Design of metal-binding sites onto self-assembled peptide fibrils

The ability to develop a rational basis for the binding of inorganic materials to specific binding sites within self-assembling biological scaffolds has important applications in nanobiotechnology. Amyloid-forming peptides are a class of such scaffolds and show enormous potential as templates for the fabrication of low resistance, conducting nanowires. Here we report the use of a self-assembling peptide building block as scaffold for the systematic introduction of metal-binding residues at specific locations within the structure. The octapeptide NSGAITIG (Asparagine-Serine-Glycine-Alanine-Isoleucine-Threonine-Isoleucine-Glycine) from the fiber protein of adenovirus has been identified in previous structural studies as an elementary fibril-forming building block. Using this building block as a scaffold, we have designed three new cysteine-containing octa-peptides to study their eventual fibril-forming ability and potential templating of metal nanoparticles. We find that the cysteine substitutions do not alter the fibril-forming potential of the peptides, and that the fibrils formed bind efficiently to silver, gold, and platinum nanoparticles; furthermore, we report unexpected behavior of serine in nucleating gold and platinum nanoparticles. We find that combination of cysteine and serine residues projecting from adjacent sites on a peptide scaffold represents a potentially useful strategy in nucleating inorganic materials. The ability to reliably produce metal-coated fibrils is a vital first step towards the exploitation of these fibrils as conducting nanowires with applications in nano-circuitry. Short, biologically inspired self-assembling peptide scaffolds derived from natural fibrous proteins with known three-dimensional structure may provide a viable approach towards the rational design of inorganic nanowires.