Researchers at Georgia Tech have created technology capable of detecting trace amounts of biological or chemical agents in a matter of seconds, much faster than traditional methods, which can take hours or up to a day. The system uses reusable hydrogel microlenses so small that millions of them can fit on a one-inch-square plate. It could greatly enhance the ability of authorities responding to a biological or chemical weapons attack as well as increase the speed of medical testing. The research appears in the February 20 edition of the chemistry journal Angewandte Chemie.

The microlenses make use of the antibody-antigen binding, the same process used by the human immune system, to detect biological or chemical agents. When antibodies on the microlenses come into contact with the antigen they are set to detect, they bind, causing the lenses to swell and become less dense. By projecting an image through the tiny lenses, researchers can view this swelling as a change in the microlens' focal length. If the projected image is normally in focus, it goes out of focus when it comes into contact with the substance.

"These are reversible, so you can use the same lenses over and over again. This is the first time someone has done this with microlenses," said L. Andrew Lyon, associate professor in the School of Chemistry and Biochemistry at the Georgia Institute of Technology.

Lyon and his colleagues tested their system on its ability to detect biotin, a B-complex vitamin. To make the two-micrometer-wide microlenses, they coated the surface of a flexible polymeric hydrogel microsphere with the antigen biotin and aminobenzophenone (ABP), a photo-cross-linking agent, which is able to chemically attach to other molecules when exposed to UV light. Adhering these microparticles on a glass substrate causes them to deform into microlenses. After binding the biotin with its antibody, scientists hit it with ultraviolet light, causing the ABP to react with the antibody, attaching it to the microlens irreversibly. The microlenses are now ready to do their job.



Source: Georgia Institute of Technology

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