Upconverting Lanthanide-doped Y2O3 Nanoparticles for Phototherapy

Abstract

Visible-to-UVB upconversion (UC) is a promising technique to treat skin diseases such as Psoriasis. In recent works, the lanthanide Ho3+-Gd3+ couple doped in the NaYF4 host lattice resulted in successful blue-to-UVB UC emission from the Gd3+ (6P7/2) state. This can be used in a topical carrier to treat skin diseases resulting in cost-effective and time-efficient treatment. An alternative host lattice: Y2O3 (yttria) was tested in this work using the Ho3+-Gd3+ and Er3+-Gd3+ blue-to-UVB UC dopant couples. Yttria is known for its excellent thermal and chemical stability. For both lanthanide couples, microcrystalline doped yttria were successfully synthesized and blue-to-UVB UC was realized. Blue-to-UVB UC was furthermore achieved in the Ho3+-Gd3+ doped yttria nanocrystals. It was found that the efficiency of the blue-to-UVB UC of the yttria particles decreases significantly when the particles size is reduced to nanocrystalline. The presented work is the first to realize Ho3+-Gd3+ doped Y2O3 (450 nm) blue-to-UVB (313 nm) upconverting nanoparticles. Further research may help to enhance the UC efficiency.