Lipid islands on liquid crystal shells*

Combining a self-closing spherical topology, dual closely spaced liquid-liquid interfaces, and fluid long-range order, liquid crystal (LC) shells are exquisite reporters of delicate self-organization processes occurring at their interfaces. Conversely, the LC actively influences such processes, its 3D bulk elasticity triggering novel 2D surface ordering phenomena. Here we show that lipids adsorbing onto LC shells phase separate and form condensed monolayer islands, inducing a locally distorted LC director field that reveals their presence with high contrast in polarizing microscopy. Lipids transfer through the shell, forming secondary islands that are attracted to primary islands via nematic elasticity. The mutual interaction between LC shells and adsorbed lipid monolayers, revealed via LC birefringence, provides an unconventional means of detecting natural lipids. This turns LC shells into a valuable platform for studying liposome adsorption on soft hydrophobic substrates, and it may be useful in low-cost minimum-resource biosensing. It also opens new avenues in making 'patchy' colloidal particles with directionally programmed interactions.