The engineering of materials containing biological structure offers the promise of new devices and processes of high potential impact on the quality of human life. Our research focuses on understanding, modeling, and controlling the incorporation of biomolecular or biomimetic entities onto or within synthetic materials. A balanced blend of theory, computer simulation, and experiment is employed, and an overall objective is to contribute fundamentally to each step along the research chain: discover ==> understand ==> model ==> control ==> create. Our efforts, summerized below, focus on the interfacial behavior of biomacromolecules and on molecular templating.

The behavior of biomacromolecules at the liquid solid interface is poorly understood yet crucial to technologies involving molecular surface placement. Of significant impact would be a universally applicable, mesoscopic model of protein adsorption kinetics. It is one of our goals to develop such a model. Toward this end, we have found the interplay of theory, simulation, and experiment to be extremely useful. As an example, we have shown that single-mode, optical waveguide biosensing allows for the isolation of diffusion and reaction limited kinetic regimes whose analysis inspires a model description linking boundary layer transport to particle adsorption and conformational transition. This technique additionally appears to be a novel means to detect adsorbed layer structural transitions through system-specific "kinetic signatures". As another example, we have shown that a simulated free energy profile linking native and conformationally altered adsorbed proteins provides mechanistic clues to the incorporation of this important event into a mesoscopic model description. Concurrent with these efforts, we seek to move beyond modeling toward actively controlling the spatial and orientational order of an adsorbed protein layer. An applied electric field offers the enticing possibility of directing biomacromolecules as they approach a surface, yet its influence on the adsorption process is largely unstudied. We have developed an optical waveguide method that allows for continuous measurement of protein adsorption under an electric field and, therefore, direct observation of the field's influence on adsorbed layer properties. A long-term goal is the use of electric field methods to create ordered biomaterial protein coatings for tissue engineering applications.

Molecular templating is a promising means to impart biomimetic structure on a synthetic material. Progress is hindered, however, by a poor overall quantitative understanding. An important goal of ours is to establish a theoretical framework through which adsorption in templated materials may be modeled. We have developed a quenched-particle description of a templated adsorbent and liquid-state theoretical techniques to determine the influence of template size, shape, and density on the adsorptive properties of these non-equilibrium materials. An important discovery has been the strong and controllable effect on phase equilibrium by templated quenched disorder. A long-term goal is to engineer biomolecular recognition into materials for biosensing or tissue engineering applications.


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