Digital holographic microscopy of phase separation in multicomponent lipid membranes

Vahideh Farzamrad; Ali-Reza Moradi; Ahmad Darudi; Lobat Tayebi

doi:10.1117/1.JBO.21.12.126016

22 December 2016 Digital holographic microscopy of phase separation in multicomponent lipid membranes

Vahideh Farzamrad, Ali-Reza Moradi, Ahmad Darudi, Lobat Tayebi

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Journal of Biomedical Optics, Vol. 21, Issue 12, 126016 (December 2016). https://doi.org/10.1117/1.JBO.21.12.126016

Abstract

Lateral in-homogeneities in lipid compositions cause microdomains formation and change in the physical properties of biological membranes. With the presence of cholesterol and mixed species of lipids, phospholipid membranes segregate into lateral domains of liquid-ordered and liquid-disordered phases. Coupling of two-dimensional intralayer phase separations and interlayer liquid-crystalline ordering in multicomponent membranes has been previously demonstrated. By the use of digital holographic microscopy (DHMicroscopy), we quantitatively analyzed the volumetric dynamical behavior of such membranes. The specimens are lipid mixtures composed of sphingomyelin, cholesterol, and unsaturated phospholipid, 1,2-dioleoyl-sn-glycero-3-phosphocholine. DHMicroscopy in a transmission mode is an effective tool for quantitative visualization of phase objects. By deriving the associated phase changes, three-dimensional information on the morphology variation of lipid stacks at arbitrary time scales is obtained. Moreover, the thickness distribution of the object at demanded axial planes can be obtained by numerical focusing. Our results show that the volume evolution of lipid domains follows approximately the same universal growth law of previously reported area evolution. However, the thickness of the domains does not alter significantly by time; therefore, the volume evolution is mostly attributed to the changes in area dynamics. These results might be useful in the field of membrane-based functional materials.

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Vahideh Farzamrad, Ali-Reza Moradi, Ahmad Darudi, and Lobat Tayebi "Digital holographic microscopy of phase separation in multicomponent lipid membranes," Journal of Biomedical Optics 21(12), 126016 (22 December 2016). https://doi.org/10.1117/1.JBO.21.12.126016

Received: 19 May 2016; Accepted: 29 November 2016; Published: 22 December 2016

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