The activation of hydroxyl groups of magnetic PVAL microspheres for covalent immobilization of enzyme was achieved by reaction with CDI.
Magnetic PVAL microspheres (5 g) were immersed in CDI solution (10 ml acetone, 20 mg ml1 CDI), and stirred at 25C for 24 h.
After removal by filtration, the microspheres were washed twice with acetone, dried under reduced pressure at 25C and kept at 4C until use.