Synthesis of magnetic gold mesoporous silica nanoparticles core shell for cellulase enzyme immobilization: Improvement of enzymatic activity and thermal stability

摘要

Magnetic gold mesoporous silica nanoparticle core shells (mAu@PSNs) were fabricated as a support and their size, morphology and structure was further characterized by X-Ray diffraction (XRD), vibrating sample magnetometer (VSM), scanning electron microscopy (SEM), energy dispersive X-ray analysis (EDAX), transmission electron microscopy (TEM), dynamic light scattering (DLS) and thermal gravimetric analysis (TGA). Cellulase (CEL) immobilization on mAu@PSNs was performed via covalent bonding. Fourier transform infrared (FTIR) spectroscopy confirmed the successful binding of enzyme to mAu@PSNs while Bradford assay determined the binding efficiency to be 76%. The enzyme activity was measured at different pHs and temperatures by FPase method using Whatman filter paper as the substrate. The immobilized enzyme maintained 58% of its initial catalytic activity after nine hours. In this research, a new nano-system was designed as a solid support for cellulase immobilization which enhanced its thermal stability and facilitated its long term storage. In addition, the immobilized enzyme can be applied in a broader temperature and pH ranges while enzyme separation can be simply carried out by an external magnet.