A nanorobot that walks by itself

Evgeny Anokhin, N+1 

A group of scientists from the Institute of Cellular and Molecular Biology at the University of Texas at Austin has developed a nanoscale "machine" capable of moving in any direction on an uneven surface. It is a single DNA molecule with a torso and two "legs", rearranging which the molecule moves. The results of the work are published in Nature Nanotechnology (Jung et al., A stochastic DNA walker that traverses a microparticle surface).

The previously presented molecules of this kind are able to walk only in a given direction along a straight line or in a plane. The new "walker" is able to move 36 steps in a row on the inhomogeneous surface of micron particles coated with DNA, unprogrammed, independently deciding where to move the "foot".

Unlike conventional molecular motor proteins, which are able to move along the surface, changing its structure (for example, kinesin moves through microtubules due to the energy of ATP hydrolysis), the presented "walkers" use hybridization for movement and do not covalently change the substrate. 

The scheme of motion of the motor protein kinesin, capable of moving along the microtubule.

Image: Wikimedia Commons

A hairpin structure is a secondary structure in a nucleic acid molecule in which complementary inverted nucleotide sequences located within the same chain join to form a double–stranded "stem", and nucleotides located between the mating regions form an unpaired single-stranded loop.

The "walker" is two single-stranded strands of DNA combined into one structure. These filaments are able to interact with the H1 oligonucleotide located on the surface of the microparticle, opening the hairpin structure. Two newly formed single-stranded DNA in H1 can hybridize with the nucleotide H2, forming a three-particle catalyst-H1-H2 complex. As the strands move, the complex is rearranged into the most thermodynamically advantageous duplex H1-H2, releasing the catalyst. Thus, the "walker" molecule moves along the surface of the microparticle.

Drawing from the press release of The University of Texas at Austin
Researchers Build Nanoscale Autonomous Walking Machine from DNA – VM

DNA molecules are like nanocomputers, with the help of independent "calculations" making a decision about the direction of movement. According to the authors, such "walkers" can be used in the analysis and diagnosis of diseases.

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03.11.2015