High-resolution microscopy for biological specimens via cathodoluminescence of Eu- and Zn-doped Y2O3 nanophosphors.

High-resolution microscopy for biological specimens was performed using cathodoluminescence (CL) of Y(2)O(3):Eu, Zn nanophosphors, which have high CL intensity due to the incorporation of Zn. The intensity of Y(2)O(3):Eu nanophosphors at low acceleration voltage (3 kV) was increased by adding Zn. The CL intensity was high enough for imaging even with a phosphor size as small as about 30 nm. The results show the possibility of using CL microscopy for biological specimens at single-protein-scale resolution. CL imaging of HeLa cells containing laser-ablated Y(2)O(3):Eu, Zn nanophosphors achieved a spatial resolution of a few tens of nanometers. Y(2)O(3):Eu, Zn nanophosphors in HeLa cells were also imaged with 254 nm ultraviolet light excitation. The results suggest that correlative microscopy using CL, secondary electrons and fluorescence imaging could enable multi-scale investigation of molecular localization from the nanoscale to the microscale.