristics of the drug including: solubility, X-ray powder diffraction pattern, crystal structure, melting point, and differential scanning calorimetry. The spectral methods that were used for both the identification and analysis of glutathione include ultraviolet spectrum, vibrational spectrum, 1H and 13C nuclear magnetic resonance spectra, and mass spectrum. The profile also includes the compendial methods of analysis and the other methods of analysis that are reported in the literature. These other methods of e-analysis are: potentiometric, voltammetric, amperometric, spectrophotometric, specrtofluorometric, chemiluminescence, chromatographic and immunoassay methods. The stability of and several reviews on drug are also provided. More than 170 references are listed at the end this comprehensive profile on glutathione.

Highly sensitive determination of reduced glutathione based on a cobalt nanoparticle implanted-modified indium tin oxide electrode

Cobalt nanoparticle modified indium tin oxide (CoNP/ITO) electrodes fabricated by ion implantation were applied for the detection of reduced glutathione (GSH).

Cobalt phthalocyanine modified electrodes utilised in electroanalysis: nano-structured modified electrodes vs. bulk modified screen-printed electrodes

Cobalt phthalocyanine (CoPC) compounds have been reported to provide electrocatalytic performances towards a substantial number of analytes. In these configurations, electrodes are typically constructed via drop casting the CoPC onto a supporting electrode substrate, while in other cases the CoPC complex is incorporated within the ink of a screen-printed sensor, providing a one-shot economical and disposable electrode configuration. In this paper we critically compare CoPC modified electrodes prepared by drop casting CoPC nanoparticles (nano-CoPC) onto a range of carbon based electrode substrates with that of CoPC bulk modified screen-printed electrodes in the sensing of the model analytes l-ascorbic acid, oxygen and hydrazine. It is found that no “electrocatalysis” is observed towards l-ascorbic acid using either of these CoPC modified electrode configurations and that the bare underlying carbon electrode is the origin of the obtained voltammetric signal, which gives rise to useful electroanalytical signatures, providing new insights into literature reports where “electrocatalysis” has been reported with no clear control experiments undertaken. On the other hand true electrocatalysis is observed towards hydrazine, where no such voltammetric features are witnessed on the bare underlying electrode substrate.

Chemically reversible reactions of hydrogen sulfide with metal phthalocyanines

Hydrogen sulfide (H₂S) is an important signaling molecule that exerts action on various bioinorganic targets. Despite this importance, few studies have investigated the differential reactivity of the physiologically relevant H₂S and HS^– protonation states with metal complexes. Here we report the distinct reactivity of H₂S and HS^– with zinc(II) and cobalt(II) phthalocyanine (Pc) complexes and highlight the chemical reversibility and cyclability of each metal. ZnPc reacts with HS^–, but not H₂S, to generate [ZnPc-SH]⁻, which can be converted back to ZnPc by protonation. CoPc reacts with HS^–, but not H₂S, to form [Co^IPc]⁻, which can be reoxidized to CoPc by air. Taken together, these results demonstrate the chemically reversible reaction of HS^– with metal phthalocyanine complexes and highlight the importance of H₂S protonation state in understanding the reactivity profile of H₂S with biologically relevant metal scaffolds.

The protonation state of H₂S influences its reactivity with different metal phthalocyanine (Pc) complexes. Both ZnPc and CoPc react with H₂S in a chemically reversible manner, with redox-inactive ZnPc binding HS⁻ and redox-active CoPc undergoing reduction. The [ZnPc-SH]⁻ product can be reverted to ZnPc by protonation, and [Co^IPc]⁻ can be redoxidized to CoPc with air.

