Factorial Optimization of CoCuFe-LDH/Graphene Ternary Composites as Electrocatalysts for Water Splitting.

The layered double hydroxides (LDHs) have demonstrated significant potential as non-noble-metal electrocatalysts for the hydrogen evolution reaction (HER) and oxygen evolution reaction (OER). Their unique compositional and structural properties contribute to their efficiency and stability as catalysts. In this study, CoCuFe-LDH composites were grown on graphene (G) via a cost-effective and straightforward one-step hydrothermal process.

Amplifying Flutamide Sensing through the Synergetic Combination of -Derived Carbon Particles and WS Platelets.

The development of electrochemical sensors for flutamide detection is a crucial step in biomedical research and environmental monitoring. In this study, a composite of -derived carbon particles (CPs) and tungsten disulfide (WS) was formed and used as an electrocatalyst for the electrochemical detection of flutamide. The CPs had an average diameter of 500 nm and contained surface hydroxyl and carbonyl groups.

Electrochemical detection of sulfanilamide using tannic acid exfoliated MoS nanosheets combined with reduced graphene oxide/graphite.

Sulfonamides are a family of synthetic drugs with a broad-spectrum of antimicrobial activity. Like other antimicrobials, they have been found in aquatic environments, making their detection important. Herein, an electrochemical sensor was designed using tannic acid exfoliated few-layered MoS sheets, which were combined with a mixture of reduced graphene oxide (rGO) and graphite flakes (G).

Development of Novel Pt(IV)-Carbohydrate Derivatives as Targeted Anticancer Agents against Osteosarcoma.

Despite the enormous importance of cisplatin as a chemotherapeutic agent, its application is impacted by dose-limiting side effects and lack of selectivity for cancer cells. Researchers can overcome these issues by taking advantage of the pro-drug nature of the platinum(IV) oxidation state, and by modifying the coordination sphere of the metal centre with specific vectors whose receptors are overexpressed in tumour cell membranes (e.g.

Magnetic nanoparticle modified electrodes for voltammetric determination of propellant stabiliser diphenylamine.

The overall aim of the work was to advance electrochemical devices capable of analysis of forensically relevant residues using rapid electrochemical sensor technology. In order to achieve this, electrochemical detection of the propellant stabiliser diphenylamine (DPA) was achieved via voltammetry with signal enhancement realised in the presence of iron oxide nanoparticle modified transducers. This allowed both mechanistic and analytical evaluation with the aim to achieve the required selectivity and sensitivity for reliable detection.

Development of highly sensitive and selective bisphenol A sensor based on a cobalt phthalocyanine-modified carbon paste electrode: application in dairy analysis.

The development of an accurate, sensitive and selective sensor for the detection of bisphenol A (BPA) based on the incorporation of a new phthalocyanine derivative, cobalt phthalocyanine, C,C,C,C-tetracarboxylic acid-polyacrylamide (CoPc-PAA) into a carbon-paste matrix is presented using voltammetry and constant potential techniques. The influence of measuring parameters such as pH and scan rate on the analytical performance of the sensor was evaluated. Several kinetic parameters such as electron transfer number (), charge transfer coefficient (), electrode surface area () and diffusion coefficient () were also calculated.

An Electrochemical Evaluation of Novel Ferrocene Derivatives for Glutamate and Liver Biomarker Biosensing.

Here, we present an evaluation of two new monosubstituted ferrocene (Fc) derivatives, 3-(1H-pyrrol-1-yl)propanamidoferrocene and 1-hydroxy-2-[2-(thiophen-3-yl)-ethylamino]ethylferrocene, as glutamate oxidase mediators, together with their preparation and characterisation. Taking into consideration the influence of the electronic effects of substituents on the redox potentials of the Fc species, two candidates with pyrrole or thiophene moieties were proposed for investigation. Film studies involved potential sweeping in the presence of pyrrole or 3,4-ethylenedioxythiophene monomers resulting in stable electroactive films with % signal loss upon cycling ranging from 1 to 7.

