HiFi molecular transmission via crisscross cooperativity
DNA origami, in which a long scaffold strand is assembled with a large number of short staple strands into parallel arrays of double helices, has proven a powerful method for custom nanofabrication of shapes up to 100 nm in size. However, the scaffold represents about half the mass of an origami, therefore the origami size is restricted by the length of the scaffold. However, it is impractical and prohibitively expensive to scale the length of the scaffold. Here I will discuss a strategy, that we call crisscross ultracooperative assembly, that combines all-or-nothing scaffold-dependent initiation of folding with scaffold-independent growth, therefore allowing for sizes unbounded by the length of the scaffold. A major application will be digital counting of molecular analytes, where each molecular detection event triggers growth of a single filament resolvable by low-cost microscopy. I also will discuss a method we have developed for scalable isolation of ssDNA from dsDNA, which will be enabling for crisscross assembly and other applications of DNA nanotechnology and DNA biotechnology.