A novel mesoporous nanocarrier: Integrating hollow magnetic fibrous silica with PAMAM into a single nanocomposite for enzyme immobilization

A well-designed mesoporous nanocarrier, integrating hollow magnetic fibrous silica with polyamidoamine (PAMAM) (H-MFS/PAMAM), was obtained for the first time to immobilize porcine pancreas lipase (PPL). The H-MFS, based on the light-weight and hollow Fe₃O₄ core and the fibrous silica shell, was first synthesized as a matrix. Following, PAMAM dendrimers were grafted onto H-MFS by using reiterative Michael addition and amidation reactions, and subsequently PPL was effectively immobilized. We discussed the effect of silica surface micro-morphologies and the length of flexible chains on the performance of immobilized lipase. As a result, the G-3 generation of PAMAM-grafted H-MFS still maintained intact fibrous morphology and proper BET surface area (89 m²/g), which exhibited the highest activity among the different generations (730 ± 2.57 U/g protein). Moreover, after recycling 8 times, the immobilized PPL still retained about 90% of its initial activity. Therefore, this fabrication strategy provided a useful reference platform to design magnetic nanobiocatalyst with high accessible surface, excellent catalytic ability and operational stability.