Detection of protein deposition on contact lens type polymeric hydrogels by Coomassie blue R staining

Using an aqueous solvent of high methanol content, we have been able to extend the use of Coomassie blue R protein staining to contact lens-type acrylate hydrogels of 35-80% water content. Protein deposition on a wide range of hydrogels was compared after exposure to protein and there was good agreement between in vitro and in vivo studies to assess deposit resistance. Staining was sensitive down to a 2 micrograms lysozyme/cm2 zone extending from one polymer surface to the other, and linear with protein content up to 40 micrograms/cm2. The staining method permits unusual deposit morphologies to be easily visualized and is best used for qualitative or semiquantitative evaluation of protein deposition during the development of new polymeric materials. We propose a new classification system for protein deposition based on the degree of Coomassie blue R staining.