CationizedThis polycationic derivative of ferritin is useful for labeling negative charges on cell surfaces. It does not have the inherent disadvantages of other cationic dyes such as ruthenium red, alcian blue, thorium hydroxide, and colloidal iron. It has the advantage of quantitating the surface charges with greater precision due to its smaller diameter size. It is effective on a variety of cells, and its geometry permits easy membrane surface counting. It is supplied as a sterile 0.15M sodium chloride solution at a concentration of 9.0-12.0 mg/ml.