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A versatile immunosensor using CdTe quantum dots as electrochemical and fluorescent labels has been developed for sensitive protein detection. This sandwich-type sensor is fabricated on an indium tin oxide chip covered with a well-ordered gold nanoparticle monolayer. Gel imaging systems were successfully introduced to develop a novel high-efficient optical immunoassay, which could perform simultaneous detection for the samples with a series of different concentrations of a target analyte. The linear range of this assay was between 0.1 and 500 ng/mL, and the assay sensitivity could be further increased to 0.005 ng/mL with the linear range from 0.005 to 100 ng/mL by stripping voltammetric analysis. The immunosensor showed good precision, high sensitivity, acceptable stability, and reproducibility and could be used for the detection of real sample with consistent results in comparison with those obtained by the ELISA method.

Abstract: Series of Dy(Co1− x Mn x )2 alloys (x =0, 0.02, 0.04, 0.06, 0.08, and 0.1) have been prepared by arc-melting method. All samples crystallize in single phase with C15 cubic MgCu2-type structure. The nature of phase transition was determined by the results of Arrott plots and Ac susceptibility, and no first order phase transition was observed for samples with x ⩾0.02. With the increase of Mn content, Curie temperature increases linearly, while the calculated magnetic entropy change shows an obvious decrease with a broader peak, which could be explained by the change of phase transition type. [Copyright &y& Elsevier]

A combined hydrothermal/hydrogen reduction method has been developed for the mass production of helical carbon nanotubes (HCNTs) by the pyrolysis of acetylene at 475 °C in the presence of Fe(3)O(4) nanoparticles. The synthesized HCNTs have been characterized by high-resolution transmission electron microscopy, scanning electron microscopy, X-ray diffraction analysis, vibrating sample magnetometry, and contact-angle measurements. The as-prepared helical-structured carbon nanotubes have a large specific surface area and high peroxidase-like activity. Catalysis was found to follow Michaelis-Menten kinetics and the HCNTs showed strong affinity for both H(2)O(2) and 3,3',5,5',-tetramethylbenzidine (TMB). Based on the high activity, the HCNTs were firstly used to develop a biocatalyst and amperometric sensor. At pH 7.0, the constructed amperometric sensor showed a linear range for the detection of H(2)O(2) from 0.5 to 115 μM with a correlation coefficient of 0.999 without the need for an electron-transfer mediator. Because of their low cost and high stability, these novel metallic HCNTs represent a promising candidate as mimetic enzymes and may find a wide range of new applications, such as in biocatalysis, immunoassay, and environmental monitoring., (Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)