Dresden 2006 – wissenschaftliches Programm

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CPP: Chemische Physik und Polymerphysik

CPP 26: POSTER Dynamics and Diffusion

CPP 26.10: Poster

Donnerstag, 30. März 2006, 17:00–19:00, P2

The interaction between single colloids grafted with DNA of varying molecular weight as measured by optical tweezers — •K. Kegler¹, C. Gutsche¹, M. Salomo², J. Reimuth¹, V. Skokov¹, and F. Kremer¹ — ¹Institute for Experimental Physics I, University of Leipzig, Linnéstr.5, 04103 Leipzig — ²ceLectra, Deutscher Platz 5, 04103 Leipzig

Optical tweezers are used to measure the interaction forces between single blank and DNA-grafted colloids (length of DNA: 1000 base-pairs (bp), 2000 bp, 3000 bp, 4000 bp). The forces are measured in two directions, parallel and perpendicular to the axis between the two colloids under study. For blank colloids on approach repulsive forces are observed which depend in their force and range on the ionic strength of the surrounding medium. At a certain separation the colloids jump into contact. This is not the case in deionised water. DNA-grafted colloids behave in principle similarly but with a softer interaction potential. Moving DNA-grafted colloids which are in contact perpendicularly to their central axis results in stick-slip phenomena. Their intensity and dynamics are studied for different molecular weights of the DNA and in media of varying ionic concentration.