Magnetic core/shell structures: a case study on the synthesis and phototoxicity/cytotoxicity tests of multilayer graphene encapsulated Fe/Fe3C nanoparticles

Abstract

This study reports on a novel and optimized synthesis procedure of multilayer graphene (MLG) encapsulated Fe/Fe3C nanoparticles using a combined method of spray drying, chemical vapor deposition (CVD) and leaching from FeCl3.6 H2O based precursor, in addition to phototoxicity/cytotoxicity tests for their potential use in biomedical applications. CVD studies were employed at various temperature/time and gas flow rate values. Based on the X-ray diffractometry (XRD), Raman spectroscopy, vibrating sample magnetometry (VSM), transmission electron microscopy/energy-dispersive spectroscopy (TEM/EDS) and differential thermal analysis/thermogravimetry (DTA/TG), CVD parameters of 900 °C, 60 min, 50 mbar and CH4/H2:1/1 were determined as optimum conditions. MLG encapsulated (d-spacing: 0.34 nm) nanoparticles consisting BCC Fe, FCC (Fe, C) and orthorhombic Fe3C phases were obtained with average core diameter of ∼45 nm and average shell thickness of ∼6 nm (8–50 layers). MLG encapsulated Fe/Fe3C nanoparticles were achieved with soft ferromagnetic (Ms: ∼64 emu/g; Hc: ∼276 Oe) property. MLG coated Fe/Fe3C nanoparticles were suspended in an aqueous media using poly/acrylic acid as a post-synthetic treatment. They were found cytocompatible even at 200 µg/mL and 75 µg/mL after 24 and 48 h exposure, respectively. Dose dependent cytotoxicity was studied on both MCF7 and HeLa cells after 72 h incubation. Light-to-heat conversion efficiency of these nanoparticles at 795 nm irradiation in water was calculated as 37.60 %. After laser irradiation, with an increased concentration of nanoparticles (75–200 µg/mL), more than 80 % cell death was observed on both MCF7 and HeLa cells lines via late apoptotic cell death as a result of photothermal effect.