Synthesis and characterization of new bifunctional nanocomposites possessing upconversion and oxygen-sensing properties.

A new type of bifunctional nanocomposites for biomedical applications, upconversion NaY F(4):Y b(3+), Tm(3+) nanoparticles coated with Ru(II) complex chemically doped SiO(2), has been developed by combining the useful functions of upconversion and oxygen-sensing properties into one nanoparticle. NaY F(4):Y b(3+), Tm(3+) nanoparticles were successfully coated with an Ru(II) complex doped SiO(2) shell with a thickness of approximately 30 nm, and the surface of the SiO(2) was functionalized with amines. The obtained nanocomposites exhibited bright blue upconversion emission, and the luminescent emission intensity of the Ru(II) complex in the nanocomposites was sensitive to oxygen. Compared with the simple mixture of Ru(II) complex and SiO(2), the core-shell nanocomposites showed better linearity between emission intensity of Ru(II) complex and oxygen concentrations. These bifunctional nanocomposites may find applications in biochemical and biomedical fields, such as biolabels and optical oxygen sensors, which can measure the oxygen concentrations in biological fluids.