Lateral diffusion measurement of membrane lipids using optical tweezers
Paper ID : 1213-MST2015-FULL
Mahsa Salami *1, Faegheh Hajizade2, Younes Farhangi3, S.Nader S.Reihani4
1Department of Physics Institute for Advanced studies in Basic Sciences (IASBS) Gava Zang Po Box 45195-1159 Zanjan 45137-66731 Iran
2Institute for Advanced Studies in Basic Sciences (IASBS)
3Instituye for Advanced Studies in Basic Sciences (IASBS)
4Sharif University of Technology
Vesicles are spherical bilayer phospholipid structures, which are known to be good mode lfor living cell membranes. According to Fluid Mosaic Model, lipid molecules diffuse freely on the surface of a membrane. To our knowledge, there are just a few reported techniques for lateral diffusion measurement based on fluorescence recovery after photobleaching and an attached nano particle tracking. The main disadvantages of the methods are: 1- fluorescence recovery after photobleaching damages the living cells and 2- Probe size is much bigger than lipids molecules, thus the accuracy of the method is not reliable.
Here, we propose a simple method to measure the lateral diffusion of lipid molecules based on temporal response of the lipids to an external force applied by optical tweezers. Optical tweezers are powerful tools to trap and manipulate at micro- and nano-scale by use of laser radiation pressure. We apply an external force to a lipids membrane using an optically trapped micro-bead. Then, a spontaneous change is applied on lipids arrangement by an external force. Due to tendency of system to be in a stable state, lipids return from disturbed situation into equilibrium. The diffusion coefficient of lipids can be experimentally measured by studying the temporal relaxation of the deformed structure.
membrane, lateral diffusion, optical tweezers
Status : Paper Accepted (Oral Presentation)