γ-Fe2O3 nanoflowers as efficient magnetic hyperthermia and photothermal agent

Abstract

Recent reports on the magnetic nanoparticles (MNPs) as an efficient and alternative photothermal agent have excited the researchers worldwide. While MNPs have been explored well for high heating performance during magnetic hyperthermia (MHT), their full potential is yet to be explored as an efficient photothermal agent. In addition, the simultaneous exposure of alternating magnetic field (for MHT) and near infrared irradiation (for photothermal therapy PTT) can drastically enhance the heating behaviour of MNPs. In the present work we explored microwave assisted polyol method to get γ-Fe2O3 nanoflowers. The use of sodium acetate in varying amounts, as an alkali source, allowed the modification of structural and magnetic properties leading to the formation of nanoflower with high heating performance during MHT and PTT. Role of defects in γ-Fe2O3 nanoflowers were investigated using photoluminescence spectroscopy which highlighted distinct role of oxygen vacancies and surface states. The nanoflowers with better crystallinity and relatively higher coercive field performed well during MHT. The observed high intrinsic loss power value of 15.21 ± 0.34 nHm2Kg-as significantly higher than the commercially available ferrofluids and previously reported values for nanoflowers. During PTT, the therapeutic temperature of 42 °C was achieved for the aqueous suspension with a concentration as low as 100 µg/mL which demonstrates the superiority of γ-Fe2O3 nanoflowers as an efficient PTT agent.