Synthesis of polyethylenimine modified Fe3O4 nanoparticles with immobilized Cu2+ for highly efficient proteins adsorption

- PEI was modified on the Fe3O4 nanoparticles using bifunctional GA as an intermediate.
- The concentration of NH2 on the NPs increased from 0.2 mmol/g to 0.53 mmol/g.
- The Fe3O4-PEI-Cu2+ NPs shows high adsorption capacity for BHb (6000 mg/g).