An outlook on the current challenges and opportunities in DNA data storage

DNA storage: The future direction for medical cold data storage

DNA storage, characterized by its durability, data density, and cost-effectiveness, is a promising solution for managing the increasing data volumes in healthcare. This review explores state-of-the-art DNA storage technologies, and provides insights into designing a DNA storage system tailored for medical cold data. We anticipate that a practical approach for medical cold data storage will involve establishing regional, in vitro DNA storage centers that can serve multiple hospitals. The immediacy of DNA storage for medical data hinges on the development of novel, high-density, specialized coding methods. Established commercial techniques, such as DNA chemical synthesis and next-generation sequencing (NGS), along with mixed drying with alkaline salts and refined Polymerase Chain Reaction (PCR), potentially represent the optimal options for data writing, reading, storage, and accessing, respectively. Data security could be promised by the integration of traditional digital encryption and DNA steganography. Although breakthrough developments like artificial nucleotides and DNA nanostructures show potential, they remain in the laboratory research phase. In conclusion, DNA storage is a viable preservation strategy for medical cold data in the near future.

ReLume: Enhancing DNA storage data reconstruction with flow network and graph partitioning

DNA storage is an ideal alternative to silicon-based storage, but focusing on data writing alone cannot address the inevitable errors and durability issues. Therefore, we propose ReLume, a DNA storage data reconstruction method based on flow networks and graph partitioning technology, which can accomplish the data reconstruction task of millions of reads on a laptop with 24 GB RAM. The results show that ReLume copes well with many types of errors, more than doubles sequence recovery rates, and reduces memory usage by about 60 %. ReLume is 10 times more durable than other representative methods, meaning that data can be read without loss after 100 years. Results from the wet lab DNA storage dataset show that ReLume's sequence recovery rates of 73 % and 93.2 %, respectively, significantly outperform existing methods. In summary, ReLume effectively overcomes the accuracy and hardware limitations and provides a feasible idea for the portability of DNA storage.

Low-cost and automated magnetic bead-based DNA data writing via digital microfluidics

The rapid growth in data generation presents a significant challenge for conventional storage technologies. DNA storage has emerged as a promising solution, offering substantially greater storage density and durability. However, the current DNA data writing process is costly and labor-intensive, hindering the commercialization of DNA data storage. In this study, we present a digital microfluidics (DMF) platform integrated with E47 DNAzyme ligation chemistry to develop a programmable, cost-effective, and automated DNA data writing process. Our method utilizes pre-synthesized single-stranded DNA as building blocks, which can be assembled into diverse DNA sequences that encode desired data. By employing DNAzymes as biocatalysts, we enable an enzyme-free ligation process at room temperature, significantly reducing costs compared to traditional enzyme-based methods. Our proof-of-concept demonstrates an automated DNA writing process with the reduced reagent input, providing an alternative solution to the high costs associated with current DNA data storage methods. The high specificity of ligation using DNAzymes obviates the need for storing each unique DNA block in its own reservoir, which greatly reduces the total number of reservoirs required to store the starting material. This simplifies the overall layout, and the associated plumbing of the DMF platform. To adapt the conventional column-purification required ligation on the DMF platform, we introduce a DNAzyme-cleavage-assisted bead purification assay. This method employs 17E DNAzymes to cleave and release biotinylated DNA from streptavidin beads, followed by a one-pot ligation with E47 DNAzymes to assemble the desired DNA strands. Our study represents a significant advancement in DNA data storage technology, offering a cost-effective and automated solution that enhances scalability and practicality for commercial DNA data storage applications.

Towards next-generation DNA encryption via an expanded genetic system

Information encryption based on DNA data archiving, referred to as DNA encryption, has been advocated for decades and has become highly appealing owing to its remarkable advantages, e.g. high storage capacity, complexity and programmability. Early DNA encryption schemes primarily leveraged the natural four-letter genetic alphabet for data storage, with message-storing DNA sequences easily decrypted by routine DNA sequencing, which is consequently vulnerable to attack and faces severe security challenges. Here, an unnatural base pair (UBP), dNaM-dTPT3, was introduced into the message and/or index DNA sequences, which can be stored either in vitro or in vivo; this approach achieved the bioorthogonal encryption of 'secret' messages, where message DNAs could be selectively, faithfully and readily retrieved or read exclusively in the presence of unnatural bases. Furthermore, a separative computational algorithm, named IM-Codec, was developed to encrypt the data into a 'key sequence' and an 'information sequence' through UBP insertion. Finally, a UBP-based multilevel DNA encryption approach was developed and validated for data encryption and decryption. The employment of the UBP expanded genetic system for data encryption should provide valuable solutions for archiving highly confidential data and thus usher in a new era of DNA encryption.

