Growth of Myelin Figures from Parent Multilamellar Vesicles

Abstract

We examine the formation and growth of isolated myelin figures and microscale multilamellar tubules from isotropic micellar solutions of an anionic surfactant. Upon cooling, surfactant micelles transform into multilamellar vesicles (MLVs) whose contact is found to trigger the unidirectional growth of myelins. While the MLV diameter grows as d MLV ∝ t 1/2, myelins grow linearly in time as L M ∝ t 1, with a fixed diameter. Combining time-resolved small-angle neutron scattering (SANS) and optical microscopy, we demonstrate that the microscopic growth of spherical MLVs and cylindrical myelins stems from the same nanoscale molecular mechanism, namely, the surfactant exchange from micelles into curved lamellar structures at a constant volumetric rate. This mechanism successfully describes the growth rate of (nonequilibrium) myelin figures based on a population balance at thermodynamic equilibrium.

Strongly Emitting Folic Acid-Derived Carbon Nanodots for One- and Two-Photon Imaging of Lyotropic Myelin Figures

“…Similar behavior was observed for the samples formed in the absence of CNDs. 96,97 In addition to the straight and slightly bent cylindrical structures characteristic for both hybrid materials and dopant-free samples, looped and oval shapes were also observed (Figure S26). We conclude that adding the FA CNDs does not affect the formation of the specific multilamellar microstructures.…”

Three-Dimensional Imaging of Bioinspired Lipidic Mesophases Using Multicolored Light-Emitting Carbon Nanodots

“…Lipids are known to self-assemble into lyotropic mesophases, vital for biologically relevant entities. − A prominent example of a lamellar liquid crystalline system of a biological origin is the myelin figure (MF). − This structure resembles the lipid-rich myelin sheath, enabling the efficient conduction of nerve impulses in vertebrates. , Typically, MFs are multilamellar cylindrical structures of self-organized concentrically wrapped layers of amphiphiles (e.g., lipids, as well as ionic and nonionic surfactants) alternating with layers of water. − Such three-dimensional (3D) organization can spontaneously occur once surfactant molecules combine with aqueous media. A deeper comprehension of the architecture, stability, and response to external stimuli of lipidic liquid crystalline materials may lead to a better understanding of native structures and advances in the design of biomimetic systems. ,− …”