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Issue 32, 2015
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MOF-templated rough, ultrathin inorganic microcapsules for enzyme immobilization

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Ultrathin titania microcapsules with rough surfaces were prepared by using a metal–organic framework (ZIF-8) as one kind of hard template to mediate the structures of the microcapsule shell. Specifically, CaCO3 particles were first coated with tannic acid (TA) followed by the deposition of hydrophobic ZIF-8 and another TA layer, the obtained particles were then assembled with protamine/TiO2 bilayers through biomimetic mineralization. Finally, the microcapsules (Z-TiO2) were obtained after simultaneously removing CaCO3 and ZIF-8 templates using ethylenediaminetetraacetic acid (EDTA). The coordination interaction between TA and ZIF-8 ensured the robust templating which endowed the microcapsules with a rough surface and an ultrathin microcapsules shell (100 nm) with 4.4 nm pore size. Moreover, the surface roughness of microcapsules can be regulated by changing the size of ZIF-8 crystals. The microcapsules were then utilized to immobilize penicillin G acylase (PGA). And PGA@Z-TiO2 retained 69% activity of equivalent free PGA with a loading capacity of 160 mg g−1. The PGA@Z-TiO2 microcapsules exhibited superior reusability: after recycling 8 times, the conversion of the enzymatic reaction remained 36.0%, which was twice higher than that of PGA@TiO2 (14.7%). Moreover, compared with free PGA and PGA@TiO2 microcapsules, PGA@Z-TiO2 microcapsules exhibited higher thermal and storage stability. After storing for 60 days, the relative activity of PGA@Z-TiO2 remained 89.6%, which was higher than that of free PGA (34.5%) and PGA@TiO2 (73.6%). ZIF-8 can be envisioned to be a novel class of hard template for preparing a broad variety of microcapsules with different hierarchical structures.

Graphical abstract: MOF-templated rough, ultrathin inorganic microcapsules for enzyme immobilization

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Article information

09 May 2015
09 Jul 2015
First published
09 Jul 2015

J. Mater. Chem. B, 2015,3, 6587-6598
Article type
Author version available

MOF-templated rough, ultrathin inorganic microcapsules for enzyme immobilization

X. Wang, J. Shi, S. Zhang, H. Wu, Z. Jiang, C. Yang, Y. Wang, L. Tang and A. Yan, J. Mater. Chem. B, 2015, 3, 6587
DOI: 10.1039/C5TB00870K

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