Complex silica composite nanomaterials templated with DNA origami

Abstract

Genetically encoded protein scaffolds often serve as templates for the mineralization of biocomposite materials with complex yet highly controlled structural features that span from nanometres to the macroscopic scale^1-4. Methods developed to mimic these fabrication capabilities can produce synthetic materials with well defined micro- and macro-sized features, but extending control to the nanoscale remains challenging^5,6. DNA nanotechnology can deliver a wide range of customized nanoscale two- and three-dimensional assemblies with controlled sizes and shapes^7-11. But although DNA has been used to modulate the morphology of inorganic materials^12,13 and DNA nanostructures have served as moulds^14,15 and templates^16,17, it remains challenging to exploit the potential of DNA nanostructures fully because they require high-ionic-strength solutions to maintain their structure, and this in turn gives rise to surface charging that suppresses the material deposition. Here we report that the Stöber method, widely used for producing silica (silicon dioxide) nanostructures, can be adjusted to overcome this difficulty: when synthesis conditions are such that mineral precursor molecules do not deposit directly but first form clusters, DNA-silica hybrid materials that faithfully replicate the complex geometric information of a wide range of different DNA origami scaffolds are readily obtained. We illustrate this approach using frame-like, curved and porous DNA nanostructures, with one-, two- and three-dimensional complex hierarchical architectures that range in size from 10 to 1,000 nanometres. We also show that after coating with an amorphous silica layer, the thickness of which can be tuned by adjusting the growth time, hybrid structures can be up to ten times tougher than the DNA template while maintaining flexibility. These findings establish our approach as a general method for creating biomimetic silica nanostructures.