title: Viscoelastic properties of semiflexible filamentous bacteriophage fd.
abstract: The cytoskeletal protein filament F-actin has been treated in a number of recent studies as a model physical system for semiflexible filaments. In this work, we studied the viscoelastic properties of entangled solutions of the filamentous bacteriophage fd as an alternative to F-actin with similar physical parameters. We present both microrheometric and macrorheometric measurements of the viscoelastic storage and loss moduli, G'(f ) and G"(f ), respectively, in a frequency range 0.01<f<4 Hz, for fd solutions in the concentration range 5<c<15 mg/ml. The onset of a narrow and slanted plateaulike region of G'(f ) is located at around 2 Hz. The variation of the plateau modulus with concentration obeys a power law G(')(N) approximately c(1.4+/-0.3), similar to that found for entangled solutions of F-actin. In the low-frequency regime, the frequency dependence of the viscoelastic moduli can be described by power laws G'(f ) approximately f(0.9-1.2) and G"(f ) approximately f(0.7-0.9), which deviate significantly from the simple theoretical predictions of G'(f ) approximately f(2) and G"(f ) approximately f(1). The latter behavior cannot yet be understood within the framework of current theories of semiflexible filament networks. For the dynamic viscosity at the low shear rate limit, a concentration dependence of eta(0) approximately c(2.6) was found. Finally, a linear scaling of the terminal relaxation time with concentration, tau(d) approximately c, was observed.
authors.affiliation: Technische Universität München, Institut für Biophysik E22, James-Franck- Strasse, D-85747 München, Germany.
authors.forename: F G
authors.initials: FG
authors.lastname: Schmidt
authors.forename: B
authors.initials: B
authors.lastname: Hinner
authors.forename: E
authors.initials: E
authors.lastname: Sackmann
authors.forename: J X
authors.initials: JX
authors.lastname: Tang
mesh_terms: D008841:Actin Cytoskeleton / Q000737:chemistry / Q000648:ultrastructure; D004548:Elasticity; D017912:Inovirus / Q000737:chemistry* / Q000648:ultrastructure; D008854:Microscopy, Electron; D018583:Pliability; D012212:Rheology; D012996:Solutions; D014783:Viscosity
chemical_list: D012996:Solutions