Stiff chains inhibit and flexible chains promote protein adsorption to polyelectrolyte multilayers

Area of Science:

• Materials Science
• Biomaterials Engineering
• Surface Chemistry

Background:

• Polyelectrolyte multilayers (PEMs) are versatile thin films with tunable properties.
• Controlling protein adsorption onto surfaces is crucial for biomedical applications.
• The influence of polymer chain stiffness on protein-PEM interactions is not fully understood.

Purpose of the Study:

• To investigate the effect of polymer chain stiffness on protein adsorption onto PEMs.
• To determine if PEMs can be engineered to either promote or inhibit protein adsorption.
• To correlate polymer conformation and flexibility with protein adsorption levels.

Main Methods:

• Fabrication of PEMs using flexible (poly(sodium 4-styrene sulfonate) and poly(diallyldimethylammonium chloride)) and semi-flexible (sulfated chitosan and cationic guar gum) polyelectrolytes.
• Creation of 8 distinct PEM systems by varying polyelectrolyte pairs and termination layers.
• Quantification of protein adsorption using optical reflectometry and quartz crystal microbalance with dissipation, with bovine serum albumin as the model protein.

Main Results:

• PEMs composed of semi-flexible polyelectrolytes exhibited minimal protein adsorption, regardless of the outermost layer.
• PEMs constructed from flexible polyelectrolytes showed significant protein adsorption.
• The extent of protein adsorption on flexible PEMs was strongly dependent on the terminating polyelectrolyte.

Conclusions:

• Polymer chain stiffness is a critical factor in modulating protein adsorption onto PEMs.
• Semi-flexible polyelectrolytes effectively create protein-repellent surfaces.
• The conformational state of the outermost polyelectrolyte layer dictates protein interaction, influenced by chain flexibility.