Information stored in nanoscale: Encoding data in a single DNA strand with Base64

Abstract DNA as a storage medium has enormous potential because of its high storage density, but the produced redundancy limits this potential. The introduction of less error corrections to fully increase the storage density in DNA remains a major challenge. To address this, an optimized Base64 method is developed and accordingly we realized a high specific storage density of 1.77 bits/nucleotide in a DNA single strand. In this strategy, by Base64 encoding, code reshaping and balancing, and data mapping, some random text information was encoded into a DNA sequence and the corresponding DNA molecule was synthesized. It was then inserted into a circular plasmid for long-term information storage. This is also particularly suitable for information replication at an exponential rate when it is transformed in a bacterium. The introduction of balance codes during the transcoding process effectively controlled the GC content and continuous base repeat, which is important to reduce the error rates in the encoded DNA synthesis and sequencing. Moreover, the circular plasmid platform enhanced the storage stability and sequencing accuracy. Therefore, our approach achieved a robust and high efficient storage and an accurate readout of digital data.