FRAP (biology)
FRAP ( fluorescence recovery after photobleaching ) refers to a method from microbiology and biophysics that is used to measure diffusion rates and binding kinetics in cells and thin liquid films. You can z. B. can be used to demonstrate the fluidity of biomembranes .
functionality
With FRAP, the molecules of interest are provided with fluorescent markers (e.g. surface proteins on cells with fluorescence-marked antibodies). The sample is observed in a fluorescence microscope . In a next step, the fluorescence intensity is measured at a specific location. This fluorescence is locally destroyed at the same location by a short laser pulse. During this process, known as photobleaching , the fluorescent molecules go irreversibly into a non-fluorescent state. As a result, a “black spot” forms in the sample, into which the molecules from the environment slowly diffuse. With this flow of molecules, fluorescent molecules come back to the bleached area and the diffusion time (or diffusion constant ) can be determined by measuring the course of the fluorescence intensity over time. The later the original intensity is reached, the slower the diffusion of the fluorescent component is.
See also
literature
- TK Meyvis, SC De Smedt, P. Van Oostveldt, J. Demeester: Fluorescence recovery after photobleaching: a versatile tool for mobility and interaction measurements in pharmaceutical research. In: Pharm Res . 16 (8), 1999, pp. 1153-1162.
Web links
- Functional graphs (Major Instruments Co., Ltd., Taiwan) ( Memento from July 17, 2009 in the Internet Archive )