"Galaxy" Encoding: Toward High Storage Density and Low Cost

DNA is considered one of the most attractive storage media because of its excellent reliability and durability. Early encoding schemes lacked flexibility and scalability. To address these limitations, we propose a combination of static mapping and dynamic encoding, named "Galaxy" encoding. This scheme uses both the "dual-rule interleaving" algorithm and the "twelve-element Huffman rotational encoding" algorithm. We tested it with "Shakespeare Sonnets" and other files, achieving an encoding information density of approximately 2.563 bits/nt. Additionally, the inclusion of Reed-Solomon error-correcting codes can correct nearly 5% of the errors. Our simulations show that it supports various file types (.gz, .tar, .exe, etc.). We also analyzed the cost and fault tolerance of "Galaxy" encoding, demonstrating its high coding efficiency and ability to fully recover original information while effectively reducing the costs of DNA synthesis and sequencing.

Ultrafast and Accurate DNA Storage and Reading Integrated System Via Microfluidic Magnetic Beads Polymerase Chain Reaction

DNA storage is expected to tackle the dilemma faced by electronic information technology for the effective storage and management of massive amounts of data in the era of big data. Efficient and reliable data retrieval is crucial for DNA storage. However, it is still challenging to actualize DNA storage with fast and accurate readout capabilities, which play a key role in the practicality and reliability of DNA storage. In this study, an integrated system was constructed using homemade microfluidic PCR and DNA magnetic beads for fast and accurate DNA storage and reading with reproducibility. The homemade microfluidic PCR and DNA magnetic beads constructed for the random access of DNA storage have the advantages of short time and low bias named MMBP. The homemade DNA magnetic beads are low cost, stable, and reproducible. The integrated DNA storage and reading system integrated by MMBP can read information not only more accurately and quickly but also at a lower sequencing depth than traditional PCR. Overall, the MMBP-based DNA information storage system (MMBP-DIS) has the advantages of reducing the cost, decreasing the random access time to 10 min, and improving the reading accuracy and sensitivity. In the future, it can be integrated with DNA electrochemical synthesis to develop a fast and accurate portable microfluidic device for DNA synthesis-preservation-reading integration.

Bead-Based DNA Synthesis and Sequencing for Integrated Data Storage Using Digital Microfluidics

DNA is considered as a prospective candidate for the next-generation data storage medium, due to its high coding density, long cold-storage lifespan, and low energy consumption. Despite these advantages, challenges remain in achieving high-fidelity, fully integrated, and cost-efficient DNA storage system. In this study, a homemade digital microfluidic (DMF)-based compact DNA data storing pipeline is orchestrated to complete the entire process from the synthesis to the sequencing. The synthetic half employs phosphoramidite chemistry on 200 nm magnetic beads (MBs), where the dimethyltrityl protecting group is removed by droplet manipulation of trichloroacetic acid. The sequencing counterpart relies on pyrophosphate releasing originated from polymerase-catalyzed primer extension, which leads to photon-countable chemiluminescence (CL) signal in 2.5-μL drops of trienzyme cascading reactions. Further by DNA denaturation, repeated pyrosequencing plus plurality voting can improve the nucleobase accuracy beyond 95 %. As a proof-of-concept trial, semantic information is saved in DNA via the Huffman coding algorithm plus the Reed-Solomon error-correction, and then robustly retrieved from this streamlined platform. As a result, it took a net total of approximately 6.5 h to writing and reading 8 bytes of data, that equal to a storaging speed of 49 min/byte, much quicker than the previously reported 2.8-4.2 h/byte. This bead-based miniaturized device promises an unattended protocol for achieving high-throughput, full-packaged, and above all, neatly precision DNA storage.

Advances and Challenges in Random Access Techniques for In Vitro DNA Data Storage

With digital transformation and the general application of new technologies, data storage is facing new challenges with the demand for high-density loading of massive information. In response, DNA storage technology has emerged as a promising research direction. Efficient and reliable data retrieval is critical for DNA storage, and the development of random access technology plays a key role in its practicality and reliability. However, achieving fast and accurate random access functions has proven difficult for existing DNA storage efforts, which limits its practical applications in industry. In this review, we summarize the recent advances in DNA storage technology that enable random access functionality, as well as the challenges that need to be overcome and the current solutions. This review aims to help researchers in the field of DNA storage better understand the importance of the random access step and its impact on the overall development of DNA storage. Furthermore, the remaining challenges and future research trends in random access technology of DNA storage are discussed, with the goal of providing a solid foundation for achieving random access in DNA storage under large-scale data conditions.

DNA-DISK: Automated end-to-end data storage via enzymatic single-nucleotide DNA synthesis and sequencing on digital microfluidics

In the age of information explosion, the exponential growth of digital data far exceeds the capacity of current mainstream storage media. DNA is emerging as a promising alternative due to its higher storage density, longer retention time, and lower power consumption. To date, commercially mature DNA synthesis and sequencing technologies allow for writing and reading of information on DNA with customization and convenience at the research level. However, under the disconnected and nonspecialized mode, DNA data storage encounters practical challenges, including susceptibility to errors, long storage latency, resource-intensive requirements, and elevated information security risks. Herein, we introduce a platform named DNA-DISK that seamlessly streamlined DNA synthesis, storage, and sequencing on digital microfluidics coupled with a tabletop device for automated end-to-end information storage. The single-nucleotide enzymatic DNA synthesis with biocapping strategy is utilized, offering an ecofriendly and cost-effective approach for data writing. A DNA encapsulation using thermo-responsive agarose is developed for on-chip solidification, not only eliminating data clutter but also preventing DNA degradation. Pyrosequencing is employed for in situ and accurate data reading. As a proof of concept, DNA-DISK successfully stored and retrieved a musical sheet file (228 bits) with lower write-to-read latency (4.4 min of latency per bit) as well as superior automation compared to other platforms, demonstrating its potential to evolve into a DNA Hard Disk Drive in the future.

