Tubulin encapsulation of carbon nanotubes into functional hybrid assemblies

Cytoskeletal protein tubulin, when complexed with multi-walled carbon nanotubes (MWCN), was found to be able to direct various types of nanotube morphologies over different length scales. Rhodamine-labeled biotinylated tubulin was physically adsorbed onto the CNTs by incubating the protein with MWNTs for 2 hrs in Pipes-based buffer at 4°C with shaking at 200rpm. The results show patterns of Tubulin-MWNT conjugates in petal-like arrangements and these patterns form similar objects carrying similar edge effects. Sidewall-tubulin attachment promotes inter-MWNT interactions through nonselective hydrophobic protein-MWNT contacts, which lead to bundle formation in radial and axial dimensions. It is also found that in the absence of free tubulin in solution, polymerization of the high-loading tubulin-MWNT conjugates followed by Alexa-streptavidin staining results in undefined architectures.