title: Encapsulation of hydrophobic dyes in polystyrene micro- and nanoparticles via swelling procedures.
abstract: Aiming at the derivation of a generalized procedure for the straightforward preparation of particles fluorescing in the visible and near-infrared (NIR) spectral region, different swelling procedures for the loading of the hydrophobic polarity-probe Nile Red into nano- and micrometer sized polystyrene particles were studied and compared with respect to the optical properties of the resulting particles. The effect of the amount of incorporated dye on the spectroscopic properties of the particles was investigated for differently sized beads with different surface chemistries, i.e., non-functionalized, amino-modified and PEG-grafted surfaces. Moreover, photostability and leaking studies were performed. The main criterion for the optimization of the dye loading procedures was a high and thermally and photochemically stable fluorescence output of the particles for the future application of these systems as fluorescent labels.
authors.affiliation: BAM Federal Institute for Materials Research and Testing, Richard-Willstaetter-Str. 11, 12489 Berlin, Germany.
authors.forename: Thomas
authors.initials: T
authors.lastname: Behnke
authors.forename: Christian
authors.initials: C
authors.lastname: Würth
authors.forename: Katrin
authors.initials: K
authors.lastname: Hoffmann
authors.forename: Martin
authors.initials: M
authors.lastname: Hübner
authors.forename: Ulrich
authors.initials: U
authors.lastname: Panne
authors.forename: Ute
authors.initials: U
authors.lastname: Resch-Genger