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A combined chemical vapor deposition with high-pressure annealing has been developed for the production of phosphorus-doped helical carbon nanofibers (P-HCNFs). The resulting P-HCNFs have a large specific surface area, well-defined three-dimensional hierarchical helical structure and rapid apparent heterogeneous electron transfer. Based on the high electrocatalytic activity, the P-HCNFs were used to develop an amperometric sensor for carbendazim detection. The experimental results demonstrated that the sensor is promising for the determination of carbendazim in food samples due to the high sensitivity, wide linear range and low detection limit. [ABSTRACT FROM AUTHOR]

In this study, a novel Pd/Mn 3 O 4 /plait-like carbon nanocoils (Pd/Mn 3 O 4 /CNCs) catalyst is synthesized by a combined chemical vapor deposition and chemical reduction method. The pretreated Mn 3 O 4 nanoparticles are applied as support materials between Pd nanoparticles and CNCs template. The functional CNCs are covered by Mn 3 O 4 nanomaterials, and the metallic Pd nanoparticles are homogeneously deposited onto the Mn 3 O 4 with smaller sizes compared with those of Pd/CNCs and Pd/VX-72. The as-fabricated electrode of Pd/Mn 3 O 4 /CNCs exhibits higher catalytic activity toward the electro-oxidation of ethanol in alkaline media, more excellent poisoning tolerance, and higher stability than other electrodes. This improved performance of the as-prepared electrocatalyst originates from not only the synergetic effects between the Pd nanoparticles and Mn 3 O 4 , but also the intrinsic characteristic of CNCs. [ABSTRACT FROM AUTHOR]

Abstract: Helical carbon nanotubes (HCNTs) as a novel carbon material have been prepared and the catalytic activities of HCNTs-modified glassy carbon electrode (GCE) towards the electrooxidation of uric acid (UA), ascorbic acid (AA), and dopamine (DA) have been investigated. Comparing with the bare GCE, the HCNTs modified GCE (HCNTs/GCE) has higher catalytic activities towards the oxidation of AA, DA, and UA. Moreover, the peak separations between AA and DA, and DA and UA at the HCNTs/GCE are 102 and 245mV, respectively. Thus the simultaneous determination of AA, DA, and UA was carried out successfully. In the co-existence system of AA, DA, and UA, the linear response range for AA, DA, and UA are 7.5–180μM, 2.5–105μM and 6.7–65μM, respectively and the detection limits (S/N =3) are 0.92μM, 0.8μM and 1.5μM, respectively. [Copyright &y& Elsevier]

Abstract: Poly(diallyldimethylammonium chloride) functionalized helical carbon nanotubes (PDDA-HCNTs) were successfully synthesized. The resulting PDDA-HCNTs composite has good conductivity, solubility and ferromagnetic property. The fabricated HCNTs could be conveniently separated and magnetically attached to the magnetic electrode owing to their excellent magnetic properties. An amperometric biosensor was firstly developed based on glucose oxidase (GOD) functionalized PDDA-HCNTs loaded on magnetic glass carbon electrode. The constructed biosensor exhibited excellent electrocatalytic activity and stability for the detection of glucose with a linear range from 5 to 85μM and a low detection limit of 0.72μM at 3σ. The present work offers a new avenue to broaden the applications of HCNTs in electrochemical biosensors. [Copyright &y& Elsevier]

Abstract: The gold nanoparticles/colloidal carbon sphere hybrid material was used for the immobilization of protein, and was developed in biosensing. The hybrid material was fabricated by the assembly of gold nanoparticles onto the surface of colloidal carbon spheres, which constructed a 3D antibody immobilization matrix on the glass carbon electrode and made the immobilized biomolecules hold high stability and bioactivity. After the sandwich-type immunoreaction, the formed HRP-labeled immunoconjugate showed good enzymatic activity for the oxidation of o-phenylenediamine by H2O2. The approach provided a linear response range between 5 and 250ng/mL with a detection limit of 1.8ng/mL. The immunosensor showed good precision, acceptable stability and reproducibility and could be used for the detection of human IgG in real samples, which provided a potential alternative tool for the detection of protein in clinical laboratory. [ABSTRACT FROM AUTHOR]

Abstract: A simple strategy for sensitive detection of human IgG using cadmium ions-functionalized polymer nanospheres as the label is presented. The polymer nanosphere consisted of hard poly-styrene core and biocompatible poly (acrylic acid) (PAA) shell. The carboxyl groups of hydrophilic shell were used to chelated with the cadmium ions, and then conjugate with antibody (Ab2) to fabricate metal ions marked bioconjugates as the label in immunoassay. For constructing the matrix of the immunosensor, the PAA-functionalized carbon nanotubes were used to modify disposable screen printed electrodes for the immobilization of antibody (Ab1). After sandwich immunoreaction, differential pulse voltammetry was used to oxidize the conjuncted cadmium for the detection of antigen. The obtained results provided a linear response range from 0.1 to 35.0pg/mL human IgG with a lower detection limit of 0.06pg/mL, which is prominently improved in comparison with conventional immunoassay. The usage of the chelation reaction offers a simple and convenient route for the preparation of metallo-immunoassay labels, and also avoids the complicated and time-consuming dissolving of metal component for ultrasensitive determination. This approach is expected to have wide applications in protein diagnostics and bioanalysis in the future. [Copyright &y& Elsevier]

