Synthesis of carbon nanotubes with catalytic iron-containing proteins

We report a novel method for the growth of carbon nanotubes (CNTs) that uses the iron-containing proteins, hemoglobin, myoglobin, or cytochrome c. The proteins were adsorbed onto amine-terminated self-assembled monolayer (SAM) by peptide bonds between the amine groups of the SAMs and the carboxyl groups of the proteins. SAM films allow proteins to be adsorbed onto films with appropriate density that can initiate the growth of well-graphitized multi-walled CNTs with a diameter of approximately 10 nm. These results show that proteins that contain iron atoms in any form have the catalytic ability to initiate the growth of CNTs.