Synthesis and Characterization of Aminoamidine-Based Polyacrylonitrile Fibers for Lipase Immobilization with Effective Reusability and Storage Stability

Lipases are extensively utilized industrial biocatalysts that play an important role in various industrial and biotechnological applications. Herein, polyacrylonitrile (PAN) was treated with hexamethylene diamine (HMDA) and activated by glutaraldehyde, then utilized as a carrier support for Candida rugosa lipase. In this regard, the morphological structure of modified PAN before and after the immobilization process was evaluated using FTIR and SEM analyses. The immobilized lipase exhibited the highest activity at pH 8.0, with an immobilization yield of 81% and an activity of 91%. The optimal pH and temperature for free lipase were 7.5 and 40 degrees C, while the immobilized lipase exhibited its optimal activity at a pH of 8.0 and a temperature of 50 degrees C. After recycling 10 times, the immobilized lipase maintained 76% of its activity and, after 15 reuses, it preserved 61% of its activity. The lipase stability was significantly improved after immobilization, as it maintained 76% of its initial activity after 60 days of storage. The calculated Km values were 4.07 and 6.16 mM for free and immobilized lipase, and the Vmax values were 74 and 77 mu mol/mL/min, respectively. These results demonstrated that synthetically modified PAN is appropriate for immobilizing enzymes and has the potential for commercial applications.

Automated summary

In this study, polyacrylonitrile (PAN) modified with hexamethylene diamine (HMDA) and glutaraldehyde activation was utilized as a carrier for immobilizing Candida rugosa lipase. The immobilized lipase showed the highest activity at pH 8.0, with a yield of 81% and an activity of 91%. After recycling and storage, the immobilized lipase maintained a significant percentage of its initial activity. The results suggest that synthetically modified PAN is a suitable support for enzyme immobilization and has potential for commercial applications.