A Physical Approach to Reduce Nonspecific Adhesion in Molecular Recognition Atomic Force Microscopy

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Willemsen, Oscar H. and Snel, Margot M.E. and Kuipers, Laurens and Figdor, Carl G. and Greve, J. and Grooth de, Bart G. (1999) A Physical Approach to Reduce Nonspecific Adhesion in Molecular Recognition Atomic Force Microscopy. Biophysical Journal, 76 (2). pp. 716-724. ISSN 0006-3495

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Abstract:Atomic force microscopy is one of the few techniques that allow analysis of biological recognition processes at the single-molecule level. A major limitation of this approach is the nonspecific interaction between the force sensor and substrate. We have modeled the nonspecific interaction by looking at the interaction potential between a conical Si3N4 tip with a spherical end face and a mica surface in solution, using DLVO (Derjaguin, Landau, Verwey, Overbeek) theory and numerical calculations. Insertion of the tip-sample potential in a simulation of an approach-retract cycle of the cantilever gives the well-known force-distance curve. Simulating a force-distance curve at low salt concentration predicts a discrete hopping of the tip, caused by thermal fluctuations. This hopping behavior was observed experimentally and gave rise to a novel approach to making measurements in adhesion mode that essentially works in the repulsive regime. The distance between tip and sample will still be small enough to allow spacer-involved specific interactions, and the percentage of nonspecific interactions of the bare tip with the mica is minimized. We have validated this physical model by imaging intercellular adhesion molecule 1 (ICAM-1) antigen with a tip functionalized with anti-ICAM-1 antibody. The measurement demonstrated that a significant decrease in the number of nonspecific interactions was realized, and the topographical image quality and the specific bonding capability of the tip were not affected.
Item Type:Article
Copyright:© 1999 Elsevier
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Link to this item:http://purl.utwente.nl/publications/74033
Official URL:http://dx.doi.org/10.1016/S0006-3495(99)77238-3
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