# DNA-Based Computer to Solve Complex Mathematical Problems

Chunlei Guo, from the University of Rochester, believes that DNA computing has the potential to solve mathematical problems that are “too difficult or even impossible to handle by current silicon-based computers.” Mr. Guo is one of the authors from the study, which computed the square root of 900 using a computer-like system made from engineered DNA.

While DNA computing is still in its infancy, scientists believe it does have the potential for solving impossible (until now) problems. The idea has been around since 1994, as renowned biologists had proposed using genetic material for performing computations. They were trying to store bits of information in DNA. When they found a way to do so, the next step was to manipulate the stored data using similar logic rules to what modern computers use.

## How does this work?

Before going into more detail, let’s have a clear picture of how this “computer” looks. It’s a vial of custom DNA strands that can connect with more DNA strands that serve as the input. The strands can fluoresce (glow) in 5 different wavelengths of light – blue, red, orange, mustard, and green. Various combinations of fluoresces represent different outputs.

Unlike regular computers, which represent bits as the presence or lack of voltage in a transistor (1 or 0), this system represents each unique bit as the presence or absence of an entire corresponding strand of DNA. Instead of using ones and zeroes, the DNA computer is using letters. For example, calculating the square root of 484, which is represented in binary as 0111100100, would require inputting strands C, F, G, H, and I to describe the 1s and leaving out the A, B, D, E, and J strands to represent the 0s.

## What was the result?

This resulted in an output of blue light, mustard light, and red light but no green or orange light to represent the five-bit binary number 10110, which is 22, the exact square root of 484. Here comes the question, why computing the square of 900 is such a big deal? Well, ten binary digits can represent numbers up to 1,023. This leaves 900 the highest perfect square that researches could represent.

In conclusion, DNA computer components will take years to develop into a workable and practical DNA computer, but the prognosis is to surpass its silicon-based predecessors with future development.