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A platinum electrode modified with lanthanum hexacyanoferrate (LaHCF) was prepared by electrochemical scanning and characterized by Fourier transform infrared spectroscopy, X-ray powder diffraction (XRD), scanning electron microscopy (SEM) and voltammetry. The results show that the deposit on the platinum substrate is composed of lanthanum potassium hexacyanoferrate (II) tetrahydrate. The electrochemical behavior of the LaHCF modified electrode was investigated preliminarily by voltammetry, and the experiments showed that hydrogen ion has a considerable effect on the electrochemical behavior of the modified electrode. [Copyright &y& Elsevier]

Abstract: An ultrathin platinum film is fabricated on a nanoporous gold (NPG) scaffold through a catalytic chemical deposition method. The morphology and active surface area of the deposited Pt film, which will greatly influence the electro-catalytic properties of the catalyst, can be controlled by adjusting the deposition condition. Compared with bare NPG and high Pt loaded NPG, the performances of methanol electro-oxidation on the low-Pt-content bimetallic film are greatly improved, both in its catalytic current enhancement and signal stability. The best condition for methanol oxidation can be achieved when the area ratio of deposited Pt and uncovered Au was 3:1. [Copyright &y& Elsevier]

Abstract: Single-walled carbon nanotubes (SWCNTs) selectively wrapped by a water-soluble, environmentally friendly, biocompatible polymer chitosan (CHI) were employed for the construction of a bioelectrochemical platform for the direct electron transfer (DET) of glucose oxidase (GOD) and biosensing purposes. Scanning electron microscopy and Raman spectroscopy were used to investigate the properties of the SWCNT–CHI film. The results show that the preferentially wrapped small-diameter SWCNTs are dispersed within the CHI film and exist on the surface of the electrode as small bundles. The DET between GOD and the electrode surface was observed with a formal potential of about ca. −460mV vs. SCE in phosphate buffer solution. The heterogeneous electron transfer rate constant and the surface coverage of GOD are estimated to be 3.0s−1 and 1.3×10−10 mol/cm2, respectively. The experimental results demonstrate that the immobilized GOD retains its catalytic activity towards the oxidation of glucose. Such a GOD/SWCNT–CHI film-based biosensor not only exhibits a rapid response time, a wide linear rang and a low detection limits at a detection potential of −400mV but also shows the effective anti-interference capability. Significantly improved analytical capabilities of the GOD/SWCNT–CHI/GC electrode could be ascribed to the unique properties of the individual SWCNTs and to the biocompatibility of CHI. [Copyright &y& Elsevier]

Here we report the studies on the electrochemical behaviors at a closed bipolar cell which is composed of two separated reaction cells containing a closed bipolar electrode (c-BPE) and its driving electrodes. The influence factors such as the concentration of the reagents, the size and material of the electrodes are studied experimentally and theoretically. And the experimental results fit with the theoretic calculation very well. Significantly, unlike the previous studies focusing on the coupling of the two c-BPE poles, this work also considers the effect of the reaction on the driving electrode on the electrochemical behavior. We believe that this research could deepen our understanding of bipolar chemistry and be useful for the future c-BPE-based applications. [ABSTRACT FROM AUTHOR]

