A trypsin–calcium carbonate hybrid nanosphere based enzyme reactor with good stability and reusability

Abstract

Controlled fabrication of CaCO₃ nanoparticles with an exquisite polymorph and morphology has received intensive attention due to their broad industrial and biomedical applications. Herein we have created trypsin–CaCO₃ hybrid nanoparticles with a well-controlled morphology and a crystal phase via a very mild biomineralization process. The incubation of a mixture of sodium carbonate and calcium chloride at room temperature using trypsin as the biotemplate leads to predominantly calcite mesocrystals with porous sphere-like nanostructures. The trypsin–CaCO₃ hybrid nanospheres behave as superior nano-biocatalysts, which display high stability against thermal and chemical denaturation as well as excellent reusability. We have demonstrated that trypsin not only acts as a novel robust biotemplate to mediate the growth of CaCO₃ crystals, but also enhances their biological properties as an excellent enzyme. This indicates that biomineralization may provide a facile and environmentally amiable approach to immobilize enzymes on calcium carbonate nanoparticles. Our studies could greatly enhance the understanding of the mechanism of the protein-mediated biomineralization of CaCO₃, and extend the applications of CaCO₃-based composite nanostructured biomaterials.