Hemozoin anchored MWCNTs for mediated reduction of hydrogen peroxide and real-time intracellular oxidative stress monitoring in colon cancer cells.

Hemozoin (HZ, a malarial pigment) is an insoluble crystalline byproduct formed during the intraerythrocytic breakdown of hemoglobin by some blood-feeding parasites, such as . It consists of polymerized iron-porphyrin molecular units linked by carboxylic bonds. Due to the rigid molecular structure, studying the electron transfer activity of HZ is challenging.

Sialic Acid-Targeted Ru(II)/Ir(III)/Re(I) Complexes for Ferroptosis Induction in Triple-Negative Breast Cancer.

Ferroptosis has been recognized as an iron-based nonapoptotic-regulated cell death process. In the quest of resisting the unyielding vehemence of triple-negative breast cancer (TNBC), herein we have showcased the ferroptosis-inducing heteroleptic [], [], and [] complexes, enabling them to selectively target "sialic acid", an overexpressed cancer cell-surface marker. The open-circuit potential (OCP) measurements in live cancer cells revealed the specific interaction between TNBC and the complexes, whereas control experiments with normal cells did not exhibit such interactions.

Electrical Wiring of Malarial Parasite Intermediate Hematin on a Tailored N-Doped Carbon Nanomaterial Surface and Its Bioelectrocatalytic Hydrogen Peroxide Reduction and Sensing.

Hematin, an iron-containing porphyrin compound, plays a crucial role in various biological processes, including oxygen transport, storage, and functionality of the malarial parasite. Specifically, hematin-Fe interacts with the nitrogen atom of antimalarial drugs, forming an intermediate step crucial for their function. The electron transfer functionality of hematin in biological systems has been scarcely investigated.

Neem biomass derived carbon quantum dots synthesized via one step ultrasonification method for ecofriendly methylene blue dye removal.

This article presents a one-step ultrasonication technique for generating biomass carbon dots (BCDs) from neem bark (Azadirachta indica) powder. The BCDs were characterized using modern techniques such as UV-Vis, FTIR, Raman, XRD, HRTEM, FESEM, EDAX, and Zeta potential analyses. Unlike traditional nanocomposite bed systems, this study utilized BCDs as a liquid-phase adsorbent for the regenerative adsorption of the environmentally harmful dye, methylene blue (MB), through an in-situ precipitation reaction.

Redox-Active Green Electrode: Plant-Based Betanin Immobilized on Carbon Black for Drift-Free Voltammetric and Potentiometric pH Sensor Applications.

The development of eco-friendly chemicals and material-based electrode systems with a reduced carbon footprint is a novel initiative for future technological applications. While electrochemical systems based on plant phytochemicals meet the requirements, comprehending the fundamental electron-transfer reactions and preparing stable surface-confined redox systems pose significant research challenges. In this study, we have demonstrated an in situ electrochemical reaction-assisted entrapment of redox-active betanin molecular species from native beetroot plants on a carbon black-modified glassy carbon surface (GCE/CB@Betn-Redox, where Betn-Redox stands for redox-active betanin molecular species) in a pH 2.

Edge and Basal Plane Anisotropy of a Preanodized Pencil Graphite Electrode Surface Revealed Using Scanning Electrochemical Microscopy and Electrocatalytic Dopamine Oxidation as a Molecular Probe.

Pencil graphite (PGE), an ultralow-cost and ready-to-use disposable-type electrode, has been used for various electrochemical and electroanalytical applications after its surface anodization (PGE*, * means preanodized surface). Indeed, systematic studies on mechanistic and surface features of PGE* have not yet been explored. Herein, we report anodized pencil graphite as a model system to study molecular level insights into the surface using a scanning electrochemical microscopy (SECM) technique and dopamine (DA) electrocatalytic oxidation reaction as a molecular probe.

A π-π Bonding-Assisted Molecular-Wiring of Folded-Cytochrome and Naphthoquinone and Its Electron-Relay-Based Bioelectrocatalytic HO Reduction Reaction Visualized by Redox-Competitive Scanning Electrochemical Microscopy.

