Exploiting a process known as molecular self-assembly, MIT chemical engineers have built three-dimensional arrays of antibodies that could be used as sensors to diagnose diseases such as malaria or tuberculosis. These sensors, which contain up to 100 stacked layers of antibodies, offer much more sensitivity than existing antibody-based sensors, which have only a single layer of antibodies. “The more antibodies you put on a surface, the lower the concentration of molecules you can detect,” says Bradley Olsen, Ph.D., an Associate Professor of Chemical Engineering at MIT. “You can have a big impact on biosensors by potentially improving the sensitivity by several orders of magnitude.” Dr. Olsen is the senior author of the study, which was published online on December 28, 2016 in the journal Angewandte Chemie. The paper’s lead author is MIT postdoc Xue-Hui Dong, and former postdoc Allie Obermeyer is also an author. The article is titled “Three-Dimensional Ordered Antibody Arrays Through Self-Assembly of Antibody–Polymer Conjugates.” The team’s new design approach relies on a phenomenon known as self-assembly, which occurs when thermodynamic interactions drive molecular building blocks to take on certain configurations. In this case, the researchers discovered that they could force antibodies and other proteins to form layers by attaching each protein to a polymer tail. The proteins and polymers repel each other, so the molecules arrange themselves in a structure that minimizes the interactions between the protein and polymer segments. “Because the protein and polymer are bonded together, they can’t separate like oil and water. They can only get apart from each other by a distance about the size of one molecule,” Olsen says.
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