Abstract
We used magnetic tweezers to measure the torsional stiffness of single micrometer-sized superparamagnetic spheres as a function of the applied magnetic field. By investigating the axial fluctuations of DNA-bound microspheres, we found that considerable rotational microsphere fluctuations can occur. Quantitative noise analysis allowed us to determine the rotational stiffness of individual microspheres, which was found to saturate at high magnetic fields. The saturation can be qualitatively explained considering the properties of the magnetic nanoparticles within the microsphere. Consequences for spatial resolution limits in single-molecule magnetic tweezer experiments and usage of DNA mechanics as a sensitive probe in magnetometry are discussed.
- Received 29 August 2008
- Corrected 1 May 2012
DOI:https://doi.org/10.1103/PhysRevLett.102.028302
© 2009 American Physical Society
Corrections
1 May 2012