Gold nanorods embedded in titanium oxide film for sensing applications.

We succeeded in fabricating a localized surface plasmon resonance (LSPR) sensor comprising gold nanorods (AuNRs) that were immobilized in a thin film of titanium oxide. First, AuNRs were electrostatically immobilized onto a glass substrate; then, dip-coating of the thin titanium oxide film was carried out. These procedures were realized to prepare well-dispersed AuNRs onto a substrate with a uniform titanium oxide layer. The titanium-oxide-coated AuNRs could retain their rod-shape, even after annealing at 300°C for 1 h, since titanium oxide effectively prevented any heat-induced shape change of the AuNRs. The peak shifts of the plasmon bands of the immobilized AuNRs were observed with the change in the environmental refractive indices, even after titanium oxide coating. In addition, the as-prepared titanium oxide layer exhibited photocatalytic activity for methylene blue dye molecule under UV irradiation. This suggests that the titanium-oxide-coated AuNRs can conveniently be reusable even for unwanted contamination with organic compounds, due to their photocatalytic decomposition with UV light.