Cholesterol oxidation using hollow fiber dialyzer immobilized with cholesterol oxidase: effect of storage and reuse

Cholesterol oxidase (COD) was covalently bonded onto the surface of polyacrylonitrile (PAN) hollow fiber via glutaraldehyde. The optimum conditions were found to be at pH 7, −20°C and in the dry state. Immobilized COD retained relative activity above 42% after a 30-day period, when storing at 25°C. After reusing for 30 times, the activity of dry-stored immobilized COD retained 58% of activity. By rinsing with PBS, the decrease in the activity can be greatly reduced. At a flow speed of 1.09 cm/s, the immobilized COD can decrease the concentration of cholesterol by about 40% in a 4-h run.