Fluorescence imaging of single molecules in polymer microspheres

We report on far-field fluorescence imaging of single molecules in spherica l polymer microparticles produced from solution by using microdroplet techn iques. The fluorescence photobleaching quantum yields of rhodamine 6G in a common water-soluble polymer (polyvinyl alcohol) are at least five times sm aller, corresponding to proportionally larger average fluorescence signals, than those in ethanolic solvents. This allows for acquisition of multiple images from a single molecule on a time scale of several minutes. We also s how that fluorescent images of single molecules in microspheres can be calc ulated from semiclassic electrodynamics, which may ultimately be useful in retrieving dynamical information from experimental images. Cytometry 36:169 -175, 1999 (C) 1999 Wiley-Liss, Inc.