High-throughput DNA synthesis for data storage

With the explosion of digital world, the dramatically increasing data volume is expected to reach 175 ZB (1 ZB = 1012 GB) in 2025. Storing such huge global data would consume tons of resources. Fortunately, it has been found that the deoxyribonucleic acid (DNA) molecule is the most compact and durable information storage medium in the world so far. Its high coding density and long-term preservation properties make itself one of the best data storage carriers for the future. High-throughput DNA synthesis is a key technology for "DNA data storage", which encodes binary data stream (0/1) into quaternary long DNA sequences consisting of four bases (A/G/C/T). In this review, the workflow of DNA data storage and the basic methods of artificial DNA synthesis technology are outlined first. Then, the technical characteristics of different synthesis methods and the state-of-the-art of representative commercial companies, with a primary focus on silicon chip microarray-based synthesis and novel enzymatic DNA synthesis are presented. Finally, the recent status of DNA storage and new opportunities for future development in the field of high-throughput, large-scale DNA synthesis technology are summarized.

Efficient data reconstruction: The bottleneck of large-scale application of DNA storage

Over the past decade, the rapid development of DNA synthesis and sequencing technologies has enabled preliminary use of DNA molecules for digital data storage, overcoming the capacity and persistence bottlenecks of silicon-based storage media. DNA storage has now been fully accomplished in the laboratory through existing biotechnology, which again demonstrates the viability of carbon-based storage media. However, the high cost and latency of data reconstruction pose challenges that hinder the practical implementation of DNA storage beyond the laboratory. In this article, we review existing advanced DNA storage methods, analyze the characteristics and performance of biotechnological approaches at various stages of data writing and reading, and discuss potential factors influencing DNA storage from the perspective of data reconstruction.

"Cell Disk" DNA Storage System Capable of Random Reading and Rewriting

DNA has emerged as an appealing material for information storage due to its great storage density and durability. Random reading and rewriting are essential tasks for practical large-scale data storage. However, they are currently difficult to implement simultaneously in a single DNA-based storage system, strongly limiting their practicability. Here, a "Cell Disk" storage system is presented, achieving high-density in vivo DNA data storage that enables both random reading and rewriting. In this system, each yeast cell is used as a chamber to store information, similar to a "disk block" but with the ability to self-replicate. Specifically, each genome of yeast cell has a customized CRISPR/Cas9-based "lock-and-key" module inserted, which allows selective retrieval, erasure, or rewriting of the targeted cell "block" from a pool of cells ("disk"). Additionally, a codec algorithm with lossless compression ability is developed to improve the information density of each cell "block". As a proof of concept, target-specific reading and rewriting of the compressed data from a mimic cell "disk" comprising up to 105 "blocks" are demonstrated and achieve high specificity and reliability. The "Cell Disk" system described here concurrently supports random reading and rewriting, and it should have great scalability for practical data storage use.

Design and Construction of a Multi-Tiered Minimal Actin Cortex for Structural Support in Lipid Bilayer Applications

Artificial lipid bilayers have revolutionized biochemical and biophysical research by providing a versatile interface to study aspects of cell membranes and membrane-bound processes in a controlled environment. Artificial bilayers also play a central role in numerous biosensing applications, form the foundational interface for liposomal drug delivery, and provide a vital structure for the development of synthetic cells. But unlike the envelope in many living cells, artificial bilayers can be mechanically fragile. Here, we develop prototype scaffolds for artificial bilayers made from multiple chemically linked tiers of actin filaments that can be bonded to lipid headgroups. We call the interlinked and layered assembly a multiple minimal actin cortex (multi-MAC). Construction of multi-MACs has the potential to significantly increase the bilayer's resistance to applied stress while retaining many desirable physical and chemical properties that are characteristic of lipid bilayers. Furthermore, the linking chemistry of multi-MACs is generalizable and can be applied almost anywhere lipid bilayers are important. This work describes a filament-by-filament approach to multi-MAC assembly that produces distinct 2D and 3D architectures. The nature of the structure depends on a combination of the underlying chemical conditions. Using fluorescence imaging techniques in model planar bilayers, we explore how multi-MACs vary with electrostatic charge, assembly time, ionic strength, and type of chemical linker. We also assess how the presence of a multi-MAC alters the underlying lateral diffusion of lipids and investigate the ability of multi-MACs to withstand exposure to shear stress.