Aqueous Biphasic Systems for Biomolecule Separation

Aqueous biphasic systems (ABS) offer a gentle and scalable route for the extraction, purification and enrichment of proteins, enzymes, nucleic acids and small molecules. By combining polymers, salts or ionic liquids at defined concentrations, two immiscible aqueous phases emerge, each with distinct polarity, ionic strength and viscosity. Biomolecules partition between phases according to subtle differences in hydrophobicity, electrostatic interactions and molecular affinity, which can be tuned by pH, temperature, polymer molecular weight or phase-forming component selection. Recent innovations have introduced stimulus-responsive and thermoreversible components, enabling single-step separation and facile phase regeneration without harsh organic solvents. The low interfacial tension and inherent biocompatibility of all-aqueous interfaces minimise denaturation and support integration with downstream assays. ABS scale readily from microlitre to industrial scale, reduce environmental impact through solvent recycling, and find applications in pharmaceutical manufacturing, vaccine processing, biomarker enrichment in clinical specimens and recovery of high-value products from microbial or algal cultures.

Research from Nature Portfolio

Recent studies have revealed the potential of stimulus-responsive biphasic systems for biomolecule extraction. One investigation demonstrated the use of protic ionic liquids to achieve thermoreversible phase switching, allowing complete recovery of value-added proteins in a single step by simple temperature adjustment. This design broadens the operational window compared with classical systems constrained by fixed critical temperatures. Another work exploited aqueous two-phase patterning to localise detection antibodies in multiplex immunoassays, eliminating cross-reactivity by confining each antibody to its matching capture spot. This approach yielded precise biomarker profiling using standard laboratory reagents and equipment, illustrating compatibility with high-throughput diagnostic workflows.

Research from all publishers

An advanced review of interfacial partitioning mechanisms highlighted how control of surface tension and affinity gradients can selectively concentrate target biomolecules, underpinning applications in biosensing and bioprinting. In green analytical chemistry, ionic liquid–based ABS were developed for one-step clean-up, microextraction and preconcentration of salivary biomarkers, achieving over 80 % protein removal and high enrichment factors in a miniaturised platform with low cytotoxicity. A comprehensive survey of liquid biphasic systems described novel phase-forming components and integration of three-phase flotation techniques to enhance throughput, purity and solvent reuse, addressing challenges in enzyme and high-value biomolecule manufacturing processes.

Aqueous Biphasic Systems for Biomolecule Separation publication trend

The graph below shows the total number of articles in aqueous biphasic systems for biomolecule separation across all publications each year (not limited to Nature Index journals).

Technical terms

Aqueous biphasic system (ABS): A liquid-liquid separation method in which two immiscible aqueous phases form upon mixing polymers, salts or ionic liquids, facilitating selective partitioning of biomolecules.

Partition coefficient: The equilibrium ratio of a solute’s concentration in one phase to its concentration in the other, indicating its preferential distribution.

Thermoreversible phase separation: A reversible transition between homogeneous solution and biphasic system triggered by temperature change, enabling controllable extraction and recovery.

Tie-line length: A measure of compositional difference between coexisting phases in a biphasic system, reflecting the driving force for separation.

Ionic liquid: A salt liquid at ambient temperature used as a phase-forming component to tune the polarity, ionic strength and selectivity of aqueous phases.

References

1. Affinity‐Controlled Partitioning of Biomolecules at Aqueous Interfaces and Their Bioanalytic Applications. Advanced Materials (2024).
2. Ionic liquid-based aqueous biphasic systems as one-step clean-up, microextraction and preconcentration platforms for the improved determination of salivary biomarkers. Green Chemistry (2023).
3. Aqueous two-phase system (ATPS): an overview and advances in its applications. Biological Procedures Online (2016).
4. Thermoreversible (Ionic-Liquid-Based) Aqueous Biphasic Systems. Scientific Reports (2016).
5. Aqueous two-phase system patterning of detection antibody solutions for cross-reaction-free multiplex ELISA. Scientific Reports (2014).
6. Liquid Biphasic System: A Recent Bioseparation Technology. Processes (2020).