A vertically aligned carbon nanotube (CNT) array is fabricated as a nanoelectrode platform for biosensor development. Prior to chemical functionalization, metal catalyst particles at the ends of CNT are removed and the closed ends are opened. We find that the oxidative treatment for generating the chemical functional groups at the opened ends of the CNT compromise the mechanical stability of the nanotubes, often leading to total collapse of the aligned CNTs. To solve this problem, we have developed a new approach for filling the gaps between CNTs with a spin-on glass (SOG). Results from the coupling of nucleic acids to the CNT arrays suggest that the SOG enhances the reactivity by providing structural support to the CNTs. The SOG also covers the length of the sidewalls of CNTs, leading to a less hydrophobic interface and thus may aid in improving the chemical reactivity.

Advanced age and presence of intracerebral amyloid deposits are known to be major risk factors for development of neurodegeneration in Alzheimer's disease (AD), and both have been associated with microglial activation. However, the specific role of activated microglia in AD pathogenesis remains unresolved. Here we report that microglial cells exhibit significant telomere shortening and reduction of telomerase activity with normal aging in rats, and that in humans there is a tendency toward telomere shortening with presence of dementia. Human brains containing high amyloid loads demonstrate a significantly higher degree of microglial dystrophy than nondemented, amyloid-free control subjects. Collectively, these findings show that microglial cell senescence associated with telomere shortening and normal aging is exacerbated by the presence of amyloid. They suggest that degeneration of microglia is a factor in the pathogenesis of AD.

We have functionalized single walled carbon nanotubes (SWNTs) with atomic hydrogen generated in a cold plasma. A band at 2924 cm-1 (3.4 μm), characteristic of the C−H stretching mode, is observed using Fourier transform infrared spectroscopy. Additional confirmation of functionalization is provided by irradiating with atomic deuterium. A band in the region 1940 cm-1 (5.2 μm) to 2450 cm-1 (4.1 μm) corresponding to the C−D stretching mode is confirmed and another weak band in the region 1050 cm-1 (9.5 μm) to 1300 cm-1 (7.7 μm) corresponding to C−D bending mode is also seen. Our approach using a glow discharge provides a clean gas-phase process to functionalize SWNTs for further application development.

Results are presented from theoretical and experimental infrared (IR) spectroscopy studies of the microstructures of poly(silsesquioxane)s (PSSQs) of varying chemical composition. The calculated IR spectra show two distinct asymmetric Si-O-Si stretch vibration bands for models of complete polyhedral cages, incomplete open cages, and short ladder structures. Close analyses of the calculated results indicate that the higher frequency IR band at about 1150 cm -1 is derived from the parallel asymmetric Si-O-Si stretch vibration mode in the (Si-O) n ring subunit while the lower frequency band at about 1050 cm -1 is due to the asymmetric Si-O-Si stretch symmetric with respect to the inversion point at the center of the (Si-O) n ring and is absent in highly symmetric cage structures. Experimentally, poly(methylsilsesquioxane) (PMSQ), poly(isobutylsilsesquioxane) (PiBSQ), and poly(phenylsilsesquioxane) (PPhSQ) exhibit a varying tendency of cage-like structures, rather than ladder structures, in as-polymerized samples. When the thermal conversion (curing) temperature is increased to 400 °C, the microstructure of PMSQ in thin solid films transforms from open cage-like structure toward a random network with lower symmetry. This change in microstructure is caused by the secondary condensation reaction and the evaporation of cage structures, and the effect of cage evaporation becomes most pronounced for PiBSQ films, which are mostly comprised of cage-like structures that evaporate around 280 °C. In comparison, PPhSQ films retain cage-like structure upon curing to 400 °C as a result of the high evaporation temperature (ca. 500 °C) of the cages.