Study of microtubule templates for fabrication of nano-interconnects

by Yang, Yi.

Microtubules (MTs), whose basic units are a and ß tubulin proteins, are selfassembled proteinaceous filaments with nanometer scale diameters and micrometer scale lengths. Their aspect ratio, directionality, the reversibility of their assembly and their ability to be metallized by electroless plating make them good candidates to serve as templates for the fabrication of nanowires and other nanoscale devices. In addition, tubulin proteins can provide biological interactions with a naturally high specificity. Toward the goal of manufacturing MT-based metallic nanowires and networks of nanowires on a silicon wafer, I studied the influence of pH, temperature, and several biomolecules on the stability of MTs in solutions, as well as the surface effect on the dynamics of disassembly of microtubules. Secondly, I demonstrated the metallization of MTs by electroless nickel plating both in solution and on hydrophilic oxidized Si surface. After being activated by Pt, nickel coated MT surfaces during the electroless plating, with a thickness of several nanometers. Due to the different kinetics of the process, MTs metallized on the oxidized Si wafer are slightly different from MTs metallized in solutions. Finally, we explored controlled nucleation and growth of microtubules directly from a collection of ?-tubulin monomers. ?-tubulins bind to modified gold electrodes on a silicon wafer through an organic linker, Glutathione s-transferase, creating a ?-tubulin layer for MT growth. MTs unambiguously originated from the surface-bound ?-tubulin 14 layer on the gold electrode, proving that the surface-bound ?-tubulin retains its biological ability of nucleating MT growth. 15