Fe3O4 NPs was synthesized by coprecipitation method and modified by gallic acid (MNPs-GA).
Trypsin enzyme was immobilized onto MNPs-GA.
Immobilization enhanced free trypsin activity.
A possible mechanism of trypsin immobilization onto Fe3O4 NPs was proposed.
Hydrolysis of BSA by immobilized trypsin was successfully performed.