Microfluidic Fabrication of Calcium Alginate/Chitosan Composite Microcapsules with Ultrathin Shells for Peroxidase Immobilization

A simple microfluidic strategy is proposed for the controllable preparation of calcium alginate/chitosan (CaA/CS) microcapsules with ultrathin shells for peroxidase immobilization. In this study, the composite microcapsules are composed of CaA and CS, which are beneficial to improve the stability of CaA microcapsules, and are generated using a two-stage capillary microfluidic device. The inner layer of the composite capsule shells is ionically cross-linked CaA, and the outer layer is covalently cross-linked CS. Moreover, the Fe3O4 magnetic nanoparticles are added to facilitate the recovery and reuse of the composite microcapsules. The morphology, permeability, encapsulation efficiency, enzyme activity, and reusability of CaA/CS microcapsules are investigated. The overall thickness of the double-layered shell is about 346 nm. Meanwhile, the microcapsules have good molecular selective permeability, excellent encapsulation performance, stable enzyme activity, and good stability for reusability. The composite microcapsules retained above 80% of residual activity after six recycle uses. The developed novel strategy for fabricating peroxidase-immobilized CaA/CS microcapsules with ultrathin shells is of great potential value for enzyme immobilization applications.