- A computer made of strands of DNA in a test tube can find square roots of square numbers from 1 to 900.
- Although it works for integers only, this is the most advanced DNA computer to date.
At present, companies like Intel and AMD are mass-producing transistors 10 nanometers across — just 10 times wider than DNA molecules.
However, there is a limit on how small these transistors can get. We will soon reach a point at which we can no longer continue to make smaller and more efficient electronic devices.
One of the promising alternatives to silicon-based computer technologies is DNA computing, which uses biochemistry, DNA, and molecular biology hardware. The field is still in its infancy but holds great promise for solving problems that existing computers can’t handle.
So far, scientists have demonstrated DNA-based circuits comprising tens of logic gates, which can perform some basic logic functions. However, they are incapable of realizing complex mathematical operations.
Now, researchers at the University of Rochester have developed a computer from strands of DNA in a test tube, that can compute the square roots of square numbers (integer only) up to 900.
This means it can find the square root of 1, 4, 9, 16, 25, 36, 49…784, 841, 900. This is achieved by designing DNA sequences and programming DNA strand displacement reactions.
Reference: Small | DOI:10.1002/smll.201903489
3 Molecular Building Blocks
To realize the 10-bit square root logic circuit via DNA strand displacement, the research team developed three molecular building blocks.
1) Cognitive Module: Inputs are encoded to recognize one or two specific DNA nano-indicators. In simple words, a number is encoded onto the DNA using a combination of 10 building blocks. The different combination represents different numbers which are connected with a fluorescent marker.
2) Biocomputing Module: 10-bit square root is realized using the hybridization reaction between different input combinations and reaction platform. It alters the fluorescent signal. The square root of the original number is then extracted from the color.
3) Definition Module: This module is required to threshold the outputs by fluorescence signals to showcase the realization of the 10-bit square root logic circuit.
It is also possible to optimize the input signals via the output feedback. This will enhance the performance in more complex logical operations.
This DNA computer provides unique structural programmability of DNA and a powerful database, opening new avenues for the development of complex computing circuits and novel functional devices.
The research team will use the same technique to simulate analog or digital signals to perform a broader range of square root calculations, instead of just calculating square roots of integers.
Overall, the study offers a more universal way for applications in bioengineering and biotechnology. And researchers do believe that DNA computers will eventually replace silicon-based computers for massive data processing and complicated computations.