Deposition of palladium nanoparticles on self-assembled, zinc-induced tubulin macrotubes and sheets.

Co-factors control the GTP-induced assembly of tubulin protein into a variety of superstructures with defined geometry at the nanometre scale: microtubules, macrotubes, sheets, or spirals/rings. We report the Zn2+ ion-induced assembly of tubulin protein into sheet-like or tubular structures. Free functional groups of amino acids on the surface of the protein biopolymer provide nucleation sites for further deposition of small metal nanoparticles. This study describes the synthesis of metal particle--protein hybrids by a two-step chemical process that directs metal nanoparticle nucleation at specific surface sites by applying these tubulin assemblies as biotemplates. The hybrids are characterized by transmission electron microscopy (TEM) and scanning force microscopy (SFM). The present study demonstrates the potential and general applicability of tubulin assemblies as tools for the nanofabrication of nanoparticle arrays exhibiting various geometries.