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Unformatted text preview: IEEE TRANSACTIONS ON NANOBIOSCIENCE, VOL. 5, NO. 3, SEPTEMBER 2006 149 Whole-Cell Sensing for a Harmful Bloom- Forming Microscopic Alga by Measuring Antibody–Antigen Forces Alexander S. Lee, Mrinal Mahapatro, David A. Caron, Aristides A. G. Requicha* , Life Fellow, IEEE , Beth A. Stauffer, Mark E. Thompson, and Chongwu Zhou Abstract—Aureococcus anophagefferens , a harmful bloom- forming alga responsible for brown tides in estuaries of the Middle Atlantic U.S., has been investigated by atomic force microscopy for the first time, using probes functionalized with a monoclonal antibody specific for the alga. The rupture force between a single monoclonal antibody and the surface of A. anophagefferens was experimentally found to be 246 11 pN at the load rate of 12 nN/s. Force histograms for A. anophagefferens and other similarly-sized algae are presented and analyzed. The results illustrate the effects of load rates, and demonstrate that force-distance measurements can be used to build biosensors with high signal-to-noise ratios for A. anophagefferens . The methods described in this paper can be used, in principle, to construct sensors with single-cell resolution for arbitrary cells for which monoclonal antibodies are available. Index Terms— Atomic force microscopy, Aureococcus anophagef- ferens , biosensors, force-distance measurements, single-cell identi- fication. I. INTRODUCTION S INGLE-CELLED microalgae play an essential ecological role in aquatic environments as the producers of organic material that constitutes much of the base of the food webs Manuscript received December 29, 2005; revised June 6, 2006. This work was supported in part by the National Science Foundation under Grant EIA-01- 21141 and Cooperative Agreement CCR-01-20778. A robotics-oriented, earlier version of this paper was presented at the IEEE BioRob 2006 Conference. As- terisk indicates corresponding author. A. S. Lee is with the Mork Department of Chemical Engineering and Mate- rials Science and the Laboratory for Molecular Robotics, University of Southern California, Los Angeles, CA 90089-0781 USA (e-mail: [email protected] com). M. Mahapatro was with the Laboratory for Molecular Robotics of the Univer- sity of Southern California, Los Angeles, CA 90089-0781 USA. He is now with Sierracin Corporation, Sylmar, CA 97342 USA (e-mail: [email protected] com). D. A. Caron and B. A. Stauffer are with the Department of Biological Sci- ences of the University of Southern California, Los Angeles, CA 90089-0371 USA (e-mail: [email protected]; [email protected]). *A. A. G. Requicha is with the Departments of Computer Science and Electrical Engineering and the Laboratory for Molecular Robotics, Univer- sity of Southern California, Los Angeles, CA 90089-0781 USA (e-mail: [email protected])....
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- Spring '08
- Algal bloom, Scanning probe microscopy, Atomic force microscopy, a. anophagefferens