Y. A. Kim

DJ-1 binds to mitochondrial complex I and maintains its activity

Parkinsons disease (PD) is caused by neuronal cell death, and oxidative stress and mitochondrial dysfunction are thought to be responsible for onset of PD. DJ-1, a causative gene product of a familial form of Parkinsons disease, PARK7, plays roles in transcriptional regulation and anti-oxidative stress. The possible mitochondrial function of DJ-1 has been proposed, but its exact function remains unclear. In this study, we found that DJ-1 directly bound to NDUFA4 and ND1, nuclear and mitochondrial DNA-encoding subunits of mitochondrial complex I, respectively, and was colocalized with complex I and that complex I activity was reduced in DJ-1-knockdown NIH3T3 and HEK293 cells. These findings suggest that DJ-1 is an integral mitochondrial protein and that DJ-1 plays a role in maintenance of mitochondrial complex I activity.

Raman Spectroscopy Study of Isolated Double-Walled Carbon Nanotubes with Different Metallic and Semiconducting Configurations

A double-walled carbon nanotube (DWNT) provides the simplest system to study the interaction between concentric layers in carbon nanotubes. The inner and outer walls of a DWNT can be metallic (M) or semiconducting (S), and each of the four possible configurations (M@M, M@S, S@S, S@M) has different electronic properties. Here we report, for the first time, detailed Raman spectroscopy experiments carried out on individual DWNTs, where both concentric tubes are measured under resonance conditions, in order to understand the dependence of their electronic and optical properties according to their configuration. Interestingly, for the three DWNTs that were studied, the inner-outer tube distance (e.g., 0.31-0.33 nm) was less than the interlayer spacing in graphite. We believe these results have important implications in the fabrication of electronic devices using different types of S and M tubular interconnects.

Synthesis and Characterization of Selenium-Carbon Nanocables

In this letter, we report the synthesis and characterization of a novel Se-C hybrid nanostructure. X-ray diffraction data indicates a high degree of crystallinity for the nanostructured Se shell. High resolution transmission electron microscopy images show that the Se-C nanostructures consist of coaxial nanocables made of single wall carbon nanotubes, as the core, surrounded by a trigonal Selenium shell. Resonance Raman spectroscopy was used to access the properties of both the carbon nanotubes and selenium. The behavior of the radial breathing mode and the G-band indicates that the Se shell primarily covers semiconducting nanotubes. X-ray photoelectron spectroscopy show that the nanocables have a thin coverage of selenium oxide. We envisage that this system could be used in the fabrication of photonic devices as an interface between electronic and photonic materials.