In situ one-pot preparation of superparamagnetic hydrophilic porous microspheres for covalently immobilizing penicillin G acylase to synthesize amoxicillin

SEM images of Fe3O4-GMH prepared with different amount of formamide. (a) ×50, 10.0 ml, (b) ×50, 12.5 ml, (c) ×50, 15.0 ml, (d) ×50, 17.5 ml, and (e) ×50, 20.0 ml.