Gong Hao, Sakaguchi Yuriko, Suzuki Tsutomu, Yanagisawa Miho, Aida Takuzo
Department of Chemistry and Biotechnology, Graduate School of Engineering, The University of Tokyo, Tokyo, Japan.
Komaba Institute for Science, The University of Tokyo, Tokyo, Japan.
Nature. 2024 Dec;636(8041):92-99. doi: 10.1038/s41586-024-08203-4. Epub 2024 Dec 4.
Although separation is entropically unfavourable, it is often essential for our life. The separation of very similar macromolecules such as deoxyribonucleic acids (DNAs) and their single nucleotide variants is difficult but holds great advantage for the progress of life science. Here we report that a particular liquid-liquid phase separation (LLPS) at a solid-liquid interface led to the partitioning of DNAs with nearly identical structures. We found this intriguing phenomenon when we did drop-casting onto a glass plate an aqueous ammonium sulfate dispersion of phase-separated droplets comprising a homogeneous mixture of poly(ethylene glycol) (PEG) samples with different termini. Even when the molecular weights of their PEG parts were identical to each other, terminally different PEGs spread competitively at the solid-liquid interface and partitioned into micrometre-scale concentric circles. We found that this competitive spreading was induced by an ammonium sulfate layer spontaneously formed on the glass surface. We successfully extended the above mechanism to partitioning a mixture of nearly identical DNAs into concentric circles followed by their selective extraction using the salting-in effect. We could isolate a human cancer-causing single nucleotide variant in 97% purity from its 1:1 mixture with the original DNA.
尽管分离在熵上是不利的，但它对我们的生命往往至关重要。分离非常相似的大分子，如脱氧核糖核酸（DNA）及其单核苷酸变体，是困难的，但对生命科学的进展具有巨大优势。在此我们报告，固液界面处的一种特殊液-液相分离（LLPS）导致了结构几乎相同的DNA的分配。当我们将由具有不同末端的聚乙二醇（PEG）样品的均匀混合物组成的相分离液滴的硫酸铵水分散体滴铸到玻璃板上时，发现了这一有趣的现象。即使它们的PEG部分的分子量彼此相同，末端不同的PEG在固液界面上竞争性地铺展并分成微米级的同心圆。我们发现这种竞争性铺展是由玻璃表面自发形成的硫酸铵层诱导的。我们成功地将上述机制扩展到将几乎相同的DNA混合物分成同心圆，然后利用盐溶效应进行选择性提取。我们可以从其与原始DNA的1:1混合物中以97%的纯度分离出一种人类致癌单核苷酸变体。
