Fabrication of Polysaccharide-inorganic Hybrid Biocapsules with Improved Catalytic Activity and Stability

In this study, a novel kind of calcium phosphate-mineralized chitosan/alginate microscapsules was prepared through a bio-inspired process for efficient encapsulation of yeast alcohol dehydrogenase (YADH). In this biomimetic process, when Ca2+-containing chitosan droplets were added into phosphate-containing solution of alginate, a thin chitosan/alginate film formed immediately around the microcapsules coupled with in situ precipitation of calcium phosphate. The biomineralization of calcium phosphate was mimicked by the counter-diffusion system in which Ca2+ ions and phosphate ions migrated into the chitosan/alginate film from opposite directions, respectively. Formation of a microcapsule was confirmed using a Zoom Stereo Microscope, the surface morphology of the microcapsule was characterized by SEM, the surface element composition of microcapsules was analyzed by XPS, and the pore-size distribution of the microcapsule shell was determined by BET. YADH encapsulated in the microcapsules exhibited significantly higher activity and recycling stability in a broader temperature range than the free YADH. We believe that such hybrid materials will find promising applications in enzyme encapsulation and drug delivery systems.