title: Diffusion of insulin-like growth factor-I and ribonuclease through fibrin gels.
abstract: A fluorescence-based method for simultaneously determining the diffusion coefficients of two proteins is described, and the diffusion coefficient of insulin-like growth factor (IGF-I) and ribonuclease (RNase) in a 0.27% fibrin hydrogel is reported. The method is based on two-color imaging of the relaxation of the protein concentration field with time and comparing the results with a transport model. The gel is confined in a thin (200 microm) capillary and the protein is labeled with a fluorescent dye. The experimentally determined diffusion coefficient of RNase (D = 1.21 x 10(-6) cm(2)/s) agrees with literature values for dilute gels and bulk aqueous solutions, thus indicating the gel and the dye had a negligible effect on diffusion. The experimental diffusion coefficient of IGF-I (D = 1.59 x 10(-6) cm(2)/s), in the absence of binding to the fibrin matrix, is consistent with the dimensions of the molecule known from x-ray crystallography and a correlation between D and molecular weight based on 14 other proteins. The experimental method developed here holds promise for determining molecular transport properties of biomolecules under a variety of conditions, for example, when the molecule adsorbs to the gel or is convected through the gel by fluid transport.
authors.affiliation: Molecular Biosensor and Imaging Center, Institute for Complex Engineered Systems, Carnegie Mellon University, Pittsburgh, Pennsylvania 15213, USA.
authors.forename: Jess V
authors.initials: JV
authors.lastname: Nauman
authors.forename: Phil G
authors.initials: PG
authors.lastname: Campbell
authors.forename: Frederick
authors.initials: F
authors.lastname: Lanni
authors.forename: John L
authors.initials: JL
authors.lastname: Anderson
mesh_terms: D003198:Computer Simulation; D004058:Diffusion; D005337:Fibrin / Q000737:chemistry*; D005782:Gels / Q000737:chemistry*; D007334:Insulin-Like Growth Factor I / Q000737:chemistry*; D008956:Models, Chemical; D008958:Models, Molecular; D012260:Ribonucleases / Q000737:chemistry*; D013050:Spectrometry, Fluorescence / Q000379:methods*
chemical_list: D005782:Gels; D007334:Insulin-Like Growth Factor I; D005337:Fibrin; D012260:Ribonucleases