Modified Random Sequential Adsorption Model for Understanding Kinetics of Proteins Adsorption at a Liquid-Solid...

Area of Science:

• Biophysics
• Surface Science
• Materials Science

Background:

• Protein adsorption on surfaces is crucial for biomaterials and biosensors.
• Understanding adsorption kinetics informs surface design and device performance.
• Hydrophobic surfaces like hexadecanethiolated gold present unique adsorption challenges.

Purpose of the Study:

• To experimentally measure and model the adsorption kinetics of human serum albumin (HSA) on a hydrophobic gold surface.
• To investigate the asymptotic behavior and jamming limit of HSA adsorption.
• To elucidate the underlying mechanisms, including interfacial transport and protein orientation.

Main Methods:

• Real-time adsorption measurements using quartz crystal resonators (83 MHz).
• Development and application of an interface-depletion modified random sequential adsorption (RSA) model.
• Molecular dynamics (MD) simulations using the ReaxFF method to study protein behavior at the interface.

Main Results:

• Experimental data aligns with the interface-depletion modified RSA model.
• MD simulations reveal specific protein orientation and significantly reduced diffusion at the interface.
• An interfacial depletion region forms, reducing protein supply and slowing adsorption.

Conclusions:

• The study elucidates the mechanism behind the slowdown of HSA adsorption on hydrophobic surfaces.
• Reduced protein diffusion and specific orientation at the interface are key factors.
• The developed RSA model accurately describes the observed adsorption kinetics.