Direct electrochemistry and electrocatalysis of glucose oxidase immobilized on glassy carbon electrode modified by Nafion and ordered mesoporous silica-SBA-15

In this paper, it was found that glucose oxidase (GOD) has been stably immobilized on glassy carbon electrode modified by ordered mesoporous silica-SBA-15 and Nafion. The sorption behavior of GOD immobilized on SBA-15 matrix was characterized by transmission electron microscopy (TEM), ultraviolet-visible (UV-vis), FTIR, respectively, which demonstrated that SBA-15 can facilitate the electron exchange between the electroactive center of GOD and electrode. The direct electrochemistry and electrocatalysis behavior of GOD on modified electrode were characterized by cyclic voltammogram (CV) which indicated that GOD immobilized on Nafion and SBA-15 matrices displays direct, nearly reversible and surface-controlled redox reaction with an enhanced electron transfer rate constant of 3.89 s(-1) in 0.1 M phosphate buffer solution (PBS) (pH 7.12).

Electrochemistry of Microperoxidase-11 (MP-11) on Glassy Carbon Electrode Modified with Chitosan

In this paper, microperoxidase-11 (MP-11) was immobilized on glassy carbon electrode surface modified with chitosan by physical adsorption. The direct electrochemistry and the electrocatalytic behaviours to O-2 and the H2O2 of MP-11 on glassy carbon electrode modified with chitosan were characterized by cyclic voltammetry. The results indicate that MP-11 on modified electrode displays a quasi-reversible electrochemical process coupled with proton transfer in the phosphate buffer solutions(pH = 7.12). Direct electrochemical reaction of MP-11 on modified electrode has been realized. MP-11 on modified electrode can catalyze reduction for O-2 and H2O2. Both of the catalytic reductions are surface-controlled electrochemical process.

Charge Transport Processes of Immobilized Heteropolyanions at Self-assembled Monolayer Modified Gold Electrode by Electrochemical Quartz Crystal Microbalance Measurement

The in situ electrochemical quartz crystal microbalance(EQCM) technique was used to investigate the ion transport of immobilized heteropolyanions at a self-assembled monolayer(SAM) modified gold electrode during electrochemical redox process. A mixed transfer method was presented to analyse the abnormal change of resonant frequency based on the simultaneous insertion/extraction of different ions. The results indicate that the migration of HSO4- anions was indispensable in the redox process of the heteropolyan ions in a I mol/L H2SO4 solution and played a key role in the abnormal change of the resonant frequency. Such a change was attributed to different packing densities derived by means of differently immobilized methods.

"Dual-Parallel-Channel" Shape-Gradient Surfaces: Toward Oriented and Reversible Movement of Water Droplets

In this paper, we prepared "dual-parallel-channel" shape-gradient surfaces, on which water droplets can reversibly and orientedly move between two adjacent pools under the guidance of an external voltage. Furthermore, it is found that the motion speed is governed by several parameters, including bath condition, gradient angle, and the working voltage. In this self-transportation process of water droplets, the external voltage works like a traffic light, which can give "moving", "stopping", "turning" and "straight-going" signals to the Water droplets.

Prussian Blue/Multiwalled Carbon Nanotube Hybrids: Synthesis, Assembly and Electrochemical Behavior

Prussian blue/carbon nanotube (PB/CNT) hybrids with excellent dispersibility in aqueous solutions were synthesized by adding CNTs to an acidic solution of Fe3+, [Fe(CN)(6)](3-) and KCl. Fourier transform infrared spectroscopy, UV-vis absorption spectroscopy and scanning electron microscopy were employed to confirm the formation of PB/CNT hybrids. The PB nanoparticles formed on the CNT surfaces exhibit a narrow size distribution and an average size of 40 nm. The present results demonstrate that the selective reduction of Fe3+ to Fe2+ by CNTs is the key step for PB/CNT hybrid formation. The subsequent fabrication of the PB/CNT hybrid films was achieved by layer-by-layer technique. The thus-prepared PB/CNT hybrid films exhibit electrocatalytic activity towards H2O2 reduction.

The structural composite effect of Au-WO3-Al interconnecting electrode on performance of each unit in stacked OLEDs

In this article, we report the effects of the thickness of metal and oxide layers of the Al/WO3/Au interconnecting structure on the electrical and optical characteristics of the and bottom units of the two-unit stacked organic-light-emitting-devices (OLEDs). It is found that light emission performance of the upper unit is sensitive to the transmittance of semitransparent Al/WO3/Au structure, which can be improved by changing the thickness of each layer of the Al/WO3/Au structure. It is important to note that the introduction WO3 between Al and Au significantly enhances the current efficiency of both the upper and bottom units with respect to that of the corresponding Al/Au structure without WO3. In addition, the emission spectra of both the upper and bottom units are narrower than that of the control device due to microcavity effect. Our results indicate that the All WO3/Au interconnecting structure is a good candidate for fabricating independently controllable high efficiency stacked OLEDs.

Functional gold nanoparticles for studying the interaction of lectin with glycosyl complex on living cellular surfaces

In this study. lectin-conjugated gold nanoparticles (GNPs) were prepared by standard biotin-streptavidin chemistry. The lectin-conjugated GNPs call be used as ail indicator for studying the interaction of lectin with glycosyl complex on living cellular Surfaces due to the high affinity of the lectin with saccharides. The interactions of two well-known lectins (Ricinus communis agglutinin and concanavalin A) and three different cell lines (HeLa, 293, and 293T) were selected here to establish this assay. Highly binding affinity of R. communis agglutinin with cells was demonstrated by conventional microscopic and UV-visible spectroscopic Studies. In addition, the binding process can be inhibited by galactose, giving further proof of the binding mechanism. (c) 2009 Elsevier Inc. All rights reserved.

