Kinetic Reconstruction of DNA-Programed Plasmonic Metal Nanostructures with Predictable Shapes and Optical Properties.

It is desirable to rationally engineer plasmonic metal nanostructures with sets of structural parameters that lead to specific functions. However, it is still challenging to predict the nanostructured outcome of a synthesis reaction by design because not only the exact kinetic path for the structural evolution is very complicated but also the relationships among various functional and structural parameters are often tangled. It is necessary to deconvolute the structure-function relationships and understand the co-evolution of structural and functional parameters as the nanostructures grow. DNA is a programable biomolecular capping ligand that was shown to be capable of precisely controlling the evolution of metal nanostructures. In this study, we systematically analyzed the evolution of two structural parameters and several functional parameters in the growth of Au-Ag nanostructures controlled by two DNA sequences. We deconvoluted the contributions from the two structural parameters in affecting the plasmonic properties in different kinetic and geometric domains. We further designed new nanostructures by exchanging DNA sequences in the growth environment, which also changed their evolution pathways. The resulting structural and functional parameters could be predictively tuned by the timing of the exchange. This study demonstrates the powerful toolbox provided by programable biomolecules in producing novel nanostructures in a predictable manner. It also shows that by understanding the kinetic evolution of the structural parameters and their relationships with the function parameters, it is possible to design the precise combinations of structural and functional parameters in the nanostructured products.