Electrochemical assay of sorbitol dehydrogenase at PEDOT modified electrodes - a new milk biomarker for confirmation of pregnancy in dairy cattle.

A robust electrochemical assay for sorbitol dehydrogenase (SORDH) activity in milk was developed using voltammetry and chronocoulometry at bare and polymer modified transducers. The motivation for the work was to evaluate the potential of SORDH as an early biomarker of bovine pregnancy using milk as sample matrix. SORDH is an enzyme involved in carbohydrate metabolism converting sorbitol, the sugar alcohol form of glucose, into fructose, with NAD+ as a cofactor being simultaneously reduced to NADH.

Development of a new bisphenol A electrochemical sensor based on a cadmium(ii) porphyrin modified carbon paste electrode.

In this study, the (5,10,15,20-tetrakis[(4-methoxyphenyl)]porphyrinato)cadmium(ii) complex ([Cd(TMPP)]) was successfully used as a modifier in a carbon paste electrode (CPE) and exploited for bisphenol A (BPA) detection. Analytical performance revealed two linear ranges from 0.0015-15 μM and 0.

Simultaneous determination of ascorbic acid, uric acid and dopamine using silver nanoparticles and copper monoamino-phthalocyanine functionalised acrylate polymer.

A silver nanoparticle and copper monoamino-phthalocyanine-acrylate (Cu-MAPA) polymer modified glassy carbon electrode was developed for the simultaneous detection of dopamine (DOP), ascorbic acid (AA) and uric acid (UA) using voltammetric techniques. Silver nanoparticles (AgNPs) were synthesised according to the citrate reduction method. Following synthesis and characterisation the copper phthalocyanine polymer was co-deposited with AgNPs realising a surface with enhanced electron transfer which lowered the overpotential required for analyte electro-oxidation.

Functionalized magnetic nanomaterials for electrochemical biosensing of cholesterol and cholesteryl palmitate.

Synthesis and functionalization of magnetite nanoparticles (FeO) was achieved with the view to covalently bind both cholesterol oxidase and cholesterol esterase biorecognition agents for the development of free and total cholesterol biosensors. Prior to enzyme attachment, FeO was functionalized with 3-aminopropyltriethoxysilane (APTES) and polyamidoamine (PAMAM) dendrimer. Characterization of the material was performed by FT-IR and UV spectroscopy, SEM/EDX surface analysis and electrochemical investigations.

Impedimetric and electrochemical evaluation of a new redox active steroid derivative for hormone immunosensing.

Preparation and electrochemical interrogation of a novel redox active progesterone derivative progesterone thiosemicarbazone (PATC) is presented here together with an investigation into its suitability as conjugate in progesterone hormone immunosensing. PATC synthesis involved a condensation reaction between progesterone acetate and thiosemicarbazone hydrochloride. Voltammetric and pulse techniques confirmed the redox behaviour of the new compound with concentration and scan rate dependant irreversible behaviour evident at glassy carbon and gold transducers - k (standard heterogeneous rate constant) was 2.

Anticancer activity, DNA binding and cell mechanistic studies of estrogen-functionalised Cu(II) complexes.

Four estrogen-functionalised copper complexes were synthesised and investigated as electrochemical active DNA binding and cleavage agents. These complexes strategically contain a biocompatible metal centre [Cu(II)], a planar aromatic ligand as DNA intercalative agent and an estradiol-derivative moiety which acts as delivery vector to target estrogen-receptor-positive (ER+) cancer cells. Cytotoxic activity was studied over a panel of estrogen-receptor-positive (ER+) and negative (ER-) human cancer cell lines by means of both 2D and 3D cell viability studies.

Electrochemical enzyme-linked immunosorbent assay (e-ELISA) for parasitic nematode Ostertagia ostertagi (brown stomach worm) infections in dairy cattle.

