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Characterization of bacterial motility by Optical tweezers (OT) (CAT#: STEM-MB-1293-WXH)

Introduction

Bacterial motility is the ability of bacteria to move independently using metabolic energy. Most motility mechanisms which evolved among bacteria also evolved in parallel among the archaea. Most rod-shaped bacteria can move using their own power, which allows colonization of new environments and discovery of new resources for survival. Bacterial movement depends not only on the characteristics of the medium, but also on the use of different appendages to propel. Swarming and swimming movements are both powered by rotating flagella. Whereas swarming is a multicellular 2D movement over a surface and requires the presence of surfactants, swimming is movement of individual cells in liquid environments.




Principle

Optical tweezers (originally called single-beam gradient force trap) are scientific instruments that use a highly focused laser beam to hold and move microscopic and sub-microscopic objects like atoms, nanoparticles and droplets, in a manner similar to tweezers. If the object is held in air or vacuum without additional support, it can be called optical levitation.
The laser light provides an attractive or repulsive force (typically on the order of piconewtons), depending on the relative refractive index between particle and surrounding medium. Levitation is possible if the force of the light counters the force of gravity. The trapped particles are usually micron-sized, or even smaller. Dielectric and absorbing particles can be trapped, too.

Applications

• Optical tweezers are used in biology and medicine (for example to grab and hold a single bacterium, a cell like a sperm cell or a blood cell, or a molecule like DNA).
• Nanoengineering and nanochemistry (to study and build materials from single molecules).
• Quantum optics and quantum optomechanics (to study the interaction of single particles with light).

Procedure

1.Sample preparation
2.Force Calibration
3.Measurement
4.Analysis

Materials

Optical tweezers