Fabrication of quantum dot-immobilized Y 2 O 3 microspheres with effective photoluminescence for cancer radioembolization therapy.

Microspheres composed of Y-containing materials are effective agents for cancer radioembolization therapy using β-rays. The distribution and dynamics of these microspheres in tissues can be easily determined by providing the microspheres with an imaging function. In addition, the use of quantum dots will enable the detection of microspheres at the individual particle level with high sensitivity. In this study, core - shell quantum dots were bound to chemically modified yttria microspheres under various conditions, and the effect of reaction conditions on the photoluminescence properties of the microspheres was investigated. The quantum dots were immobilized on the surfaces of the microspheres through dehydration - condensation reactions between the carboxy groups of quantum dots and the amino groups of silane-treated microspheres. As the reaction time increased, the photoluminescence peak blue shifted, and the photoluminescence intensity and lifetime decreased. Therefore, a moderate period of the immobilization process was optimal for imparting effective photoluminescence properties. This study is expected to facilitate particle-level tracking of microsphere dynamics in biological tissues for the development of minimally invasive cancer radiotherapy of deep-seated tumors.