We are developing DNA nanostructure–based nanotags as versatile tools for electron microscopy (EM) imaging. Owing to their precise programmability, defined geometries, biomolecular conjugation capacity, and compatibility with cryogenic sample preparation, these nanotags hold great promise for multiplexed EM visualization of complex biological systems. In parallel, we are designing DNA origami scaffolds integrated with site-specific incorporation of unnatural amino acids (UAA) to precisely define the orientation and spatial arrangement of antigen display. This programmable approach enables systematic investigation of multivalent antigen–antibody interactions and provides structural insights into viral assemblies such as dengue and HIV.