Fluorescence amplification in self-assembled organic nanoparticles by excitation energy migration and transfer

The self-assembly of a low molecular weight organic chromophore occurs upon reprecipitation in water and yields 120 nm wide disk-like nanoparticles (NPs), as shown by fluorescence correlation spectroscopy (FCS) and atomic force microscopy (AFM). The NPs are able to incorporate perylene molecules previously present in water at nanomolar concentrations, thus switching ON and sensitizing their fluorescence. The doped NPs display a very high brightness as a result of their significant fluorescence quantum yield (up to 48%), the cumulated molecular absorbance, and the light-harvesting process. Fluorescence polarization spectroscopy also reveals that the efficiency of the donor-to-acceptor energy transfer process is amplified by a donor-to-donor excitation energy migration. © 2010 American Chemical Society.