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Synthesis of fibrous and non-fibrous mesoporous silica magnetic yolkâ??shell microspheres for immobilization of Lipase

Zafar Ali

 The mesoporous yolk-shell nanoparticles (MYSNs), with a movable Fe3O4 core inside the hollow capsules, with two different morphologies (1)Fe3O4@SiO2@hollow@fibrous SiO2 (Yolk Shell-1) (2)Fe3O4@SiO2@hollow@mesoporousSiO2(Yolk Shell-2) were fabricated as carriers for Candida rugosa lipase (CRL) immobilization, through a template-assistant selectively etching method. Firstly the hydrophobic Fe3O4 nanoparticles were synthesized according to the solvothermal method. Then, SiO2 shell was coated on the Fe3O4 nanoparticle surface by a sol–gel reaction. Subsequently, the resorcinol farmaldehyde (RF) shell was covered on the surface of as-prepared Fe3O4@SiO2 composites and sandwiched Fe3O4@SiO2@RF composites were formed, which were finally provided with mesoporous fibrous (KCC) in the Yolk Shell-1 and mesoporous Silica in the Yolk Shell-2(non fibrous ). After selectively etching CTAB and the middle RF layer, the two kinds of yolk/shells composites were obtained. By utilization of their large and open mesopores (20-50nm) with good surface area (457.78-625.54 m2/g,) CRL was immobilized after amino functionalization using glutaraldehyde as a linker. The ICRL on Y.S-1, Y.S-2 showed good loaded (797-501 mg/g) and enzyme activity of (1503-837 U/g) respectively, thermal stability, resistance to pH, recycling and storage capacity were improved as compare to free lipase.