Counterion-mediated protein adsorption into polyelectrolyte brushes.

Area of Science:

• Biophysics
• Polymer Science
• Computational Chemistry

Background:

• Proteins can enter like-charged polymer brushes, a phenomenon not fully explained by electrostatic interactions alone.
• Understanding protein-polyelectrolyte interactions is crucial for biomaterial design and biological process modeling.

Purpose of the Study:

• To investigate the mechanism of protein adsorption onto polyelectrolyte brushes using molecular dynamics simulations.
• To explore how inhomogeneous charge distribution on protein surfaces influences adsorption behavior.

Main Methods:

• Molecular dynamics simulations were employed to model the interactions.
• Varying charge distributions on fullerene-like protein models were simulated.
• Analysis focused on electrostatic and entropic contributions to adsorption.

Main Results:

• Proteins with localized positive and negative charges strongly adsorb to like-charged polyelectrolyte brushes, even if overall neutral.
• Charged protein patches act as multivalent counterions, facilitating adsorption.
• Significant release of mobile ions from the brush and surrounding environment was observed.

Conclusions:

• Inhomogeneous protein surface charge is a key factor driving adsorption into like-charged polymer brushes.
• Entropic forces, particularly counterion release, play a significant role in strong protein adsorption.
• These findings provide insights into protein-brush interactions and the role of charge patterning.