| Quantitative modeling and optimization of magnetic tweezers. | |
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MedLine Citation:
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PMID: 19527664 Owner: NLM Status: MEDLINE |
Abstract/OtherAbstract:
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Magnetic tweezers are a powerful tool to manipulate single DNA or RNA molecules and to study nucleic acid-protein interactions in real time. Here, we have modeled the magnetic fields of permanent magnets in magnetic tweezers and computed the forces exerted on superparamagnetic beads from first principles. For simple, symmetric geometries the magnetic fields can be calculated semianalytically using the Biot-Savart law. For complicated geometries and in the presence of an iron yoke, we employ a finite-element three-dimensional PDE solver to numerically solve the magnetostatic problem. The theoretical predictions are in quantitative agreement with direct Hall-probe measurements of the magnetic field and with measurements of the force exerted on DNA-tethered beads. Using these predictive theories, we systematically explore the effects of magnet alignment, magnet spacing, magnet size, and of adding an iron yoke to the magnets on the forces that can be exerted on tethered particles. We find that the optimal configuration for maximal stretching forces is a vertically aligned pair of magnets, with a minimal gap between the magnets and minimal flow cell thickness. Following these principles, we present a configuration that allows one to apply > or = 40 pN stretching forces on approximately 1-microm tethered beads. |
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Authors:
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Jan Lipfert; Xiaomin Hao; Nynke H Dekker |
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Publication Detail:
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Type: Journal Article; Research Support, Non-U.S. Gov't |
Journal Detail:
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Title: Biophysical journal Volume: 96 ISSN: 1542-0086 ISO Abbreviation: Biophys. J. Publication Date: 2009 Jun |
Date Detail:
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Created Date: 2009-06-16 Completed Date: 2009-08-25 Revised Date: 2010-09-24 |
Medline Journal Info:
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Nlm Unique ID: 0370626 Medline TA: Biophys J Country: United States |
Other Details:
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Languages: eng Pagination: 5040-9 Citation Subset: IM |
Affiliation:
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Kavli Institute of Nanoscience, Delft University of Technology, Delft, The Netherlands. |
Export Citation:
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| MeSH Terms | |
Descriptor/Qualifier:
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Finite Element Analysis Iron Magnetics / instrumentation, methods* Models, Theoretical* |
| Chemical | |
Reg. No./Substance:
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7439-89-6/Iron |
| Comments/Corrections | |
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine
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