Three-dimensional DNA nanostructures for colorimetric assay of nucleic acids.

Here, we propose a kinetically controlled DNA self-assembly pathway based on exponential hairpin assembly (EHA) to obtain a novel DNA network-like structure. This method is very simple over existing DNA self-assembly techniques, only requiring the input of four DNA hairpins to form dendritic nanostructures. AFM imaging reveals the expected dendritic nanostructures, and they interweave to form a regular nanoporous structure that has a mesh size ranging from 200 to 400 nm. The network-like structure is very large and almost isotropic along all directions. At present, so large and regular self-assembly nanomaterials are very rare. The DNA network can potentially be used as a nanoporous material and a general signal carrier for bioanalytical application. As a model, the DNA nanomaterial has been successfully applied to detect nucleic acids coupled with the AuNP colorimetric strategy with a detection limit of 25 pM for the naked eye within 15 min.