Ionic liquid-based aqueous two-phase systems (IL-ATPSs) have been studied comprehensively as a potential alternative method for protein purification. One of the distinct features of IL-ATPS is that the polarity of the IL can be adjusted by different combinations of cation and anion, providing flexibility in governing the partition of proteins between phases. However, the conventional IL-ATPS usually has poor environmental footprint and low recyclability, thereby hampering the systems for practical use in protein separation. To address these shortcomings, here we explored the distillable CO₂-based alkyl carbamate ILs as phase-forming components. N,N-dimethylammonium N′,N′-dimethylcarbamate (DIMCARB) was able to form ATPS with polypropylene glycol (PPG). The liquid–liquid equilibrium data of ATPSs composed of PPG with different molecular mass and DIMCARB were determined. As both phase-forming components are thermosensitive, the effect of temperature on the phase diagram of the PPG 400 + DIMCARB system was also evaluated. The partition behavior of model proteins (i.e., bovine serum albumin and lysozyme) in the PPG + DIMCARB systems were assessed. Both model proteins tend to migrate to the more hydrophilic IL-rich phase, when a higher temperature or a higher molecular mass of PPG was used. The DIMCARB was recovered via rotary evaporation, while the PPG 400 was recovered from a secondary two-phase system thermally induced from the primary ATPS. The recovered components were subsequently used to prepare a new batch of ATPS. The phase composition of the new system as well as the partition coefficients of both model proteins in the recycled system were maintained, thereby proving the feasibility of reusing both phase-forming components. Overall, the recyclable and biodegradable phase-forming components used in the newly developed PPG + DIMCARB system make the ATPS a sustainable and eco-friendly system for protein purification.

中文翻译：

---

由可蒸馏的基于CO ₂的氨基甲酸烷基酯离子液体组成的环保良性和可循环利用的水两相系统

离子液体为基础的水两相系统（IL-ATPSs）已被广泛研究作为蛋白质纯化的潜在替代方法。IL-ATPS的独特特征之一是可以通过阳离子和阴离子的不同组合来调节IL的极性，从而在控制蛋白质在各相之间的分配方面提供了灵活性。然而，常规的IL-ATPS通常具有不良的环境足迹和低的可回收性，从而妨碍了该系统在蛋白质分离中的实际应用。为了解决这些缺点，在这里我们探索了可蒸馏的基于CO ₂的氨基甲酸烷基酯ILs作为相形成组分。N，N-二甲基铵N '，N'-二甲基氨基甲酸酯（DIMCARB）能够与聚丙二醇（PPG）形成ATPS。确定了由不同分子量的PPG和DIMCARB组成的ATPS的液-液平衡数据。由于两个相形成成分都对热敏感，因此还评估了温度对PPG 400 + DIMCARB系统相图的影响。评估了模型蛋白（即牛血清白蛋白和溶菌酶）在PPG + DIMCARB系统中的分配行为。当使用更高温度或更高分子量的PPG时，两种模型蛋白都倾向于迁移到亲水性更高的富含IL的相。DIMCARB是通过旋转蒸发回收的，而PPG 400是从由初级ATPS热诱导的次级两相系统中回收的。回收的成分随后用于制备新的ATPS批次。维持了新系统的相组成以及回收系统中两种模型蛋白的分配系数，从而证明了重用两种相形成成分的可行性。总体而言，新开发的PPG + DIMCARB系统中使用的可循环利用和可生物降解的相形成成分使ATPS成为可持续且环保的蛋白质纯化系统。