Self-assembled peptide beads used as a template for ordered gold nanoparticle superstructures

Using peptide-based materials to tailor self-assembled, nano-scaled hybrid materials with potentially high biocompatibility/biodegradability is gaining importance in developing a broad range of new applications, in areas such as diagnostics and medicine. Here, we investigated how the self-assembly ability of amphiphilic peptides can be used to create organized inorganic materials, i.e. gold nanoparticles. A bead-forming, purely peptidic amphiphile Ac-[K(Ac)](3)-[W-l](3)-W-NH2, containing acetylated (Ac) L-lysine (K), L-tryptophan (W) and D-leucine (1), was C-terminally modified with a L-cysteine (C) and linked to gold nanoparticles. Subsequent peptide-driven self-assembly of the peptide-coated gold nanoparticles with increasing water content led to controlled aggregation of the gold-core micelles, forming composite peptide-gold superstructures. The individual gold nanoparticles did not agglomerate but were separated from each other by a peptide film within the composite material, as revealed by electron microscopy studies. Structural investigation on 2D template-stripped gold demonstrated the ability of the peptides to form self-assembled monolayers. Structural elements of beta-turns and weak hydrogen bonding of the hydrophobic moiety of the peptide were evident, thereby suggesting that the secondary structure remains intact. (C) 2013 Elsevier B.V. All rights reserved.