Selective, Controllable, and Reversible Aggregation of Polystyrene Latex Microspheres via DNA Hybridization

The directed three dimensional self-assembly of microstructures and nanostructures through the selective hybridization of DNA is the focus of great interest toward the fabrication of new materials. Single stranded DNA is covalently attached to polystyrene latex microspheres and functions as a ``smart Velcro'' by only bonding to another strand of DNA of complementary sequence. The attached DNA increases the charge stabilization of the microspheres and allows controllable aggregation of microspheres by hybridization of complementary DNA sequences. The process is reversible by heating, with a characteristic ``aggregate dissociation temperature'' that is dependent on salt concentration, and the evolution of aggregate dissociation with temperature is observed with optical microscopy.