Magnetic combined cross-linked enzyme aggregates of horseradish peroxidase and glucose oxidase: an efficient biocatalyst for dye decolourization

In this study, the magnetic combined cross-linked enzyme aggregates (combi-CLEAs) of glucose oxidase (GOD) and horseradish peroxidase (HRP) were designed and prepared successfully. The magnetic combi-CLEAs were fabricated by co-precipitation and cross-linking for the immobilization of GOD and HRP onto amino-functionalized Fe3O4 particles. Ethanol and glutaraldehyde were used as precipitant and cross-linker, respectively. In order to evaluate the catalytic performance, the magnetic combi-CLEAs were applied in the removal of direct black-38 (DB38). The results indicated that the magnetic combi-CLEAs exhibited high removal efficiency for DB38 at pH 6.0 and 40 degrees C. Under optimal conditions, the highest removal efficiency of DB38 was 92.28%, which was higher than that of free enzymes (46.82%). After 8 cycles of reuse, the DB38 removal efficiency could still reach 55.53%, indicating that the magnetic combi-CLEAs had good reusability. Due to the easy separation and high reusability, this study shows that magnetic combi-CLEAs may potentially be an environmentally friendly and cost effective biocatalyst for dye removal and water treatments.