Mechanisms of fibrinogen adsorption at solid substrates

Area of Science:

• Biophysics
• Surface Science
• Physical Chemistry

Background:

• Fibrinogen adsorption is crucial for biomaterial interactions and thrombosis.
• Understanding protein adsorption mechanisms on surfaces is essential for biomedical applications.
• Existing models often simplify protein structure and adsorption dynamics.

Purpose of the Study:

• To theoretically investigate fibrinogen adsorption using the random sequential adsorption (RSA) model.
• To differentiate and quantify irreversible (side-on) and reversible (end-on) fibrinogen adsorption.
• To predict adsorption isotherms, kinetics, and binding energies for fibrinogen.

Main Methods:

• Utilized the random sequential adsorption (RSA) model to simulate fibrinogen adsorption.
• Modeled fibrinogen as a linear chain of beads of varying sizes.
• Calculated maximum surface concentrations for both irreversible and reversible adsorption layers.
• Determined the surface blocking function (ASF) for end-on adsorption.
• Predicted adsorption isotherms and kinetics under diffusion and convection.
• Interpreted experimental data from TIRF and ellipsometry.

Main Results:

• Maximum surface concentration for the end-on (reversible) monolayer is 6.13 × 10^3 μm⁻².
• Maximum surface concentration for the side-on (irreversible) monolayer is 2.27 × 10^3 μm⁻².
• Total maximum surface concentration for both orientations is 8.40 × 10^3 μm⁻².
• Equilibrium adsorption constant for end-on adsorption is 8.04 × 10⁻³ m.
• Predicted adsorption energy minimum of -17.4 kT (ΔG = -41.8 kJ mol⁻¹).

Conclusions:

• The RSA model successfully predicts fibrinogen adsorption behavior, including distinct reversible and irreversible binding.
• Theoretical predictions align with experimental data, validating the model's accuracy.
• The study provides insights into anisotropic protein adsorption mechanisms on heterogeneous surfaces.
• Findings contribute to understanding protein-surface interactions for biomaterial design and diagnostics.