Effect of surface functionalization on the heating efficiency of magnetite nanoclusters for hyperthermia application

Abstract

Here we report the effect of surface functionalization on Fe3O4 assembled nanoclusters with biopolymers, like chitosan and dextran using the solvo-thermal route. XRD analyses confirmed the formation of cubic spinel structure with crystallite sizes ranging from 11 to 14 nm. HRTEM analyses revealed the formation of spherical nanoclusters. Magnetic measurements demonstrate the typical ferromagnetic behavior with saturation magnetization (Ms) up to 71.048, 69.829 and 68.228 Am2Kg−1 for Fe3O4 (FO), chitosan coated Fe3O4 (CFO) and dextran coated Fe3O4 (DFO) respectively at room temperature. Negligible coercivity (Hc) and remenance (Mr) at room temperature implies nearly superparamagnetic behavior. Field cooled (FC) and Zero field cooled (ZFC) measurements of magnetization at an applied field of 100 Oe resulting in the blocking temperature above room temperature for all the samples. Induction heating ability of the samples under alternating magnetic field were studied by means of specific absorption rate measurements (SAR). It is shown that the surface functionalization significantly enhanced the SAR value up to 40% i.e., from 144.08 W/g for FO to 233.28 W/g for DFO at 1 mg/ml concentration. The study also concluded that the dipolar interactions are solely responsible for self-heating behavior of the nanoparticles. It was observed that by changing the sample concentration and different coatings, the final temperature can be tuned to the intended therapeutic (hyperthermia) temperature range (40–44 °C). The in vitro cytocompatibility test resulted in cell viability of more than 90%, which proved that the prepared nanomaterials are promising for the hyperthermia applications.