Well-defined bioarchitecture for immobilization of chloroperoxidase on magnetic nanoparticles and its application in dye decolorization.

Molecular orientation of chloroperoxidase (CPO) on surface of Fe 3 O 4 magnetic nanoparticles (MNPs) was achieved through layer-by-layer (LBL) controlled assembly by site specific interactions of avidin and biotin. Enzymatic oxidative decolorization of soluble aniline blue was employed to evaluate the catalytic performance of immobilized CPO (I-CPO). The decolorization efficiency of dye by I-CPO was higher than 90% within 10 min. Moreover, I-CPO displayed improved thermostability and kept higher activity in wider pH range and in the presence of high concentration of oxidant (H 2 O 2 ) compared to that of free enzyme. When incubated at 70 °C for an hour, 42.35% of the activity of immobilized enzyme was reserved compared with that at 25 °C, whereas free CPO remained only 8.46%. The tolerance to H 2 O 2 was improved from 2 mmol L −1 to 4 mmol L −1 , and the suitable pH range become wider. The relative activities of I-CPO in the 20 times use maintained 62% of that in the first run. The enzymatic kinetic constants confirmed that the entrapping CPO into this well-defined architecture could reduce diffusional limitation of reactants and products. [ABSTRACT FROM AUTHOR]