Measuring Molecular Diffusion in Dynamic Subcellular Nanostructures by Fast Raster Image Correlation Spectroscopy and...

Area of Science:

• Cellular dynamics and biophysics
• Molecular imaging and spectroscopy
• Subcellular nanostructure analysis

Background:

• Understanding molecular dynamics within organelles is crucial for cell biology.
• Subcellular nanostructures (organelles, vesicles) are dynamic and mobile within cells.
• Existing methods struggle to analyze molecular motion within moving subcellular environments.

Purpose of the Study:

• To demonstrate fast fluorescence fluctuation spectroscopy as a robust method for analyzing molecular dynamics in moving subcellular nanostructures.
• To extract information on organelle properties like viscosity and molecular aggregation.
• To validate results by accounting for nanostructure movement.

Main Methods:

• Raster Image Correlation Spectroscopy (RICS) at microsecond timescales.
• Analysis of fluorescently labeled molecules within lysosomes and insulin secretory granules (ISGs).
• Integration of RICS with feedback-based 3D orbital tracking to correct for nanostructure motion.

Main Results:

• Fast RICS quantified increased lysosomal viscosity in Krabbe disease.
• Differential aggregation propensity of peptides within ISGs was revealed.
• Method successfully decoupled molecular diffusion from nanostructure movement, validating findings.

Conclusions:

• Fast fluorescence fluctuation spectroscopy is a powerful tool for studying molecular dynamics in complex cellular systems.
• The approach provides quantitative insights into organelle pathophysiology and molecular behavior.
• This technique advances the understanding of cell function at the subcellular level.