Bending elasticity and thermal fluctuations of lipid membranes. Theoretical and experimental requirements

Direct Cytoskeleton Forces Cause Membrane Softening in Red Blood Cells

“…Experimental approaches to the flickering phenomenon suffer from restricted time resolution and the limited spatial discrimination of membrane motions in the submicron scale. The use of ultrafast optical microscopy (28) renders the classical flickering method (29,30) capable of tracking cell contour fluctuations at very high sampling rates with subpixel resolution, thus allowing noninvasive detection of signal correlations over broad timescales. Normal RBCs have a characteristic biconcave or discocyte shape, a symmetry property that facilitates the detection, in Fourier space, of the active contributions to the normal modes of membrane motion at the equatorial rim.…”

Communication: Rigidification of a lipid bilayer by an incorporated n-alkane

“…• C through analysis of the shape fluctuation of the spherical giant vesicle 20 observed by phase contrast microscopy (detailed results are provided in the supplementary material 17 ). Since κ is approximately 1.5 × 10 −19 J without TD, 7 the effect of TD on κ in the liquid-crystalline phase is much smaller than that in the gel phase.…”

A novel method for measuring the bending rigidity of model lipid membranes by simulating tethers

“…Bending rigidities have been measured experimentally by various techniques, [5][6][7][8][9][10][11][12][13][14][15] all ultimately based on one of two general approaches: One may either utilize the dependence of thermal undulations on a membrane's rigidity or measure the force needed to actively bend it. The traditional realization of the first approach is to monitor the fluctuations of vesicles as a function of wavelength by light microscopy, a method termed "flicker spectroscopy."…”

“…The traditional realization of the first approach is to monitor the fluctuations of vesicles as a function of wavelength by light microscopy, a method termed "flicker spectroscopy." [5][6][7] A related experimental method is based on micropipette manipulation techniques. There, the flicker spectrum is successively suppressed by increasing the pipette pressure, and the bending rigidity can then be obtained from the low-tension regime of the tension-area curve.…”