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Pat Unwin's and Julie Macpherson's electrochemistry group make the cover of Chemical Communications

Ioana Dumitrescu, Patrick R. Unwin and Julie V. Macpherson make the cover of Chem.Commun with their feature article on Electrochemistry at carbon nanotubes (CNTs): It is a large and growing field, but one in which there is still uncertainty about the fundamental activity of CNTs as electrode materials. On the one hand, there are many reports which focus on the favourable electrochemical properties of CNT electrodes, such as enhanced detection sensitivity, electrocatalytic effects and reduced fouling. On the other hand, other studies suggest that CNTs may be no more electroactive than graphitic powder. Furthermore, it has been proposed that the catalytic nanoparticles from which CNTs are formed may dominate the electrochemical characteristics in some instances. A considerable body of the literature presumes that the CNT sidewall is inert and that edge-plane-graphite-like open ends and defect sites are responsible for the electron transfer activity observed. In contrast, studies of well characterised single-walled nanotube (SWNT) electrodes, either as individual tubes or as two-dimensional networks, suggest sidewall activity. This review highlights how the various discrepancies in CNT electrochemistry may have arisen, by taking a historical view of the field and identifying crucial issues that still need to be solved. When assessing the behaviour of CNT electrodes, it is vitally important that careful consideration is given to the type of CNT used (SWNT or multi-walled), the quality of the material (presence of impurities), the effect of chemical processing steps in the fabrication of electrodes and the experimental arrangements adopted. Understanding these key features is an essential requirement to develop a fundamental understanding of CNT electrochemistry, to allow a wide range of electroanalytical applications, and to move the field forward rationally. As part of this process, high resolution electrochemical and electrical imaging techniques are expected to play a significant role in the future, as well as theoretical developments which examine the fundamentals of electron transfer at different types of CNTs and their characteristic surface sites. http://dx.doi.org/10.1039/b909734a


Sun 15 November 2009, 22:37 | Tags: publications PCCP

Stefan Bon's team and collaborators show microfluidic fabrication of "clickable" porous beads and rods from high internal phase emulsions.

The fabrication of micrometer-sized monodisperse highly porous polymer particles, of both spherical and rodlike shapes, using a simple microfluidic setup is demonstrated. Droplets were generated in a coflow device from a water-in-oil high internal phase emulsion (HIPE), hereby creating a water-in-oil-in-water (W/O/W) emulsion. The individual droplets of monomer HIPE were polymerized downstream in the channel through photopolymerization. The polymer particles produced via this strategy possess very large macropores in comparison with the more conventional porous polymer beads synthesized by inducing in situ phase separation throughout the polymerization process through the use of porogenic solvents. Epoxy-functionalized porous particles made using the HIPE microfluidic method showed superior performance in a consecutive azide and cycloaddition “click”−“click” modification procedure monitored by IR. Our microfluidic approach led to the successful miniaturization of monodisperse submillimeter spherical poly(HIPE) beads, down to diameters of 400 μm. More strikingly is the production of poly(HIPE) rods, which were obtained by using a viscous HIPE, which in coflow emulsification formed an unstable jet that broke up into rodlike sections. These rodlike droplets maintained their shapes throughout the microfluidic channel and did not relax back into spherical droplets, allowing for production of poly(HIPE) rods upon photopolymerization. The nonspherical shape in this case is not determined by confined channel geometries, which to the best of our knowledge is unprecedented as a strategy to produce nonspherical polymer particles with microfluidics. http://dx.doi.org/10.1021/ma9018679

Tue 10 November 2009, 09:33 | Tags: publications Mat

Behavior of key peptide which triggers Alzheimer's disease can be detected directly

Alzheimer's Peptide Aβ1-42, an amyoid beta peptide, is found in plagues in the brains of Alzheimer's disease patients, and accumulation of this very hydrophobic peptide is thought to be the direct cause of the disease. However, the reason for accumulation is not clear. A common theory is that the balance between production and degradation of this peptide is disrupted in the disease. One method whereby degradation of the peptide can be inhibited is by modification into a form which is resistant to enzymatic degradation (proteolysis). In peptides, isomerization of aspartic acid into isoaspartic acid (where the peptide bond is via the side-chain beta carbon rather than the normal backbone alpha carbon) is known to inhibit enzymatic degradation, and may be the elusive Alzheimer's "trigger", which results in decreased degradation and therefore accumulation of the peptide. Nadia Sargaeva of Prof.  Peter O'Connor's group has developed a new mass spectrometric method for detecting this isomerization and tested it out on the worst variant of the amyloid beta peptide, the full length version containing amino acids 1-42. 

Read the paper 


Fri 30 October 2009, 11:55 | Tags: publications PCCP

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Page contact: Stefan Bon Last revised: Tue 10 Nov 2009
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