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Journal of Nanophotonics

Tethered particle motion mediated by scattering from gold nanoparticles and darkfield microscopy
Author(s): Heidelinde Regina Christina Dietrich; Bernd Rieger; Frank G. M. Wiertz; Frederik H. de Groote; Hendrik A. Heering; Ian Ted Young; Yuval Garini
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Paper Abstract

We measured light scattered from gold nanoparticles with darkfield microscopy in order to perform single molecule detection based on tethered particle motion (TPM). This combination results in a signal to noise ratio of about 40 dB, which allowed us to use 80 nm diameter gold particles as reporters instead of the typically used polystyrene particles whose sizes are up to 1 μm. The particle size is crucial in TPM experiments as it can induce a volume-exclusion effect, which results in a stretching force acting on the DNA tether. This affects both the biophysical and statistical properties of the anchored DNA and hence the interpretation of the experimental data. We demonstrated that the gold nanoparticles and darkfield microscopy can be used to characterize the confined Brownian motion of dsDNA-tethered gold particles with a spatial precision of 3 nm. Physical parameters such as the spring constant of the tethered DNA fragment and the persistence length can be derived from the two dimensional (2D) (x, y) projected image data. We have applied this method to various MgCl2 and glycerol concentrations as a proof of principle.

Paper Details

Date Published: 1 July 2009
PDF: 17 pages
J. Nanophoton. 3(1) 031795 doi: 10.1117/1.3174445
Published in: Journal of Nanophotonics Volume 3, Issue 1
Show Author Affiliations
Heidelinde Regina Christina Dietrich, Technische Univ. Delft (Netherlands)
Bernd Rieger, Technische Univ. Delft (Netherlands)
Frank G. M. Wiertz, Leiden Univ. (Netherlands)
Frederik H. de Groote, Leiden Univ. (Netherlands)
Hendrik A. Heering, Leiden Univ. (Netherlands)
Ian Ted Young, Technische Univ. Delft (Netherlands)
Yuval Garini, Bar-Ilan Univ. (Israel)

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