Temperature-Programmed Assembly of DNA:Au Nanoparticle Bioconjugates

Temperature has been used to control the order of assembly events in a solution containing three types of particles to be linked by two different sets of complementary DNA. At higher temperatures, only the duplexes having higher thermal stability were able to form. By starting at a high temperature and then cooling the sample, these more stable sequences hybridized first, followed by the less stable sequences at lower temperatures. Because of the use of thiolated DNA on Au particles, some loss and exchange of the DNA strands occurred at elevated temperatures. However, since cooperativity favors the "correct" assemblies, Au−S bond lability did not appreciably impact the order of the assembly process. Temperature programming combines the selectivity of DNA-directed assembly with the ability to control the order in which several complementary strands hybridize in a common solution and could contribute to the synthesis of more complex nanostructured materials.