Self-assembly of tetrakis (3-trifluoromethylphenoxy) phthalocyaninato cobalt(II) on multiwalled carbon nanotubes and their amperometric sensing application for nitrite

In this work, the soluble cobalt phthalocyanine functionalized multiwalled carbon nanotubes (MWCNTs) are synthesized by π-π stacking interaction between tetrakis (3-trifluoromethylphenoxy) phthalocyaninato cobalt(II) (CoPcF) complex and MWCNTs. The physical properties of CoPcF-MWCNTs hybrids are evaluated using spectroscopy (UV-vis, XPS, and Raman) and electron microscopy (TEM and SEM). Subsequently, an amperometric nitrite electrochemical sensor is designed by immobilizing CoPcF-MWCNTs hybrids on the glassy carbon electrode. The immobilized CoPcF complex shows the fast electron transfer rate and excellent electrocatalytic activity for the oxidation of nitrite. Under optimum experimental conditions, the proposed nitrite electrochemical sensor shows the fast response (less than 2 s), wide linear range (9.6 × 10(-8) to 3.4 × 10(-4) M) and low detection limit (6.2 × 10(-8) M) because of the good mass transport, fast electron transfer rate, and excellent electrocatalytic activity.

Microfluidic electrochemical sensor for on-line monitoring of aerosol oxidative activity

Particulate matter (PM) air pollution has a significant impact on human morbidity and mortality; however, the mechanisms of PM-induced toxicity are poorly defined. A leading hypothesis states that airborne PM induces harm by generating reactive oxygen species in and around human tissues, leading to oxidative stress. We report here a system employing a microfluidic electrochemical sensor coupled directly to a particle-into-liquid sampler (PILS) system to measure aerosol oxidative activity in an on-line format. The oxidative activity measurement is based on the dithiothreitol (DTT) assay, where, after being oxidized by PM, the remaining reduced DTT is analyzed by the microfluidic sensor. The sensor consists of an array of working, reference, and auxiliary electrodes fabricated in a poly(dimethylsiloxane)-based microfluidic device. Cobalt(II) phthalocyanine-modified carbon paste was used as the working electrode material, allowing selective detection of reduced DTT. The electrochemical sensor was validated off-line against the traditional DTT assay using filter samples taken from urban environments and biomass burning events. After off-line characterization, the sensor was coupled to a PILS to enable on-line sampling/analysis of aerosol oxidative activity. Urban dust and industrial incinerator ash samples were aerosolized in an aerosol chamber and analyzed for their oxidative activity. The on-line sensor reported DTT consumption rates (oxidative activity) in good correlation with aerosol concentration (R(2) from 0.86 to 0.97) with a time resolution of approximately 3 min.

Nanostructured cobalt phthalocyanine single-walled carbon nanotube platform: electron transport and electrocatalytic activity on epinephrine

The fabrication, characterization and application of edge-plane pyrolytic graphite electrode modified with acid-functionalized single-walled carbon nanotubes, nanostructured cobalt phthalocyanine and a mixture of both, towards epinephrine detection and analysis are described. The morphological features of the films were evaluated using atomic force microscopy (AFM). Electrochemistry of these electrodes in [ Fe ( CN )6]3−/4− using cyclic voltammetry and electrochemical impedance spectroscopy showed higher peak current responses with accompanying low electron-transfer resistances in comparison to the bare electrode. The edge-plane pyrolytic graphite-single-walled carbon nanotubes-nanostructured cobalt phthalocyanine electrode exhibited good electrocatalytic activity towards epinephrine oxidation with enhanced peak currents. Analytical studies using edge-plane pyrolytic graphite-single-walled carbon nanotubes-nanostructured cobalt phthalocyanine electrode proved that the electrode is suitable for sensitivity determination of epinephrine in pH 5 conditions judging from the good sensitivity (8.71 ± 0.31 A.M−1), and limit of detection (0.04 µM) and quantification (1.31 µM) obtained. Determination of EP in the absence and presence of ascorbic acid in phosphate buffer pH 5 conditions was carried out and it was established that the presence of AA did not interfere in EP analysis. Rotating disk electrode experiments proved that the catalytic rate constant was 2.28 × 1016 mM−1.s−1.