Enhanced reduction of single-wall carbon nanotube cytotoxicity in vitro: Applying a novel method of arginine functionalization.

Biomedical applications of carbon nanotubes (CNTs) have attracted a lot of attention in recent years. However, the applications of CNTs in these fields of research are challenged by some properties such as their insolubility and cytotoxicity. To improve their solubility in physiological solutions or to reduce cytotoxicity, a variety of engineered biologically active molecules through functionalization processes are being designed. Application of appropriate biomolecules has become an interesting research area these days from both fundamental and application standpoints. In the present report, arginine amino acids were used for single-wall carbon nanotubes (SWCNTs) functionalization because of their bulky and polar side chain. The efficiency of SWCNTs conjugation with arginine was demonstrated by Fourier transform infrared and Raman spectroscopies and Sakaguchi assay. Cytotoxicity of functionalized CNTs was investigated by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay on three different cell lines. Results indicated that functionalization of SWCNTs with arginine reduced their cytotoxicity extremely and hence make them more appropriate for biomedical applications. Moreover, it was concluded that sensitivity to CNT cytotoxicity depends on the type of tissue and cell line. Here, an impressive and novel method for biological functionalization of CNTs has been introduced.