Synthesis of calix[n]arene-based silica polymers for lipase immobilization

The objective of this study was to prepare new calix[n]arene-based silica polymers for immobilization of Candida rugosa lipase. The amino functionalized calix[4]arene (C4P), calix[6]arene (C6P) and calix[8]arene (C8P)-based silica polymers were used for the covalent attachment of C. rugosa lipase using glutaraldehyde as a coupling agent. The characterization of synthesized CnP polymers and immobilized lipases were made by Fourier transform infrared spectroscopy (FTIR), thermal gravimetric analysis (TGA) and scanning electron microscope (SEM) techniques. The hydrolytic activities of immobilized lipases (CnP-L) were evaluated and compared with the free enzyme. The activity recovery of immobilized CRL (C. rugosa lipase) based on the carrier C4P, C6P and C8P reaches 74.6%, 68.5% and 51.4%, respectively. The optimal pH and temperature region of the immobilized lipases for the hydrolysis of p-NPP were 7.0 and 50 °C. Nevertheless, the immobilized lipase has good stability, adaptability and reusability in comparison with the free enzyme.