Application of Multifunctional Carbon Nanotubes to kill Cancer Cells

The main goal of this project is the application of carbon nanotubes to kill cancer cells. This can be accomplished directly by absorption of near-infrared radiation or indirectly by attaching toxins or siRNA to the nanotubes; serving as a delivery system. Furthermore, protein targeting ligands can be used to specifically target cancer cells.

As a first step, pristine carbon nanotubes have to be purified, solubilised and functionalised. This can be achieved by either covalent or non-covalent functionalisation. The covalent technique is based upon nitric acid treatment, introducing carboxylic groups and removing metallic catalyst particles. Non-covalent methods include wrapping the nanotubes with RNA, proteins, polymers or surfactants. Our work will particularly focus upon RNA-wrapping, as this technique has been shown to suppress recognition by the mammalian immune system and is thus highly suitable to be applied in vivo. By the use of cationic polymers, DNA can be attached to the nanotubes for gene delivery. To prove our concept, the first transfection experiments have been carried out using GFP (Green Fluorescent Protein) plasmid and pGL3 plasmid for luciferase expression as model systems.

Confocal Microscopy was used to visualize fluorescent carbon nanotubes inside cells and to prove their ability to successfully deliver functional DNA cargo into cancer cells on the basis of GFP expression. Furthermore, Raman Microscopy was applied to observe unlabelled carbon nanotubes inside cells. The carbon nanotubes appear as little black spots inside the cell, which can be further analysed and confirmed by Raman Spectroscopy.