Polysaccharides as stabilizers for the synthesis of magnetic nanoparticles

In this study, superparamagnetic Fe3O4 nanoparticles were individually prepared with one of three polysaccharides as stabilizer, i.e. soluble starch, carboxymethyl cellulose sodium (CMC) and agar. Since polysaccharides present the dynamic supramolecular associations facilitated by inter- and intra-molecular hydrogen bonding, they can act as templates for the growth of nanosized Fe3O4. The resultant polysaccharide–Fe3O4 were characterized by Fourier transform infrared (FTIR) spectroscopy, thermogravimetric (TG) analysis, transmission electron microscopy (TEM), X-ray diffraction (XRD) and magnetic properties. TEM revealed that Fe3O4 was encapsulated by polysaccharides. The particle size of starch–Fe3O4 (SF) was obviously smaller than those from CMC–Fe3O4 (CF) and agar–Fe3O4 (AF). TG analysis was used to calculate the Fe3O4 contents of SF, CF and AF—62.7, 47.8 and 57.4%, respectively. The saturation magnetization (20.43 emu/g) of AF was much lower than that of SF (36.16 emu/g) and CF (35.75 emu/g). The polysaccharide–Fe3O4 exhibited an extremely small hysteresis loop and low coercivity.