Shape analysis of giant vesicles with fluid phase coexistence by laser scanning microscopy to determine curvature, bending elasticity, and line tension.

Membrane shape parameters such as curvature, bending elasticity, and lateral tension, are relevant to the lateral organization and function of biomembranes, and may critically influence the formation of lateral clustering patterns observed in living cells. Fluorescence laser-scanning microscopy can be used to image vesicles and cell membranes, and from shape analysis of these images mechanical membrane parameters can be quantified. Methods to analyze images of equatorial sections obtained by confocal or multiphoton microscopy are detailed, in order to estimate curvature, lateral tension, line tension, relative differences in mean curvature and Gaussian curvature bending moduli, and fluorescence dye intensity profiles, typically within coexisting liquid-ordered and liquid-disordered membrane domains. A variety of shape tracing and shape fitting methods are compared.