Merging of covalent cross-linking and biomimetic mineralization into an LBL self-assembly process for the construction of robust organic-inorganic hybrid microcapsules

A mild and efficient method for the construction of robust organic-inorganic hybrid microcapsules was developed by merging of covalent cross-linking and biomimetic mineralization into a layer-by-layer (LBL) self-assembly process. The diatom cell-inspired microcapsule structure had a biocompatible inner organic layer which could create a suitable microenvironment for biologically active substances inside the microcapsules and an inorganic layer which could function as a supporting membrane to maintain the intact morphology of the microcapsules. When in 40% PSS solution, only 5% of the hybrid microcapsules were deformed indicating that the hybrid microcapsule had a higher mechanical stability. The combination of the advantages of both the organic layer and the inorganic layer was applied for the immobilization of catalase (CAT). After being reused 7 times, the CAT in the hybrid microcapsules retained 78% of its initial activity. A buffering effect was created by the capsule wall and the immobilized CAT had a higher pH stability than the free CAT. After storing for 45 days, the CAT in the hybrid microcapsules retained 78% of its initial activity. It is envisaged that the as-prepared hybrid microcapsules can be extended to many applications such as biocatalysis, drug/gene delivery and biosensor fields.