Adsorption of soft materials under non-equilibrium conditions

The adsorption of soft materials to biological interfaces is a key motif in many systems of interest for biomedical applications. For example, the ability of lipid bilayers to modulate traffic into and out of cells is highly dependent on the ability of external objects to adsorb to the cell membrane and trigger endocytosis. In most biological systems, adsorption occurs under non-equilibrium conditions due to the presence of strong flows or due to the dynamics of the components of the system. We are interested in developing a theoretical understanding of how adsorption to biological interfaces can depend on system dynamics, and use these ideas for both biomedical and bioengineering applications. We are particularly interested in:

  1. Blood-clotting inspired polymer adsorption in flow

    The globular protein von Willebrand Factor plays an important role in blood clotting by adsorbing at the site of a wound and then adhering to platelets to form what is known as a plug. However, vWF is only capable of adsorption at specific flow rates, allowing adhesion to only occur under conditions associated with a wound. The group is interested in this adsorption behavior for both medical applications and the development of novel responsive materials that could be used in particle deposition and adhesion.

  2. Responsive materials for targeted drug delivery

    Soft nano-carriers are becoming the standard in drug or gene delivery technologies. These tiny carriers are typically composed of three parts: the core that contains an active substance (i.e. the drug), the shell, and the functional groups necessary for specific targeting which are often polymeric in nature. In the past, most theoretical studies have focused on the formation process of these structures, but a detailed analysis of their dynamics during the delivery process is still lacking. A fundamental understanding of these issues, and novel approaches inspired by local clot formation could lead to novel therapeutics used not only to treat cancer, but also auto-immune diseases, arteriosclerosis, etc.

Selected publications

Penetration of lipid bilayers by nanoparticles with environmentally-responsive surfaces: simulations and theory
R. C. Van Lehn and A. Alexander-Katz
Soft Matter 7, 11392-11404 (2011).

Non-monotonic hydrodynamic lift force on highly-extended polymers near surfaces
C.E. Sing, A. Alexander-Katz
Europhys. Lett. 95, 48001 (2011).

Near-surface hydrodynamic effects can drive the dynamic behavior of collapsed polymers in the presence of shear flows, giving rise to a competition between a hydrodynamic lift force and attractive surface interactions.

Inspired by the conformational changes observed in biological systems, we analyze the adsorption of environmentally-responsive nanoparticles to lipid bilayers using both coarse-grained simulations and analytical theory.

Department of Materials Science and Engineering MIT