Measuring size distribution in highly heterogeneous systems with fluorescence correlation spectroscopy

Area of Science:

• Biophysics
• Physical Chemistry
• Spectroscopy

Background:

• Fluorescence Correlation Spectroscopy (FCS) is a key technique for diffusion measurement.
• Conventional FCS analysis using least-square fitting struggles with highly heterogeneous systems.
• Existing methods fail to accurately represent complex diffusion dynamics.

Purpose of the Study:

• Introduce a novel Maximum Entropy Method based fitting routine (MEMFCS) for FCS data analysis.
• Develop a method capable of analyzing quasicontinuous distributions of diffusing components.
• Improve the accuracy of diffusion analysis in complex biological and chemical systems.

Main Methods:

• Developed MEMFCS, a fitting routine based on the Maximum Entropy Method.
• Applied MEMFCS to analyze FCS data from homogeneous and heterogeneous systems.
• Incorporated a goodness-of-fit criterion and compared MEMFCS with conventional least-square fitting.

Main Results:

• MEMFCS provides results comparable to conventional fitting for homogeneous systems.
• MEMFCS accurately models quasicontinuous distributions of diffusing species in heterogeneous systems.
• MEMFCS successfully reproduces the essential features of complex diffusion distributions, unlike conventional methods.

Conclusions:

• MEMFCS offers a superior approach for analyzing FCS data from heterogeneous systems.
• The method provides a more accurate representation of diffusion dynamics.
• MEMFCS enhances the utility of FCS for studying complex molecular interactions and environments.