Magazine article Science News

Taking the Pop out of Cell-Like Balloons

Magazine article Science News

Taking the Pop out of Cell-Like Balloons

Article excerpt

When balloons suddenly burst at a child's party, tears may flow. However, when microscopic, balloon-like vesicles spilled open recently in a French laboratory, they took their time deflating, bringing smiles to the researchers' faces.

In a flow vital to life, nutrients, intercellular signals, and many other substances travel through pores in cell membranes. To study the physics of cross-membrane transport (SN: 12/21&28/96, p. 389) and to explore ways to ferry drugs or DNA into target cells, scientists make vesicles of artificial membranes enclosing droplets of liquid.

A hole induced in a vesicle wall allows molecules to flow through the breach, as they do through a cell-membrane pore. As fluid exits the vesicle, this sac deflates, the surface tension of its membrane subsides, and the hole closes up again.

In watery solutions used routinely in vesicle experiments, fluids gush out much like air racing from a balloon. Consequently, pores stop growing before they are large enough to be seen with an optical microscope, says Olivier Sandre of the Curie Institute in Paris. The holes also close up too quickly for experimenters to observe stages of their disappearance.

Now, however, such windows can stay open wider and longer.

Sandre, Francoise Brochard-Wyart, also of the Curie Institute, and Laurent Moreaux of the Ecole Superieure de Physique et de Chimie Industrielles in Paris have discovered a slow-motion switch for pore shrinkage. …

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