• Computer simulations show soap in a new light

    Computer simulations show soap in a new light
    Date:31 August 2010 Tags:

    A team from Temple University uses the Lincoln supercomputer at the University of Illinois' National Centre for Supercomputing Applications (NCSA) to model surfactants. Surfactants are used in common household products like detergents and shampoo. By simulating surfactants on a computer, researchers wash away expensive and slow laboratory work as they design these new products.

    Mixtures of surfactants, water, and other molecules are exceptionally challenging to model. They aggregate themselves into structures that can trap materials. The image shows one such structure, a self-assembled micelle, in water. A micelle is an aggregate of molecules that have both water-attracting and water-repelling ends (such as the molecules in soaps), and due to the nature of the liquid surrounding the molecules, have coalesced into a coherent structure such as a sphere or cylinder. The self-assembly process takes place at the micrometer scale over the course of hundreds of nanoseconds, and it often includes hundreds of millions of atoms.
    To capture this complicated process, the team uses an approach known as coarse-grain molecular dynamics. Molecule fragments are modelled as spherical "pseudo-particles", dramatically reducing the number of particles and thus the number of particle interactions that must be computed. Runs of the coarse-grain method on NCSA's Lincoln have shown tremendous speedups over calculations on other supercomputers.

    The Temple team is also exploring another class of surfactants as a way of controlling the delivery of drugs in the body and improving their impact.

    Using NCSA's Abe supercomputer and partnering with a team of experimental chemists at the University of Pennsylvania, they're simulating self-assembling dendrimeric molecules (branching molecules) that can be tailored to particular shapes and properties. Ultimately, these molecules could be used to build customised "containers" for drugs. Self-assembled capsules would be built around the drug, which might otherwise be destroyed as it made its way through the body.

    — Bill Bell, University of Illinois

    Image credit: Axel Kohlmeyer, Temple University

    In collaboration with the National Science Foundation and Livescience.com
     

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