Electrochemical Immunosensor for NT-proBNP Detection in Artificial Human Saliva: Heart Failure Biomedical Application

Monitoring of circulating N-terminal proBNP (NT-proBNP) biomarkers is crucial for the diagnosis of people suffering from heart failure (HF). In this work, we describe a novel ultra-sensitive NT-proBNP immunosensor for NT-proBNP detection in artificial human saliva. The surface of the developed immunosensor based on gold working microelectrodes (WEs) was biofunctionalized through carboxyl diazonium to immobilize anti-NT-proBNP antibodies. The chemical surface modification of WEs was carried out by cyclic voltammetery CV whilst the quantification of NT-proBNP biomarkers was made by electrochemical impedance spectroscopy (EIS). The immunosensor has demonstrated a linear detection response within the range 1–20 pg/mL for NTproBNP detection in artificial human saliva with a good selectivity in the presence of other interferences.

A Comparative Study of the Electrooxidation of Ethylene Glycol on Transition Metal Electrodes in Alkaline Solution

Electrodes made of group VIII and IB metals were examined for their redox process and electrocatalytic activities towards the oxidation of ethylene glycol in alkaline solutions. The method of cyclic voltammetery (CV) and Open circuit potentials measurement (OCP) was employed. It is found that considerable electrooxidation current are observed for silver and copper but lower anodic overpotential for oxidation is obtained for gold and platinum. Oxide layer produced on the surface of all electrodes in alkaline solution under anodic scan participates in ethylene glycol electrooxidation. Oxidation current observed in the reverse scans for platinum and gold are higher than those observed in forward potential scan. Open circuit potential measurements have shown the interaction of ethylene glycol and electrodes.

Composite FeF3•3H2O/C Cathode Material for Lithium Ion Battery

Composite FeF3•3H2O/C was prepared by mixing FeF3•3H2O with acetylene black through high-energy milling, and used as cathode material for Li-ion battery. The structure and the morphology of the as-prepared composite FeF3•3H2O/C were investigated by X-ray diffraction (XRD) and scanning electron microscopy (SEM). When compared with FeF3•3H2O synthesized by a liquid-phase method, the composite FeF3•3H2O/C had no distinct difference in crystal structure, but shows that a well distributed particle size of 100~1000nm. The electrochemical performances of FeF3•3H2O/C composite were evaluated by charge-discharge test and cyclic voltammetery (CV). With a current density of 23.7mAg-1 in the voltage range of 2.0~4.5V at room temperature, the FeF3•3H2O/C composite achieved a maximum discharge capacity of 112 mAhg-1, as well as a good cycling performance.

Structural and optical properties of WO3 electrochromic layers prepared by the sol-gel method

Thin layers of tungsten trioxide have been prepared from an aqueous solution of peroxotungstic acid (PTA) using the sol-gel method. Compositional, structural and optical characteristics of WO3 coated on indium tin oxide (ITO) conductive glass substrates were studied using X-ray diffractometery (XRD), cyclic voltammetery (CV), scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDX). Monoclinic and triclinic crystalline structures for thin film and powdered WO3 were confirmed by XRD analysis. SEM micrograph of annealed samples revealed micro cracks due to a decrease in density and a contraction of layers. EDX analysis showed that 1∶2 ratio of oxygen and tungsten atoms in the prepared films is obtained at heat treatment temperatures higher than 200 °C. Furthermore, the annealed samples showed very good electrochromic behavior in cyclic voltammetery studies. Refractive index “n” and extinction coefficient “k” values were found to be reduced by increasing the wavelength and decreasing the temperature.

Properties and single-crystal X-ray structure of Bis[3,3″-bis(4-methylphenyl)-2,2′:6′,2″-terpyridine]iron(II) hexafluorophosphate - acetonitrile - diisopropyl ether (1/1.5/1)

Absorption and electrochemical properties are reported for the iron(II) complex of the unusually substituted ligand 3,3″-bis(4-methylphenyl)-2,2′:6′,2″-terpyridine, along with the structure determination of the complex by single-crystal X-ray crystallography. Crystal data for C67H64.5F12FeN7.5OP2, M 1336.6: triclinic, a 12.768(3), b 15.789(4), c 17.160(4) Å, α 85.553(6), β 77.756(6), γ 66.754(5)˚, V 3106.1(12) Å3, space group P 1, Z 2, ρ 1.43 g cm–3, µ 0.30 mm-1 for λ 0.6849 Å, R 0.091 for 4456 observed (I > 2σ(I) ) reflections, wR2 0.241, Δρ1.68 e Å–3. The structural analysis reveals that, as observed in analogous bisterpyridineiron(II) complexes, the ligands adopt the preferred meridional binding motif. As a result, the ‘pulling-in’ of the outer pyridine rings forces each pair of 3,3″ substituted tolyl groups to diverge, resulting in an average distance between the tolyl methyl groups of c. 11.6 Å. The cyclic voltammetery of the complex in MeCN displays upon oxidative scanning a reversible one-electron wave (E˚ = + 0.99 V v. s.c.e.) and three one-electron waves under reducing conditions (E1˚ = –1.27 V, E2˚ = –1.51 V, E3˚ = –1.96 V v. s.c.e.). The electronic spectrum in acetonitrile contained an MLCT band centred at 571 nm, with a molar absorption coefficient of 18210 M–1 cm–1. When compared to similar phenyl-substituted terpyridine ligand iron(II) complexes this is a relatively low value and is assigned to reduced electronic delocalization throughout the terpyridine backbone.