Preparation, Characterization and Cellular Biological Impact of Water Soluble Multiwalled Carbon Nanotubes

Abstract

Biological effect and multiple application potentials of carbon nanotubes have been becoming important issues attracting intense research interests and concerns. In this work, water dispersible oxidized multiwalled carbon nanotubes (o-MWNTs) were prepared by an optimal combination of ultrasonication and concentrated acids oxidation; stable concentrations of 0.3mg/ml were obtained in deionized water of surfactant free. The o-MWNTs dispersing in water displayed a strong characteristic adsorption at 253nm in the spectra of UV/VIS/NIR. XPS analysis showed the presence of carboxylated groups on the o-MWNTs. SEM observation indicated that after the oxidation, the as received MWNTs were cut short; the average length was around 500nm-800nm, the maximum effective size obtained by DLS measurement was about 340nm. It was inferred that the oxidation degree was one major key factor to determine the stable dispersion concentration of o-MWNTs in water. The o-MWNTs dispersing in water entered into the cells and located in the cytoplasm. Cells proliferation and living cycle were affected by the o-MWNTs dispersing in the culture medium in a concentration dependant manner; the cells cultivated in the medium with high concentration of o-MWNTs underwent apoptosis to a point determined by flowcytometry and TEM respectively, while low concentration of o-MWNTs induced light suppression of cells proliferation examined with cell viability assay.