Micro Magnetic Tweezers for Nanomanipulation Inside Live Cells

Biophys J. 2005 Mar;88(3):2137-44. doi: 10.1529/biophysj.104.052035. Epub 2004 Nov 19.


This study reports the design, realization, and characterization of a multi-pole magnetic tweezers that enables us to maneuver small magnetic probes inside living cells. So far, magnetic tweezers can be divided into two categories: I), tweezers that allow the exertion of high forces but consist of only one or two poles and therefore are capable of only exerting forces in one direction; and II), tweezers that consist of multiple poles and allow exertion of forces in multiple directions but at very low forces. The magnetic tweezers described here combines both aspects in a single apparatus: high forces in a controllable direction. To this end, micron scale magnetic structures are fabricated using cleanroom technologies. With these tweezers, magnetic flux gradients of nablaB = 8 x 10(3) T m(-1) can be achieved over the dimensions of a single cell. This allows exertion of forces up to 12 pN on paramagnetic probes with a diameter of 350 nm, enabling us to maneuver them through the cytoplasm of a living cell. It is expected that with the current tweezers, picoNewton forces can be exerted on beads as small as 100 nm.

Publication types

  • Evaluation Study
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Cell Culture Techniques / instrumentation*
  • Cell Culture Techniques / methods
  • Cells, Cultured
  • Equipment Design
  • Equipment Failure Analysis
  • Granulocytes / physiology*
  • Humans
  • Magnetics*
  • Micromanipulation / instrumentation*
  • Micromanipulation / methods
  • Microspheres
  • Miniaturization
  • Molecular Probe Techniques / instrumentation*
  • Nanotechnology / instrumentation*
  • Nanotechnology / methods
  • Physical Stimulation / instrumentation*
  • Physical Stimulation / methods
  • Stress, Mechanical