Dresden 2011 – scientific programme

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CPP: Fachverband Chemische Physik und Polymerphysik

CPP 39: Colloids and Complex Liquids II - Dynamics and Mechanical Properties

CPP 39.7: Talk

Thursday, March 17, 2011, 12:00–12:15, ZEU 222

The effective hydrodynamic radius of single DNA-grafted colloids as measured by fast Brownian motion analysis — •Olaf Ueberschär, Carolin Wagner, Tim Stangner, Christof Gutsche, and Friedrich Kremer — Universität Leipzig

Optical tweezers accomplished with fast position detection enable one to carry out Brownian motion analysis of single DNA-grafted (grafting density: ~1000 molecules per particle, molecular weight: 4000 bp) colloids in media of varying NaCl concentration. By that the effective hydrodynamic radius of the colloid under study is determined and found to be strongly dependent on the conformation of the grafted DNA chains. Our results compare well both with recent measurements of the pair interaction potential between DNA-grafted colloids (Kegler et al. Phys Rev Lett 2008;100:118302) and with microflu-idic studies (Gutsche et al. Microfluid Nanofluid 2006;2:381-386). The observed scaling of the brush height with the ion concentration is in full accord with the theoretical predic-tions by Pincus, Birshtein and Borisov.