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Updated: Jun 27, 2026

Molecular Diffusion in Plasma Membranes of Primary Lymphocytes Measured by Fluorescence Correlation Spectroscopy
Published on: February 1, 2017
Macromolecular diffusion in the extracellular matrix measured by fluorescence correlation spectroscopy
Nina Kristine Reitan1, Aphirak Juthajan, Tore Lindmo
1The Norwegian University of Science and Technology, Department of Physics, 7491 Trondheim, Norway. nina.reitan@ntnu.no
Fluorescence correlation spectroscopy (FCS) effectively measures macromolecule diffusion in tumor models, revealing complex transport behaviors not seen with fluorescence recovery after photobleaching (FRAP). This highlights FCS for extracellular drug delivery research.
Area of Science:
- Biophysics
- Biomaterials Science
- Cancer Research
Background:
- Effective tumor drug delivery requires understanding macromolecule diffusion through the extracellular matrix.
- Tumor extracellular matrix presents a complex environment for therapeutic agent transport.
Purpose of the Study:
- To compare the capabilities of fluorescence correlation spectroscopy (FCS) and fluorescence recovery after photobleaching (FRAP) in characterizing macromolecule diffusion in model tumor extracellular matrix.
- To investigate the diffusion of various macromolecules (IgG and dextrans) in solution, hydrogel, and multicellular spheroids.
Main Methods:
- Utilized one-photon fluorescence correlation spectroscopy (FCS) to measure diffusion coefficients.
- Employed dextrans (155 kDa, 2 MDa) and IgG (150 kDa) as model macromolecules.
- Used 5% gelatin hydrogel and multicellular spheroids as in vitro models for the tumor extracellular matrix.
- Compared FCS results with two-photon fluorescence recovery after photobleaching (FRAP) data obtained on the same microscope system.
Main Results:
- Macromolecule diffusion was influenced by environmental complexity, molecular size, and shape.
- FCS and FRAP yielded comparable diffusion coefficients in simple solutions.
- FCS detected anomalous or multicomponent diffusion in hydrogels and spheroids, which FRAP could not resolve.
- One-photon FCS demonstrated good agreement with two-photon FRAP measurements.
Conclusions:
- One-photon FCS is a viable technique for studying extracellular transport of macromolecules in tumor tissues.
- FCS offers superior resolution for detecting complex diffusion behaviors in the tumor microenvironment compared to FRAP.
- This study validates FCS as a powerful tool for advancing research in macromolecule-based drug delivery to tumors.
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