Size-defined synthesis of magnetic nanorods by Salvia hispanica essential oil with electromagnetic excitation properties useful in microwave imagining

Salvia hispanica (chia) essential oil was applied for successful production of magnetic nanorods. The influence of several parameters, i.e. temperature of the reaction mixture, volume of the S. hispanica essential oil solution, stirring speed of the reaction mixture, and flow rate of the N₂ protective gas, on their axial length was studied. A design of experiments (DOE) approach followed by the response surface methodology (RSM) identified the optimal conditions for synthesis of ∼3 nm magnetic nanorods. The granulometric and magnetic properties of these magnetite nanorods were analyzed using transmission electron microscopy (TEM), energy dispersive X-ray scattering (EDX), selected area electron diffraction spectroscopy (SAED), X-ray diffraction (XRD), and superconducting quantum interference device (SQUID) magnetometer. These methods revealed that the produced magnetic nanorods had a crystalline cubic inverse spinel structure with an average axial length of 43.4 ± 20.5 nm, diameter of 3.6 ± 0.9 nm, and aspect ratio of 12.1 ± 5.2 nm, and they suggested the presence of spin glass-like (mictomagnetic) behavior with both ferro- and antiferromagnetic interactions. In addition, attenuated total reflectance Fourier transform infrared spectroscopy (ATR FT-IR) was used to identify functional groups of the organic compounds present in S. hispanica essential oil that were possibly responsible for production and surface functionalization of the magnetite nanorods. The resultant magnetic nanofluid displayed electromagnetic excitation when exposed to microwave radiation, and therefore it could be useful in microwave-imaging of tissues.