Synthesis of Functionalized Carbon Nanotubes
using DNA and Gold Nanoparticles
Goo-Hwan Jeong, Satoru Suzuki and Yoshihiro Kobayashi
Material Science Laboratory
Due to the outstanding physical, chemical and electrical properties of carbon nanotubes (CNT), a number of applications in various fields are expected. Especially, extensive researches related with CNT-functionalization using foreign atom or molecules have been performed to control electronic property of CNT because diameter- or chirality-controlled growth has not been realized yet, which is determining factor of electronic property. Here, we introduce our CNT-functionalization study for the application of CNT-based nanoelectronics or biosensor. DNA and Au nanoparticles (NP) are selected among various materials to functionalize CNT  owing to their specific assembling and strong coupling properties.
Ferritin covered with protein shell and contains Fe clusters in its 6-nm diameter inner space was used to synthesize diameter-controlled single-walled carbon nanotubes (SWNTs). A Co-ferritin, Fe is replaced by Co, was also used. By controlled methane CVD experiments at 900oC, suspended SWNTs are successfully synthesized on Si or SiO2 pillar-structured substrates using not only ferritin but also Co-ferritin, which is the first report . A scanning electron microscope (SEM) image [Fig. 1(a)] and Raman spectrum [Fig. 1(b)] of the suspended SWNTs grown using Co-ferritin catalyst are presented.
SWNTs-functionalization was performed by covalent coupling between carboxyl and amine groups produced by acid and aminopropyltriethoxysilane (APTES) treatment, respectively. DNA/Au hybrids were made by simple mixing of thiolated-DNA and Au NP (5nm diameter). Finally, SWNTs are modified by Au NP or DNA/Au hybrids.
Figure 2 shows SEM images obtained from SWNTs/Au [Fig. 2(a) and (b)] and SWNTs/DNA/Au hybrids [Fig. 2(c)]. The density of Au NP attached along the suspended SWNTs was controlled by changing treatment time and Au-colloid concentration. In addition, the change of Raman spectra was also observed from the SWNTs/DNA/Au hybrid , which implies the different electronic or optical properties are expected. These results show functionalized CNT can be developed to electronic and optical applications.
 M. Zheng et al., Science 302 (2003) 1545-1548.
 G.-H. Jeong et al., J. Am. Chem. Soc., submitted 2005.
 G.-H. Jeong et al., MRS 2005 Spring Meeting, San Francisco, March 2005.
Fig. 1. Suspended SWNTs from Co-ferritin.(a) SEM image and (b) Raman result. Fig. 2. SEM images of CNT/Au hybrids [(a),(b)] and CNT/DNA/Au hybrid (c).
[back] [Top] [Next]