Long-lasting liposomes.A coat of nanoparticles can prevent a popular lab-made capsule from fusing with its neighbors in solution and losing its structure, researchers report. Liposomes Liposomes Aqueous compartments enclosed by lipid bilayer membranes; liposomes are also known as lipid vesicles. Phospholipid molecules consist of an elongated nonpolar (hydrophobic) structure with a polar (hydrophilic) structure at one end. are hollow, spherical capsules made from phospholipids, the same components found in cell membranes Cell membrane The membrane that surrounds the cytoplasm of a cell; it is also called the plasma membrane or, in a more general sense, a unit membrane. This is a very thin, semifluid, sheetlike structure made of four continuous monolayers of molecules. . They can be used to carry drugs or other biological cargo. But individual liposomes are fragile and tend to fuse into blobs after a couple of days, spilling their contents prematurely in the process, says Steve Granick of the University of Illinois at Urbana-Champaign Early years: 1867-1880 The Morrill Act of 1862 granted each state in the United States a portion of land on which to establish a major public state university, one which could teach agriculture, mechanic arts, and military training, "without excluding other scientific . "We want to keep them discrete," he says. Granick and graduate student Liangfang Zhang studded the liposomes with polystyrene polystyrene (pŏl'ēstī`rēn), widely used plastic; it is a polymer of styrene. Polystyrene is a colorless, transparent thermoplastic that softens slightly above 100°C; (212°F;) and becomes a viscous liquid at around 185°C; particles 20 nanometers (nm) in diameter. The nanopartieles covered about 25 percent of the 200-nm-diameter liposomes. The enhanced liposomes remained stable in solution for 50 days, the researchers report in the April Nano Letters. The method may enable researchers to make liposomes in high concentrations, in contrast to the dilute solutions used today to "prevent them from banging into each other," says Graniek. About 75 percent of an enhanced liposome s liposome (lī`pəsōm', lĭp`ə–), microscopic, fluid-filled pouch whose walls are made of layers of phospholipids identical to the phospholipids that make up cell membranes. surface is still free for attachments of biological molecules that can direct the liposome to a specific target, notes Granick.--A.C. |
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