AFM Study of Elastic Module of Physical-Vapor-Deposited Phospholipid Membranes
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2018
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The physical study of artificial phospholipid membranes on solid substrates has become a relevant way to gain insights into the physical behavior of cell membranes. The study of mechanical properties of artificial membranes (lab-made) has become possible with the use of atomic force microscopy. Here, we analyze the Young's modulus and adhesion force of several phospholipidic membranes as a function of temperature using Scanning Force Spectroscopy (SFS). Phospholipids were deposited onto double-polished silicon substrates by physical vapor deposition (PVD), as we have recently reported [1, 2]. We have used Raman spectroscopy to show that the chemical structure of our deposited phospholipid remains unaltered after PVD. After PVD we performed AFM and SFS measurements on the following phospholipids: DPPC, DMPC and DSPC. Measurements using AFM in liquid confirm the self-assembly of the phospholipid bilayer. By using SFS of the deposited membrane in liquid, we observe 2 phase transitions, both in Younǵs Modulus, as well as adhesion channels. The measured phase transitions are consistent with the ripple-gel transition and the gel-liquid crystalline phases. Furthermore, we have studied the frequency dependence of these phase transitions by changing the tip velocity in SFS experiments. Supported by FONDECYT grant # 1141105 (UGV), FONDECYT INICIACION grant # 11160664 (TPC), CONICYT Fellowships (RC and MC), Postdoctoral Fellowship FONDECYT 3160803 (MJR) and CONICYT-PIA ACT 1409. [1] María J. Retamal, Marcelo A. Cisternas, Sebastian E. Gutierrez-Maldonado, Tomas Perez-Acle, Birger Seifert, Mark Busch, Patrick Huber and Ulrich G. Volkmann, J. Chem. Phys. 141, 104201 (2014). [2] María Jose Retamal, Tomas P. Corrales, Marcelo A. Cisternas, Nicolas H. Moraga, Diego I. Diaz, Rodrigo E. Catalan, Birger Seifert, Patrick Huber, and Ulrich G. Volkmann. Biomacromolecules 17 (3), 1142 (2016).
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Volkmann, Ulrich Georg, Catalán, Rodrigo, Retamal, María José, Cisternas, Marcelo A, Moraga, Nicolas, Díaz, Diego, Corrales, Tomás P, Párez-Acle, Tomás, Soto-Arriaza, Marco, Huber, Patrick. AFM Study of Elastic Module of Physical-Vapor-Deposited Phospholipid Membranes. Biophysical Journal. 2018;114:105A-105A.