Towards the Development of an Electrochemical Random Access DNA Memory (e-RADM)

Over the last decades, we have produced an unprecedented and exponentially growing amount of information, now approaching the limit that current technology can physically store. Storage demand is in fact likely to exceed the capacity of silicon-based devices within 20 years. Current storage technologies, such as magnetic tapes, have limitations such as large power requirements and cooling systems, as well as only offering limited lifetime that requires periodically transferring data to new devices. As a result, new alternative data storage technologies are required that are space and cost-effective, and able to store large amounts of information in a small contained volume, with minimum power consumption.<br/><br/>As an alternative data storage material, DNA has attracted a lot of attention thanks to several intrinsic properties that make it a desirable data storage medium. First, even very long DNA molecules can be condensed into a small physical space as seen in living organisms, and it can hold 2 bits of information per nucleotide. A single gram of DNA has the potential to store two orders of magnitude more data than the amount of data expected to be produced by 2025. The DNA’s extraordinary capacity is also coupled with an excellent inherent stability. But the most important aspect that makes DNA such a viable material is the large number of biotechnological tools that have been developed for the manipulation of this biopolymer.<br/><br/>Current strategies aiming to use DNA as a data storage material rely on sequencing technologies for data recovery. However, on a DNA-based memory, having to fully sequence all DNA strands for retrieving a specific subset of information would imply very high levels of latency and risking integrity of information. As a result, random access strategies are required.<br/><br/>Here, we present the first stages of an electrochemical Random Access DNA memory (e-RADM), which utilizes DNA origami nanostructures and localized strand displacement reactions (SDRs) for data manipulation. Short DNA hairpins containing toeholds complementary to the sequences of adjacent hairpins are attached to the DNA origami such that cascades of SDRs can occur. When a data retrieval query is submitted in the form of a short oligonucleotide, only those hairpins with toeholds complementary to the oligo will open, potentially triggering a cascade reaction. After the cascade reaction, the loops of the hairpins are exposed, containing the information related to the query. The unzipping of these hairpins can be monitored by electrochemical means (Squarewave Voltammetry, SWV), as opened hairpins increase the average distance to the surface, preventing electrons from a redox active molecule attached to the end of the sequence to be transferred to the electrode. The final aim of this work is to develop a fully functional electrochemical device in which functionalized DNA origami structures are immobilize on a gold microelectrode array.