Optimum conditions for lipase immobilization on chitosan-coated Fe3O4 nanoparticles

► Facile preparation of Fe3O4-chitosan nanoparticles for enzyme immobilization. ► The characterizations of Fe3O4 and Fe3O4-chitosan nanoparticles were analyzed. ► Optimal immobilized activity 20 U/g obtains at 2.14 h, pH 6.37, and E/S ratio 0.73. ► Immobilized lipase could reuse 20 times while retaining 83% of its activity. ► The immobilized lipase shows better thermal, pH, and storage stability.