title: Influence of fluorescent labelling of polystyrene particles on phagocytic uptake, surface hydrophobicity, and plasma protein adsorption.
abstract: OBJECTIVE
  To investigate the influence of fluorescent labelling of polystyrene particles on phagocytic uptake, surface hydrophobicity and protein adsorption.
  
  
  METHODS
  Phagocytic uptake was analysed using chemiluminescence. Hydrophobicity was quantified by adsorption measurements of a hydrophobic dye. Protein adsorption was evaluated by two-dimensional electrophoresis.
  
  
  RESULTS
  Commercially available fluorescently labelled particles showed marked differences when compared to unlabelled particles: phagocytic uptake and surface hydrophobicity of labelled particles were diminished. Also the plasma protein adsorption pattern was found to be different from the unlabelled particles: for example, the amount of fibrinogen adsorbed was strongly reduced on the labelled particles. On the other hand, some unknown proteins could be detected on the fluorescently marked particles. In contrast, plain polystyrene particles and labelled ones could be successfully synthesised by Paulke which did not show any considerable differences in phagocytic uptake, surface hydrophobicity and protein adsorption. Polysorbate 20 added as stabilizer to particle suspensions led to completely different behaviour of the particles: the particles showed altered protein adsorption patterns, dominated by immunoglobulins and especially by apolipoproteins. Furthermore, these particles were not phagocytized at all.
  
  
  CONCLUSIONS
  Surface hydrophobicity and phagocytic uptake in vitro as well as the interactions with plasma proteins of commercially available polystyrene particles were strongly affected by fluorescent labelling. Particles synthesised by Paulke remained unchanged after labelling. The results show the importance of thorough surface characterization for using particles in test systems in vitro and in vivo.
authors.affiliation: Department of Pharmaceutics, Biopharmaceutics & Biotechnology, The Free University of Berlin.
authors.forename: R H
authors.initials: RH
authors.lastname: Müller
authors.forename: D
authors.initials: D
authors.lastname: Rühl
authors.forename: M
authors.initials: M
authors.lastname: Lück
authors.forename: B R
authors.initials: BR
authors.lastname: Paulke
mesh_terms: D000327:Adsorption; D001798:Blood Proteins / Q000737:chemistry*; D002460:Cell Line; D004591:Electrophoresis, Polyacrylamide Gel; D005456:Fluorescent Dyes; D006801:Humans; D010316:Particle Size; D010587:Phagocytosis; D011136:Polysorbates; D011137:Polystyrenes / Q000737:chemistry* / Q000378:metabolism; D012235:Rhodamines; D013499:Surface Properties
chemical_list: D001798:Blood Proteins; D005456:Fluorescent Dyes; D011136:Polysorbates; D011137:Polystyrenes; D012235:Rhodamines; C029773:rhodamine B