The relationship between contact lens surface charge and in-vitro protein deposition levels

• Published in: Biomaterials Vol. 22; no. 24; pp. 3257 - 3260
• Main Authors: Soltys-Robitaille, Christine E., Ammon, Daniel M., Valint, Paul L., Grobe III, George L.
• Format: Journal Article
• Language: English
• Published: Netherlands Elsevier Ltd 01-12-2001
• Subjects: Absorption; Adsorption; Anionic; Bicinchoninic acid (BCA) assay; Biocompatible Materials - adverse effects; Biocompatible Materials - chemistry; Cationic; Contact Lenses, Hydrophilic - adverse effects; Human serum albumin (HSA); Humans; Hydrogels; Hydrogels - adverse effects; Hydrogels - chemistry; Hydrogen-Ion Concentration; In Vitro Techniques; Lysozyme; Mass spectrometry; Materials Testing; Matrix assisted laser desorption ionization mass spectrometry (MALDI-ToF MS); Muramidase - metabolism; Negative ions; Non-ionic; Osmosis; pH effects; Positive ions; Proteins - metabolism; Quinolines; Serum Albumin - metabolism; Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization; Static Electricity; Surface Properties; Ultraviolet radiation; Anionic; Cationic; Matrix assisted laser desorption ionization mass spectrometry (MALDI-ToF MS); Bicinchoninic acid (BCA) assay; Human serum albumin (HSA); Non-ionic; Lysozyme
• ISSN: 0142-9612; 1878-5905
• DOI: 10.1016/S0142-9612(01)00163-6

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.