Interaction of proteins with phase boundaries in aqueous two-phase systems under electric fields

Area of Science:

• Biophysics
• Chemical Engineering
• Microfluidics

Background:

• Proteins can be transported across liquid-liquid interfaces using electric fields.
• Aqueous two-phase systems (ATPS) offer a platform for studying such phenomena.
• Understanding protein behavior at interfaces is crucial for separation and manipulation.

Purpose of the Study:

• To investigate electric-field driven protein transport across a liquid-liquid interface in a microfluidic device.
• To explore the potential for protein separation based on interfacial transport resistance.
• To develop and validate a mathematical model for protein transport at the interface.

Main Methods:

• Utilized a microfluidic device with an aqueous two-phase system (polyethylene glycol/dextran).
• Employed fluorescence microscopy to observe protein (bovine serum albumin, bovine γ-globulins) behavior.
• Developed a mathematical model incorporating adsorption, desorption, electric fields, and Donnan potential.

Main Results:

• Proteins accumulated at the liquid-liquid interface, particularly near the three-phase contact line.
• Bovine γ-globulins exhibited higher transport resistance than bovine serum albumin.
• A significantly larger molar flux of bovine serum albumin into the PEG-rich phase was observed.
• The mathematical model showed good agreement with experimental data.

Conclusions:

• Protein transport across liquid-liquid interfaces can be controlled by electric fields.
• Differences in interfacial transport resistance can be exploited for protein separation.
• The developed model accurately describes the underlying physical mechanisms of electric-field driven protein transport.