Magnetic tweezers

Magnetic tweezers

A magnetic tweezer is a scientific instrument for exerting and measuring forces on magnetic particles using a magnetic field gradient. Typical applications are single-molecule micromanipulation, rheology of soft matter, and studies of force-regulated processes in living cells. Forces are typically on the order of pico- to nanonewtons. Due to their simple architecture, magnetic tweezers are one of the most popular and widespread biophysical techniques.

Types of magnetic tweezers

Depending on the implementation, magnetic tweezers can be divided into several categories including translational or rotational, unipolar or multipolar.

The most simple setup is the unipolar translational magnetic tweezer. It consists of an electromagnet with a paramagnetic core material and a tip-shaped end. This results in a high field gradient around the tip. Any paramagnetic material within that gradient is magnetized and pulled towards the tip. The force magnitude depends on the magnitude and gradient of the magnetic field. While the magnitude can be controlled by the current that drives the electromagnet, the gradient depends on the distance to the tip of the core. Alternatively, the electromagnet can be replaced by a permanent magnetic needle.

Several electromagnets can be combined into a multipolar magnetic tweezer setup, allowing for three-dimensional translation, rotation and trapping of magnetic particles.

When permanently magnetized particles are subjected to a magnetic field, their internal magnetic moment will try to align with the external field, resulting in a rotational or twisting force. Magnetic twisting has been used to study the viscoelastic properties of living cells and biological materials.

While early experiments used magnetic powder as probes and measured the resulting change of the magnetic field, nowadays magnetic microbeads of varying sizes and well-known magnetic properties are commercially available, and microscope image processing can be used to detect the displacement of the probes.

Other biophysical techniques used to apply and measure microscopic forces are Atomic Force Microscopy and Optical Tweezers.

Examples of research groups using magnetic tweezers

USA:
[1] Ingber Lab (Harvard Medical School)
[2] Saleh Lab (Material science department UC Santa Barbara)
[3] Mechanobiology Group (MIT, Roger Kamm)
[4] Nanosystems Measurement & Controls Lab (Department of Mechanical Engineering & Material Science, University of Pittsburgh)
[5] So Lab (MIT)
[6] Forgacs Lab (Department of Physics & Astronomy, University of Missouri)
[7] Wirtz Lab (Johns Hopkins University)
[8] Bustamante Lab (University of California, Berkeley)
[9] Marko Lab (Northwestern University)
[10] Precision Measurement & Control Lab ([The Ohio State University])
Canada:
[11] Forde Lab (Simon Fraser University, British Columbia)
Asia:
[12] Kazuhiko Kinosita (Waseda University, Tokyo)
[13] Jie YAN (National University of Singapore, Singapore)
Europe:
[14] Biological Physics Research Group (University of Manchester, Uk)
[15] Single Molecule Nanomanipulation (Institut Jacques Monod, Paris, France)
[16] Molecular and Nanoscale Physics Group (University of Leeds, Leeds, England)
[17] Erich Sackmann (Technical University of Munich, Germany)
[18] Biophysical Engineering Group (University of Twente, The Netherlands)
[19] Fabry Lab (University of Erlangen-Nuremberg, Germany)
[20] Joachim Spatz (University of Heidelberg, Germany)
[21] Cécile Sykes (Curie Institute, Paris, France)
[22] David Bensimon and Vincent Croquette (École Normale Supérieure, Paris, France)
[23] Nynke Dekker - Molecular Biophysics (Technical University Delft, The Netherlands)
[24] Ralf Seidel - DNA Motors group (Technical University of Dresden, Germany)


Wikimedia Foundation. 2010.

Игры ⚽ Поможем написать курсовую

Look at other dictionaries:

  • Tweezers — are tools used for picking up small objects that are not easily handled with the human hands. They are probably derived from tongs, pincers, or scissors like pliers used to grab or hold hot objects from the dawn of recorded history.Tweezers make… …   Wikipedia

  • Magnetic trap — refers to one of three types of traps used for atoms or charged particles: Magnetic trap (atoms), used to trap neutral atoms in a magnetic field gradient Penning trap, used to trap charged particles or ions in a combination of electrostatic… …   Wikipedia

  • Optical tweezers — (originally called single beam gradient force trap ) are scientific instruments that use a highly focused laser beam to provide an attractive or repulsive force (typically on the order of piconewtons), depending on the refractive index mismatch… …   Wikipedia

  • Force spectroscopy — is a dynamic analytical technique that allows the study of the mechanical properties of single polymer molecules or proteins, or individual chemical bonds. It is performed by pulling on the system under scrutiny with controlled forces. As a… …   Wikipedia

  • Microrheology — Microrheology[1] is a technique to measure the rheological properties of a medium, such as microviscosity, via the measurement of the trajectory of a flow tracer (a micrometre size particle). It is a new way of doing rheology, traditionally done… …   Wikipedia

  • Outline of biophysics — The following outline is provided as an overview of and topical guide to biophysics: Biophysics – interdisciplinary science that uses the methods of physical science to study biological systems.[1] Contents 1 Nature of biophysics 1.1 Biophysics… …   Wikipedia

  • Biophysical techniques — are methods used for gaining information about biological systems on an atomic or molecular level. They overlap with methods from other branches of science.Main biophysical techniques are: *Circular dichroism, a method for detecting chiral groups …   Wikipedia

  • Single-molecule experiment — A single molecule experiment investigates the properties of a single individual molecule that can be isolated or distinguished for the purpose of an experiment or analysis. Single molecule studies may be contrasted with measurements on an… …   Wikipedia

  • Molecular motor — Molecular motors are biological molecular machines that are the essential agents of movement in living organisms. Generally speaking, a motor may be defined as a device that consumes energy in one form and converts it into motion or mechanical… …   Wikipedia

  • Chromatin Structure Remodeling (RSC) Complex — complex and is essential for mitotic growth.cite journal | author = Cairns BR, Lorch Y, Li Y, Zhang M, Lacomis L, Erdjument Bromage H, Tempst P, Du J, Laurent B, Kornberg RD | title = RSC, an essential, abundant chromatin remodeling complex |… …   Wikipedia

Share the article and excerpts

Direct link
Do a right-click on the link above
and select “Copy Link”