Surface charge control for zwitterionic polymer brushes: Tailoring surface properties to antifouling applications

Area of Science:

• Materials Science
• Surface Chemistry
• Biomaterials

Background:

• Electrostatic interactions are critical in biomacromolecule and microorganism adhesion.
• Zwitterions are known for antifouling properties due to their purported zero charge valence.
• Zwitterionic materials may not be charge-neutral in aqueous environments, necessitating pH-dependent surface charge adjustment for biomedical applications.

Purpose of the Study:

• To investigate the pH-dependent surface charge of zwitterionic polymer brushes.
• To demonstrate the ability to tune surface zeta potential by copolymerization.
• To evaluate the antifouling performance of surfaces with controlled zeta potential.

Main Methods:

• Surface-initiated atom transfer polymerization was used to create polysulfobetaine methacrylate (pSBMA) brushes.
• Copolymerization of SBMA with cationic methacryloyloxyethyltrimethyl ammonium chloride (METAC) controlled surface zeta potential.
• Surface properties (zeta potential, roughness, free energy, thickness) and antifouling performance were assessed.

Main Results:

• pSBMA brushes exhibited a zeta potential of -40 mV across a wide pH range.
• Incorporating 2% METAC shifted the zeta potential to zero at physiological pH with minimal impact on other surface properties.
• Zero and negative zeta potential surfaces demonstrated superior resistance to fouling by bovine serum albumin, Escherichia coli, and Staphylococcus aureus.
• Zero zeta potential surfaces were most effective at reducing lysozyme fouling.

Conclusions:

• Surface zeta potential of zwitterionic polymer brushes can be precisely tuned to achieve charge neutrality at physiological pH.
• Controlled surface charge is a key factor in achieving effective antifouling performance for biomaterials.
• This approach offers a strategy for developing advanced antifouling surfaces for biomedical applications.