Abstract: This paper describes the combination of electrochemical immunosensor using gold nanoparticles (GNPs)/carbon nanotubes (CNTs) hybrids platform with horseradish peroxidase (HRP)-functionalized gold nanoparticle label for the sensitive detection of human IgG (HIgG) as a model protein. The GNPs/CNTs nanohybrids covered on the glass carbon electrode (GCE) constructed an effective antibody immobilization matrix and made the immobilized biomolecules hold high stability and bioactivity. Enhanced sensitivity was obtained by using bioconjugates featuring HRP labels and secondary antibodies (Ab2) linked to GNPs at high HRP/Ab2 molar ratio. The approach provided a linear response range between 0.125 and 80ng/mL with a detection limit of 40pg/mL. The immunosensor showed good precision, acceptable stability and reproducibility and could be used for the detection of HIgG in real samples, which provided a potential alternative tool for the detection of protein in clinical laboratory. [Copyright &y& Elsevier]

Abstract: A novel quantum dots (QDs) ECL biosensor for the detection of lysozyme was developed. Lysozyme was first incubated with probes immobilized at Au electrode in order to form the aptamer-lysozyme bioaffinity complexes. And the free probes were hybridized with the 5′-biotin modified cDNA oligonucleotides to form double-stranded DNA (ds-DNA) oligonucleotides. Avidin-QDs were bound to these hybridized cDNA through the biotin-avidin-system. The ECL signal of the biosensor was responsive to the amount of QDs bonded to the cDNA oligonucleotides, which was indirectly inverse proportional to the combined target protein. [Copyright &y& Elsevier]

Abstract Bimetallic nanoporous alloys have attracted considerable attention for electrochemical sensor applications due to their excellent electrocatalytic activity and structural stability. In the present work, nanoporous PtFe (NP-PtFe) alloy was fabricated by chemical dealloying ternary PtFeAl alloy ribbons. The structure and morphology of NP-PtFe alloy was characterized by scanning electronmicroscopy, transmission electron microscopy and X-ray diffraction. A highly sensitive and selective biosensor based on NP-PtFe alloy and graphene was successfully developed for direct detection of bisphenol A. Under optimal conditions, the proposed sensor showed an efficient electrocatalytic activity towards the redox of bisphenol A. Differential pulse voltammetry was applied to the electrochemical determination of bisphenol A with a wide linear concentration range from 0.2 μM to 96 μM and a low limit of detection of 0.17 μM (S/N = 3). This strategy provides a novel and simple approach for sensitive and selective detection of bisphenol A, holding promising applications in the determination of organic pollution in real water samples. [ABSTRACT FROM AUTHOR]

Recently, a new type of exchange bias (EB) after zero-field cooling has attracted considerable interest mainly in bulk magnetic competing systems. Here, we use a detailed magnetotransport investigation to probe the ground state and zero-field cooled EB (ZEB) in Mn 50 Ni 41 Sn 9 ribbon. Both ZEB and field cooled EB were detected in magnetoresistance results consistent with magnetic measurement. A pure spin-glass ground state is proposed based on parabolic shape of low-field magnetoresistance combined with AC magnetization, memory effect. The appearance of ZEB is attributed to the field-induced nucleation and growth of ferromagnetic domains in the spin glass matrix forming unidirectional anisotropy at the interface. [ABSTRACT FROM AUTHOR]

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]

Three-dimensional nanoporous copper (NP-Cu) for the first time has been used as an enhanced material for ultrasensitive detection of carbendazim by electrochemistry method. The NP-Cu was fabricated by dealloying Al Cu alloy ribbons, which was characterized by scanning electron microscopy, high-resolution transmission electron microscopy, X-ray diffraction and X-ray photoelectron spectroscopy. The NP-Cu shows bicontinuous nanoporous structure with ligaments of ~20 nm. Based on the large specific surface area and high electrocatalytic activity, the NP-Cu was used to develop an amperometric sensor for carbendazim detection. Sensing parameters such as accumulation time, suspension volume, pH, scan rate, and concentration of carbendazim were discussed. The sensor can be applied to quantification of carbendazim in the concentration range of 0.5–30 μM (R2 = 0.998), with a detection limit of 0.09 μM (S/N = 3). Moreover, the sensor showed good stability, high selectivity, and satisfactory anti-interference ability. The proposed approach was approvingly applied to electrochemical determination of carbendazim in practical sample. • Electrochemical carbendazim sensor using three-dimensional nanoporous Cu/graphene composite • The sensor exhibits low detection limit, wide linear range, high sensitivity and stability. • The sensor was successfully applied to the analysis of carbendazim in pond water. [ABSTRACT FROM AUTHOR]