Rare-earth doped particles with tunable infrared emissions for biomedical imaging

The tunability, brightness, and energy efficiencies of infraredemitting rare earth doped nanomaterials are important performance parameters for biomedical imaging applications. In this work, hexagonal phase NaYF₄:Yb³⁺, Ln³⁺ (Ho³⁺, Tm³⁺ and Pr³⁺) was synthesized and optimized using a facile hydrothermal method in the presence of poly(vinylpyrrolidone). Distinct infrared emission peaks were measured at 1185, 1310 and 1475 nm upon excitation at 980 nm. The optical efficiencies of NaYF₄:Yb³⁺, Ln³⁺ at optimal concentrations were measured to quantify the brightness of these particles in comparison to that of NaYF₄:Yb³⁺, Er³⁺ particles. Efficiencies were ranked as Er³⁺>Ho³⁺>Tm³⁺>Pr³⁺.