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Three-dimensional nanoporous PtSi (NP-PtSi) alloy was prepared by dealloying ternary PtSiAl alloy ribbons. By combining the nanoporous morphology of PtSi and graphene (GR), a new composite material was developed, which was used to modify the surface of a glassy carbon electrode (GCE). The resulting modified electrodes showed an excellent electrocatalytic activity towards the electro oxidation of bisphenol A. Based on differential pulse voltammetry measurements, NP-PtSi/GR/GCE showed linear response over the concentration range 0.30 to 85 μM bisphenol A, while the detection limit was found to be 0.11 μM (S/N = 3). NP-PtSi/GR/GCE showed also satisfactory stability and selectivity over various compounds present in real samples, and they were successfully applied to the determination of bisphenol A in inoculated milk samples. [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 (NPC) was fabricated by dealloying ribbons of an Al-Cu alloy. NPC possesses a clean metal surface and high electrical conductivity. Subsequently, a non-enzymatic electrochemical sensor was obtained by modifying a glassy carbon electrode with nanocomposites containing nanoporous copper and carbon black (NPC-CB) in a nafion matrix. The sensor, if operated at a working voltage of 0.6 V (vs. SCE) in 50 mM NaOH solution, has a linear analytical range that extends from 6.0 μM to 3.4 mM of glucose, and a 2.6 μM detection limit (at an S/N ratio of 3). It also shows good selectivity over ascorbic acid, uric acid, dopamine and carbohydrates (fructose, saccharose, and maltose). The sensor also has a rapid amperometric response to hydrogen peroxide which can be quantified with a 1.2 μM detection limit. [Figure not available: see fulltext.] [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: 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]