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Herein, three-dimensional reduced graphene oxide/helical carbon nanotubes (RGO/HCNTs) nanocomposites were synthesized by a combined solution-based method and chemical vapor deposition. This synergistic structure of graphene and helical carbon nanotube exhibited large flexibility, rapid transport kinetics, and excellent electrochemical characteristic. The hemoglobin (Hb) was immobilized on the surface of the RGO/HCNTs nanocomposites for amperometric sensing of HO. The dependence of the electrochemical performance of Hb on the composition of RGO/HCNTs composites is systematically investigated by varying the weight ratio of reduced RGO/HCNTs. Compared with alone graphene or HCNTs electrodes modified with Hb, the catalytic current for HO reduction at the Hb-modified RGO/HCNTs electrode increased due to the increase in the surface coverage of Hb and the excellent electrocatalytic activity of RGO/HCNTs. The constructed biosensor displayed a fast electron transfer of Hb and an excellent electrochemical activity for the detection of HO with high selectivity and sensitivity. [ABSTRACT FROM AUTHOR]

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]

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: 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]

The key step in the fabrication of highly active electrochemical sensors is seeking multifunctional nanocomposites as electrode modified materials. In this study, the gold nanoparticle-decorated helical carbon nanotube nanocomposites (AuNPs-HCNTs) were fabricated for rutin detection because of its superior sensitivity, the chemical stability of AuNPs, and the superior conductivity and unique 3D-helical structure of helical carbon nanotubes. Results showed the prepared nanocomposites exhibited superior electrocatalytic activity towards rutin due to the synergetic effects of AuNPs and HCNTs. Under the optimized conditions, the developed sensor exhibited a linear response range from 0.1 to 31 μmol/L for rutin with a low detectable limit of 81 nmol/L. The proposed method might offer a possibility for electrochemical analysis of rutin in Chinese medical analysis or serum monitoring owing to its low cost, simplicity, high sensitivity, good stability, and few interferences against common coexisting ions in real samples. [ABSTRACT FROM AUTHOR]

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]