论文部分内容阅读
In this work, a new immobilization method based on dopamine (DA) self-polymerization was developed for laccase immobilization on magnetic nanoparticles (Fe3O4 NPs). To optimize the immobilization condition including reaction pH, DA concentration and enzyme con-centration, a central composite response surface method was applied. The optimal condition was determined as pH value of 5.92, laccase concentration of 0.25 mg mL-1 and DA concentration of 12.74 mg mL-1, under which a high enzyme activity recovery of 88.17％ was obtained. By comparing with free laccase, the stabilities of immobilized laccase towards pH, thermostability, storage were enhanced significantly. Approximately 60％ of relative activity for immobilized laccase was remained after being incubated for 6 h at 50 ℃, but the free laccase only remained 25％. After 40 days of storage at 4 ℃, the laccase immobilized by DA kept about 89％ of its original activity, but the free laccase only retained 48％. After recycled 10 times, the relative activity of immobilized laccase still retained 70％. The immobilized laccase was then applied to catalyze the degradation of 4-chlorophenol (4-CP), 86％ percentage of 4-CP was removed within 2 h. After degraded 10 times, the relative activity of immobilized laccase still remained 64％ of its initial activity, which exhibits an excellent reusability and operational stability.