Diffusion of carbon nanotubes with single-molecule fluorescence microscopy

Single walled carbon nanotubes (SWNTs) are a promising gene and drug delivery system since their physical dimensions mimic nucleic acids. Towards this aim, the hydrophobicity of SWNTs was averted by coating with ribonucleic acid (RNA) polymer [poly(rU)] or bovine serum albumin (BSA) and the consequent diffusion of these synthetic-biomolecular hybrids was studied by single-molecule fluorescence microscopy. The diffusion coefficient for SWNT-poly(rU) was measured at 0.374+/-0.045 mum(2)/s and for SWNT-BSA it was 0.442+/-0.046 mum(2)/s. Our diffusion study provides a fundamental guidance to gene delivery using SWNT as transporters. (C) 2004 American Institute of Physics.