Nozomi Nakayama

The fate and biological effects of carbon nanotubes in animals are critical to potential applications in vivo. Efficient targeting of integrin positive –tumour in mice is achieved with Single-walled carbon nanotubes (SWNTs) coated with poly(ethylene glycol) chains linked to an arginine–glycine–aspartic acid peptide. A high tumour accumulation is attributed to the multivalent effect of the SWNTs. The Raman signatures of SWNTs are used to directly probe the presence of nanotubes in mice tissues and confirm the radio-label-based results. The high optical absorbance of SWNTs in the near-infrared regime causes heating under laser irradiation, which is useful for destroying cancer cells that are selectively internalized with nanotubes. The fact that much of the radioactivity remained in the mice at 24 h p.i. suggested relatively slow excretion of SWNTs, which differed from the previous finding where SWNTs acted as small molecules, with little RES uptake and free excretion from mice.

We report the fabrication of single-walled carbon nanotube (SWNT) DNA sensors and the sensing mechanism. The simple and generic protocol for label-free detection of DNA hybridization is demonstrated with random sequence 15mer and 30mer oligonucleotides. DNA hybridization on gold electrodes, instead of on SWNT sidewalls, is mainly responsible for the acute electrical conductance change due to the modulation of energy level alignment between SWNT and gold contact. This work provides concrete experimental evidence on the effect of SWNT-DNA binding on DNA functionality, which will help to pave the way for future designing of SWNT biocomplexes for applications in biotechnology in general and also DNA-assisted nanotube manipulation techniques.