Incorporation of sequenced peptides on nanotubes for Pt coating:: smart control of nucleation and morphology via activation of metal binding sites on amino acids

A new method to fabricate morphology-controlled Pt nanotubes has been demonstrated by using sequenced peptide-functionalized nanotubes as templates. The sequenced peptide, His-Pro-Gly-Ala-His, was immobilized on template nanotubes, and the biomolecular recognition efficiently anchored Pt ions to nucleate Pt nanocrystals on the nanotubes. The morphology of the Pt coating on the nanotubes was controlled by switching Pt nucleation sites among the amino acids as a function of pH. While monodisperse Pt nanocrystals of average diameter 12 nm were grown on the nanotube surfaces in pH < 8 growth solutions, the Pt coating became nearly continuous in pH > 8 solutions. This method that mimics biomineralization in nature can be used to produce nanotubes with controlled electrical properties from semiconducting to metallic in a simple and economical procedure, and this type of tunability may enable the resulting nanotubes to be applicable as smart building blocks in nanometer-scaled electronic devices and chemical sensors.