title: Macromolecules released from polymers: diffusion into unstirred fluids.
abstract: Polymers that release macromolecules may be useful for preventing and treating human disease. In certain applications of polymeric controlled release, like drug therapy of brain disease and immunoprotection of mucus epithelia, effectiveness may be limited by diffusion through an unstirred fluid near the polymer. Using computer-assisted epifluorescence microscopy, we have examined the local distribution of fluorescently labelled macromolecules released from an ethylene-vinyl acetate copolymer matrix into unstirred layers of phosphate-buffered water and mid-cycle human cervical mucus. Diffusion coefficients in the fluid were determined by observing the concentration profiles as a function of time. Diffusion coefficients determined for fluorescein, bovine serum albumin, and three classes of human immunoglobulins (IgG, sIgA and IgM) in phosphate-buffered water were in good agreement with literature values. For fluorescein, albumin and IgG, diffusion in mucus was comparable with diffusion in water: the largest molecule tested was slowed by only a factor of 3.
authors.affiliation: Department of Chemical Engineering, Johns Hopkins University, Baltimore, MD 21218.
authors.forename: M L
authors.initials: ML
authors.lastname: Radomsky
authors.forename: K J
authors.initials: KJ
authors.lastname: Whaley
authors.forename: R A
authors.initials: RA
authors.lastname: Cone
authors.forename: W M
authors.initials: WM
authors.lastname: Saltzman
mesh_terms: D001672:Biocompatible Materials; D002582:Cervix Mucus / Q000378:metabolism; D003692:Delayed-Action Preparations / Q000737:chemistry*; D004058:Diffusion; D005260:Female; D019793:Fluorescein; D005452:Fluoresceins / Q000737:chemistry / Q000493:pharmacokinetics; D006801:Humans; D007070:Immunoglobulin A / Q000737:chemistry / Q000493:pharmacokinetics; D007074:Immunoglobulin G / Q000737:chemistry / Q000493:pharmacokinetics; D007075:Immunoglobulin M / Q000737:chemistry / Q000493:pharmacokinetics; D066298:In Vitro Techniques; D008856:Microscopy, Fluorescence; D008954:Models, Biological; D011108:Polymers / Q000737:chemistry*; D012709:Serum Albumin / Q000737:chemistry / Q000493:pharmacokinetics; D014867:Water / Q000737:chemistry
chemical_list: D001672:Biocompatible Materials; D003692:Delayed-Action Preparations; D005452:Fluoresceins; D007070:Immunoglobulin A; D007074:Immunoglobulin G; D007075:Immunoglobulin M; D011108:Polymers; D012709:Serum Albumin; D014867:Water; D019793:Fluorescein