Evaluation of electron radiation damage to green fluorescent protein.

Green fluorescent protein (GFP) emits light when irradiated by not only light but also electrons. This electron-induced light emission called cathodoluminescence (CL) can be used to realize a high-resolution light emission microscopy based on the irradiation of a very narrow electron beam. To implement CL mapping in life sciences the investigation of the damage resistance of GFP to electron irradiation needs to be clarified. In this study, we investigated the electron radiation damage to GFP by analyzing the change in the CL intensity during electron beam irradiation. Since some of the CL spectra changed in shape during electron irradiation, the change in the intensity between 585 and 605 nm were measured. The characteristic doses at different electron current densities and electron energies were investigated. The characteristic dose of EGFP is much larger than that of coronene, which is one of the stable organic molecules against the electron beam irradiation.