Small-scale glues stick to surfaces.A blob of glue might work for assembling a model airplane, but connecting microscopic particles for nanotechnology applications With nanotechnology, a large set of materials and improved products rely on a change in the physical properties when the feature sizes are shrunk. Nanoparticles for example take advantage of their dramatically increased surface area to volume ratio. Their optical properties, e.g. requires more precise adhesives. A new study shows that by choosing materials known to bind to to contract; as, to bind one's self to a wife s>. See also: Bind a particular surface at the molecular level, researchers can create the nanoscale glues they need. Roger J. Davey and his colleagues at the University of Manchester Institute of Science and Technology The University of Manchester Institute of Science and Technology (UMIST) was a university based in the centre of the city of Manchester in England. It specialised in technical and scientific subjects and was a major centre for research. in England, used crystals of saccharin saccharin (săk`ərĭn), C7H5NSO3, white, crystalline, aromatic compound. It was discovered accidentally by I. Remsen and C. Fahlberg in 1879. Pure saccharin tastes several hundred times as sweet as sugar. to test the ability of three compounds to act as molecular glues. Saccharin crystals can assume a structure known as a twin: The planes of atoms come together to form an interface with one side presenting the mirror image of the other. "Since we had a structural model of the twin interface," says Davey, "we decided to see if we could design a molecule that would bridge the interface and act as a glue." The researchers chose ethylene glycol ethylene glycol: see glycol. ethylene glycol Simplest member of the glycol family, also called 1,2-ethanediol (HOCH2CH2OH). It is a colourless, oily liquid with a mild odour and sweet taste. , indigo, and hydroquinone hydroquinone /hy·dro·quin·one/ (hi?dro-kwi-non´) the reduced form of quinone, used topically as a skin depigmenting agent. hy·dro·qui·none n. as adhesives that could bind to exposed oxygen atoms on both sides of an interface. When Davey and his colleagues added ethylene glycol or indigo to a solution of saccharin and allowed the mixture to crystallize crys·tal·lize also crys·tal·ize v. crys·tal·lized also crys·tal·ized, crys·tal·liz·ing also crys·tal·iz·ing, crys·tal·liz·es also crys·tal·iz·es v.tr. 1. , the saccharin formed twins much more frequently than a pure saccharin solution did, indicating that the added molecules helped twin surfaces adhere to each other. "Knowing the interfacial structure, we could select glue molecules that fit across the interface like pieces in a jigsaw," Davey says. Ethylene glycol and indigo molecules are both 0.47 nanometers across--just the right size to bridge the gap and stabilize the twinned crystals. Hydroquinone, however, is too large to fit in the space, so it destabilized the crystals. Indeed, the researchers saw that almost no twins formed in that saccharin solution. Davey and his colleagues report their findings in the Dec. 16, 1999 NATURE. In addition to gluing together tiny particles, molecular adhesives could attach small amounts of active chemicals to a crystal matrix that would later dissolve, Davey suggests, thus creating controlled-release drugs. |
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