Protein adsorption: kinetics and history dependence

Area of Science:

• Biophysics
• Surface Science
• Materials Science

Background:

• Macromolecular adsorption is often history-dependent due to slow relaxation of non-equilibrium structures.
• Adsorption rates are sensitive to interfacial structure, making kinetics a tool to study history dependence.

Purpose of the Study:

• To identify and quantify history dependence in protein adsorption using kinetic measurements.
• To investigate the influence of interfacial structure on protein adsorption dynamics.

Main Methods:

• Utilized optical waveguide lightmode spectroscopy (OWLS) in a multistep mode for kinetic analysis.
• Alternately exposed surfaces to protein solutions and protein-free solutions to compare adsorption rates.
• Isolated contributions from adsorption rate constants, desorption rate constants, and interfacial cavity function.

Main Results:

• Adsorption rates and interfacial cavity functions significantly increased from the first to subsequent adsorption steps for fibronectin, cytochrome c, and lysozyme.
• Observed a clustering transition among adsorbed protein molecules, influencing adsorption kinetics.
• Determined structural and temporal information regarding the clustering event from kinetic data.

Conclusions:

• Protein adsorption kinetics, measured by OWLS, can effectively quantify history dependence.
• Protein clustering is a key factor driving changes in adsorption rates and interfacial structure.
• OWLS provides valuable insights into the dynamic behavior of adsorbed protein layers.