Levich Institute Seminar Announcement, 12/06/2005
Steinman Hall, Room #312
(Chemical Engineering Conference Room)
Professor Sanat K. Kumar
Renssalaer Polytechnic Institute
Chemical and Biological Engineering Department
"Dynamics of Polymers Adsorbed on Lipid Bilayers"
The transport properties of biomolecules adsorbed on supported lipid bilayers are important to understanding cell function. Such ideas are also relevant to designing biomimetic high sensitivity DNA separation strategies, membrane disrupting therapeutics, multivalent inhibitors and cellular effectors, and drug delivery, and gene therapy. The current understanding of these situations is still incomplete since the role of transport resistances from the surface and the lipid bilayer is poorly understood.
We have explored this issue in two ways. Experimentally, we varied the transport resistance of supported lipid bilayers by varying the temperature while considering phospholipids molecules close to their gel-liquid transition: we studied the lateral transport of adsorbed flexible single stranded DNA oligonucleotides on this bilayer. We show that the diffusivity of the flexible DNA adsorbate quantitatively tracks that of the lipid, even though the bilayer mobility changes by over two orders of magnitude due to the proximity of the gel-liquid transition. Thus, in this limit, the DNA mobility is slaved to lipid mobility, and the underlying surface has little effect.
In parallel, we have considered the transport behavior of macromolecules through the aid of Molecular Dynamics simulations. To date, we have examined the simpler case of polymer diffusion on hard surfaces. These results shed light on the experimental results, and also on other related situations- however, these simulations are complicated by the unusual finite size effects which play a role here. We discuss these issues, and explain how these theoretical ideas allow us to model these biologically relevant situations.
BRIEF ACADEMIC/EMPLOYMENT BACKGROUND:
Physics of Synthetic and Biological Macromolecules