Aqueous biphasic system (ABS) is widely used in the recovery, extraction, purification and separation of proteins, enzymes, nucleic acids and antibodies. The ABS with high water content and low interfacial tension offers a biocompatible environment for the recovery of labile biomolecules. Process integration can be achieved using ABS by incorporating multiple-steps of purification, concentration and purification of biomolecules in a single-step operation which often results in high product recovery yield and purity. Conventional ABS is usually formed by aqueous solutions of two polymers or a polymer and a salt above a critical concentration. The high viscosity of polymer-based ABS causes slow phase separation and hinders the mass transfer of biomolecules, whereas polymer/salt ABS is characterized by high ionic strength resulting in the loss of bioactivity of recovered biomolecules. These limitations have encouraged the development of novel ABS which is more cost-effective for various biotechnological applications. This review discusses the characteristics and mechanisms of several types of emerging unconventional ABS using phase-forming components such as hyperbranched polymers, special salts, surfactants, magnetic fields, the addition of nanoparticles and incorporation of various solvent. Moreover, several novel applications of ABS for different separation purposes such as microfluidic-based ABS, ABS bioreactors, application of ABS as an analytical tool, and ABS micropatterning are discussed in this review. In the last section of this review, a comprehensive summary of process integration using ABS for extractive fermentations, bioconversion, crystallization and precipitation is also supplemented for the comprehensive review of various types and applications of ABS in recent years.

中文翻译：

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非常规含水双相系统的最新发展：特征，机理和应用。

双相水相系统（ABS）广泛用于蛋白质，酶，核酸和抗体的回收，提取，纯化和分离。具有高含水量和低界面张力的ABS为回收不稳定的生物分子提供了生物相容性环境。使用ABS可以通过将生物分子的纯化，浓缩和纯化的多个步骤合并到一个步骤的操作中来实现过程集成，这通常会导致高产品回收率和纯度。常规的ABS通常由两种聚合物或一种聚合物和一种高于临界浓度的盐的水溶液形成。聚合物基ABS的高粘度导致缓慢的相分离并阻碍生物分子的传质，而聚合物/盐ABS的特点是离子强度高，导致回收的生物分子的生物活性丧失。这些局限性鼓励了新型ABS的开发，该新型ABS对于各种生物技术应用而言更具成本效益。这篇综述讨论了使用相形成组分（例如超支化聚合物，特殊盐，表面活性剂，磁场，纳米颗粒的添加以及各种溶剂的掺入）形成的几种新型非常规ABS的特性和机理。此外，在这篇综述中讨论了ABS用于不同分离目的的几种新颖应用，例如基于微流体的ABS，ABS生物反应器，作为分析工具的ABS应用和ABS微图案化。在本评论的最后部分，