Preparation of carriers based on magnetic nanoparticles grafted polymer and immobilization for lipase

► Super paramagnetic nanoparticles were prepared by a surface-initiated radical polymerization. ► This nanoparticle was provided with positive charge and active epoxy groups simultaneously. ► The candida rugosa lipase (CRL) was immobilized via electrostatic adsorption and covalent binding. ► The lipase loading amount was 68.3 ± 0.5 mg CRL/g support and the activity recovery reached to 60.4% (±1.6%). The super paramagnetic nanoparticles Fe 3O 4/(2-hydroxyethty methacrylate-co-dimethyl dially ammonium chloride) copolymer, i.e. Fe 3O 4/P(HEMA–DMDAAC), with positive charge and active epoxy groups simultaneously, were synthesized by a surface-initiated radical polymerization and activation reaction with epoxy chloropropane. The production particles were characterized by Fourier transform infrared spectroscopy (FT-IR), thermogravimetric analysis (TG), transmission electron microscopy (TEM), and vibrating sample magnetometry (VSM). It was verified that the magnetic microspheres held small diameters of 80–100 nm and displayed super paramagnetic property with saturation magnetization of 38.9 emu/g. The candida rugosa lipase (CRL), meanwhile, was immobilized onto the magnetic microspheres via electrostatic adsorption and covalent binding, the loading amount of lipase was 68.3 ± 0.5 mg CRL/g support and the activity recovery of the obtained immobilized lipase reached to 60.4% (±1.6%).