Scientists say they have made a dramatic step forward in efforts to store information as molecules of DNA.
The magnetic hard drives we currently use to store computer data can take up lots of space and also have to be replaced as they age.
Using life’s preferred storage medium to back up our precious data would allow vast amounts of information to be archived in tiny molecules.
The data would also last thousands of years, according to scientists.
A team in Atlanta, US, has now developed a chip that they say could improve on existing forms of DNA storage by a factor of 100.
“The density of features on our new chip is [approximately] 100x higher than current commercial devices,” Nicholas Guise, senior research scientist at Georgia Tech Research Institute (GTRI), told BBC News.
“So once we add all the control electronics – which is what we’re doing over the next year of the program – we expect something like a 100x improvement over existing technology for DNA data storage.”
The technology works by growing unique strands of DNA one building block at a time. These building blocks are known as bases – four distinct chemical units that make up the DNA molecule.
The bases, sometimes known as DNA letters, can then be used to encode information, in a way that’s analogous to the strings of ones and zeroes (binary code) that carry data in traditional computing.
There are different potential ways to store this information in DNA – for example, a zero in binary code could be represented by the bases adenine or cytosine and the one represented by guanine or thymine. Alternatively, a one and zero could be mapped to just two of the four bases.
It’s all part of a project between GTRI and other partners that’s called SMASH (Scalable Molecular Archival Software and Hardware).
Scientists have said that, if formatted in DNA, every movie ever made could fit inside a volume smaller than a sugar cube.
Given how compact and reliable it is, it’s not surprising there is now broad interest in DNA as the next medium for archiving data that needs to be kept indefinitely.
The structures on the chip used to grow the DNA are called microwells and are a few hundred nanometres deep – less than the thickness of a sheet of paper.
The current prototype microchip is about 2.5cm (one-inch) square and includes multiple microwells, allowing several DNA strands to be synthesised in parallel. This will allow larger amounts of DNA to be grown in a shorter space of time.
Once the sequence of chemical bases that stores data has been completed, the DNA strands will be stripped off the surface and dried for long-term storage.
Because it’s a prototype, not all the microwells are wired up yet. This means the total amount of DNA data that can be written with this particular chip is currently less than what leading synthesis companies can produce on commercial chips.
However, Dr Guise explained, when everything’s up and running, that will change.
“For comparison purposes, the largest published demonstration of DNA digital data storage is [around] 200MB (megabytes), by a group at University of Washington and Microsoft (Organick et al., 2018). Writing all the DNA for that demonstration required multiple runs on commercial synthesis chips,” he told BBC News.
“A single synthesis run for data storage purposes usually takes about 24 hours – which just depends on the length of DNA strands you are writing, not the number of strands you are writing in parallel. With our new chips, in principle we will be able to write ~100x more DNA data than the current record, in the same amount of time.”
One challenge experts have been working to overcome has been the high cost of DNA storage. Thus far, this has restricted the technology to “boutique customers”, such as those seeking to archive information in time capsules.
The team at GTRI believes their work could help reshape the cost curve. It has partnered with two California biotech companies to make a commercially-viable demonstration of the technology. San Francisco-based Twist Bioscience are working on the techniques for “writing” or synthesising the DNA. San Diego-based Roswell Biotechnologies will provide the technology for “reading” the DNA.
DNA data storage won’t initially replace server farms for information that must be accessed quickly and often. Because of the time required for reading the sequence, the technique would be most useful for information that must be kept available for a long time, but accessed infrequently.
This type of data is currently stored on magnetic tapes which should be replaced around every 10 years.
With DNA, however, “as long as you keep the temperature low enough, the data will survive for thousands of years, so the cost of ownership drops to almost zero”, Dr Guise explained.
“It only costs much money to write the DNA once at the beginning and then to read the DNA at the end. If we can get the cost of this technology competitive with the cost of writing data magnetically, the cost of storing and maintaining information in DNA over many years should be lower.”
Another disadvantage of storing data in DNA is a higher error rate – considerably higher than what computer engineers would tolerate with conventional hard drive storage.
In collaboration with the University of Washington, GTRI researchers have come up with a way of identifying and correcting those errors to protect the data..
The work has been backed by the Intelligence Advanced Research Projects Activity (IARPA), which supports science that overcomes challenges relevant to the US intelligence community.
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