DNA is a multifunctional biomolecule that has unique properties and performs a number of functions. Man was able to supplement the range of its capabilities with artificial ones — and now a nanoscale motor based on DNA origami technology and capable of self-assembly has been added to them.
DNA, or deoxyribonucleic acid, is one of the key biomolecules whose role is to store and copy genetic information. However, its functions are actually quite diverse: DNA can actively participate in the regulation of gene expression, change its structure and interact with proteins.
In addition, scientists and engineers were able to give the DNA molecule other artificial capabilities. For example, the ability to catalyze chemical reactions (DNKzims), store digital information (“DNA flash drive” technology) or serve as the basis for extremely diverse, dynamic and at the same time reliable nanoconstructions.
We are talking about the so-called DNA origami: such nanotechnology allows you to synthesize many specific molecules that bind each other according to the principle of complementarity and eventually spontaneously form complex aggregates. The longer DNA chains in this case serve as the basis to which short molecules are attached.
This technology is more than 15 years old, and it has already helped to obtain a number of unique objects — from spectacular nanomailics to effective means for targeted drug delivery.
Earlier, evolution created many natural nanomotors — these are proteins that perform the functions of molecular machines like ATP synthase, which uses a kind of “carousel” in order to convert the potential difference on the biomembrane into the energy of chemical bonds. Another example is “walking proteins” like kinesin, capable of purposefully moving along microtubules, dragging payloads on themselves.
It is quite difficult to create such artificial molecular engines using conventional methods, so the authors of a new article in Nature resorted to bioengineering and DNA origami.
“We have been developing this assembly technology for many years and now we can create complex objects with high precision — say, molecular switches or hollow containers that capture viral particles. And if you get DNA strands with the right sequence, these objects will assemble themselves,” explained Hendrik Dietz, head of the new study from the University of Munich (Germany).
The following technical characteristics of the nanomotor are given.
It consists of three parts: a base, a platform and a rotary lever. The base is approximately 40 nanometers high and is chemically sewn to a glass substrate. The rotor arm is about 500 nanometers in length, movably attached to the base. There is a platform between them that has obstacles that restrict the movement of the lever — this forces it to deform when turning. In fact, we are talking about a molecular ratchet.
The movement occurs due to fluctuating electrical forces acting on the DNA engine. The authors call the capabilities of this device unprecedented: the maximum torsional moment is ten piconewtons per nanometer of lever length. The nanomotor can be switched on and off, and its speed and direction of rotational movement can be controlled.
The authors are convinced that the molecular engine assembled from DNA origami will find many technical applications, including for conducting controlled chemical reactions.