Estimation of protein and drug adsorption onto silicone-coated glass surfaces.

Porous glass coated with silicone adsorbed proteins such as albumin, globulin, hemoglobin, lysozyme, and peroxidase in pH 7.2 phosphate-buffered saline in the amount of 33--53 mg of protein/g of glass (39.4 m2/g of glass). These proteins were not absorbed from distilled water (except peroxidase). The amounts of albumin adsorbed onto coated glass from several buffers at ionic strength greater than 0.05 mu were similar to amounts adsorbed from saline, despite the difference in salts and pH. The enzymes adsorbed onto coated glass were stable for at least 1 month. Drugs such as insulin, atropine sulfate, physostigmine salicylate, and epinephrine were adsorbed onto the coated glass in the amounts of 28, 0.32, 1.53, and 0.01 mg/g of glass, respectively. The adsorption of pharmaceutical biologicals composed proteins such as hormones and vaccines onto silicone-coated glass contains must be recognized and compensated for, particularly at low concentrations. Protein adsorption onto coated glass might be caused by hydrophobic interaction.