Fluorescence recovery after photobleaching

FRAP ( fluorescence recovery after photobleaching ) refers to a method of microbiology and biophysics, which is used to measure the diffusion rates in cells and thin liquid films. It can be used for example to detect the fluidity of biological membranes.

Operation

FRAP in the molecules of interest are provided with fluorescent labels (e.g., surface proteins on cells with fluorescence-labeled antibodies). The observation of the sample is carried out in a fluorescent microscope. In a next step, the fluorescence intensity is measured at a specific location. In the same place this fluorescence is destroyed locally by a short laser pulse. In this process called photobleaching fluorescent molecules go irreversibly to a non- fluorescing state. As a result, a " black spot " in the sample forms, slowly diffuse the molecules from the environment into the. This molecular flow again fluorescent molecules come to the bleached spot and the diffusion time (or diffusion coefficient ) can be determined by measuring the profile of the fluorescence intensity over time. The later the original intensity is achieved, the slower is diffusion of the fluorescent component.

See also

• Fluid mosaic model