Spatial fluorescence cross-correlation spectroscopy by means of a spatial light modulator

Area of Science:

• Biophysics
• Spectroscopy
• Molecular dynamics

Background:

• Fluorescence Correlation Spectroscopy (FCS) is a powerful tool for studying molecular dynamics.
• Spatial FCS (sFCS) is an under-explored variant that cross-correlates signals from distinct observation volumes.
• This technique offers new possibilities for analyzing complex biological systems.

Purpose of the Study:

• To demonstrate the feasibility and potential of spatial fluorescence cross-correlation spectroscopy (sFCS).
• To measure molecular flow and investigate membrane permeability using sFCS.
• To provide theoretical descriptions and compare sFCS with alternative methods.

Main Methods:

• Utilizing a spatial light modulator and adjustable pinholes to create two spatially separated observation volumes.
• Cross-correlating fluorescence signals from these two volumes.
• Applying the technique to measure molecular flow in solutions and membrane permeability in giant unilamellar vesicles.

Main Results:

• Successfully measured molecular flows in the range of 0.2-1.5 microm/ms using fluorescent nanobeads and rhodamine molecules.
• Investigated the permeability of phospholipidic membranes to hydrophilic and hydrophobic molecules.
• Demonstrated the capability of sFCS to simulate and analyze active transport phenomena and membrane transport.

Conclusions:

• Spatial fluorescence cross-correlation spectroscopy is a viable technique for quantitative analysis of molecular transport.
• sFCS provides valuable insights into molecular flow and membrane permeability.
• The study highlights the potential of sFCS as an alternative to existing fluorescence correlation spectroscopy-based methods.