Single Lipid Diffusion in Langmuir Monolayers

Abstract

Individual lipid movement in a monolayer is studied over long time intervals (500 s) by darkfield microscopy of single lipids labeled with gold colloids (30 or 100 nm in diameter). Dimyristoyl phosphatidylcholine in the fluid phase shows normal diffusion, with a diffusion coefficient of (1.1 ± 0.2) × 10-8 cm2/s. Since this is consistent with values derived from the diffusive transport of many lipids, the analysis of gold-tagged lipids in a monolayer provides a reliable picture of lipid diffusion on the level of single molecules.

Sum-frequency vibrational spectroscopic studies of Langmuir monolayers

“…Complex patterns of LC domains, such as dendritic and polygonal shapes, were observed in the phase coexistence region [27]. Motion of a fluorescent bead in a Langmuir monolayer was probed to discover that its diffusion is confined to the LC domain boundaries [28]. Various X-ray techniques have made classification of different phases of Langmuir monolayers and their conformation possible at the molecular scale [19].…”

Dynamics in Ultrathin Films: Particle Tracking Microrheology of Langmuir Monolayers

“…The two lines represent the tracking of the trajectories of individual particles, and of the relative motion of pairs of particles. The last method has the advantage that any global drift (due to air currents or to local heating) can be removed [50]. As it can be observed, the slope of both lines, and therefore the values of D, is essentially the same.…”

“…The possibility of tuning the chemical nature of the microparticle's surface makes it possible to reduce or even eliminate the "stick-slip" problems that can be found in some concentrate monolayers when oscillatory shear rheometers are used. However, few applications to the rheology of monolayers have appear so far in the literature [48][49][50][51][52][53], and in general they deal with diffusion coefficients but do not calculate the surface shear viscosity, a non trivial problem as demonstrated by Danov et al [54].…”

Errors in two particle tracking at close distances

“…Gold beads attached to single lipids in Langmuir monolayers can serve as a model system for diffusion of lipids in membranes [2]. Furthermore, surface modified polystyrene beads can be used as model proteins for diffusion studies in membranes [3].…”