AVS 50th International Symposium
    Applied Surface Science Tuesday Sessions
       Session AS+BI-TuA

Paper AS+BI-TuA7
In-situ Spectroscopic Study of Thermal Phase Transition of Supported Hybrid Bilayer Membranes

Tuesday, November 4, 2003, 4:00 pm, Room 324/325

Session: Biomaterials Characterization
Presenter: C.S.-C. Yang, National Institute of Standards and Technology
Authors: C.S.-C. Yang, National Institute of Standards and Technology
K.A. Briggman, National Institute of Standards and Technology
J.C. Stephenson, National Institute of Standards and Technology
L.J. Richter, National Institute of Standards and Technology
Correspondent: Click to Email
Hydrated phospholipid structures (Langmuir-Blodget films, supported bilayers, vesicles, etc.) have been widely studied as model systems for biological membranes. We report a study of the thermal phase transitions of fully hydrated hybrid bilayer membranes, i.e. phospholipid monolayers self-assembled onto a Au surface previously modified by a self-assembled monolayer of octadecane thiol (ODT). Using Sum Frequency Generation, a non-destructive interface-sensitive nonlinear optical probe, the structure and conformation of both the ODT and phospholipid alkyl chains have been characterized as a function of temperature from 25 to 60 °C. There is very little change in the ODT alkyl chain order over the temperature range studied. There are significant changes in the lipid chain order that are attributed to the transition from the ordered gel phase to disordered fluid phase, allowing us to determine the phase transition temperatures of the two-dimensional lipid layer. The gel-fluid phase transitions for a series of saturated phospholipids in the hybrid bilayers are observed at ~ 10 °C higher temperatures than those in corresponding multilamellar vesicles.