(755e) Measuring Lipid Bilayer Curvature Using Micro-Fabricated Cantilevers

Cell membranes are mainly constructed of lipid molecules which assemble into a flexible bilayer. These bilayers are ofterntimes described using the fluid mosaic model. The micromechanical behavior of these bilayersare important in many biological events, such as membrane fusion, and its curvature and elastic modulus are usually studied by laborious micropipette techniques. We come up with a novel method to detect the real time curvature of a lipid membrane using microcantilevers. We observe bilayer formation onto the cantilevers by flowing 100 nm vesicles past the cantilevers and monitoring their adhesion and rupture onto a solid substrate. Our cantilevers are a gold on silicon nitride structure that ranges from 500-750 microns in length and 100 microns wide. The cantilever deflection is measured using a photo sensitive diode. A large cantilever deflection is observed upon intact vesicles adhering to the gold surface, indicating a surface stress change between adjacent vesicles. Surfaces which have been modified with self-assembled monolayers, such as hydrophilic polyethylene glycol (PEG) or hydrophobic dodecanthiol, are tested for vesicle rupture behavior. By modifying these surfaces, we can assemble lipid monolayers, lipid bilayers, or vesicle multilayers on the cantilever., Ultimately, we can utilize this technique for characterization of various lipid membrane curvature. Adding membrane proteins to the lipid assembly can also change the membrane curvature. Microcantilevers offer characterization of a surface by detecting the stress changes associated with planar lipid membrane assemblies.