Ternary protein adsorption onto brushes: strong versus weak

Area of Science:

• Biomaterials Science
• Surface Chemistry
• Polymer Science

Background:

• Attractive interactions between proteins and polyethylene glycol (PEG) lead to ternary adsorption within PEG brushes.
• Two modes of ternary adsorption exist: weak (nonspecific protein-surface attraction) and strong (specific PEG-protein binding).
• Ternary adsorption influences the effectiveness of PEG brushes in preventing protein adsorption and can affect surface biocompatibility.

Purpose of the Study:

• To theoretically compare adsorption isotherms and protein concentration profiles for different ternary adsorption modes in PEG brushes.
• To analyze the impact of grafting density (1/Sigma), PEG chain length (N), and protein characteristics on adsorption.
• To investigate the relationship between adsorption mode and the resulting protein concentration profiles.

Main Methods:

• Theoretical modeling of adsorption isotherms and protein concentration profiles.
• Analysis of "parabolic" brushes under varying parameters: grafting density (Sigma), PEG degree of polymerization (N), and protein size.
• Comparison of weak, terminal strong, and backbone strong adsorption scenarios.

Main Results:

• The amount of adsorbed protein per unit area (Gamma) shows a mode-specific maximum for all three cases.
• Gamma scales approximately with N for backbone and weak adsorption, and with N^0 for terminal adsorption.
• The protein concentration profile exhibits a maximum (zmax > 0) that shifts outward with decreasing Sigma, except for weak/backbone adsorption at high Sigma.

Conclusions:

• Ternary adsorption modes significantly influence protein adsorption behavior and capacity within PEG brushes.
• Strong antibody adsorption can potentially trigger immune responses, impacting surface biocompatibility.
• The theoretical framework provides insights into optimizing PEG brush design for specific protein interactions and surface applications.