Mesoporous silica-coating of gold nanorods by a templated method

Mesoporous silica with tunable morphology, pore architecture and crystallinity was successfully coated on gold nanorods by a template method based on the self-assembly of anionic surfactants with inorganic precursors. Varying the molar ratio of acid to surfactant or the volume ratio of ethanol to water resulted in products with different shapes, ranging from rods to spherical particles. A phase transformation of the mesoporous silica shell from 2D hexagonal to 3D cubic occurred due to an increased acid/surfactant ratio. Increasing the proportion of ethanol also gradually caused the disappear of 2D hexagonal symmetry of silica. The charge density matching relationship and solution polarity induced by varied reaction composition are believed to be the driving forces for the change of morphology and mesostructure.