Label free electrochemiluminescence protocol for sensitive DNA detection with a tris(2,2'-bipyridyl)ruthenium(II) modified electrode based on nucleic acid oxidation

Label free electrochemiluminescence (ECL) DNA detection based on catalytic guanine and adenine bases oxidation using tris(2,2'-bipyridyl)ruthenium(II) [Ru(bpy)(3)(2+)] modified glassy carbon (GC) electrode was demonstrated in this work. The modified GC electrode was prepared by casting carbon nanotubes (CNT)/Nafion/Ru(bpy)(3)(2+) composite film on the electrode surface. ECL signals of doublestranded DNA and their thermally denatured counterparts can be distinctly discriminated using cyclic voltammetry (CV) with a low concentration (3.04 x 10(-8) mol/L for Salmon Testes-DNA). Most importantly, sensitive single-base mismatch detection of p53 gene sequence segment was realized with 3.93 x 10(-10) mol/L employing CV stimulation (ECL signal of C/A mismatched DNA oligonucleotides was 1.5-fold higher than that of fully base-paired DNA oligonucleotides). Label free, high sensitivity and simplicity for single-base mismatch discrimination were the main advantages of the present ECL technique for DNA detection over the traditional DNA sensors.

Enhanced electrochemiluminescence sensor from tris(2,2 '-bipyridyl) ruthenium(II) incorporated into MCM-41 and an ionic liquid-based carbon paste electrode

The electrochemiluminescence (ECL) of tris(2,29-bipyridyl) ruthenium(II) [Ru(bpy)(3)(2+)] ion-exchanged in the sulfonic-functionalized MCM-41 silicas was developed with tripropylamine (TPrA) as a co-reactant in a carbon paste electrode (CPE) using a room temperature ionic liquid (IL) as a binder. The sulfonic-functionalized silicas MCM-41 were used for preparing an ECL sensor by the electrostatic interactions between Ru( bpy)(3)(2+) cations and sulfonic acid groups. We used the IL as a binder to construct the CPE (IL-CPE) to replace the traditional binder of the CPE (T-CPE)-silicone oil. The results indicated that the MCM-41-modified IL-CPE had more open structures to allow faster diffusion of Ru( bpy)(3)(2+) and that the ionic liquid also acted as a conducting bridge to connect TPrA with Ru( bpy)(3)(2+) sites immobilized in the electrode, resulting in a higher ECL intensity compared with the MCM-41-modified T-CPE. Herein, the detection limit for TPrA of the MCM-41-modified IL-CPE was 7.2 nM, which was two orders of magnitude lower than that observed at the T-CPE. When this new sensor was used in flow injection analysis (FIA), the MCM-41-modified IL-CPE ECL sensor also showed good reproducibility. Furthermore, the sensor could also be renewed easily by mechanical polishing whenever needed.

One-step synthesis of Ru(2,2 '-bipyridine)(3)Cl-2-immobilized silica nanoparticles for use in electrogenerated chemiluminescence detection

One-step synthesis of Ru (bpy)(3) Cl-2-immobilized (bpy = 2,2'-bipyridine) silica nanoparticles (Ru-silica nanoparticles) for use in electrogenerated-chemiluminescence (ECL) detection is reported. Ru-silica nanoparticles are prepared by using the Stober method. Compared with free Ru(bpy)(3)Cl-2, Ru-silica nanoparticles are seen to exhibit a red-shift of the UV-vis absorbance peak and a longer fluorescence lifetime, which are attributed to the electrostatic interaction of Ru(bpy)(3)(2+) and silica. Because silica nanoparticles are used as immobilization matrices, the surfaces of Ru-silica nanoparticles are easily modified or functionalized via the assembly of other nanoparticles, such as Au. For ECL detection, Au-colloid-modified Ru-silica nanoparticles are immobilized on a 3-mercaptopropyl-trimethoxysilane-modified indium tin oxide electrode surface by Au-S interaction; the surface concentration of electroactive Ru(bpy)(3)Cl-2 is obviously higher than that in silica films.

Electrochemiluminescence-based DNA detection using guanine oxidation at electrostatic self-assembly of Ru(bpy)(3)(2+)-doped silica nanoparticles on indium tin oxide electrode

A Ru(bpy)(3)(2+)-doped silica nanoparticle-[Ru@Silica] modified indium tin oxide electrode was prepared by simple electrostatic self-assembly technique, and one-electron catalytic oxidation of guanine bases in double-strand and denatured DNA was realized using the electrochemiluminescence detection means.

Tris(2,2 '-bipyridyl) ruthenium(II) doped silica film modified indium tin oxide electrode and its electrochemiluminescent properties

An approach was reported to synthesize silica hybridized ruthenium bipyridyl complex through amidation reaction by covalent attachment of bis(bipyridyl)-4,4'-dicarboxy-2,2'-bipyridyl-ruthenium to (3-aminopropyl)-triethoxysilane. The hybrid complex then was gelatinized through acid catalytic hydrolysis method and a sol-gel modified indium, tin oxide electrode was prepared via spin coating technique. As prepared indium tin oxide electrode possesses good stability therein with excellent electrochemiluminescence behavior.

A general route to transform normal hydrophilic cloths into superhydrophobic surfaces

Herein, we describe a simple and inexpensive method for forming superhydrophobic cloths with the highest water contact angle of close to 180 degrees, in which normal commercial cloths serving as pristine materials are modified with suitable gold micro/nanostructures.