IUVSTA 15th International Vacuum Congress (IVC-15), AVS 48th International Symposium (AVS-48), 11th International Conference on Solid Surfaces (ICSS-11)
    Biomaterials Monday Sessions
       Session BI-MoM

Invited Paper BI-MoM1
Chemical Recognition on Lipid Membrane Surfaces

Monday, October 29, 2001, 9:40 am, Room 102

Session: Molecular Recognition
Presenter: D.Y. Sasaki, Sandia National Laboratories
Correspondent: Click to Email
Cell communication and sensing are processes mediated by chemical recognition events that occur on the lipid membrane surface. Chemical signals in bulk solution are recognized by membrane receptors, which subsequently organize into specific structures that activate signal cascades. Through a biomimetic approach, we have examined chemically induced molecular reorganization events in lipid membranes in an effort to learn how to control this process for sensor applications and nanoscale architecture. By using a synthetic approach we have simplified interactions between molecular species to evaluate their effects on molecular reorganization. Simple two-component lipid bilayer assemblies were prepared with receptors for heavy metal ions, proteins, and polypeptides. The aggregational state of these fluorophore-labeled receptor molecules, as they responded to chemical recognition events, were monitored globally by spectroscopic means (e.g., excimer formation of pyrene labels) and locally via in situ atomic force microscopy (AFM). We found that the dispersion and aggregation of receptors in a bilayer can be directed through multiple levels of interactions, such as electrostatic charge from metal ion chelation, multiple-point binding interaction with polyfunctional guests, and phase separation. In situ AFM studies observed that nanoscale structures composed of aggregated receptors but could be made to disappear or reappear upon the addition or removal of specific chemical ligands. At a slightly larger scale, the functionalized bilayers displayed a unique ability to self-assemble into hierarchical structures of stacked bilayers through a process mediated by chemical recognition. These lipid bilayers with their unique optical response, biocompatibility, and self-organizational properties demonstrate a versatile array of possibilities for sensing and nanoarchitecture.