Magnetic birefringence of iron oxyhydroxide nanoparticles stabilised by sucrose

Magnetically induced optical birefringence is used to investigate pharmaceutically important iron–sucrose aqueous suspensions. XRD and TEM measurements of the system of oxyhydroxide particles stabilised by sucrose have shown that this system contains iron oxyhydroxide in the form of 2–5 nm particles. The mineral form of the iron-core is suggested to be akaganeite. Anisotropy of the optical polarizability and magnetic susceptibility of akaganeite nanoparticles are calculated. The permanent dipole moment obtained for the nanoparticles studied was found to be negligible, in agreement with the characteristic superparamagnetic behaviour of the magnetic nanoparticles observed at room temperature. The Neel temperature of these nanoparticles is estimated as below 276 K. The results obtained are discussed against a background of the earlier studies of similar nanoscale systems.

Research highlights
► Polysaccharides iron complex, important in pharmaceutical applications, was studied by magnetic birefringence.
► Magnetic and optical properties of the akaganeite core has been obtained. The superparamagnetic behaviour of the core has been confirmed.
► The experiment suggests that the Neel temperature of these nanoparticles should be set below 276 K. The results show the importance of the magneto-optical method in recognition of magnetic properties of biologically important substances.