Ultralow interfacial tensions of aqueous two-phase systems measured using drop shape

Area of Science:

• Biophysical Chemistry
• Separation Science
• Materials Science

Background:

• Aqueous two-phase systems (ATPS) offer a biocompatible environment for biomolecule separation.
• Interfacial tension is critical for biomolecule partitioning in ATPS but challenging to measure due to ultralow values.
• Existing methods lack reproducibility for determining these subtle interfacial forces.

Purpose of the Study:

• To develop and validate a precise method for measuring ultralow interfacial tensions in polymeric ATPS.
• To systematically investigate interfacial tensions in polyethylene glycol (PEG)/dextran (DEX) ATPS.
• To establish reproducible experimental criteria for interfacial tension determination.

Main Methods:

• Utilized sessile and pendant drop techniques with axisymmetric drop shape analysis (ADSA).
• Studied eight different ATPS formulations composed of PEG and DEX.
• Implemented specific criteria for reproducible measurement of ultralow interfacial tensions.

Main Results:

• Achieved high reproducibility, with pendant and sessile drop methods yielding results within 0.001 mJ/m(2) of each other.
• Measured interfacial tensions ranging from 0.012 ± 0.001 mJ/m(2) to 0.381 ± 0.006 mJ/m(2).
• Demonstrated that interfacial tension varies with polymer concentrations in the ATPS phases.

Conclusions:

• The developed ADSA method provides reliable and reproducible measurements of ultralow interfacial tensions in ATPS.
• Accurate interfacial tension data is essential for optimizing ATPS applications in biomolecule separation and analysis.
• These findings will advance the understanding of biomolecule behavior and partitioning within ATPS.