New York University researchers led by Paul Chaikin have found a way to use synthetic DNA to make molecules that reproduce themselves. The technique gives scientists a tool to create different combinations on the DNA that aren't necessarily available in nature. That opens up billions of possibilities for building completely new materials and even molecular machines. Chaikin and his colleaques reported their results in this week's journal Nature.
NYU scientists have developed artificial structures that can self-replicate, a process that has the potential to yield new types of materials. These structures consist of triple helix molecules containing three DNA double helices. Image courtesy of Nature.
“This is the first step in the process of creating artificial self-replicating materials of an arbitrary composition,” said Paul Chaikin, a professor in NYU’s Department of Physics and one of the study’s co-authors. “The next challenge is to create a process in which self-replication occurs not only for a few generations, but long enough to show exponential growth.”
“While our replication method requires multiple chemical and thermal processing cycles, we have demonstrated that it is possible to replicate not just molecules like cellular DNA or RNA, but discrete structures that could in principle assume many different shapes, have many different functional features, and be associated with many different types of chemical species,” added Nadrian Seeman, a professor in NYU’s Department of Chemistry and a co-author of the study.
DNA tiles The researchers used artificial structures of DNA - so-called DNA tiles - dissolved in water to demonstrate the new process. These tiles are several tens of nanometres in size and consist of compactly folded DNA strands, from which four loose ends with a specific sequence of the bases A, C, G and T protrude. Like a barcode, these sticky ends determine the identity of a tile and ensure that tiles with complementary ends attach to each other: A always adheres to T, and C to G. When joined, the ends of the two tiles together form the characteristic double helix structure.
Sticking The researchers arranged seven tiles with two different identities (for example indicated with the letters X and Y) to form the ‘word’ X-Y-Y-X-Y-X-Y. Subsequently, tiles with complementary sticky ends, X' and Y', spontaneously attached themselves in the right order to this initial structure (X'-Y'-Y'-X'-Y'-X'-Y'). The sticky ends only stick at a lower temperature and so the 'daughter word' was separated from the initial structure by briefly increasing the temperature. After this the researchers repeated the process with the remaining separate tiles until these formed 'granddaughters' with exactly the same XY sequence of letters