WHY THIS MATTERS IN BRIEF
As the amount of information we create and store increases exponentially we need new radical ways to store it for long periods of time.
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Books can burn. Computers get hacked. DVDs degrade. But despite, or perhaps in spite of these flaws technologies to store information keep advancing, whether it’s developments in traditional flash and hard drive storage technologies, as well as atomic, bacterial, DNA, and molecular storage, or more obscure technologies that include glass, and even polymers.
As the data boom continues to boom, society keeps finding itself having to store more information in less space. Even the “cloud,” whose very name promises opaque, endless amounts of storage space will eventually run out of space, and that’s before we discuss how it can be hacked, and the sheer amount of energy “it” consumes. Now scientists have announced a new way to store information that could, allegedly, stably store data for millions of years, that lives outside the hackable internet, and, once written to, uses no energy. And all you need is a chemist, some cheap molecules, and your precious information.
“Think storing the contents of the New York Public Library with a teaspoon of protein,” says Brian Cafferty, Ph.D., first author on the paper that describes the new technique and a postdoctoral fellow at Harvard University who worked with Milan Mrksich, Ph.D., and his group at Northwestern University. The team reported their new approach in ACS Central.
“At least at this stage, we do not see this method competing with existing methods of data storage,” Cafferty says. “We instead see it as complementary to [today’s] technologies and, as an initial objective, well suited for long-term archival data storage.”
Cafferty’s chemical tool might not replace traditional cloud storage, even though Microsoft’s newest storage service, DNA storage in the cloud which they’re releasing in 2020, might. But despite his thoughts on whether this new type of storage is “cloud fit” the filing system Cafferty and his team developed offers an enticing alternative to other biological storage technologies like Microsofts.
Recently scientists managed to store 215 petabytes of information in just a gram of customised DNA, but while DNA storage is tiny when compared to today’s flash and hard drive storage platforms, by molecular standards it’s a huge molecule. Plus, DNA synthesis requires skilled and often repetitive labor – just ask the guys at Catalog DNA who are on track to release their DNA storage platform in 2019. So, if Cafferty and his team had taken this biological approach of needing to create and write custom DNA strands everytime they wanted to store something then macromolecule storage could become long and expensive work, potentially making it a non starter, for now at least.
“[As a result] we set out to explore a strategy that does not borrow directly from biology,” Cafferty says. “We instead relied on techniques common in organic and analytical chemistry, and developed an approach that uses small, low molecular weight molecules to encode information.”
With just one synthesis, the team can produce enough small molecules to encode multiple cat videos at a time, making this approach less labor intensive and cheaper than one based on DNA. For their low-weight molecules, the team selected Oligopeptides, which are two or more peptides bonded together, that are common, stable, and smaller than DNA, RNA or proteins.
Oligopeptides also vary in mass, depending on their number and type of amino acids. Mixed together, they are distinguishable from one another, like letters in alphabet soup.
Making words from the letters is a bit complicated – in a microwell, which is like a miniature version of a whack-a-mole but with 384 mole holes, each well contains oligopeptides with varying masses. Just as ink is absorbed on a page, the oligopeptide mixtures are then assembled on a metal surface where they are stored. If the team wants to read back what they “wrote,” they take a look at one of the wells through a mass spectrometer, which sorts the molecules by mass. This tells them which oligopeptides are present or absent: Their mass gives them away.
Then, to translate the jumble of molecules into letters and words, they borrowed the binary code. An “M,” for example, uses four of eight possible oligopeptides, each with a different mass. The four floating in the well receive a “1,” while the missing four receive a “0.” The molecular-binary code points to a corresponding letter or, if the information is an image, a corresponding pixel.
With this method, a mixture of eight oligopeptides can store one byte of information; 32 can store four bytes; and more could store even more.
So far, Cafferty and his team “wrote,” stored, and “read” physicist Richard Feynman’s famous lecture “There is plenty of room at the bottom,” a photo of Claude Shannon, and Hokusai’s woodblock painting The Great Wave off Kanagawa. Since the global digital archive is estimated to hit 44 trillion gigabytes by 2020, which is ten times that of 2013, an image of a tsunami seems appropriate.
Right now, the team can retrieve their stored masterpieces with 99.9% accuracy. Their “writing” averages 8 bits per second and “reading” averages 20 bits per second. Although their “writing” speed far outpaces writing with synthetic DNA, reading could be both quicker and cheaper with the macromolecule. But, with faster technology, the team’s speeds are sure to increase. An inkjet printer, for example, could generate drops at rates of 1,000 per second and cram more information into smaller areas. And, improved mass spectrometers could take in even more information at a time.
The team could also improve the stability, price, and capacity of their molecular storage with different classes of molecules. Their oligopeptides are custom-made and, therefore, more expensive. But future library builders could purchase inexpensive molecules, like alkanethiols, that would cost just one cent to record 100,000,000 bits of information.
Unlike other molecular information storage systems, which rely on one specific molecule, this approach can use any malleable molecule as long as it can be manipulated into distinguishable bits. And oligopeptides, and similar choices, are already resilient.
“Oligopeptides have stabilities of hundreds or thousands of years under suitable conditions,” according to the paper. The hardy molecules could endure without light or oxygen, in high heat and drought. And, unlike the cloud, which hackers can access from their favourite easy chair, the molecular storage can only be accessed in person. Even if a thief finds the data stash, a little chemistry is needed to retrieve the code.
Cafferty’s scalable molecular library is a stable, zero-energy, and corruption-resistant option for future information storage. So, if books do burn, computers get hacked, and DVDs fail, a whack-a-mole full of information could persist to remind future humankind just how much we love a good cat video.
The study was funded by DARPA.
Source: Harvard University
