Cellulose-biotemplated silica nanowires coated with a dense gold nanoparticle layer

Cellulose nanocrystals, which can be isolated from natural cellulose fibres by controlled acid hydrolysis, are promising biomolecule templates for the fabrication of hierarchical organised materials. In this work, we addressed the problem of gold deposition on cellulose and silica-coated cellulose nanocrystals to form metal nanowires. Nanostructures consisting of a dielectric core with a thin goldlayer show interesting optical properties. The gold nanoparticles could be attached to the surface of the biotemplated silica nanowires through functionalisation with amine-groups. They formed a gold shell by the addition of weak reducing agents. The fabricated cellulose nanocrystals, silica nanowires and gold shell nanowires were characterised by transmission electron microscopy and ultraviolet and visible spectroscopy. The TEM results and the optical absorption measurements in the ultraviolet and visible range showed a successful deposition of the metal particles on the silica nanowires. The fabrication of size-controlled metal nanowires using cellulose nanocrystals as biomolecular templates might offer a facile route to design gold nanowires with different sizes and unique optical properties.