title: The relationship between contact lens surface charge and in-vitro protein deposition levels.
abstract: The adsorption of lysozyme and human serum albumin (HSA) onto hydrogel contact lenses was investigated as a function of lens surface charge. Anionic, cationic and non-ionic contact lenses were deposited using single protein solutions of identical pH and osmolarity. Protein deposition was analyzed using matrix assisted laser desorption ionization mass spectrometry (MALDI-ToF MS) and compared to a direct UV protein analysis method, the bicinchoninic acid (BCA) assay. The results showed remarkable consistency between the two techniques. By inference of results from analyses of sample solutions, lysozyme, a positively charged protein at physiological pH, was only detected on the anionic surface charged contact lenses, presumably a result of electrostatic interactions. Neither the cationic nor the non-ionic lenses deposited lysozyme, possibly due to charge repulsion. HSA, a negatively charged protein at physiological pH, was detected on the cationic lenses, again as a result of electrostatic interactions. The fact that HSA was not observed on either the anionic or non-ionic charged species further demonstrates the effect of charge repulsion.
authors.forename: C E
authors.initials: CE
authors.lastname: Soltys-Robitaille
authors.forename: D M
authors.initials: DM
authors.lastname: Ammon
authors.forename: P L
authors.initials: PL
authors.lastname: Valint
authors.forename: G L
authors.initials: GL
authors.lastname: Grobe
mesh_terms: D000327:Adsorption; D001672:Biocompatible Materials / Q000009:adverse effects* / Q000737:chemistry*; D003263:Contact Lenses, Hydrophilic / Q000009:adverse effects*; D006801:Humans; D020100:Hydrogels / Q000009:adverse effects / Q000737:chemistry; D006863:Hydrogen-Ion Concentration; D066298:In Vitro Techniques; D008422:Materials Testing; D009113:Muramidase / Q000378:metabolism; D011506:Proteins / Q000378:metabolism*; D011804:Quinolines; D012709:Serum Albumin / Q000378:metabolism; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization; D055672:Static Electricity; D013499:Surface Properties
chemical_list: D001672:Biocompatible Materials; D020100:Hydrogels; D011506:Proteins; D011804:Quinolines; D012709:Serum Albumin; C047117:bicinchoninic acid; D009113:Muramidase