The electron-transfer (ET) reaction of cytochrome (Cytc) protein with biomolecules is a cutting-edge research area of interest in understanding the functionalities of natural systems. Several electrochemical biomimicking studies based on Cytc-protein-modified electrodes prepared via electrostatic interaction and covalent bonding approaches have been reported. Indeed, natural enzymes involve multiple types of bonding, such as hydrogen, ionic, covalent, and π-π, etc.

Surface-Activated Pencil Graphite Electrode for Dopamine Sensor Applications: A Critical Review.

Pencil graphite electrode (PGE) is an alternative, commercially available, ready-to-use, screen-printed electrode for a wide range of electroanalytical applications. Due to the complex-matrix composition and unpredictable electro-inactive nature of PGE in its native form, a surface pre-treatment/activation procedure is highly preferred for using it as an electroactive working electrode for electroanalytical applications. In this article, we review various surface pre-treatment and modification procedures adopted in the literature with respect to the sensitive and selective detection of dopamine as a model system.

A Size-Controlled Graphene Oxide Materials Obtained by One-Step Electrochemical Exfoliation of Carbon Fiber Cloth for Applications to In Situ Gold Nanoparticle Formation and Electrochemical Sensors-A Preliminary Study.

A simple, one-step and facile method has been introduced to prepare fluorescent and electrochemically active carbon nanoparticles with single-size distribution and good long-term stability by electrochemical exfoliation of polyacrylonitrile-based carbon fibers in an alkaline solution-phase condition. The preparation condition was systematically optimized by studying the effect of temperature and electrolytes. It has been found that an electrochemical exfoliation reaction carried out at an applied potential of 2 V vs.

A prototype device of microliter volume voltammetric pH sensor based on carbazole-quinone redox-probe tethered MWCNT modified three-in-one screen-printed electrode.

As an alternate for the conventional glass-based pH sensor which is associated with problems like fragile nature, alkaline error, and potential drift, the development of a new redox-sensitive pH probe-modified electrode that could show potential, current-drift and surface-fouling free voltammetric pH sensing is a demanding research interest, recently. Herein, we report a substituted carbazole-quinone (Car-HQ) based new redox-active pH-sensitive probe that contains benzyl and bromo-substituents, immobilized multiwalled carbon nanotube modified glassy carbon (GCE/MWCNT@Car-HQ) and screen-printed three-in-one (SPE/MWCNT@Car-HQ) electrodes for selective, surface-fouling free pH sensor application. This new system showed a well-defined surface-confined redox peak at an apparent standard electrode potential, E' = - 0.

electro-organic synthesis of hydroquinone using anisole on MWCNT/Nafion modified electrode surface and its heterogeneous electrocatalytic reduction of toxic Cr(vi) species.

Owing to its electro-inactive character, anisole (phenylmethyl ether, PhOCH) and its related derivatives have been used as electrolytes in electrochemistry. Herein, we report a simple one-step electro-organic conversion of PhOCH to hydroquinone (HQ) on a pristine-MWCNT-Nafion modified electrode glassy carbon electrode surface, GCE/Nf-MWCNT@HQ, in pH 2 KCl-HCl solution within 15 min of working time. The chemically modified electrode showed a highly redox-active and well-defined signal at an apparent standard electrode potential, ' = 0.

Vitamin B12-Immobilized Graphene Oxide for Efficient Electrocatalytic Carbon Dioxide Reduction Reaction.

A naturally occurring water-soluble cobalt-complex cyanocobalamin (Vitamin B12) has been identified as a new and efficient electrocatalyst for the CO -to-CO reduction reaction in aqueous solution. Heterogeneous B12-electrocatalysts prepared by a simple electrochemical immobilization technique on graphene-oxide (GO)-modified glassy carbon and carbon paper (CP) electrodes, without any non-degradable polymer-binders, showed a highly stable and well-defined surface-confined redox peak at E'=-0.138 V vs.

