BACKGROUNDImmobilization of more than one peroxidase on the same support is an ideal technology for application because such a multi-enzyme catalytic system may show high activity over a very wide optimal range of pH, temperature and H2O2 concentration. In this work, chloroperoxidase (CPO) and horseradish peroxidase (HRP) were co-immobilized on ZnO nanowires/macroporous SiO2 composite support through an in situ cross-linking method. An anionic bi-epoxy cross-linker was used by adsorption on the surface of ZnO nanowires before cross-linking. RESULTSThe cross-linking was carried out under suitable conditions: pH 6.5, reaction temperature 15 degrees C and reaction time 15 h. Using a 1/1 mixture of CPO and HRP resulted in a co-immobilized enzyme with loading 79.6 mg(CPO) g(support)(-1) and 52.8 mg(HRP) g(support)(-1), and total specific activity up to 15.7 U per mg(support). The co-immobilized enzyme also showed good stability after 60 days of storage, and excellent reusability over 20 repeat uses. CONCLUSIONSFor the decolorization of azo dyes the co-immobilized CPO (60%)/HRP (40%) exhibited high catalytic activity over very wide ranges of pH, temperature and H2O2 concentration. Using this robust biocatalyst, complete decolorizations of azo dyes have been realized within 3 h of reaction. (c) 2017 Society of Chemical Industry