Chondroitinase ABCI (cABCI) is a drug enzyme that can be used to treat spinal cord injuries. Due to low thermal stability of cABCI, this enzyme was immobilized on Fe3O4 nanoparticle to increase its thermal stability. The size and morphology, structure and magnetic property of the Fe3O4 nanoparticles were characterized by the analyses of SEM, XRD and VSM, respectively, and FTIR spectroscopy was employed to confirm the immobilization of cABCI on the surface of Fe3O4 nanoparticles. The results indicated that the optimum conditions for pH, temperature, cABCI-to-Fe3O4 mass ratio and incubation time in immobilization process were 6.5, 15 °C, 0.75 and 4.5 h, respectively, and about 0.037 mg cABCI was bound to 1 mg of Fe3O4 nanoparticles at these conditions. The value of Vmax was the same for free and immobilized cABCI, but Km value for immobilized cABCI was 1.6 times higher than that for free one. The storage stability of immobilized cABCI was significantly enhanced at low temperatures, e.g. free cABCI retained 19% of its activity after six days at -20 °C, while the immobilized one retained 96% of its activity. In vitro release of cABCI from Fe3O4 particles showed that about 94% of the enzyme was released after 6 h.
Keywords: release; FeO nanoparticle; chondroitinase ABCI; immobilization; thermal stability.