Facile Electrochemical Demethylation of 2-Methoxyphenol to Surface-Confined Catechol on the MWCNT and Its Efficient Electrocatalytic Hydrazine Oxidation and Sensing Applications.

Owing to its biological significance, preparation of stable surface-confined catechol (CA) is a long-standing interest in electrochemistry and surface chemistry. In this connection, various chemical approaches such as covalent immobilization (using amine- and carboxylate-functionalized CA, diazotization-based coupling, and Michael addition reaction), self-assembled monolayer on gold (thiol-functionalized CA is assembled on the gold surface), CA adsorption on the ad-layer of a defect-free single-crystal Pt surface, π-π bonding, CA pendant metal complexes, and CA-functionalized polymer-modified electrodes have been reported in the literature. In general, these conventional methods are involved with a series of time-consuming synthetic procedures.

π-Self-Assembly of a Coronene on Carbon Nanomaterial-Modified Electrode and Its Symmetrical Redox and HO Electrocatalytic Reduction Functionalities.

The structure-electroactivity relationship of graphene has been studied using coronene (Cor), polyaromatic hydrocarbon (PAH), and a subunit of graphene as a model system by chemically modified electrode approach. In general, graphene and PAH do not show any redox activity in their native form. Herein, we report a simple electrochemical approach for the conversion of electro-inactive coronene to a highly redox-active molecule (Cor-Redox; °' = 0.

Molecular wiring of glucose oxidase enzyme with Mn polypyridine complex on MWCNT modified electrode surface and its bio-electrocatalytic oxidation and glucose sensing.

A simple method for molecular wiring of glucose oxidase (GOx) enzyme with a low cost Mn polypyridine complex, Mn(phen)Cl, carboxylic acid functionalized multiwalled carbon nanotube (f-MWCNT) and Nafion (Nf), which is useful for glucose oxidation and sensing application in pH 7 phosphate buffer solution, has been demonstrated. In the typical preparation, f-MWCNT, Mn(phen)Cl, Nafion and GOx solution/suspension were successfully drop-casted as layer-by-layer on a cleaned glassy carbon electrode and potential cycled using cylic voltametric (CV) technique. In this preparation procedure, the Mn(phen)Cl complex is in-situ converted as a dimer complex, Mn(phen)(O)(Cl).

Electrochemical Reaction Assisted 2D π-Stacking of Benzene on a MWCNT Surface and its Unique Redox and Electrocatalytic Properties.

Turning the π-structure and electronic properties of carbon nanotubes (CNTs) is a cutting-edge research topic in interdisciplinary areas of material chemistry. In general, chemical functionalization of CNT has been adopted for this purpose, which has resulted in a few monolayer thickness increment of CNT diameter size. Herein, we report an interesting observation of >10-fold increment in the apparent diameter of multiwalled carbon nanotubes (MWCNTs) brought about by a process of self-assembly of the BZ moiety on MWCNT, which is formed by electrochemical oxidation of a surface-adsorbed benzene-water cluster, {BZ-HO}.

Improved Electrical Wiring of Glucose Oxidase Enzyme with an Immobilized Mn(1,10-Phenanthroline)Cl-Complex/Multiwalled Carbon Nanotube-Modified Electrode Displaying Superior Performance to Os-Complex for High-Current Sensitivity Bioelectrocatalytic and Biofuel Cell Applications.

The search for a new and efficient transducer that can electrically connect enzyme active sites, like flavin adenine dinucleotide in glucose oxidase (GOx), with the electrode surface is a cutting-edge research area. Currently, Os(bpy)-complex pendent polyvinylpyridine/polyvinyl imidazole/pyridinium hydrogel based chemically modified electrodes have been widely used for this purpose (bpy = 2,2'-bipyridine). Herein, we report, a [Mn(phen)(O)(Cl)] complex/Nafion-immobilized carboxylic acid-functionalized multiwalled carbon nanotube modified glassy carbon electrode (GCE/f-MWCNT@Mn(Phen)O(Cl)-Nf, phen = 1,10-phenanthroline), prepared by an electrochemical method using the precursor, Mn(phen)Cl, as an efficient and low cost alternate to the Os-complex transducer, for the glucose oxidase enzyme (GOx) based bio-electro-catalytic system.

