title: Direct measurements of DNA-mediated colloidal interactions and their quantitative modeling.
abstract: DNA bridging can be used to induce specific attractions between small particles, providing a highly versatile approach to creating unique particle-based materials having a variety of periodic structures. Surprisingly, given the fact that the thermodynamics of DNA strands in solution are completely understood, existing models for DNA-induced particle interactions are typically in error by more than an order of magnitude in strength and a factor of two in their temperature dependence. This discrepancy has stymied efforts to design the complex temperature, sequence and time-dependent interactions needed for the most interesting applications, such as materials having highly complex or multicomponent microstructures or the ability to reconfigure or self-replicate. Here we report high-spatial resolution measurements of DNA-induced interactions between pairs of polystyrene microspheres at binding strengths comparable to those used in self-assembly experiments, up to 6 k(B)T. We also describe a conceptually straightforward and numerically tractable model that quantitatively captures the separation dependence and temperature-dependent strength of these DNA-induced interactions, without empirical corrections. This model was equally successful when describing the more complex and practically relevant case of grafted DNA brushes with self-interactions that compete with interparticle bridge formation. Together, our findings motivate a nanomaterial design approach where unique functional structures can be found computationally and then reliably realized in experiment.
authors: Department of Chemical and Biomolecular Engineering, University of Pennsylvania, Philadelphia, PA 19104, USA.
authors: W Benjamin
authors: WB
authors: Rogers
authors: John C
authors: JC
authors: Crocker
mesh_terms: D000465:Algorithms; D003102:Colloids / Q000737:chemistry*; D003198:Computer Simulation; D004247:DNA / Q000737:chemistry*; D008863:Microspheres; D008956:Models, Chemical; D049329:Nanostructures / Q000737:chemistry; D009690:Nucleic Acid Conformation; D011137:Polystyrenes / Q000737:chemistry; D013696:Temperature; D013816:Thermodynamics; D013997:Time Factors
chemical_list: D003102:Colloids; D011137:Polystyrenes; D004247:DNA