A group of scientists led by researchers from the California Institute of Technology was able to take a small but significant step in the development of arbitrarily programmable chemical computers. As basic computing elements in such systems, DNA sets are used, which, by their nature, have the ability to self-organize and grow. All that is needed to run DNA-based computing systems is warm brackish water, a DNA-encoded growth algorithm, and basic standard sets of DNA sequences.
Until now, "calculations" with DNA have been carried out strictly using any one sequence. For arbitrary calculations, the existing methods were not suitable. Scientists from Caltech (Caltech) were able to overcome this limitation and presented a technology that can execute arbitrary algorithms using one basic set of conditionally logical DNA elements and a sample of 355 basic DNA sequences responsible for the "calculation" algorithm - analogous to computer instructions. A logical βseedβ and a set of βinstructionsβ are introduced into the saline solution, after which the calculation begins - the assembly of the sequence.
The basic element or "seed" is a DNA fold (origami DNA) - it is a nanotube 150 nm long and 20 nm in diameter. The structure of the "seed" remains almost unchanged regardless of the algorithm that will be calculated. The periphery of the "seed" is formed in such a way that the assembly of DNA sequences starts at its end. A growing strand of DNA is known to be assembled from sequences that match the proposed sequences in terms of molecular structure and chemical composition, and not randomly. Since the periphery of the "seed" is presented in the form of six conditional valves, where each valve has two inputs and two outputs, DNA growth begins to obey a given logic (algorithm) which, as mentioned above, is represented by a given set of DNA sequences placed in a solution of 355 basic options.
Scientists in the course of experiments have shown the possibility of executing 21 algorithms, including counting from 0 to 63, choosing a leader, determining division by three and others, although everything is not limited to these algorithms. The calculation process proceeds step by step, as the DNA strands grow on all six outlets of the "seed". This process can take from one to two days. It takes significantly less time to make a "seed" - from an hour to two. The result of the calculations can be seen with your own eyes under an electron microscope. The tube unfolds into a ribbon, and on the ribbon, at the locations of each β1β value on the DNA sequence, a protein molecule visible under a microscope is attached. Zeros are not visible under a microscope.
Of course, in the presented form, the technology is far from performing full-fledged calculations. So far, it looks like reading a tape from a teletype, stretched over two days. However, the technology works and leaves a lot of room for improvement. It became clear in which direction you can move, and what needs to be done to bring chemical computers closer.
Source: 3dnews.ru