(629g) Hydration Properties of Candidate Nonfouling Materials

While significant advances in biocompatible and environmentally benign materials have been made, one of the remaining challenges is to understand surface resistance to protein adsorption and cell adhesion. Our research has demonstrated a strong link between surface hydration and resistance to protein adsorption. Experimental data and molecular simulations have shown that surfaces with tightly bound and structured hydrating water will generate repulsive forces on approaching proteins and prevent non-specific adsorption.

Direct evaluation of the non-fouling properties of a candidate material requires a lengthy process of synthesis, separation, and characterization before the protein adsorption experiments can even begin. However, the strong correlation found between hydration and non-fouling properties provide an opportunity for easy and inexpensive screening of potential new materials. Therefore, simulations and experiments were conducted to evaluate the hydration of a spectrum of functional moieties representing a wide range of nonfouling abilities.

The extent of hydration of biologically relevant functional groups, like oligo-ethylene glycol, carboxy betaine, and sugar alcohols, was evaluated by measuring the solution density as a function of concentration. When calculated, the partial molar volume change due to hydration was then compared to protein adsorption isotherms on self-assembled monolayer surfaces presenting the same functional groups. A critical hydration parameter was obtained that suggests a minimum level of intrinsic hydration, that when matched with appropriate surface packing density, may predict nonfouling ability. By relating a simple measurement of the change in partial molar volume due to hydration to protein adsorption measurements, a rapid screening technique for candidate nonfouling moieties was evaluated.