Herein, a facile and sensitive dual mode sensing strategy for amantadine (AMD) level evaluation by coupling the plasmonic Au nanorod (NR) and supramolecular SH-cyclodextrin (CD) through strong Au-S bond is proposed. Methylene blue (MB) molecules can be inserted into the cavity of CD molecules through the hydrophobic interaction, which would cause the plasmon resonance energy transfer (PRET) process as well as electrochemical signal response due to the spectrum overlap between Au NR and MB molecules and the electrochemical conversion activity of MB molecules. Subsequently, AMD would induce the replacement of MB molecules because of the stronger interaction with CD, resulting the recovery of scattering intensity of Au NR and decrease of the electrooxidation current of MB. On one hand, the increase of Au NR scattering intensity is linearly proportional to AMD with the concentration from 0.4 to 3.0 μM, and reaches a limit of detection (LOD) of 0.28 μM. On the other hand, electrochemical measurement method enlarged the detection range of AMD. The variation of electrochemical oxidation peak current of MB is linearly proportional to the logarithm value of AMD concentration from 2.5 to 375.0 μM, with LOD of 1.9 μM. Subsequently, the proposed dual mode response sensing strategy was successfully employed for the detection of AMD in human serum samples with great selectivity and sensitivity, with a recovery percentage ranged from 92.6 to 112.0%. Overall, this Au NR@SH-CD-MB nanoparticle based single particle plasmonic and electrochemical dual mode sensing method provides great potential in the field of clinical drug detection or metabolic process investigation in the future. Au NR@SH-CD-MB NPs for dual mode AMD detection. [Display omitted] • The CD molecules were introduced for simpler and more effective construction of PRET based plasmonic sensors. • Au NR@SH-CD-MB NPs could produce scattering and electrochemical dual signals for AMD detection. • The prepared Au NR@SH-CD-MB NPs have a good sensitivity and selectivity toward AMD. • The dual signal responsive detection method could achieve a lower LOD and broader dynamic range in biosensing. [ABSTRACT FROM AUTHOR]

Abstract: Here we report a novel approach for the detection of adenosine in cancer cells by electrochemiluminescence (ECL) on a wireless indium tin oxide bipolar electrode (BPE). In this approach, ferrocene (Fc) which is labeled on adenosine aptamer is enriched on one pole of the BPE by hybridization with its complementary DNA (ssDNA) and oxidized to Fc+ under an external voltage of 5.0V at the two ends of BPE. Then, a reversed external voltage was added on the BPE, making Fc+ enriched pole as cathode. The presence of Fc+ promotes the oxidation reaction on the anodic pole of the BPE, resulting in a significant increase of ECL intensity using Ru(bpy)3 2+/tripropylamine (TPA) system as test solution. The presence of target adenosine was reflected by the ECL signal decrease on the anodic pole caused by the target-induced removal of ferrocene-aptamer on the cathodic pole. The decrease of ECL signal was logarithmically linear with the concentration of ATP in a wide range from 1.0fM to 0.10μM. This ECL biosensing system could accurately detect the level of adenosine released from cancer cells. [Copyright &y& Elsevier]

Abstract: Quinones are a group of potent antineoplastic agents. Here we described effective and facile routes to synthesize a series of ubiquinone analogues (UQAs). These unique compounds have been investigated by electrochemistry and in situ UV–vis spectroelectrochemistry to explore their electron-transfer processes and radical properties in aprotic media. The structure–activities relationships of inhibiting cancer cell proliferation of UQAs were examined in murine melanoma B16F10 cells using a 72 h continuous exposure MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) assay. Our results revealed that UQAs had improved antiproliferative activity and displayed better inhibitory effects than natural ubiquinone 10. The cytotoxic activities of UQAs were correlated to the semiubiquinone radicals, which were confirmed by in situ electron spin resonance (ESR). In the cytotoxicity test, 6-vinylubiquinone 5 and 6-(4′-fluorophenyl) ubiquinone 7 that possess half maximal inhibitory concentration value (IC50) of 6.1 μM and 6.2 μM. This would make them as valuable candidates for future pharmacological studies. [Copyright &y& Elsevier]

