Reversibility and relaxation behavior of polyelectrolyte complex micelle formation

Area of Science:

• Supramolecular Chemistry
• Polymer Science
• Biophysical Chemistry

Background:

• Polyelectrolyte complex micelles are self-assembled structures formed by oppositely charged polymers and/or proteins.
• Understanding the equilibration dynamics of these complex micelles is crucial for controlling their properties and applications.

Purpose of the Study:

• To investigate the equilibration of polyelectrolyte complex micelles formed with different combinations of polymers and proteins.
• To determine the relaxation times associated with the formation of these complex structures.
• To assess the influence of mixing protocols on the final micellar structures.

Main Methods:

• Dynamic Light Scattering (DLS) titrations were employed to study micelle formation and disintegration.
• Time-evolution studies of samples at fixed compositions were conducted.
• pH-dependent charged polymers and proteins were utilized.

Main Results:

• Polyelectrolyte complex micelles composed of PDMAEMA(150), PAA(42)-PAAm(417), and lysozyme slowly equilibrated over approximately 2 days, yielding consistent structures irrespective of mixing order.
• In contrast, polyelectrolyte complex micelles with PAA(139), P2MVP(41)-PEO(205), and alpha-lactalbumin did not equilibrate.
• The latter system's structure was dependent on the mixing method and remained unchanged for at least a week.

Conclusions:

• The equilibration behavior of polyelectrolyte complex micelles is highly dependent on the specific components involved.
• Lysozyme-containing complexes exhibit thermodynamic equilibrium, while alpha-lactalbumin-containing complexes display kinetic control.
• These findings highlight the importance of component selection and mixing strategies in designing functional polyelectrolyte assemblies.