Programming DNA origami assembly for shape-resolved nanomechanical imaging labels.

Atomic force microscopy (AFM)-based nanomechanical imaging provides a high-resolution approach for imaging biomolecules with nanometer resolution. Nevertheless, the lack of appropriate nanomechanical labels poses a limit to biological applications. Here, we describe how to generate a set of shape-resolved nanomechanical labels by exploiting self-assembled DNA origami technology. By designing 'mediator' strands that can hybridize with both the origami shapes and the target DNA, these origami shape IDs can be used to site-specifically label genomic DNA with high efficiency and high throughput. When DNA origami shape IDs are used to label target sequences containing two single-nucleotide polymorphisms (SNPs), this approach is capable of differentiating adjacent labeling sites separated by only 30 nucleobases (~10 nm) under AFM imaging. This resolution is a threefold improvement of that which can be obtained with imaging-based genotyping using super-resolution imaging. We further demonstrate how to use origami shape IDs for high-resolution genotyping of SNPs in disease-associated genes in patients. The entire protocol takes ~2 d to complete.