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A critical challenge in nanotechnology is developing means to routinely manipulate material structure and morphology at the nanoscale. Often, scientists use templates that render shape, form and structure to the final product.

A team led by ���ϲ����� researcher Radhakrishna Sureshkumar, professor and chair of the Department of Biomedical and Chemical Engineering in the and professor of physics in , has discovered a new and broadly applicable technique to engineer nanoscale templates.

This technique, reported in the March 21 issue of the journal Nature Materials (), does not rely on complicated and laborious chemical synthesis. Simply put, it is a “flow and gel” technique. Specifically, Sureshkumar and his fellow researchers discovered that when translucent suspensions of nano-rods, made up of ubiquitous “soapy” molecules or “surfactants,” flow through microfluidic channels, i.e., channels with width and height comparable to one-tenth the size of a human hair, the rods spontaneously self-assemble into highly stable networks, thereby causing the fluid to form soft gels.

“Such networks offer tremendous potential to be functionalized to produce nanomaterials useful for molecular detection (sensors), cellular delivery of therapeutics, catalysis and photonics, including efficient harvesting of solar energy,” says Sureshkumar.

Surfactants are present in almost every walk of life and technology—laundry detergents and shampoos, emulsions, therapeutics, cosmetics, fire-fighting chemicals, fluid mixtures used in enhanced oil recovery, and even in our lungs to ensure normal alveolar function.

“Hence, one can envision numerous exciting applications of the ‘flow and gel’ process,” says Sureshkumar. “Further, it is a continuous and non-caustic process that can be scaled up. Functionalizing the nanogel could be done by integrating a second flow stream containing the desired active agent, such as nanoparticles or therapeutic molecules, into the flow system.”

The discovery team consists of Sureshkumar’s former graduate student Mukund Vasudevan at Washington University in St. Louis (now at Cytec Industries, Stamford, Conn.), undergraduate researcher Eric Buse and graduate student Hare Krishna at Washington University in St. Louis, postdoctoral fellow Donglai Lu and professor Amy Shen at the University of Washington, Seattle, and professors Bamin Khomami and Ramki Kalyanaraman of the University of Tennessee, Knoxville.

Sureshkumar’s research group is now exploring robust means to modify the “flow and gel” process to incorporate optically active nanoparticles into the surfactant templates in an effort to make broadband antennas for efficiently harnessing the sun’s energy. Another focus of his research is to understand the fundamental mechanisms of flow-induced self-assembly by utilizing large-scale molecular dynamics simulations. These efforts are supported in part by the National Science Foundation.