title: Determination of albumin sorption to intraocular lenses by radiolabeling and confocal laser scanning microscopy.
abstract: OBJECTIVE
  To determine albumin adsorption profiles and penetration depth of 3 intraocular lens (IOL) materials over time using confocal laser scanning microscopy (CLSM) and radiolabeling.
  
  
  METHODS
  Centre for Contact Lens Research, School of Optometry, and Department of Biology, University of Waterloo, Waterloo, Ontario, Canada.
  
  
  METHODS
  Poly(methyl methacrylate) (PMMA), silicone, and foldable hydrophilic acrylic IOLs were incubated in 0.5 mg/mL bovine serum albumin (BSA) for 1, 7, and 14 days. The BSA was conjugated with lucifer yellow VS to allow identification of the protein location by fluorescent imaging with CLSM. Next, the protein uptake was quantified using 2% (125)I-labeled BSA.
  
  
  RESULTS
  Confocal laser scanning microscopy showed increasing BSA uptake for silicone and PMMA IOLs after 14 days of incubation (P<.05), with an apparent penetration depth of 8.7 microm +/- 1.9 (SD) and 9.2 +/- 1.4 microm, respectively. For hydrophilic acrylic IOLs, BSA was detected at a depth of 38 +/- 7.4 microm after 1 day, followed by an increase to 192.7 +/- 16.2 microm after 14 days. Despite the penetration depth into the hydrophilic acrylic IOLs, quantitative results confirmed that PMMA and hydrophilic acrylic deposited significantly less BSA (mean 278.3 +/- 41.7 ng and 296.5 +/- 33.1 ng, respectively) than silicone IOLs (mean 392.6 +/- 37.6 ng) (P<.05).
  
  
  CONCLUSIONS
  Silicone and PMMA IOL materials showed BSA sorption near the lens surface only, while BSA penetrated deep into the hydrophilic acrylic IOL matrix. Combining the qualitative CLSM method and quantitative radiolabeling technique provided detailed information on protein interactions with implantable biomaterials.
authors.affiliation: Centre for Contact Lens Research, School of Optometry, University of Waterloo, Waterloo, Ontario, Canada. dluensma@uwaterloo.ca
authors.forename: Doerte
authors.initials: D
authors.lastname: Luensmann
authors.forename: Miriam
authors.initials: M
authors.lastname: Heynen
authors.forename: Lina
authors.initials: L
authors.lastname: Liu
authors.forename: Heather
authors.initials: H
authors.lastname: Sheardown
authors.forename: Lyndon
authors.initials: L
authors.lastname: Jones
mesh_terms: D000327:Adsorption; D005456:Fluorescent Dyes; D007457:Iodine Radioisotopes / Q000378:metabolism; D007546:Isoquinolines / Q000378:metabolism; D007910:Lenses, Intraocular; D008689:Methacrylates; D018613:Microscopy, Confocal / Q000379:methods*; D011108:Polymers; D019904:Polymethyl Methacrylate; D011485:Protein Binding; D012710:Serum Albumin, Bovine / Q000493:pharmacokinetics*; D012826:Silicone Elastomers
chemical_list: D005456:Fluorescent Dyes; D007457:Iodine Radioisotopes; D007546:Isoquinolines; D008689:Methacrylates; D011108:Polymers; D012826:Silicone Elastomers; C104020:poly(methylmethacrylate-co-ethylhexylmethacrylate); D012710:Serum Albumin, Bovine; D019904:Polymethyl Methacrylate; C017475:lucifer yellow