Regensburg 2025 – scientific programme

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CPP: Fachverband Chemische Physik und Polymerphysik

CPP 45: Charged Soft Matter, Polyelectrolytes and Ionic Liquids II

CPP 45.2: Talk

Friday, March 21, 2025, 11:45–12:00, H38

How charge regulation affects adsorption of proteins into polyelectrolyte brushes: A simulation study — •Keerthi Radhakrishnan and Christian Holm — Institute for Computational Physics, University of Stuttgart, D-70569 Stuttgart, Germany

In recent years, polyelectrolyte (PE) brushes have drawn significant attention for their industrial and biomedical applications, particularly their ability to immobilize proteins via electrostatic interactions, even beyond the isoelectric point where both brush and protein share a similar charge. This counterintuitive phenomenon is normally attributed to "charge patch" effects from protein surface heterogeneity or "charge regulation" involving reionization and charge reversal near charged entities.

Using coarse-grained simulations, we investigate weak PE brushes interacting with pH-responsive ampholytic nanoparticles exhibiting patchy and non-patchy charge distributions. Building on prior single-ion models, we incorporate realistic protein models with asymmetric charge group distributions to explore higher-order and charge patch-induced effects. Our findings reveal the critical role of charge regulation stemming from anisotropic nanoparticle surface charge, brush potential, and brush-induced pH modulation in driving protein adsorption beyond the isoelectric point.

[1] K. Radhakrishnan, D. Beyer, and C. Holm, How Charge Regulation Affects pH-Responsive Ampholyte Uptake in Weak Polyelectrolyte Brushes, https://doi.org/10.26434/chemrxiv-2024-b10lj-v2., Macromolecules, in print.

Keywords: Weak polyelectrolytes; proteins; charge regulation; brushes; simulations