Analysis of serum proteins adsorbed to a hemodialysis membrane of hollowfiber type by thermal lens microscopy

To analyze serum proteins adsorbed to a hemodialysis membrane. immunostaining with colloidal gold and thermal-lens microscopy were employed. A total of 14 types of hemodialysis membranes were tested. The cross sections of the membranes were stained with fluorescent antibodies. Observations of these specimens using a laser microscope revealed that serum proteins, such as albumin and immune globulins, tended to adsorb into the inner wall of these membranes. The degree of adsorption of serum proteins varied according to various conditions, such as what materials the membranes were made of or what proteins were adsorbed. For a better quantitative analysis of these proteins. the membranes were stained with immunogold and were observed by a thermal lens microscope. Colloidal gold coated with various anti-human serum proteins was used for the staining. and the quantity of colloidal gold was measured with a thermal-lens microscope. The quantity of colloidal gold, coated with anti-human sera antibody, gradiently decreased from the inner to the outer wall of the membrane. Probably, proteins with larger molecules were adsorbed to the inner parts, and those with smaller molecules were adsorbed to the outer parts of the membrane wall. High-resolution thermal-lens microscopy makes possible the sensitive detection of localized proteins adsorbed to a membrane without extracting it. Thus, the analysis of adsorbed proteins should serve to determine the adaptability of medical appliances to the human body and should also be helpful to a retrospective analysis of substances like drugs which are conjugated to the serum proteins.