title: Macromolecular diffusion in the extracellular matrix measured by fluorescence correlation spectroscopy.
abstract: Diffusion of therapeutic macromolecules through the extracellular matrix of tumor tissue is a crucial step in drug delivery. We use fluorescence correlation spectroscopy (FCS) to measure diffusion of IgG (150 kDa) and dextrans (155 kDa and 2 MDa) in solution, 5% gelatin hydrogel, and multicellular spheroids. Gel and spheroids are used as model systems for the extracellular matrix. The diffusion depends on the complexity of the environment, as well as on the size and structural shape of the diffusing molecules. The results based on one-photon FCS are in good agreement with diffusion coefficients obtained with two-photon fluorescence recovery after photobleaching (FRAP) using the same microscope (Zeiss LSM510 META/Confocor2). However, FCS reveals anomalous or multicomponent diffusion in gel and spheroids, which are not resolvable with FRAP. This study demonstrates that one-photon FCS can be used to study the extracellular transport of macromolecules in tumor tissue, and that FCS provides additional information about diffusion properties compared to FRAP.
authors.affiliation: The Norwegian University of Science and Technology, Department of Physics, 7491 Trondheim, Norway. nina.reitan@ntnu.no
authors.forename: Nina Kristine
authors.initials: NK
authors.lastname: Reitan
authors.forename: Aphirak
authors.initials: A
authors.lastname: Juthajan
authors.forename: Tore
authors.initials: T
authors.lastname: Lindmo
authors.forename: Catharina
authors.initials: C
authors.lastname: de Lange Davies
mesh_terms: D000465:Algorithms; D002460:Cell Line; D004058:Diffusion; D005109:Extracellular Matrix / Q000737:chemistry*; D006801:Humans; D046911:Macromolecular Substances / Q000737:chemistry*; D008856:Microscopy, Fluorescence / Q000379:methods*; D013050:Spectrometry, Fluorescence / Q000379:methods*; D018874:Spheroids, Cellular / Q000737:chemistry*
chemical_list: D046911:Macromolecular Substances