Filtration Shell Mediated Power Density Independent Orthogonal Excitations-Emissions Upconversion Luminescence.

Lanthanide doped core-multishell structured NaGdF4:Yb,Er@NaYF4:Yb@NaGdF4:Yb,Nd@NaYF4@NaGdF4:Yb,Tm@NaYF4 nanoparticles with power-density independent orthogonal excitations-emissions upconversion luminescence (UCL) were fabricated for the first time. The optical properties of these core-multishell structured nanoparticles were related to the absorption filtration effect of the NaGdF4:Yb,Tm layer. By tuning the thickness of the filtration layer, the nanoparticles can exhibit unique two independent groups of UCL: Tm(3+) prominent UV/blue (UV=ultraviolet) UCL under the excitation at 980 nm and Er(3+) prominent green/red UCL under the excitation at 796 nm. The filtration-shell mediated orthogonal excitations-emissions UCL are power-density independent. As a proof of concept, the core-multishell nanoparticles are used in multi-dimensional security design and imaging-guided combined photodynamic therapy and chemotherapy.