Achievements of DNA robotics
The work of two groups of American researchers has brought scientists one step closer to creating molecular robots capable of performing complex tasks, such as assembling biomolecules or delivering drugs to target tissues. Or rather, for as many as fifty steps with a total length of as much as 200 nanometers :)
The DNA-based robots created by the authors can independently move along a certain route or build various nanoparticles along a given assembly line. The results of the work are described in the articles "A proximity-based programmable DNA nanoscale assembly line" and "Molecular robots guided by prescriptive landscapes" published in the journal Nature on May 13.
Described in the first of the articles, the walking "DNA spider" is able to move along a flat surface formed by a folded DNA chain, the so-called "DNA origami". The DNA spider is a protein molecule to which three "legs" are attached - single–stranded DNKZYMES, synthetic DNA molecules with enzymatic properties. The "spider" gets the energy necessary to move from chemical reactions in which its single-stranded DNA legs enter the DNA origami surface. To make a step, the legs of the DNA spider complementarily bind to the DNA strands forming the surface. After that, they catalyze the shortening reaction of one of these chains, which weakens the force of its interaction with the corresponding leg. This frees the foot, which gets the opportunity to take the next step.
The authors have developed a DNA origami capable of directing the movement of DNA spiders along a predetermined route. The video clip shown in the note in The Scientist (DNA robots get sophisticated), created using fluorescence microscopy, demonstrates the movement of the DNA spider from the start marked in green to the finish marked in red. Each colored dot shows the position of the spider at a certain point in time during a 40-minute observation period.
The new walking DNA robot can take up to 50 steps, the direction of each of which is determined by the DNA sequence of the surface, and stops when interacting with the DNA sequence, which it is able to shorten. For comparison, earlier versions of similar robots could do only 2-3 steps.
The researchers claim that they have managed to create a DNA robot that responds to environmental signals and independently executes a program assigned to it. In the near future, they plan to expand the robot's capabilities by complicating the commands received by the robot from the surface. The ultimate goal of this work is to use DNA robots to repair damaged tissues.
The authors of the second article have developed a walking DNA robot of a different type. Their brainchild is a DNA structure with four legs and three single-stranded arms capable of binding gold nanoparticles. Unlike an autonomous DNA spider, this DNA robot is part of a system that also includes DNA guide chains and an assembly line consisting of three carrier structures, each of which contains a gold nanoparticle of one of three types.
During the demonstration of the described system, the DNA robot traveled a path less than 200 nanometers long along the assembly line, collecting gold nanoparticles along the way. Carrier structures can be programmed to hold a nanoparticle, or to transfer it to a DNA robot, so eight different products can be the result of its journey.
One of the possible directions of further work is to use the results obtained by both groups of authors to create a more complex autonomous DNA robot. Experts also believe that, to begin with, you can try to lengthen the path taken by robots and complicate their behavior.
One of the popular ideas is the use of DNA robots to create nanomaterials, which cannot be obtained using traditional methods. Another possible area of work is the creation of DNA robots for targeted drug delivery. However, all experts admit that to date, the possibilities of practical application of such nanostructures have not been determined, and recent achievements, despite their importance, are nothing more than "proof of principle".
Evgeniya Ryabtseva
Portal "Eternal youth" http://vechnayamolodost.ru based on the materials of TechnologyReview: DNA Robots on the Move and The Scientist: DNA robots get sophisticated.
17.05.2010