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Membrane Interferometer
     
Membrane Interferometer
  About the Figure: The images on the right side show two fluorophores, DiI and Cy5, which are associated with the lipid bilayer, and carboxyfluorescein, which is trapped in the well beneath the lipid bilayer. The DiI and Cy5 images, where the membrane is located, both show interference rings; this indicates that the bilayers are actually slightly curved, not flat. Using VIA-FLIC, we have calculated exactly how curved these bilayers are. [265]  
         
 

Supported membranes offer many advantages, including the ability to use surface characterization techniques. Fluorescence Interference Contrast Microscopy (FLIC [230]) and Variable Incidence Angle-FLIC (VIA-FLIC [233]) are two such techniques used in our lab to probe lipid bilayers. FLIC and VIA-FLIC use interferometry, or the interference of light waves off a reflective surface, to precisely determine the height of fluorescent objects relative to the surface.  Our lab has developed a new geometry where lipid bilayers are suspended over a well in silicon dioxide, as shown in the cartoon above. [265] This positions the suspended bilayer within a few hundred nm of an atomically flat mirror, so that the precise positions of fluorophores and small conformational changes in labeled proteins can be measured by FLIC or VIA-FLIC.   Current work is directed towards incorporating electrodes into the device so that simultaneous high precision optical and electrical measurements can be made on the same protein, e.g. on ion channels. 

 
         
  Recent Publications      
  "A Membrane Interferometer." Prasad V. Ganesan and Steven G. Boxer. PNAS, 106, 14, 5627-2632, (2009). [pdf]

"Variable Incidence Angle Fluorescence Interference Contrast Microscopy for Z-Imaging Single Objects. Caroline M. Ajo-Franklin, Prasad V. Ganesan, and Steven G. Boxer. Biophysical Journal, 89, 2759-2769, (2005). [pdf]

 
 
     
The Boxer LaboratoryStanford UniversityDepartment of Chemistry • 380 Roth Way, Stanford, California, 94305-5012 • (650) 723-4482
Questions about this website may be directed to Debra Frank. • Website updated March 2012.