Abstract:
:We used micron-sized latex spheres to probe the phase state and the viscoelastic properties of dimyristoylphosphatidylcholine (DMPC) bilayers as a function of temperature. One or two particles were manipulated and stuck to a DMPC giant vesicle by means of an optical trap. Above the fluid-gel main transition temperature, T(m) congruent with 23.4 degrees C, the particles could move on the surface of the vesicle, spontaneously (Brownian motion) or driven by an external force, either gravity or the laser beam's radiation pressure. From the analysis of the particle motions, we deduced the values of the membrane hydrodynamic shear viscosity, eta(s), and found that it would increase considerably near T(m). Below T(m), the long-distance motion of the particles was blocked. We performed experiments with two particles stuck on the membrane. By optical dynamometry, we measured the elastic resistance of the membrane to a variation in the interparticle distance and found that it would decrease considerably (down to zero) when the temperature was increased to T(m). We propose an interpretation relating the elastic response to the membrane curvature modulus, k(C). In this scheme, the two-bead dynamometry experiments provide a direct measurement of k(C) in the P'(beta) phase of lipid bilayers.
journal_name
Biophys Jjournal_title
Biophysical journalauthors
Dimova R,Pouligny B,Dietrich Cdoi
10.1016/S0006-3495(00)76296-5subject
Has Abstractpub_date
2000-07-01 00:00:00pages
340-56issue
1eissn
0006-3495issn
1542-0086pii
S0006-3495(00)76296-5journal_volume
79pub_type
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