چكيده به لاتين
Abstract:
Nowadays, cellulase immobilization by metal affinity technique is considered in different industries because of its increased stability by maintaining activity and reusability. In the present study, cellulase was immobilized on iron oxide magnetic nanoparticle by metal affinity method. Fe3O4 magnetic nanoparticles were synthesized by co-precipitation method and then part of them was covered by docusate sodium salt (AOT) and the other part was not. Afterwards, copper ion was loaded on both parts. Affecting parameters on copper ion loading were investigated with one factor at a time experimental design method. According to the results, copper ion was loaded at about 100% on both Fe3O4-AOT and Fe3O4 in terms of using sodium phosphate buffer pH 8, 30 µmol buffer to mg copper in 30 minutes. Immobilization of celulase on Fe3O4-AOT and Fe3O4 was obtained by using sodium phosphate buffer 30 mM in 200 rpm and 30 °C. The highest cellulase immobilization were obtained at 60 min and pH 5 with maximum value of about 1097 mg enzyme/g MNPs and the immobilized cellulase maintained 87.5% of activity compared to the free cellulase. Then, affecting parameters on cellulase activity were investigated. The results of testing enzyme activity in different circumstances showed that the stability of immobilized cellulase was increased over time and in different temperatures and pHs compared to free cellulase. Also, immobilized cellulase on Fe3O4-AOT had better performance than immobilized cellulase on Fe3O4 without AOT coverage. Optimal pH and temperature in order to achieve the most activety of immobilize enzyme were obtained 3 and 50 °C, respectively.
Keywords: Cellulase immobilization, Iron oxide magnetic nano particles, Metal affinity binding, Copper ligand.
