Nanomachines are structures close to the size of atoms, allowing them to perform specialized movements on the nano-scale, such as poking holes into cells. DNA origami uses DNA as a building block to create nano-scale structures, but these methods traditionally could only be used to build static structures. More recently, new DNA origami methods enabled the creation of movable DNA structures, which can be used to build nanomachines. However, there are still problems with them assembling properly, surviving environmental exposure, and preventing spontaneous disassembly. In a new study, Pierre Stömmer and colleagues have designed DNA origami structures with a step-wise assembly mechanism that addresses these problems and dwarfs previous designs.

The design consists of a rod and tubular segments made from DNA helices, which are two DNA strands twisted around each other as in the famous double helix. Proper assembly is made possible due to DNA’s ability to stick to other pieces of complementary DNA. Each part of the design locks into the right place due to their shapes and this sticky property, like jigsaw pieces attached with Velcro. This stickiness also prevents the spontaneous disassembly that was observed in earlier methods. Additional tubular segments attach, forming pipes with the rods functioning as moving pistons inside. This design allows the rod to move unobstructed at speeds 100,000 times that of previous nanomachines, while the pipe enclosure offers protection from the environment. In a brilliant twist, due to DNA’s negative electrical charge, the rod’s movement can also be controlled remotely using electricity.

This structure can be used as a piston on the nano-scale, which can find applications as microscopic syringes to deliver drugs directly into cells or as gates that can constrict blood vessels. One caveat is that the efficiency of this assembly mechanism is not very high, so relatively few tubes are actually properly assembled from the raw materials. However, this mechanism is the first of its kind, and many improvements can be expected in the coming years.

The lead author, Pierre Stömmer, is a Ph.D. student in Hendrik Dietz’ lab. He got his MSc in Physics at the TUM in 2017. Hendrik Dietz is a Professor for Biophysics at the Technical University Munich. His thesis research for both his diploma and Ph.D. was on the molecular mechanics of the green fluorescent protein, which colors his research interests to this day.

Managing Correspondent: Raphael Haslecker

Original Journal Article: https://www.nature.com/articles/s41467-021-24675-8

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