Highly efficient covalent immobilization of catalase on titanate nanotubes

In this study, titanate nanotubes (TNTs) with desirable biocompatibility and hydrophilicity have been synthesized by a facile and cost-effective alkaline hydrothermal method, and used to immobilize the enzyme. The characterization results reveal that the prepared TNTs have a regular tubular morphology with a length about 100–180   nm and an outer diameter about 10   nm, and a BET specific surface area of 305.4   m 2   g −1 . Catalase (CAT), as the model enzyme, was pre-modified by 3-(3,4-dihydroxyphenyl) propionic acid (3,4-diHPP) via 1-ethyl-3-[3-dimethylaminopropyl] carbodiimide hydrochloride (EDC) and N-hydroxysuccinimide (NHS) coupling chemistry, and then covalently immobilized on the TNTs surface by the chelation of catechol groups with Ti 4+ ions. It is found that TNTs exhibits excellent performances as the immobilized supporter of enzyme: the enzyme loading is as high as 820   mg   g of support −1 ; the relative activity of immobilized enzyme is about 60% of that of free enzyme; the immobilized CAT demonstrates enhanced storage and recycling stability.