Near-infrared active superparamagnetic iron oxide nanoparticles for magnetomotive optical coherence tomography imaging and magnetic hyperthermia therapeutic applications

A green chemistry-based approach to nanoparticle synthesis is an eco-friendly, simple, and cost-effective way to fabricate nanoparticles. This study aims at the biomedical applications of green synthesized near-infrared (NIR) active superparamagnetic iron oxide nanoparticles (SPIONs). The SPIONs obtained by the green synthesis route are non-toxic and their surface is free from any chemical impurity. The MTT [3-(4, 5-Dimethylthiazol-2-yl)-2, 5-Diphenyltetrazolium Bromide] assay was accomplished on human cervical cancer (HeLa) cells and shows that the SPIONs are biocompatible and thus safe for cells even at higher concentrations up to 500 mu g/ml. The syn-thesized SPIONs display an absorbance in the tissue transparent NIR wavelength region. The SPIONs exhibit a superparamagnetic behavior with high saturation magnetization of 66 emu/g. Owing to their excellent optical and magnetic properties, the potential of these green synthesized SPIONs as an exogenous contrast agent in deep -tissue magnetomotive optical coherence tomography (MM-OCT) imaging was evaluated ex-vivo using chicken breast tissue. A significant enhancement in the contrast and the penetration depth was observed with time. The heating response of green synthesized SPIONs was evaluated under the application of an external magnetic field. The results suggest that these SPIONs could be used as theranostic agents for deep tissue biomedical imaging and therapeutic applications.