This title appears in the Scientific Report :
2007
Please use the identifier:
http://hdl.handle.net/2128/14052 in citations.
Two-Focus Fluorescence Correlation Spectroscopy
Two-Focus Fluorescence Correlation Spectroscopy
Fluorescence Correlation Spectroscopy (FCS) has been invented more than 30 years ago and experienced a renaissance after stable and affordable laser sources and low-noise single-photon detectors have become available. Its ability to measure diffusion coefficients at nanomolar concentrations of analy...
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Personal Name(s): | Dertinger, Thomas (Corresponding author) |
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Contributing Institute: |
Zelluläre Biophysik; INB-1 |
Imprint: |
Jülich
Forschungszentrum Jülich GmbH Zentralbibliothek, Verlag
2007
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Physical Description: |
V, 86 p. |
Dissertation Note: |
Köln, Univ., Diss., 2007 |
Document Type: |
Book Dissertation / PhD Thesis |
Research Program: |
Funktion und Dysfunktion des Nervensystems |
Series Title: |
Berichte des Forschungszentrums Jülich
4250 |
Subject (ZB): | |
Link: |
OpenAccess |
Publikationsportal JuSER |
Fluorescence Correlation Spectroscopy (FCS) has been invented more than 30 years ago and experienced a renaissance after stable and affordable laser sources and low-noise single-photon detectors have become available. Its ability to measure diffusion coefficients at nanomolar concentrations of analyte made it a widely used tool in biophysics. However, in recent years it has been shown by many authors that aberrational (e.g. astigmatism) and photophysical effects (e.g. optical saturation) may influence the result of an FCS experiment dramatically, so that a precise and reliable estimation of the diffusion coefficient is no longer possible. In this thesis, we report on the development, implementation, and application of a new and robust modification of FCS that we termed two-focus FCS (2fFCS) and which fulfils two requirements: (i) It introduces an external ruler into the measurement by generating two overlapping laser foci of precisely known and fixed distance. (ii) These two foci and corresponding detection regions are generated in such a way that the corresponding molecule detection functions (MDFs) are sufficiently well described by a simple two-parameter model yielding accurate diffusion coefficients when applied to 2fFCS data analysis. Both these properties enable us to measure absolute values of the diffusion coefficient with an accuracy of a few percent. Moreover, it will turn out that the new technique is robust against refractive index mismatch, coverslide thickness deviations, and optical saturation effects, which so often trouble conventional FCS measurements. This thesis deals mainly with the introduction of the new measurement scheme, 2fFCS, but also presents several applications with far-reaching importance. |