Synthesis of NaYF4:Nd@NaLuF4@SiO2@PS colloids for fluorescence imaging in the second biological window☆

Abstract Nd doped nanoparticles is commonly used as bioimaging agents but presents poor stability. Here, a polymer coating is applied to NaYF 4 :Nd nanoparticles using a versatile step-by-step coating strategy. The as-synthesized NaYF 4 :Nd@NaLuF 4 @SiO 2 @PS colloids show good stability in various polar solvent and are very stable in water at least for 6 months. These NaYF 4 :Nd@NaLuF 4 @SiO 2 @PS colloids can exhibit strong down converting photoluminescence when excited by 808 nm lasers. Moreover, these NaYF 4 :Nd@NaLuF 4 @SiO 2 @PS colloids accumulate in liver of mice when used as bio-imaging agents, which exhibit strong fluorescence luminescence in NIR II window.