title: Impact of polymer surface characteristics on the microrheological measurement quality of protein solutions - A tracer particle screening.
abstract: Microrheological measurements prove to be suitable to identify rheological parameters of biopharmaceutical solutions. These give information about the flow characteristics but also about the interactions and network structures in protein solutions. For the microrheological measurement tracer particles are required. Due to their specific surface characteristic not all are suitable for reliable measurement results in biopharmaceutical systems. In the present work a screening of melamine, PMMA, polystyrene and surface modified polystyrene as tracer particles were investigated at various protein solution conditions. The surface characteristics of the screened tracer particles were evaluated by zeta potential measurements. Furthermore each tracer particle was used to determine the dynamic viscosity of lysozyme solutions by microrheology and compared to a standard. The results indicate that the selection of the tracer particle had a strong impact on the quality of the microrheological measurement dependent on pH and additive type. Surface modified polystyrene was the only tracer particle that yielded good microrheological results for all tested conditions. The study indicated that the electrostatic surface charge of the tracer particle had a minor impact than its hydrophobicity. This characteristic was the crucial surface property that needs to be considered for the selection of a suitable tracer particle to achieve high measurement accuracy.
authors.affiliation: Institute of Process Engineering in Life Sciences, Section IV: Biomolecular Separation Engineering, Karlsruhe Institute of Technology (KIT), Karlsruhe, Germany.
authors.forename: Katharina Christin
authors.initials: KC
authors.lastname: Bauer
authors.affiliation: Institute of Process Engineering in Life Sciences, Section IV: Biomolecular Separation Engineering, Karlsruhe Institute of Technology (KIT), Karlsruhe, Germany.
authors.forename: Marie-Therese
authors.initials: MT
authors.lastname: Schermeyer
authors.affiliation: Institute of Process Engineering in Life Sciences, Section IV: Biomolecular Separation Engineering, Karlsruhe Institute of Technology (KIT), Karlsruhe, Germany.
authors.forename: Jonathan
authors.initials: J
authors.lastname: Seidel
authors.affiliation: Institute of Process Engineering in Life Sciences, Section IV: Biomolecular Separation Engineering, Karlsruhe Institute of Technology (KIT), Karlsruhe, Germany. Electronic address: juergen.hubbuch@kit.edu.
authors.forename: Jürgen
authors.initials: J
authors.lastname: Hubbuch
mesh_terms: D006863:Hydrogen-Ion Concentration; D057927:Hydrophobic and Hydrophilic Interactions; D009113:Muramidase / Q000737:chemistry*; D011108:Polymers / Q000737:chemistry*; D019904:Polymethyl Methacrylate / Q000737:chemistry; D011137:Polystyrenes / Q000737:chemistry; D011506:Proteins / Q000737:chemistry*; D012212:Rheology / Q000379:methods*; D012996:Solutions; D055672:Static Electricity; D013499:Surface Properties; D014227:Triazines / Q000737:chemistry; D014783:Viscosity
chemical_list: D011108:Polymers; D011137:Polystyrenes; D011506:Proteins; D012996:Solutions; D014227:Triazines; D019904:Polymethyl Methacrylate; D009113:Muramidase; C011907:melamine
keywords: Dynamic viscosity; Hydrophobicity; Microrheology; Polymer–protein interaction; Tracer particle