Load-dependent surface diffusion model for analyzing the kinetics of protein adsorption onto mesoporous materials

Area of Science:

• Materials Science
• Biochemistry
• Physical Chemistry

Background:

• Protein adsorption onto porous materials is vital for biosensors and drug delivery.
• Xerogels offer tunable porosity for controlled biomolecule interactions.

Purpose of the Study:

• To investigate the adsorption behavior and kinetics of cytochrome c (cyt c) on organic and carbon xerogels.
• To develop and validate a load-dependent surface diffusion model (LDSDM) for protein adsorption.

Main Methods:

• Transient and equilibrium batch adsorption experiments were conducted.
• Redlich-Peterson isotherms were used to analyze equilibrium adsorption.
• A novel load-dependent surface diffusion model (LDSDM) was developed and numerically solved.

Main Results:

• Equilibrium adsorption followed quasi-Langmuirian behavior, forming a cyt c monolayer (∼4nm depth).
• The LDSDM provided a better fit to kinetic data than the homogeneous surface diffusion model.
• Surface diffusion coefficients decreased with increasing protein load, especially in smaller pores.

Conclusions:

• Intraparticle surface diffusion is the rate-limiting step in cyt c adsorption.
• Protein-xerogel interactions and pore confinement significantly influence diffusion coefficients.
• The LDSDM accurately models protein adsorption kinetics on xerogel materials.