title: Diffusion of protein through the human cornea.
abstract: OBJECTIVE
  To determine the rate of diffusion of myoglobin and bovine serum albumin (BSA) through the human cornea. These small proteins have hydrodynamic diameters of approximately 4.4 and 7.2 nm, and molecular weights of 16.7 and 66 kDa, for myoglobin and BSA, respectively.
  
  
  METHODS
  Diffusion coefficients were measured using a diffusion chamber where the protein of interest and balanced salt solution were in different chambers separated by an ex vivo human cornea. Protein concentrations in the balanced salt solution chamber were measured over time. Diffusion coefficients were calculated using equations derived from Fick's law and conservation of mass in a closed system.
  
  
  RESULTS
  Our experiments demonstrate that the diffusion coefficient of myoglobin is 5.5 ± 0.9 × 10(-8) cm(2)/s (n = 8; SD = 1.3 × 10(-8) cm(2)/s; 95% CI: 4.6 × 10(-8) to 6.4 × 10(-8) cm(2)/s) and the diffusion coefficient of BSA is 3.1 ± 1.0 × 10(-8) cm(2)/s (n = 8; SD = 1.4 × 10(-8) cm(2)/s; 95% CI: 2.1 × 10(-8) to 4.1 × 10(-8) cm(2)/s).
  
  
  CONCLUSIONS
  Our study suggests that molecules as large as 7.2 nm may be able to passively diffuse through the human cornea. With applications in pharmacotherapy and the development of an artificial cornea, further experiments are warranted to fully understand the limits of human corneal diffusion and its clinical relevance.
authors.affiliation: Department of Ophthalmology, Byers Eye Institute at Stanford, Stanford, Calif., USA.
authors.forename: Resmi A
authors.initials: RA
authors.lastname: Charalel
authors.forename: Kristin
authors.initials: K
authors.lastname: Engberg
authors.forename: Jaan
authors.initials: J
authors.lastname: Noolandi
authors.forename: Jennifer R
authors.initials: JR
authors.lastname: Cochran
authors.forename: Curtis
authors.initials: C
authors.lastname: Frank
authors.forename: Christopher N
authors.initials: CN
authors.lastname: Ta
mesh_terms: D002853:Chromatography, Liquid; D003315:Cornea / Q000378:metabolism*; D004058:Diffusion; D004797:Enzyme-Linked Immunosorbent Assay; D006801:Humans; D008970:Molecular Weight; D009211:Myoglobin / Q000378:metabolism*; D010316:Particle Size; D012710:Serum Albumin, Bovine / Q000378:metabolism*; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization
chemical_list: D009211:Myoglobin; D012710:Serum Albumin, Bovine