Periodically Patterned Au-TiO₂ Heterostructures for Photoelectrochemical Sensor

Periodically patterned Au nanorods in TiO₂ nanocavities (Au NRs@TiO₂) were fabricated via magnetron sputtering followed by a thermal dewetting process. This innovative Au NRs@TiO₂ heterostructure was used as a plasmonic sensing platform for photoelectrochemical detection of glucose and lactose. This Au NRs@TiO₂ patterned heterostructure possesses superior sensing properties to other Au nanoparticle-based sensors because (i) localized surface plasmon resonance (LSPR) generated at Au/TiO₂ interfaces enhanced sensitivity of glucose (lactose) amperometric detection; (ii) periodic Au nanocrystals in TiO₂ nanocavities accelerated charge separation and transfer rate, especially under monochromatic blue light irradiation; (iii) discrete planar architectures comprising Au NRs immobilized on TiO₂ substrates significantly improved stability and reusability of the sensors. A low detection limit of 1 μM (10 μM) and a high sensitivity of 812 μA mM^-1 cm^-2 (270 μA mM^-1 cm^-2) were achieved on the Au NRs@TiO₂ heterostructures for glucose (lactose) detection without the addition of enzymes. Good selectivity and superb stability over more than 8 weeks was also demonstrated using these Au NRs@TiO₂ heterostructures for glucose (lactose) detection. Additionally, this cost-efficient technique can be easily extended to other photoelectrochemical sensing systems when considering the combination of sensing and visible or infrared light source enhancement.