title: Competitive Effects from an Artificial Tear Solution to Protein Adsorption.
abstract: OBJECTIVE
  To compare the adsorption of lysozyme, lactoferrin, and albumin to various contact lens materials, between single-protein solutions and a multicomponent artificial tear solution (ATS). Additionally, extra steps were taken to distinguish loosely and tightly bound protein, the latter of which may be fully or partially denatured.
  
  
  METHODS
  Using a previously described ATS, we measured the time-dependent adsorption of lys, lac, and alb onto one conventional hydrogel and four silicone hydrogel contact lens materials between the first minute and up to 1 week of protein interaction with the material surface. Proteins were quantified using I radiolabeling of each protein individually in ATS and buffered saline. Extra steps were taken to limit the amount of unbound I and to quantify the amount of reversibly bound protein.
  
  
  RESULTS
  Comfilcon A, balafilcon A, and etafilcon A did not show any relevant competitive adsorption between the ATS components and lys, lac, or alb until after 1 week. Competitive adsorption effects for lys, lac, and alb were observed in as little as 1 minute on lotrafilcon B. Lotrafilcon B had no reversibly bound protein at any time points. The ionic materials balafilcon A and etafilcon A deposited significant amounts of reversibly bound lysozyme and lactoferrin in just 10 minutes. Senofilcon A apparent deposition was below our thresholds of confidence for this protein quantification method.
  
  
  CONCLUSIONS
  Both the competition between lys, lac, and alb and ATS components and the reversibility of these bound proteins is material specific. Coadsorption of lys, lac, and alb with ATS components can increase the reversibility of their adsorption.
authors.affiliation: *PhD †PhD, FCOptom, FAAO Centre for Contact Lens Research, School of Optometry and Vision Science (all authors), and Department of Physics and Astronomy and Guelph-Waterloo Physics Institute (LWJ, JAF), University of Waterloo, Waterloo, Ontario, Canada.
authors.forename: Brad
authors.initials: B
authors.lastname: Hall
authors.forename: Lyndon W
authors.initials: LW
authors.lastname: Jones
authors.forename: James A
authors.initials: JA
authors.lastname: Forrest
mesh_terms: D000327:Adsorption; D000418:Albumins / Q000378:metabolism*; D001667:Binding, Competitive; D003263:Contact Lenses, Hydrophilic; D020100:Hydrogels; D007781:Lactoferrin / Q000378:metabolism*; D065346:Lubricant Eye Drops / Q000737:chemistry*; D009113:Muramidase / Q000378:metabolism*; D011485:Protein Binding; D012828:Silicones
chemical_list: D000418:Albumins; D020100:Hydrogels; D065346:Lubricant Eye Drops; D012828:Silicones; D009113:Muramidase; D007781:Lactoferrin