Entropic Colloidal Interactions in Concentrated DNA Solutions

Ritu Verma, J. C. Crocker, T. C. Lubensky, and A. G. Yodh
Phys. Rev. Lett. 81, 4004 – Published 2 November 1998
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Abstract

We explore the entropic interactions between a pair of micron-sized colloidal spheres in DNA solutions. By confining the particles in a line-scanned optical tweezer, we directly measured the functional form of the interaction potential with sub- kBT resolution in samples where the spheres and the polymer coils were of comparable size. The potential is well described by the Asakura-Oosawa depletion model even in the semidilute regime where DNA coils overlap strongly. Its range and depth increase with increasing concentration in a manner consistent with a crossover from a dilute solution of Gaussian coils to the weakly fluctuating semidilute regime dominated by two-point collisions which is unique to semiflexible polymers.

  • Received 9 July 1998

DOI:https://doi.org/10.1103/PhysRevLett.81.4004

©1998 American Physical Society

Authors & Affiliations

Ritu Verma, J. C. Crocker, T. C. Lubensky, and A. G. Yodh

  • Department of Physics and Astronomy, University of Pennsylvania, 209 S. 33rd Street, Philadelphia, Pennsylvania 19104

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Vol. 81, Iss. 18 — 2 November 1998

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