Use of the self-assembly of tyrosine-containing bolaamphiphile molecules as a reactive template for metal deposition

A novel bolaamphiphile molecule exploiting biochemical functionality was synthesized and self-assembled to form a spherical reactive template for the preparation of composite metallic nanoshells. A tyrosine-containing bolaamphiphile, bis(N-alpha-amido-tyrosine)-1,7-heptane dicarboxylate, self-assembles instantaneously in an aqueous solution forming nanoscaled spheres. Instantaneous assembly of the prepared bolaamphiphile is driven by the polarity and stacking of phenol moiety in tyrosine. Through spectroscopic investigations, molecular interactions such as hydrogen bonding and pi-pi stacking of aromatic rings were found to induce the self-assembly of the molecule. The phenol moiety of tyrosine is exposed to the surface of the spherical assembly due to its polarity. Under basic conditions, the spherical assembly was used as a reactive template on which metal clusters were deposited. The surface-exposed phenol group reduced the silver ions to solid clusters, and these clusters were further exploited as catalysts for the gold layer deposition. This study illustrates that the bolaamphiphilic molecule with designed biochemical functionality provides a facile way to prepare supramolecular structures with chemical activity. (c) 2012 Elsevier B.V. All rights reserved.