Semi-permeable vesicles composed of natural clay
The authors report a way to produce semi-permeable vesicles from montmorillonite, a natural plate-like clay mineral that occurs widely in the environment. Simple shearing forces can assemble an aqueous suspension of montmorillonite clay plates onto air bubbles producing clay-armoured bubbles. Replacing the water with organic liquids will displace the air pocket inside the clay-armour with the liquid forming vesicles. Clay vesicles are microporous, exhibit size-selective permeability. This is the first time that any group has demonstrated self-assembly of inorganic minerals into structured compartments.
Clay armoured bubbles are produced by sandwiching a suspension of clay plates and air bubbles between two glass slides, and sliding them. The trapped air bubble will gather sufficient clay plates to form clay-armoured bubbles. A schematic is shown in the figure below. The bubbles range from 5 to 100 microns in radius. The clay armoured bubbles can created by sliding this bubbly clay suspension between other hydrophilic suspensions such as aluminum, copper and stainless steel.
1. A.B. Subramaniam, J. Wan, A. Gopinath and H.A. Stone, "Semi-permeable vesicles composed of natural clay", Soft Matter, 2011, 7, 2600-2612
2. M.M. Hanczyc, S.M. Fujikawa and J.W. Szostak, "Experimental Models of Primitive Cellular Compartments: Encapsulation, Growth, and Division", Science, 2003, 302 5645, 618-622