Single Microgels in Core-Shell Equilibrium: A Novel Method for Limited Volume Studies.

Area of Science:

• Polymer science
• Colloid science
• Biophysics

Background:

• Anionic polyacrylate microgels are versatile materials with tunable properties.
• Understanding interactions between microgels and charged molecules is crucial for material design.

Purpose of the Study:

• Investigate the interactions of dodecyltrimethylammonium bromide (surfactant) and cytochrome c (protein) with polyacrylate microgels.
• Characterize the resulting microgel structures and binding behaviors.

Main Methods:

• Micropipette technique used to study single microgels in microscopic droplets.
• Experiments conducted at ionic strength 0.01 M and pH 8.
• Quantitative swelling and binding isotherms were measured.

Main Results:

• First evidence of a stable biphasic core-shell state in microgels with surfactant partitioning to the shell.
• Uniform distribution of cytochrome c protein within the microgels.
• Semiquantitative agreement between experimental data and recent gel theory predictions.

Conclusions:

• Surfactant-induced phase separation occurs in polyacrylate microgels.
• Polyion-mediated attractions are key to understanding protein binding isotherms.
• The study provides valuable insights into microgel-biomolecule interactions.