Counting single Rhodamine 6G dye molecules in organosilicate nanoparticles

► Hybrid nanoparticles are groundbreaking to tailored fluorescent markers. ► We examine organosilicate nanoparticles doped with Rhodamine 6G on a single particle level. ► Fluorescence time traces can be classified according to the number of on-levels. ► We can determine the average number of enclosed dye molecules to about 1.3-1.7.