Carbon-coated functionalized magnetic nanoparticles for biomedical applications

Abstract

Carbon-coated magnetite nanoparticles (NPs) were synthetized by the mechanochemical method with hematite as precursor and amorphous carbon as inorganic reductor. After 18 hours of milling in an inert atmosphere, a nanocomposite material of magnetite and carbon was obtained. Structural and magnetic properties of the NPs were investigated by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), energy dispersive X-ray spectroscopy (EDS) and vibrating sample magnetometry. XRD patterns, refined with the Rietveld method, show that magnetite is present in samples milled from 6 hours onward and that after milling for 18 hours and annealing in Ar, the sample contains a single crystalline phase. Magnetization curves for samples with different milling times show saturation magnetization values that range from 34.1 emu/g after 1 h to 78.0 emu/g after 18 h. Coercive fields are about 500 Oe for all samples. TEM studies reveal that the samples are made of amorphous carbon clusters with magnetite NPs of 20 nm. The obtained NPs, associated to electrochemical transducers, show an improved enhancement of the charge transfer for redox processes involving different bioanalytes. Thus, these NPs offer unique properties as a catalyst in biosensing strategies for the electrochemical detection of high-impact markers and the development of theranostics smart-devices for biomedical applications.