Colloids dragged through a polymer solution: Experiment, theory, and simulation.
We present microrheological measurements of the drag force on colloids pulled through a solution of lambda-DNA (used here as a monodisperse model polymer) with an optical tweezer. The experiments show a drag force that is larger than expected from the Stokes formula and the independently measured viscosity of the DNA solution. We attribute this to the accumulation of DNA in front of the colloid and the reduced DNA density behind the colloid. This hypothesis is corroborated by a simple drift-diffusion model for the DNA molecules, which reproduces the experimental data surprisingly well, as well as by corresponding Brownian dynamics simulations.
Gutsche
Christof
C
Institut für Experimentalphysik I, Universität Leipzig, 04103 Leipzig, Germany.
Kremer
Friedrich
F
Krüger
Matthias
M
Rauscher
Markus
M
Weeber
Rudolf
R
Harting
Jens
J
D002627:Chemistry, Physical / Q000379:methods*; D003102:Colloids / Q000737:chemistry*; D004247:DNA / Q000737:chemistry; D004058:Diffusion; D015233:Models, Statistical; D008970:Molecular Weight; D009038:Motion; D052898:Optical Tweezers; D011108:Polymers / Q000737:chemistry*; D012212:Rheology; D012996:Solutions; D012997:Solvents / Q000737:chemistry
D003102:Colloids; D011108:Polymers; D012996:Solutions; D012997:Solvents; D004247:DNA