One-pot preparation of magnetic chitosan beads

A new one-pot method for preparation of magnetic chitosan beads comprising in situ prepared magnetite nanoparticles was proposed. The main advantage of the proposed method is the simultaneous obtaining of the ferromagnetic material and formation of chitosan beads by combination of two methods ― the sol-gel method and capillary extrusion. In addition, appropriate conditions for effective involving of pre-formed suspension of magnetic nanoparticles into chitosan beads without losses of magnetic material during the extrusion were found. Moreover, the sol-gel method allowed considerable amounts of magnetite to be incorporated in the beads. The equilibrium swelling degree of the prepared beads depended on pH of the medium. Optical and scanning electron microscopy revealed that the core of the beads had highly porous structure. The measurements of the magnetization of the beads showed that saturation could not be reached even at a maximum external magnetic field of 6 kOe. The Mossbauer analyses revealed that the in situ formed magnetic nanoparticles were in superparamagnetic state and a part of them was in intermediate state between superparamagnetic and ferrimagnetic one.