Axial Coordination Site-Turned Surface Confinement, Electron Transfer, and Bio-Electrocatalytic Applications of a Hemin Complex on Graphitic Carbon Nanomaterial-Modified Electrodes.

Understanding the relation between the chemical bonding and the electron-transfer (ET) reaction of surface-confined hemin (a five-coordinated Fe-porphyrin-with-chlorine complex) is a special interest in the biomimicking studies of heme proteins. Owing to the difficulty in ET function, scanty electrochemical reports of hemin in aqueous solution were reported. It has been noticed that in most of the reported procedures, the sixth axial coordination position of the hemin complex has been unknowingly turned by attaching with water molecules (potential cycling in alkaline conditions or heating), solvents such as ethanol and dimethyl sulfoxide, and nitrogen-donating compounds that have helped for the heme ET reaction.

A blood-serum sulfide selective electrochemical sensor based on a 9,10-phenanthrenequinone-tethered graphene oxide modified electrode.

The sulfide ion and its associated species (HS and HS) are widely referred to as toxic chemicals. However, at concentrations of ∼10-100 μM, it serves as a neurotransmitter and signaling agent in biological systems. Abnormalities in blood serum sulfide can be an indication of several diseases, including diabetes, wherein there is a significant reduction in the sulfide ion concentration (<10 μM).

In Situ Structural Elucidation and Selective Pb Ion Recognition of Polydopamine Film Formed by Controlled Electrochemical Oxidation of Dopamine.

Owing to the versatility and biocompatibility, a self-polymerized DA (in the presence of air at pH 8.5 tris buffer solution) as a polydopamine (pDA) film has been used for a variety of applications. Indeed, instability under electrified condition (serious surface-fouling) and structural ambiguity of the pDA have been found to be unresolved problems.

Undiluted human whole blood uric acid detection using a graphitized mesoporous carbon modified electrode: a potential tool for clinical point-of-care uric acid diagnosis.

Direct sensing of uric acid (UA) in an undiluted whole blood sample is reported here taking human whole blood as an analyte and a self-supporting electrolyte. Among various solid electrodes (Pt, Au, GCE, and GCE/Nafion) and carbon nanomaterials (carbon nanofibers, graphene oxide, graphite nanopowder, graphitized mesoporous carbon (GMC), single-walled carbon nanotubes, and multiwalled carbon nanotubes) tested, a GMC-modified glassy carbon electrode, designated as GCE/GMC, showed a remarkable response towards direct electrochemical oxidation of blood uric acid at ∼0.25 V vs.

An Elegant Analysis of White Spot Syndrome Virus Using a Graphene Oxide/Methylene Blue based Electrochemical Immunosensor Platform.

White spot syndrome virus (WSSV) is a major devastating virus in aquaculture industry. A sensitive and selective diagnostic method for WSSV is a pressing need for the early detection and protection of the aquaculture farms. Herein, we first report, a simple electrochemical immunosensor based on methylene blue dye (MB) immobilized graphene oxide modified glassy carbon electrode (GCE/GO@MB) for selective, quick (35 ± 5 mins) and raw sample analysis of WSSV.

Electrochemical behavior of the 1,10-phenanthroline ligand on a multiwalled carbon nanotube surface and its relevant electrochemistry for selective recognition of copper ion and hydrogen peroxide sensing.

1,10-Phenanthroline (Phen) is a well-known benchmark ligand and has often been used in the coordination chemistry for the complexation of transition metal ions, such as Fe(2+), Ni(2+), and Co(2+). Because the electro-oxidation potential of Phen is much higher (>2 V versus Ag/AgCl) than the water decomposition potential, i.e.