Abstract: This work presents a photoinducedly electrochemical preparation of Prussian blue from a single sodium nitroprusside and insertion of cetyltrimethylammonium cations into Prussian blue as counter ions. The product of photoinducedly electrochemical reactions has a couple of voltammetric peaks at E°=0.266V in 0.2moll−1 KCl solution, the measurements of X-ray powder diffraction and FT-IR spectroscopy show that it is Prussian blue (PB). The formation mechanism of a pre-photochemical reaction and subsequent electrochemical reaction is suggested. The cyclic voltammetric treatment of the freshly as-prepared PB film in 1.0mmoll−1 cetyltrimethylammonium (CTA) bromide solution leads to the insertion of cetyltrimethylammonium cations into the channels of Prussian blue, which substitutes for potassium ions as counter ions in Prussian blue. The Prussian blue containing CTA counter ions shows two couples of voltammetric peaks at E°=−0.106V and E°=0.249V in 0.2moll−1 KCl solution containing 1.0mmoll−1 cetyltrimethylammonium bromide. Compared with the electrochemical behaviors of KFeFe(CN)6 in 0.1moll−1 KOH alkali solution, CTAFeFe(CN)6 shows relatively durable voltammetric currents due to the hydrophobic effects of cetyltrimethylammonium. The diffusion coefficients for CTA and potassium cations were estimated to be D CTA 1.25×10−12 cm2 s−1, D K 2.59×10−12 cm2 s−1, respectively. The peak current of electro-catalytic oxidization on hydrogen peroxide showed a linear dependence from 6.59×10−6 to 2.20×10−4 moll−1 with R =0.99947 (n =8). The linear regression equation was I p (mA)=0.82949+0.00594C (μmoll−1) with errors of ±7.92833×10−5 for the slope and ±0.01085 for the intercept with the detection limit of 1.46×10−6 moll−1. Thus, it is expected to find its application in neutral or weak alkali medium for biosensors. [Copyright &y& Elsevier]

Abstract: The cationic luminescence probe, tris(2,2′-bipyridyl)ruthenium(II) complex ([Ru(bpy)3]2+), was incorporated into laponite-modified glassy carbon electrode (GCE) via two strategies, namely, the adsorption and intercalation methods. These two incorporation methods resulted in different microenvironment for the immobilized [Ru(bpy)3]2+ within laponite as well as the different host–guest and guest–guest interactions. Herein, cyclic voltammetry and electrochemiluminescence (ECL) were innovatively performed to monitor the interactions. Tripropylamine (TPA) was used as coreactant in the electrochemical and ECL system. [Copyright &y& Elsevier]

Abstract: Direct electrochemistry of hemoglobin (Hb) was observed at glassy carbon electrode (GCE) modified with undoped nanocrystalline diamond (UND) and Hb multilayer films via layer-by-layer assembly. UV–VIS absorbance spectroscopy, electrochemical impedance spectroscopy and cyclic voltammograms were employed to characterize the film. The results showed that the UND had the effect of enhancing the electron transfer between Hb and the electrode surface. Hb in the multilayer films maintained its bioactivity and structure. It also exhibited a good catalytic activity towards the reduction of H2O2. The reciprocal of catalytic current showed a linear dependence on the reciprocal of H2O2 concentration ranging from 0.5 μM to 0.25 mM with a detection limit of 0.4 μM. The apparent Michaelis–Menten constant was estimated to be 0.019 mM. [Copyright &y& Elsevier]

Abstract: The hollow spherical CdSe QD assemblies were synthesized via a sonochemical approach that utilizes β-cyclodextrin as a template reagent in aqueous solution. The hollow nanospheres have an average diameter of 70nm and are found to consist of an assembly of monodispersed 5nm sized CdSe quantum dots. Following an electrochemical reaction with persulfate ions, strong electrogenerated chemiluminescence (ECL) was observed from the CdSe nanoassemblies suspended in an aqueous solution of pH⩽7.95. The study indicates that the morphology of the 70nm nanoassembly plays an important role in generating the stable ECL since individually dispersed quantum dots did not exhibit any significant ECL. The unique ECL intensity and stability of the synthesized spherical nanoassemblies could allow for potential sensor applications of CdSe quantum dots in water. [Copyright &y& Elsevier]

Abstract: An in-situ induction precipitation approach via electrochemical reduction has been successfully used to prepare CdS-Polyamidoamine (CdS–PAMAM) nano-composite membranes on electrode surfaces, and that the resulting film showed 55-fold enhanced red electrogenerated chemiluminescence compared with that of CdS nano-film without PAMAM and the stability of the ECL can be modulated by electrochemical methods for the first time. It would open a way in preparation of stable and strong ECL nano-composite films for analytical application. [Copyright &y& Elsevier]