title: Comparative analysis of viscosity of complex liquids and cytoplasm of mammalian cells at the nanoscale.
abstract: We present a scaling formula for size-dependent viscosity coefficients for proteins, polymers, and fluorescent dyes diffusing in complex liquids. The formula was used to analyze the mobilities of probes of different sizes in HeLa and Swiss 3T3 mammalian cells. This analysis unveils in the cytoplasm two length scales: (i) the correlation length ξ (approximately 5 nm in HeLa and 7 nm in Swiss 3T3 cells) and (ii) the limiting length scale that marks the crossover between nano- and macroscale viscosity (approximately 86 nm in HeLa and 30 nm in Swiss 3T3 cells). During motion, probes smaller than ξ experienced matrix viscosity: η(matrix) ≈ 2.0 mPa·s for HeLa and 0.88 mPa·s for Swiss 3T3 cells. Probes much larger than the limiting length scale experienced macroscopic viscosity, η(macro) ≈ 4.4 × 10(-2) and 2.4 × 10(-2) Pa·s for HeLa and Swiss 3T3 cells, respectively. Our results are persistent for the lengths scales from 0.14 nm to a few hundred nanometers.
authors.affiliation: Department of Soft Condensed Matter, Institute of Physical Chemistry PAS, Kasprzaka 44/52 01-224 Warsaw, Poland.
authors.forename: Tomasz
authors.initials: T
authors.lastname: Kalwarczyk
authors.forename: Natalia
authors.initials: N
authors.lastname: Ziebacz
authors.forename: Anna
authors.initials: A
authors.lastname: Bielejewska
authors.forename: Ewa
authors.initials: E
authors.lastname: Zaboklicka
authors.forename: Kaloian
authors.initials: K
authors.lastname: Koynov
authors.forename: Jedrzej
authors.initials: J
authors.lastname: Szymański
authors.forename: Agnieszka
authors.initials: A
authors.lastname: Wilk
authors.forename: Adam
authors.initials: A
authors.lastname: Patkowski
authors.forename: Jacek
authors.initials: J
authors.lastname: Gapiński
authors.forename: Hans-Jürgen
authors.initials: HJ
authors.lastname: Butt
authors.forename: Robert
authors.initials: R
authors.lastname: Hołyst
mesh_terms: D016475:3T3 Cells; D000818:Animals; D002460:Cell Line; D003593:Cytoplasm / Q000378:metabolism*; D004058:Diffusion; D006367:HeLa Cells; D006801:Humans; D051379:Mice; D008823:Micelles; D008970:Molecular Weight; D053758:Nanoparticles / Q000737:chemistry; D036103:Nanotechnology / Q000379:methods*; D011108:Polymers / Q000737:chemistry; D011137:Polystyrenes / Q000737:chemistry; D011312:Pressure; D014783:Viscosity
chemical_list: D008823:Micelles; D011108:Polymers; D011137:Polystyrenes