Nanoparticles can be the bricks for constructing materials from the ground up, with DNA linkers as the mortar that holds them together. Because of the difficulty of attaching DNA strands to nanoparticles, the approach has so far been limited to a few types of nanoparticles. Chad A. Mirkin and coworkers at Northwestern University have devised a general approach that expands the types of nanoparticles that can be used with DNA-guided assembly (Nat. Mater. 2013, DOI: 10.1038/nmat3647). Mirkin and coworkers take advantage of the fact that most nanoparticles are capped with hydrophobic ligands. They coat those ligands with an azide-containing amphiphilic polymer. They use DNA that contains a strained octyne ring and attach the DNA to the polymer via azide-alkyne cycloaddition. The nanoparticles are then ready to be used as building blocks in DNA-based colloidal crystallization. The researchers make colloidal lattices with various nanoparticles, including CdSe/ZnS core-shell quantum dots, gold nanoparticles, iron oxide nanoparticles, and platinum nanoparticles. They control the size and crystal packing of the lattices by changing the radius of the nanoparticles and the length of the DNA linkers.