The effect of biocompatible coating layers on magnetic properties of superparamagnetic iron oxide nanoparticles

The effect of the surface coating on the magnetic properties of superparamagnetic iron oxide nanoparticles (SPION) with 8 nm in size has been studied. Four different biocompatible coating layers are considered: poly L,L-lactic acid (PLLA), poly epsilon-caprolactone (PCL), bovine serum albumin (BSA) and gold. The presence of coating layer on the surface of SPION is confirmed by FT-IR spectroscopy. Mossbauer spectroscopy and magnetic susceptibility measurements show that for uncoated SPION and Au@SPION the superparamagnetic fraction is retained. The formation of clusters in the case of BSA@SPION and chain-like structure for PCL@SPION and PLLA@SPION increase the inter-particle interactions resulting in hyperfine magnetic structure observed in the Mossbauer spectra at ambient temperature.