A sensitive electrochemical immunoassay (e-ELISA) has been developed for the detection of the gastrointestinal parasitic nematode Ostertagia ostertagi (brown stomach worm) in infected and control serum samples. An antigen-indirect immunoassay format was employed to detect the presence of O. ostertagi antibodies, coupled with an anti-species monoclonal horseradish peroxidase (HRP) conjugate.

Scanning electrochemical microscopy imaging of poly (3,4-ethylendioxythiophene)/thionine electrodes for lactate detection via NADH electrocatalysis.

Herein we report the use of scanning electrochemical microscopy (SECM) together with electrochemical and spectroscopic techniques to develop and characterise a stable and uniformly reactive chemically modified platinum electrode for NADH electrocatalysis. In order to achieve this, a range of different approaches for thionine entrapment within an electropolymerised poly (3,4-ethylendioxythiophene) (PEDOT) film were evaluated using SECM imaging in the presence of NADH, demonstrating the uniformity of the reactive layer towards NADH oxidation. The effect of electrolyte type and time scale employed during PEDOT electropolymerisation was examined with respect to thionine loading and the resulting charge transport diffusion coefficient (D) estimated via chronoamperometry.

Determination of prostate cancer biomarker acid phosphatase at a copper phthalocyanine-modified screen printed gold transducer.

In this work, a novel sensor based on immobilised copper phthalocyanine, 2,9,16,23-tetracarboxylic acid-polyacrylamide (Cu(II)TC Pc-PAA) was developed for determination of acid phosphatase (ACP) levels in nanomolar quantities. Detection was based on the measurement of enzymatically generated phosphate, with initial studies focused on phosphate detection at a Cu(II)TC Pc-PAA modified screen-printed gold transducer. The sensor was characterised in relation to operational performance (pH, response time, stability, linearity, and sensitivity) and common anionic interferents (nitrate, sulphate, chloride, and perchlorate).

Simultaneous voltammetric detection of 5-hydroxyindole-3-acetic acid and 5-hydroxytryptamine using a glassy carbon electrode modified with conducting polymer and platinised carbon nanofibers.

The authors describe a method for simultaneous voltammetric determination of 5-hydroxytryptamine (serotonin; 5-HT) and its metabolite 5-hydroxyindoleacetic acid (5-HIAA). A glassy carbon electrode was modified with poly(pyrrole-3-carboxylic acid) and with platinised carbon nanofibers to obtain a sensor that can quantify 5-HT and 5-HIAA with detection limits of 10 nM and 20 nM, respectively. The peak currents, best measured at voltages of 170 mV and 500 mV (vs.

Quantum Dot Nanotoxicity Investigations Using Human Lung Cells and TOXOR Electrochemical Enzyme Assay Methodology.

Recent studies have suggested that certain nanomaterials can interfere with optically based cytotoxicity assays resulting in underestimations of nanomaterial toxicity. As a result there has been growing interest in the use of whole cell electrochemical biosensors for nanotoxicity applications. Herein we report application of an electrochemical cytotoxicity assay developed in house (TOXOR) in the evaluation of toxic effects of mercaptosuccinic acid capped cadmium telluride quantum dots (MSA capped CdTe QDs), toward mammalian cells.

A highly oriented hybrid microarray modified electrode fabricated by a template-free method for ultrasensitive electrochemical DNA recognition.

Highly oriented growth of a hybrid microarray was realized by a facile template-free method on gold substrates for the first time. The proposed formation mechanism involves an interfacial structure-directing force arising from self-assembled monolayers (SAMs) between gold substrates and hybrid crystals. Different SAMs and variable surface coverage of the assembled molecules play a critical role in the interfacial directing forces and influence the morphologies of hybrid films.

Inside/outside Pt nanoparticles decoration of functionalised carbon nanofibers (Pt(19.2)/f-CNF(80.8)) for sensitive non-enzymatic electrochemical glucose detection.

