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An amperometric uric acid (UA) sensor incorporating a multi-walled carbon nanotubes (MWCNT) network in Nafion and electropolymerized β-cyclodextrin (β-CD) layer is investigated. The electrochemical sensor is comprised of a glassy carbon... more
An amperometric uric acid (UA) sensor incorporating a multi-walled carbon nanotubes (MWCNT) network in Nafion and electropolymerized β-cyclodextrin (β-CD) layer is investigated. The electrochemical sensor is comprised of a glassy carbon electrode modified with Nafion-MWCNT nanocomposite film, a β-CD polymer inner selective layer, and a Hydrothane polyurethane (HPU) outer selective coating. The surface morphology and electronic structure of the electrode material are characterized using transmission electron microscopy (TEM), scanning electron microscope (SEM), and Fourier transform infrared (FTIR) spectroscopy. The electrocatalytic activity of the sensor is studied using cyclic voltammetry (CV), chronocoulometry (CC) and differential pulse voltammetry (DPV). Analytical performance of the electrochemical sensor scheme with and without MWCNT and/or β-CD polymer is determined from direct UA injection during an amperometric analysis. The effective surface area is notably higher for Nafi...
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ABSTRACT
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Zinc oxide (ZnO) nanostructures are ideal materials for biosensing applications due to their desireable properties, such as having a relatively high cond., wide band gap, high exciton binding energy, fast electron transfer... more
Zinc oxide (ZnO) nanostructures are ideal materials for biosensing applications due to their desireable properties, such as having a relatively high cond., wide band gap, high exciton binding energy, fast electron transfer characteristics, and ease of prepn. In this study, ZnO multiwalled carbon nanotube (MWNT) composites were synthesized using a 90°C hydrothermal treatment prior to sonochem. attachment to carboxylic acid functionalized MWNTs, which were then incorporated onto glassy carbon electrodes (GCE) for potentiometric measurements. The material was effective for selective detection of uric acid (UA), acetaminophen (APAP), and hydrogen peroxide (H2O2). Electrochem. oxidn./redn. peaks in the cyclic voltammetry (CV) for UA, APAP, and H2O2 were obsd. at potentials of +0.44, +0.49, and -0.36 V, resp. Linear response in the 0.1 to 20 mM concn. range of analyte was obsd.
Hydrogen peroxide (H2O2) plays a significant role as a signaling molecule in regulating diverse biological processes. A non-enzymatic H2O2 sensor was produced by controlling the morphology of zinc oxide (ZnO) nanostructures using... more
Hydrogen peroxide (H2O2) plays a significant role as a signaling molecule in regulating diverse biological processes. A non-enzymatic H2O2 sensor was produced by controlling the morphology of zinc oxide (ZnO) nanostructures using hydrothermal synthesis at various lower treatment temperatures (30-90°C), prior to attachment to carboxylic acid functionalized multi-walled carbon nanotubes (COOH-MWNTs) for sensing applications. The composites were characterized using scanning electron microscopy (SEM), transmission electron microscopy (TEM), energy dispersive X-ray spectroscopy (EDS) and X-ray photoelectron spectroscopy (XPS). Needle-like shaped nanostructures dominate at lower treatment temperatures. TEM images of the ZnO nanoparticles treated at 90°C showed that the powder had predominantly, a nanometric semi-spherical morphology. These prepared ZnO nanostructures were used to decorate COOH-MWNTs to form the ZnO-MWNT nanocomposite. The as-prepared nanocomposite was incorporated onto gl...
Hydrogen peroxide (H2O2) is an important marker for detecting the onset of food spoilage, oxidative stress and management of cardiovascular disease. The synthesis of zinc oxide (ZnO) nanostructures followed by attachment to multiwalled... more
Hydrogen peroxide (H2O2) is an important marker for detecting the onset of food spoilage, oxidative stress and management of cardiovascular disease. The synthesis of zinc oxide (ZnO) nanostructures followed by attachment to multiwalled carbon tubes is shown, resulting in a composite with a unique synergistic effect. Morphology and size of ZnO was controlled using hydrothermal synthesis, varying the hydrothermal treatment temp., prior to attachment to carboxylic acid functionalized multi-walled carbon nanotubes for sensing applications. A strong dependence of electrocatalytic activity on nanosized ZnO shape was shown. Higher activity for H2O2 reduction was achieved when nanocomposite precursors with a roughly semi-spherical morphology (no needle-like particles present) formed at 90°C. A 2.4-fold increase in cyclic voltammetry current accompanied by decrease in overpotential from the composites made from the nanosized, needle-like-free ZnO shapes was observed as compared to those comp...
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Global increasing demand in the need of energy leads to the development of non-conventional, high power energy sources. Supercapacitors (SCs) are one of the typical non-conventional energy storage devices which are based on the principle... more
Global increasing demand in the need of energy leads to the development of non-conventional, high power energy sources. Supercapacitors (SCs) are one of the typical non-conventional energy storage devices which are based on the principle of electrochemical energy conversion. SCs are promising energy storage devices for better future energy technology. Increasing progress has been made in the development of applied and fundamental aspects of SCs. Manganese oxide electrode materials have been well studied; however, their capacitive performance is still inadequate for practical applications. Recent research is mainly focused on enhancing manganese oxide capacitive performance through the incorporation of electrically conductive materials and by controlling its morphology to reveal a more active surface area for redox reactions. In this review, progress in the applications of manganese oxide carbon-based materials towards the development of highly effective SCs is briefly discussed. In ...
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A first-generation amperometric galactose biosensor has been systematically developed utilizing layer-by-layer (LbL) construction of xerogels, polymers, and carbon nanotubes toward a greater fundamental understanding of sensor design with... more
A first-generation amperometric galactose biosensor has been systematically developed utilizing layer-by-layer (LbL) construction of xerogels, polymers, and carbon nanotubes toward a greater fundamental understanding of sensor design with these materials and the potential development of a more efficient galactosemia diagnostic tool for clinical application. The effect of several parameters (xerogel silane precursor, buffer pH, enzyme concentration, drying time and the inclusion of a polyurethane (PU) outer layer) on galactose sensitivity were investigated with the critical nature of xerogel selection being demonstrated. Xerogels formed from silanes with medium, aliphatic side chains were shown to exhibit significant enhancements in sensitivity with the addition of PU due to decreased enzyme leaching. Semi-permeable membranes of diaminobenzene and resorcinol copolymer and Nafion were used for selective discrimination against interferent species and the accompanying loss of sensitivit...