NRL Developing Single Molecular Detector

3/20/1996 - 26-96r
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Scientists at the Naval Research Laboratory (NRL) are developing a novel, high-sensitivity biosensor for applications in environmental monitoring of airborne or water-borne contaminants and clinical tests where ultra-sensitive detection is needed.

The force amplified biological sensor (FABS) uses ultra-sensitive force transducers to detect molecular recognition forces between DNA molecules, metal ions-chelators, antibodies antigens, or other ligand-receptor molecules. The transducers, originally developed for atomic force microscopy, are sensitive enough to detect the forces between a single pair of molecules. This gives FABS near-single-molecule sensitivity, an improvement of six to eight orders of magnitude over competitive techniques. The transducers are also micromachined, so FABS devices could eventually be miniaturized.

Presently, the NRL team, led by Drs. Gil Lee, David Baselt and Richard Colton of the Chemistry Division's Surface Chemistry Branch, is concentrating on antibody-antigen interactions and developing the FABS hardware.

The instrument uses an immunobead assay consisting of a cantilever force transducer to which antibodies have been bound. When the sample solution is introduced into the instrument, the antibodies bind any antigen -- the protein, virus, or bacterium of interest -- that might be present. Micron-sized, antibody-coated magnetic particles then bind to another part of the antigen, creating a particle-antigen-cantilever sandwich. After washing away excess particles, a magnetic field is turned on, which pulls on the particles, causing the cantilever to bend. The amount of bending indicates how many particles are bound to the cantilever, and therefore, how much antigen was present in the sample. The assay is expected to take about ten minutes to run.

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The U.S. Naval Research Laboratory provides the advanced scientific capabilities required to bolster our country's position of global naval leadership. The Laboratory, with a total complement of approximately 2,500 personnel, is located in southwest Washington, D.C., with other major sites at the Stennis Space Center, Miss., and Monterey, Calif. NRL has served the Navy and the nation for over 90 years and continues to advance research further than you can imagine. For more information, visit the NRL website or join the conversation on Twitter, Facebook, and YouTube.

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