8th Liquid Matter Conference September 6-10, 2011 Wien, Austria ...

Wed 711:10-14:00P5.97Connecting sticky ends: numerical study ofDNA-mediated colloidal interactions and phase behaviorMirjam Leunissen 1 and Daan Frenkel 21 FOM Institute AMOLF, Science Park 104, 1098 XG, Amsterdam, Netherlands2 University of Cambridge, Cambridge, NetherlandsOver the past decade, surface functionalization with DNA ’sticky ends’ has been actively investigatedas a method for guiding the self-assembly of nano- and micrometer-sized particles intocomplex larger-scale structures. However, progress has been hampered by the lack of quantitativeunderstanding of the DNA-mediated interactions. We present results of Monte Carlo simulationsthat provide explicit expressions for the pair-interaction as a function of the DNA grafting density,the binding strength of the sticky ends and the size of the particles. Based on the calculatedinteraction potentials, we expect that gas-liquid coexistence only occurs for particles with radiismaller than a few tens of nanometers, which may explain the experimentally observed differencesin crystallization behavior between nanoparticle systems and micrometer-sized colloids. Wealso highlight the (under-appreciated) role that entropic effects play in the interaction between thesurface-tethered DNA sticky ends or, more generally, any tethered binding group. The entropiccontributions have a magnitude similar to the bulk hybridization free energy and they can thusconsiderably change the effective tethered sticky-end binding strength. The presented method andresults should provide direct guidelines for the rational design of new self-assembling materialswith DNA as a ’smart glue’. Moreover, the same fundamental insights apply to any other systemwith interactions mediated by tethered binding groups, for instance in the area of biorecognitionand drug targeting.97