Crystals produced from creatine phosphate, a metabolite similar to those used in a new digital storage device Antonio Romero/SPL

DNA isn’t the only molecule we could use for digital storage. It turns out that solutions containing sugars, amino acids and other small molecules could replace hard drives too.

Jacob Rosenstein and his colleagues at Brown University, Rhode Island, stored and retrieved pictures of an Egyptian cat, an ibex and an anchor using an array of these small molecules. They say the approach could make storage that is less vulnerable to hacking and that could function in more extreme environmental conditions.

Inspired by recent research showing that it is possible to store data on DNA, Rosenstein’s team wanted to see if smaller and simpler molecules could also encode abstract information.


Digital sugar

To test this out, they created mixtures of common metabolites – solutions containing sugars, amino acids and other small molecules that humans and other living organisms use to digest food and to carry out other important chemical functions. Their idea was to use the presence or absence of particular metabolites in the mixtures as the binary 1s and 0s that can encode digital information.

For instance, to generate the picture of the ibex, the team used mixtures of six different metabolites dotted onto a plate by liquid-handling robots. They produced 1024 dots in total, and within each dot the six metabolites were either absent or present, providing enough binary information to encode the 6142-pixel image.

Rosenstein and his colleagues were then able to retrieve the data with around 99 per cent accuracy. They did this by using a mass spectrometer to analyse the chemical mix within each dot. They also made an even higher resolution image of a cat from an Egyptian tomb using mixtures of 12 metabolites.

Dense data

They used standardised plates, the size of the palm of your hand, to encode the roughly thumbnail-sized images. But Rosenstein says the physical size of metabolite storage devices could be much smaller.

Metabolite molecules are much smaller than DNA and proteins, and there is a wide variety of them. This means they can represent small amounts of data more densely than DNA, he says.

“They do not require any energy once written, and depending on the molecules and the environmental conditions, the data can last for months or years,” says Rosenstein. In fact, molecular memory could be more stable than electronic memory in conditions such as extreme temperature, pressure and mechanical forces, depending on the characteristics of the molecules.

Molecular storage could also make it possible to store large amounts of data offline, rather than in the cloud, providing protection from hacking.

So far, the technology Rosenstein and his colleagues created is slow compared with electronic computers. However, it does have some advantages over DNA memory.

“Compared to DNA, our metabolite data has low latency, in that we can write and read data sets quickly from start to finish,” says Rosenstein, adding that DNA is still currently superior for encoding large data sets.

“These ideas are ready to be used in research labs, but we would need to speed things up and shrink the size of the analysis hardware before it would be practical outside the lab,” says Rosenstein.

The work was funded by the US Department of Defense’s research arm, DARPA.

Journal reference: PLoS One, DOI: 10.1371/journal.pone.0217364