Chinese scientists have developed what is believed to be the first programmable DNA computer, capable of running billions of different circuits, according to a study published in the journal Nature. DNA computers rely on the molecules used by nature to encode the blueprints of life, rather than traditional silicon microchips. The advantage of DNA computing lies in its ability to store large amounts of data and perform a vast number of computations in parallel with low energy consumption. In theory, DNA can store up to one exabyte per cubic millimeter, and trillions of DNA molecules can fit in a drop of water.
The working principle of DNA computers lies in the way DNA strands, made up of four different molecules known as bases (adenine, thymine, cytosine, and guanine), bind with each other. These bases can be encoded as number pairs, similar to how zeroes and ones are used in traditional electronics. By mixing DNA molecules with specially designed sequences, they can bind together and serve as logic gates, performing operations such as AND, OR, and NOT, which are the building blocks of digital circuits in regular computers.
One major challenge in DNA computing has been developing programmable arrays of logic gates. Most DNA computers are designed to perform specific algorithms or a limited number of computational tasks, unlike general-purpose computers. However, the Chinese scientists have created DNA-based programmable gate arrays capable of implementing more than 100 billion distinct circuits, making them more versatile.
In terms of technical challenges, the random flow of DNA molecules in multiple directions has been a hurdle in bringing logic gates together for computations. To overcome this, the researchers designed DNA origami, allowing them to manipulate the DNA strands into specific shapes. DNA origami acts as registers, guiding the flow of data and instructions within the DNA computers and helping to control the random collisions of DNA molecules.
The DNA computers developed by the researchers were able to accurately find square roots and identify kidney-cancer-related genetic molecules. However, it is important to note that these DNA computers are not intended to replace regular computers in conventional tasks, as they currently take several hours to carry out computations.
Nevertheless, the researchers believe that DNA computers have potential in biomedical applications, such as cellular programming and molecular diagnostics. By using DNA as both input and output material, DNA computers can be designed to respond to specific genes by releasing DNA strands with biological effects. This opens up possibilities for environmental monitoring, disease treatment, and other healthcare applications.
One limitation highlighted by the scientists is that programming and running DNA computers currently require manual operations. However, they are working on automating DNA computing by combining molecular reactions with electrically controlled liquid transfer. In the future, the researchers aim to demonstrate the advantages of DNA computing by performing complex algorithms and diagnosing various diseases using their programmable DNA computers.