Synthesis of Nanophosphors for Bioimaging using Electron Beam Excitation

Abstract

Cathodoluminescence (CL) microscopy, which is a combination of optical microscopy and electron microscopy, has the potential to realize multi-color bioimaging with nanoscale spatial resolution. To achieve this biological CL imaging, development of small nanophosphors with similar size to protein molecules and bright CL nanophosphors is indispensable. In this research, we developed nanophosphors for CL bioimaging using laser ablation method and homogeneous precipitation method. The size distribution of laser-ablated nanophosphors was large, and the CL intensity of single nanophosphor with size of a few tens nm was not enough to image. In homogeneous precipitation method, mono-dispersed nanophosphors with size of about 40 nm were obtained with small size distribution. Improvement of CL intensity was also achieved with varying concentration of rare-earth ions, calcination temperature, and addition of co-doing ions.