Poly(N-isopropylacrylamide) (pNIPAM) microgels are soft and deformable particles, which can adsorb at liquid interfaces. In the present paper, we study the two-dimensional organization of charged and quasi-neutral microgels with different cross-linking densities, under compression at the air-water interface and the transfer of the microgel monolayer onto a solid substrate at different surface pressures. At low cross-linking densities, the microgels form highly ordered hexagonal lattices on the solid substrate over large areas, with a unique lattice parameter that decreases continuously as the surface pressure increases. We thus prove that the microgel conformation evolves at the air-water interface. The microgels undergo a continuous transition from a highly flattened state at low surface coverage, where the maximal polymer segments are adsorbed at the interface, to entangled flattened microgels, and finally the thickening of the layer up to a dense hydrogel layer of compacted microgels. Moreover, two batches of microgels, with and without charges, are compared. The contribution of electrostatic interactions is assessed via changing the charge density of the microgels or modulating the Debye length. In both cases, electrostatics does not change the lattice parameter, meaning that, despite the microgel different swelling ratio, charges do not affect neither interactions between particles at the interface nor microgels adsorption. Conversely, the cross-linking density has a strong impact on microgel packing at the interface: increasing the cross-linking density strongly decreases the extent of microgel flattening and promotes the occurrence of coexisting hexagonally ordered domains with different lattice parameters.

Short carbon nanotubes have been modified selectively on one end with metal using a bulk technique based on bipolar electrochemistry. A stabilized suspension of nanotubes is introduced in a capillary containing an aqueous metal salt solution, and a high electric field is applied to orientate and polarize the individual tubes. During their transport through the capillary under sufficient polarization (30 kV), each nanotube is the site of water oxidation on one end and the site of metal ion reduction on the other end with the size of the formed metal cluster being proportional to the potential drop along the nanotube.

Recent work on the preparation of highly organized macroporous electrodes and nanoporous ultramicroelectrodes has been combined and extended to elaborate macroporous ultramicroelectrodes (UMEs) by template synthesis using colloidal crystals and following two different and complementary methods. On the one hand, arched porous UMEs were prepared, and on the other hand, cylindrical porous UMEs were obtained by using cavity UMEs. These macroporous UMEs have an active surface area which is up to 2 orders of magnitude higher compared to that of a classical disk UME as characterized by cyclic voltammetry. To study their analytical performance, the macroporous UMEs have been modified with a redox-active thiol and also a model bioelectrocatalytical system containing a redox mediator, a cofactor, and glucose-dehydrogenase. In both cases the electrochemical signal is amplified by up to 2 orders of magnitude, which increases significantly the analytical performance of such electrodes and therefore opens up new applications for this kind of miniaturized electrochemical system.

A novel array of optoelectrochemical submicrometer sensors for remote electrochemiluminescence (ECL) imaging is presented. This device was fabricated by chemical etching of a coherent optical fiber bundle to produce a nanotip array. The surface of the etched bundle was sputter-coated with a thin layer of indium tin oxide in order to create a transparent and electrically conductive surface that is insulated eventually by a new electrophoretic paint except for the apex of the tip. These fabrication steps produced an ordered array of optoelectrochemical sensors with submicrometer dimensions that retains the optical fiber bundle architecture. The electrochemical behavior of the sensor array was independently characterized by cyclic voltammetry and ECL experiments. The steady-state current indicates that the sensors are diffusively independent. This sensor array was further studied with a co-reactant ECL model system, such as Ru(bpy)(3)(2+)/TPrA. We clearly observed an ordered array of individual ECL micrometer spots, which corresponds to the sensor array structure. While the sensors of the array are not individually addressable electrochemically, we could establish that the sensors are optically independent and individually readable. Finally, we show that remote ECL imaging is performed quantitatively through the optoelectrochemical sensor array itself.

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A bulk procedure based on bipolar electrochemistry is proposed for the generation of Janus-type carbon tubes. The concept is illustrated with carbon tubes that are selectively modified at their ends with various metals and conducting polymers. No surface or interface is required to break the symmetry and therefore this approach could be used for the mass production of Janus micro- and nano-objects. We show evidence that the technique is very versatile, allowing the choice of the kind of material that is deposited and whether the end product is mono- or bifunctionalized.

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A straightforward method to synthesize quasi‐monodisperse gold microspheres from a commercial gold plating solution is reported. The size and the surface roughness of the obtained particles can easily be tuned. In particular, raspberry‐like particles with a high active surface area are obtained. The microspheres are assembled on indium tin oxide (ITO) electrodes using the layer‐by‐layer technique and the overall electroactive surface area is increased, as characterized by cyclic voltammetry. The as‐prepared products were characterized by scanning electron microscopy (SEM), powder X‐ray diffraction (XRD), cyclic voltammetry, and light microscopy.