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Nano-γ-Al2O3 is dispersed onto the glass carbon electrode (GCE) by polishing. This nanostructured modified GCE exhibits a great enhancement to the redox responses of 3-nitrobenzaldehyde thiosemicarbazone (3-NBT). In comparison with bare GCE, 3-NBT gives a more sensitive voltammetric response because of the nanoparticle’s unique properties. The lowest detectable concentration (3σ) of 3-NBT is estimated to be 1.18 × 10-6M (accumulation for 4min). The linear relationship between peak current and concentration of 3-NBT holds in the range 1.0 × 10-5M to 1.0 × 10-4M (r = 0.9981). The electrochemical properties of 3-NBT on this modified electrode have been investigated with various electrochemical methods. The results indicate that the transference of one electron and one proton involves electrode radical reaction processes I and II, respectively. The coverage value (Γ) of 1.62 × 10-9molcm-2 was calculated and the electrochemical parameters, diffusion coefficient D (2.54 × 10-3cm2s-1, 2.03 × 10-3cm2s-1) and reaction rate constant ks (5.9573s-1, 7.15 × 10-2cms-1) were obtained for quasi-reversible system I and irreversible system II, respectively. [Copyright &y& Elsevier]

A novel of eco-friendly molecularly imprinted electrochemical luminescence biosensor was designed, based on nanomaterials, CdSeTe/ZnS core-shell QDs and molecularly imprinted polymer composites modified glass carbon electrode. Combining the superior selectivity of molecularly imprinted polymer and the high sensitivity of electrochemical luminescence would achieve the trace determination of dopamine. And the cavities in molecularly imprinted polymer after eluting were applied as the substrate to capture target molecular dopamine. The electron transform channel for the redox reaction of CdSeTe/ZnS QDs and co-reaction K 2 S 2 O 8 was blocked with the increase of dopamine concentration, resulting in the cathodic ECL intensity decreased correspondingly. Therefore, the dopamine was detected in the concentration range from 1 × 10 −14 mol/L to 2.5 × 10 −12 mol/L, with the low detection limit of 3.3 × 10 −15 mol/L. The MIP-ECL biosensor showed easy preparation, low lost, lower detection limit, good selectivity and stability, and could be used for the detection of dopamine in the human serum successfully. [ABSTRACT FROM AUTHOR]

Abstract: A novel cholesterol biosensor was fabricated on hydrophobic ionic liquid (IL)/aqueous solution interface. The hydrophobic IL thin film played a signal amplification role because it not only enriched the cholesterol from the aqueous solution, but also immobilized matrix for cholesterol oxidase (ChOx). Prussian blue (PB) as advanced sensing materials was used as effective low-potential electron transfer mediation toward hydrogen peroxide (H2O2). The fabricated IL-ChOx/PB/Glassy carbon electrode (GCE) was characterized by electrochemical impedance spectroscopy (EIS) and cyclic voltammogram (CV), respectively. And it exhibited a linear response to cholesterol in the range of 0.01–0.40mM with a detection limit of 4.4μM. In addition, the kinetics behavior of cholesterol at IL-Chox/PB/GCE electrode was examined, and the electrocatalytic mechanism was proposed as shown in first scheme. ChOx immobilized in hydrophobic IL thin film was used as the first electrocatalyst for the cholesterol into H2O2, and the PB film onto the GCE was used as the second electrocatalyst for the 2e− reduction of the produced H2O2 into H2O. [Copyright &y& Elsevier]