TY - JOUR A1 - Hennig, Andreas A1 - Hatami, Soheil A1 - Spieles, Monika A1 - Resch-Genger, Ute T1 - Excitation energy migration and trapping on the surface of fluorescent poly(acrylic acid)-grafted polymer particles JF - Photochemical & photobiological sciences N2 - The surface of poly(methyl methacrylate) particles with different amounts of a grafted layer of poly(acrylic acid) was labeled with varying degrees of an amino derivative of fluorescein isothiocyanate. The resulting fluorescent polymer particles were analyzed by absorption spectroscopy and by steady-state and time-resolved fluorescence spectroscopy including measurements of the fluorescence anisotropy. The combined results indicate that the overall decrease in fluorescence intensity with increasing surface concentrations of the fluorophore can be traced back to the formation of non-fluorescent aggregates. A mechanism is proposed, in which the excitation energy migrates between identical fluorophores until it is transferred to non-fluorescent aggregates acting as an energy trap. Increases in the surface fluorophore concentration increase both the probability for energy transfer between identical fluorophores and the probability for energy transfer to non-fluorescent aggregates. Furthermore, we suggest that this mechanism also applies to fluorescent protein conjugates and rationalizes the nonlinear dependence of the fluorescence emission on the labeling density. PY - 2013 DO - https://doi.org/10.1039/c2pp25364j SN - 1474-905X SN - 1474-9092 VL - 12 IS - 5 SP - 729 EP - 737 PB - Royal Society of Chemistry CY - Cambridge AN - OPUS4-28522 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -