Steric and electrostatic surface forces on sulfonated PEG graft surfaces with selective albumin adsorption

Area of Science:

• Biomaterials Science
• Surface Chemistry
• Polymer Science

Background:

• Polyethylene glycol (PEG) graft layers are used to resist protein adsorption.
• Ionized terminal groups on PEG layers can influence interfacial forces and protein interactions.
• Understanding these interactions is crucial for designing effective biomaterials.

Purpose of the Study:

• To investigate the effect of terminal sulfonate groups on PEG graft layers.
• To characterize the interfacial forces and protein resistance of PEG-aldehyde (PEG-CHO) and sulfonated PEG (PEG-SO3) graft layers.
• To determine surface forces relevant to protein resistance and bio-interfacial interactions.

Main Methods:

• X-ray Photoelectron Spectroscopy (XPS) for surface characterization.
• Colloid probe Atomic Force Microscopy (AFM) for measuring interaction forces.
• Analysis of interaction forces as a function of ionic strength.

Main Results:

• PEG-CHO surfaces exhibited repulsive steric barrier forces independent of ionic strength.
• PEG-SO3 surfaces showed repulsive steric forces, but net interaction forces varied with ionic strength.
• Albumin adsorbed onto PEG-SO3 surfaces at 0.15 M salt, but not onto PEG-CHO surfaces; adsorption decreased at lower ionic strength.
• Fibrinogen and lysozyme did not adsorb on either surface.

Conclusions:

• Terminal sulfonate groups on PEG grafts modulate interfacial forces and protein adsorption.
• Protein adsorption behavior on PEG-SO3 surfaces is dependent on ionic strength due to electrical double-layer interactions.
• This finding offers an alternative explanation for thromboresistance observed with PEG-sulfonate coatings.