Functionalization of Iron Oxide Nanoparticles With HSA Protein for Thermal Therapy

Over the past two decades, important progress has been made in the development of nanomaterials, especially for biomedical applications. The surface of magnetic nanoparticles (MNPs) can be modified and functionalized with a targeting agent in order to improve their longevity in the blood, their cell internalization, and their efficiency. However, after this functionalization, some of their physical properties may be modified. In this paper, spinel iron-oxide single crystals 10 nm in diameter were elaborated and functionalized with human serum albumin (HSA) protein, to give an MNP-HSA nano-platform. Physicochemical studies were performed to evaluate this nano-platform utility in nanomedicine. X-ray photoelectron spectroscopy and thermogravimetry were used to establish the presence of protein at the surface of MNP. MNP-HSA shows very good colloidal stability with a zeta potential of -35.4 +/- 0.6 mV at physiological pH (7.4). MNP-HSA is superparamagnetic and exhibits a saturation magnetization (Ms) of 63 emu. g(-1) at 310 K and produces localized heat in an alternating magnetic field; the specific absorption rate (SAR) of an aqueous suspension of MNP-HSA is 123 W. g(-1). To identify the relative contributions of Brownian and Neel relaxations in its heating process, MNP-HSA was immobilized in an agarose gel, where the SAR was found to be the same as in water. This indicates that Neel relaxation is the dominant nanoheating mechanism.