A highly efficient and reproducible approach for effective Pt nanoparticles dispersion and excellent decoration (inside/outside) of functionalised carbon nanofibers (f-CNF) is presented. The surface morphological, compositional and structural characterisations of the synthesised Pt(19.2)/f-CNF(80.

Pt based nanocomposites (mono/bi/tri-metallic) decorated using different carbon supports for methanol electro-oxidation in acidic and basic media.

Pt based mono/bi/tri-metallic nanocomposites on different carbon based supports (activated carbon (AC), carbon nanotubes (CNTs) and carbon nanofibers (CNFs)) were synthesised and Pt surface enrichment achieved. The overall theoretical metallic content (Pt + Au + Sn) was 20% (w/w) in all mono/bi/tri-metallic nanocomposites and was found to be uniformly distributed in the supporting matrix (80%). The surface morphology and composition of the synthesised materials was characterised using scanning electron microscopy (SEM), energy-dispersive X-ray spectrometry (EDX), transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FTIR), thermo-gravimetric analysis (TGA), X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS), while cyclic voltammetry was employed in order to confirm their typical metallic electrochemical characteristics.

Voltammetry of [R(4)N](4)[M(18)O(54)(SO(3))(2)] and [Ru(bpy)(3)](2)[M(18)O(54)(SO(3))(2)] (M = Mo, W) as microcrystals adhered to a glassy carbon electrode surface in contact with ionic liquid media.

Based on studies with microcrystals of [Ru(bpy)(3)](2)[alpha-W(18)O(54)(SO(3))(2)] adhered to an electrode surface in contact with the ionic liquids [BMIM][PF(6)] and [BMIM][BF(4)], it has been found that a series of well defined monoelectronic reduction processes associated with the tungsten-oxo cage of the [alpha-W(18)O(54)(SO(3))(2)](4-) species are observed at much less negative potentials than found in conventional organic solvents. Furthermore, since the potentials of the [Ru(bpy)(3)](2+) 2,2'-bipyridyl ligand based reduction processes are not strongly medium dependent, ionic liquid investigations allowed the characterisation of the [Ru(bpy)(3)](2)[alpha-W(18)O(54)(SO(3))(2)] complex without extensive overlap of the ligand based reductions from the [Ru(bpy)(3)](2+) cation and the [W(18)O(54)(SO(3))(2)](4-) anions. In the case of the Mo analogues, [alpha and beta-Mo(18)O(54)(SO(3))(2)](4-), the much higher reactivity of the reduced forms precluded access to well defined monoelectronic reversible steps at negative potentials in all media examined, even though reduction is far easier and hence availability of extensively reduced species should be simpler, in a thermodynamic sense.

A stable and selective electrochemical biosensor for the liver enzyme alanine aminotransferase (ALT).

An electrochemical method to determine alanine aminotransferase (ALT) activity over its normal and elevated physiological range was developed based upon detection of L-glutamate at a glutamate oxidase-modified platinum electrode. Measurements were carried out in the presence of ALT co-substrates L-alanine and alpha-ketoglutarate and current response from either the oxidation of hydrogen peroxide or the re-oxidation of the mediator ferrocene carboxylic acid was employed. The enzyme electrode was tested over a 6-month period and found to retain 79% of its original activity towards ALT detection with >200 measurements performed over this time.

Photophysics of ruthenium polypyridyl complexes formed with lacunary polyoxotungstates with iron addenda.

The interactions between luminophore [Ru(bpy)3]2+, and the lacunary Dawson heteropolyanions, [P2W17O61(FeOH2)]7-, [P2W17O61(FeBr)]6- and [P2W17O61]10- were investigated using a combination of photophysics, optical and Raman spectroscopy. Extensive quenching of the excited state of [Ru(bpy)3]2+ was observed in each case. Quenching is attributed to the formation of association complexes between [Ru(bpy)(3)]2+ and the heteropolyanions in which the charge on the heteropolyanions is fully compensated for by the ruthenium polypyridyl species.