Novel ferrocene-anchored ZnO nanoparticle/carbon nanotube assembly for glucose oxidase wiring: application to a glucose/air fuel cell.

Glucose oxidase (GOx) is immobilized on ZnO nanoparticle-modified electrodes. The immobilized glucose oxidase shows efficient mediated electron transfer with ZnO nanoparticles to which the ferrocenyl moiety is π-stacked into a supramolecular architecture. The constructed ZnO-Fc/CNT modified electrode exhibits high ferrocene surface coverage, preventing any leakage of the π-stacked ferrocene from the newly described ZnO hybrid nanoparticles. The use of the new architecture of ZnO supported electron mediators to shuttle electrons from the redox centre of the enzyme to the surface of the working electrode can effectively bring about successful glucose oxidation. These modified electrodes evaluated as a highly efficient architecture provide a catalytic current for glucose oxidation and are integrated in a specially designed glucose/air fuel cell prototype using a conventional platinum-carbon (Pt/C) cathode at physiological pH (7.0). The obtained architecture leads to a peak power density of 53 µW cm(-2) at 300 mV for the Nafion® based biofuel cell under "air breathing" conditions at room temperature.

Comparison of three labeled silica nanoparticles used as tracers in transport experiments in porous media. Part I: syntheses and characterizations.

The synthesis and the characterization of three kinds of labeled silica nanoparticles were performed. Three different labeling strategies were investigated: fluorescent organic molecule (FITC) embedded in silica matrix, heavy metal core (Ag(0)) and radioactive core ((110m)Ag) surrounded by a silica shell. The main properties and the suitability of each kind of labeled nanoparticle in terms of size, surface properties, stability, detection limits, and cost were determined and compared regarding its use for transport studies. Fluorescent labeling was found the most convenient and the cheapest, but the best detection limits were reached with chemical (Ag(0)) and radio-labeled ((110m)Ag) nanoparticles, which also allowed nondestructive quantifications. This work showed that the choice of labeled nanoparticles as surrogates of natural colloids or manufactured nanoparticles strongly depends on the experimental conditions, especially the concentration and amount required, the composition of the effluent, and the timescale of the experiment.

A comparative study of non-covalent encapsulation methods for organic dyes into silica nanoparticles.

Numerous luminophores may be encapsulated into silica nanoparticles (< 100 nm) using the reverse microemulsion process. Nevertheless, the behaviour and effect of such luminescent molecules appear to have been much less studied and may possibly prevent the encapsulation process from occurring. Such nanospheres represent attractive nanoplatforms for the development of biotargeted biocompatible luminescent tracers. Physical and chemical properties of the encapsulated molecules may be affected by the nanomatrix. This study examines the synthesis of different types of dispersed silica nanoparticles, the ability of the selected luminophores towards incorporation into the silica matrix of those nanoobjects as well as the photophysical properties of the produced dye-doped silica nanoparticles. The nanoparticles present mean diameters between 40 and 60 nm as shown by TEM analysis. Mainly, the photophysical characteristics of the dyes are retained upon their encapsulation into the silica matrix, leading to fluorescent silica nanoparticles. This feature article surveys recent research progress on the fabrication strategies of these dye-doped silica nanoparticles.

Remarkable isolation, structural characterisation and electrochemistry of unexpected scrambling analogues of 5-ferrocenyl-10,20-diphenylporphyrin.

Selective condensation of 5-ferrocenyldipyrromethane, 1, and dipyrromethane, 2, with benzaldehyde, 3, led to 5-ferrocenyl-10,20-diphenylporphyrin, 5. During the condensation, an unusually large amount of scrambling was observed which led to the isolation of two further ferrocenylated porphyrin analogues 6 and 7. The structure of 6 was confirmed by a single-crystal X-ray study. A mechanism is proposed for this atypical scrambling which is likely to involve acid-catalysed reversion of the dipyrromethane synthesis. (1)H NMR further elucidated the structures of each complex and showed the existence of atropisomerism. An electrochemical study (cyclic voltammetry, Osteryoung square wave and linear sweep voltammetry) showed that there exists a linear relationship between the sum of the group electronegativities of meso substituents of the obtained porphyrins and the formal reduction potentials of the two observed ring-centred reduction processes, the meso substituent ferrocenyl-based oxidation process and the first ring-centred oxidation wave. These four relationships could be mathematically quantified. Due to the strong electron-withdrawing properties of the oxidised ferrocenium group, the second ring centred oxidation wave fell outside the potential window of dichloromethane as solvent.