Plasmon modulated luminescent modes of upconversion nanoparticle by coupling with AuNR@SiO2 nanostructure

•The upconversion luminescence performance of UCNPs was regulated.•The effect of silica shell thickness on ET in UCNPs was studied.•The effect of surface charge with silica shell on ET in UCNPs was explored. Lanthanide-doped upconversion nanoparticles (UCNPs) can convert near-infrared light into visible light emission, and have attracted more and more interests due to their great potential in ultrasensitive biosensors. However, it is still a huge challenge to manipulate the intensity ratio between different emission lines and realize the modulated up-conversion. In this work, the upconversion luminescence performance of UCNPs was regulated by coupling with Au nanorod-silicon core–shell (AuNR@SiO2) nanostructures. By changing the thickness and surface charge of the silica shell, the influence of the thickness and surface charge on the energy transfer of the UCNPs was explored. It is expected that the up-conversion luminescence effect of this composite nanostructure regulated by plasmons can provide a basis for the extensive exploration of biological detection and sensing applications.