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A novel glutathione (GSH) photoelectrochemical biosensor was fabricated using the newly synthesized graphene-CdS (GR-CdS) nanocomposites. The GR-CdS nanocomposites were prepared by a fast, one-step, aqueous reaction. The as-prepared GR-CdS structure inherited the excellent electron transport of GR and facilitated the spatial separation of photo-generated charge carrier, therefore resulting in the enhanced photocurrent, and making it a promising candidate for developing photoelectrochemical biosensors. The proposed GSH sensor displays satisfactory analytical performance with an acceptable linear range from 0.01 to 1.5 mmol L(-1) with a detection limit of 0.003 mmol L(-1) at a signal-to-noise ratio of 3, and also shows an excellent specificity against anticancer drugs and can be successfully applied for GSH detection in real samples. The as-synthesized GR-CdS nanocomposites exhibited obviously enhanced photovoltaic properties, which could be extended to the detection of other enzymes and biomolecules, thus providing a promising platform for the development of photoelectrochemical biosensors.

Porous titanium phosphate (TiP) nanoparticles with high water solubility have been synthesized by using the surfactant sodium dodecyl sulfate (SDS) as the structure-directing agent. The TiP nanoparticles can be functionalized with Cd(2+) and can be further used as labels for electrochemical detection of proteins due to their excellent ion-exchange property., (This journal is © The Royal Society of Chemistry 2012)

A silver nanoparticle-hollow titanium phosphate sphere (AgNP-TiP) hybrid is successfully synthesized and used as a label for electrochemical detection of human interleukin-6 (IL-6). Hollow TiP spheres with a diameter of 430 nm and an average thickness of 40 nm are synthesized by a template approach. The AgNPs are incorporated in situ into the TiP shell via an exchange process. The as-prepared AgNP-TiP hybrid shows outstanding biocompatibility, good dispersity and solubility in water, and high silver loading properties (289.2 mg of silver in 1.0 g of TiP). These advantages make the AgNP-TiP hybrid an effective candidate as an amplification label in immunoassay systems. Herein, the as-prepared AgNP-TiP hybrid is attached to a signal antibody (Ab(2) ) to produce Ab(2) -AgNP-TiP labels in the fabrication of an electrochemical immunosensor. The nanoparticle-based amplification labels, upon coupling with a magnetic sensing array, give rise to an extremely sensitive response to IL-6 in a linear range of 0.0005-10 ng mL(-1) with a detection limit of 0.1 pg mL(-1) . The proposed sensor exhibits high specificity, good reproducibility, and long-term stability, and may be a promising technique for protein and DNA detection., (Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

A novel type of colloidal carbon sphere array (CSA) was developed for the fabrication of disposable electrochemical immunosensor. The CSA was successfully prepared on indium tin oxide (ITO) substrate in a simple manner and the scanning electron micrograph confirmed that a single-layered arrangement of the carbon spheres with its (111) plane paralleled the substrate's surface. The CSA modified electrode has a higher surface area and exhibits a more sensitive electrochemical response than a normal carbon-based electrode with the same geometric area. An Immunoglobin A (IgA) immunosensor was constructed by the covalent bonding of IgA antibody molecules with the CSA aided by large numbers of carboxyl groups on the surface of carbon spheres. The immunosensor exhibited a wide linear response to IgA ranging from 0.1 to 200 ng mL(-1) by electrochemical impedance spectroscopy (EIS) technique. The detection of IgA levels in three sera obtained from hospital samples showed acceptable accuracy., (Copyright 2009 Elsevier B.V. All rights reserved.)

A novel label-free highly sensitive electrochemical impedance spectroscopy (EIS) immunosensor was fabricated based on the highly ordered macroporous gold film (HOMGF) in the presence of room-temperature ionic liquid (IL) for the detection of human Apolipoprotein B-100 (ApoB-100). The antibody of ApoB-100 (Ab) was adsorbed directly onto the HOMGF electrode surface and maintained its bioactivity. After the residual active sites at the electrode were passivated by BSA, the mixture of BMIm+BF4−and silica sol was dropped onto the electrode to entrap the adsorbed Ab and BSA molecules firmly. The addition of IL could prevent the inactivation of Ab by releasing alcohol during the sol–gel process, and the conductivity of the IL-gel membrane was increased. Of particular interest is the fact that the fabricated immunosensor could be used at 60 °C. This could be attributed to the interconnected porosity of the IL-gel membrane, which can prevent Ab from unfolding and losing its bioactivities. The immunosensor also exhibited a highly sensitive response to ApoB-100 with the lowest concentration of 5 fg mL−1. The detection of ApoB-100 levels in five sera samples obtained from hospital showed acceptable accuracy with that using commercial immunonephelometry method. [ABSTRACT FROM AUTHOR]

The RuO[sub 2]·xH[sub 2]O/C composites were prepared directly based on a sol-gel process under ultrasonic wave (50Hz). The specific capacitance of pure RuO[sub 2]·xH[sub 2]O materials obtained by the method reached a value of 760F/g. Physical properties of the material and electrochemical characteristics of electrodes were described. [ABSTRACT FROM AUTHOR]