Carbon nanotubes (CNTs) are unique nanostructures with fascinating electrical, mechanical, chemical and optical properties. One of the challenges in the use of CNTs is the difficulty to manipulate them, e.g. for positioning, attachment to electrodes, controlled modification of their properties, etc. One of the most promising ways to overcome these problems is by chemical modification, taking advantage of the molecular properties of CNTs. By following this route, we functionalized single-wall carbon nanotubes (SWNTs) with biotin at the ends and side-walls of the nanotubes in a series of chemical reactions. Streptavidin-coated gold nanoparticles were attached to the biotin-modified SWNTs in solution in a self-assembly process. Gold nanoparticles which connected two SWNTs were selected and contacted for transport measurements. At low temperatures, Coulomb blockade oscillations were observed as a function of gate voltage. In another experiment, thiolized SWNTs were prepared and selectively attached to gold electrodes.