Protein – polymer substrate interactions can have a profound effect on the efficacy of several applications such as medical implants, bioassays, biosensors, drug delivery, marine fouling and bioseparations.These interactions are primarily quantified in terms of approach or non-contact force and adhesion or pull-off force between protein and substrate.The Derjaguin Landau Verwey Overbeek (DLVO) theory for intermolecular forces was developed to describe the force-separation behavior between aqueous immersed surfaces. It comprises van der Waal and electrostatic forces and can accurately predict protein-substrate interactions in aqueous media at large separations (&gt; 5 nm). Often a short-ranged hydration force or Lewis acid-base force (&lt; 5 nm), is empirically modeled as an added exponential term to the DLVO theory and called the extended DLVO (x-DLVO) theory. In the current work, the DLVO theory was insufficient to explain the protein-membrane interactions at various pH and ionic strength. However, the x-DLVO theory was able to accurately describe the molecular interactions between streptavidin coated polystyrene spheres (SA-PS) and two commercial hydrophilic membranes: modified polyvinylidene fluoride (mPVDF) and modified polyether sulfone (mPES). We further investigated the extent and strength of hydrogen bonding at the water-membrane and water-protein interface using solvation shell spectroscopy and correlated it to adhesion forces for both membranes. Zeta potential measurements for the two membranes and the SA-PS particles demonstrated that both membranes were negatively charged at all solution pH and ionic strengths. However, the SA-PS particles displayed isoelectric points between pH 4 and 5 depending on the ionic strength. The interfacial adhesion forces obtained from AFM measurements were higher for mPES than mPVDF at lower pH and these results correlate with the higher fouling behavior exhibited by mPES during the filtration experiments. By fitting the force-separation approach curves to the x-DLVO theory and using initial estimates of the surface potentials, the effective Hamaker constant, the hydration constant or cohesive energy, the decay length of hydration force and revised surface potentials of membrane and particle were determined. These intermolecular force parameters are being used with the theories for fluid and particle transport through porous media to refine a previously developed <i>in-silico </i>tool for predicting filtration behavior.

Short-range hydration forces are critical in describing molecular interactions between streptavidin and polymeric membranes

Where thousands of chemistry professionals meet to share ideas and advance scientific and technical knowledge. Spring 2023 abstracts, posters, and presentations will launch at the end of March.

ACS Spring 2023

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.