Magnetic iron oxide nanoparticles in the 10-40 nm size range and with a reduced distribution in size have been synthesized under argon by using ammonium bases R 4 NOH (R = CH 3 , C 2 H 5 , C 3 H 7 ) and a hydrothermal treatment. The size is tuned owing to the base to iron ratio and to the length of the alkyl chain R. We precipitate first ferric hydroxides at pH 1.5-2, then ferrous hydroxide at pH 5.5-6. The rapid increase of pH up to basic pH leads to the formation of magnetic iron oxide particles of 12 nm. For [base] to [Fe] ratio above 3.5, a homogeneous growth occurs during further hydrothermal treatment at 250°C. The higher the quantity of base added and the longer the alkyl chain used, the smaller the particle size produced. For sizes above 20 nm, the Verwey transition at 120 K, characteristic of magnetite, is observed on the field cooling-zero field cooling magnetization curve. The nanoparticles can be described by a core-shell model, that is, a magnetite core surrounded by an oxidized layer close to maghemite. The fractional volume of maghemite increases as the particle size decreases so that below 20 nm, nanoparticles cannot be properly labeled as "magnetite".

Bystromite (MgSb2O6) nanorods were prepared using a colloidal method in the presence of ethylenediamine, after a calcination step at 800 °C in static air. From X-ray powder diffraction analyses, a trirutile-type structure with lattice parameters a = 4.64 Å and c = 9.25 Å and space group P42/mnm was identified. Using scanning electron microscopy (SEM), microrods with sizes from 0.2 to 1.6 μm were observed. Transmission electron microscopy (TEM) analyses revealed that the nanorods had a length of ~86 nm and a diameter ~23.8 nm. The gas-sensing properties of these nanostructures were tested using pellets elaborated with powders of the MgSb2O6 oxide (calcined at 800 °C) at temperatures 23, 150, 200, 250 and 300 °C. The pellets were exposed to different concentrations of carbon monoxide (CO) and propane (C3H8) at these temperatures. The results showed that the MgSb2O6 nanorods possess excellent stability and high sensitivity in these atmospheres.

With the aim improving drug delivery, liposomes have been employed as carriers for chemotherapeutics achieving promising results; their co-encapsulation with magnetic nanoparticles is evaluated in this work. The objective of this study was to examine the physicochemical characteristics, the pharmacokinetic behaviour, and the efficacy of pegylated liposomes loaded with cisplatin and magnetic nanoparticles (magnetite) (Cis-MLs). Cis-MLs were prepared by a modified reverse-phase evaporation method. To characterize their physicochemical properties, an evaluation was made of particle size, ζ-potential, phospholipid and cholesterol concentration, phase transition temperature (Tm), the encapsulation efficiency of cisplatin and magnetite, and drug release profiles. Additionally, pharmacokinetic studies were conducted on normal Wistar rats, while apoptosis and the cytotoxic effect were assessed with HeLa cells. We present a method for simultaneously encapsulating cisplatin at the core and also embedding magnetite nanoparticles on the membrane of liposomes with a mean vesicular size of 104.4 ± 11.5 nm and a ζ-potential of −40.5 ± 0.8 mV, affording a stable formulation with a safe pharmacokinetic profile. These liposomes elicited a significant effect on cell viability and triggered apoptosis in HeLa cells.

LaCoO3nanoparticles with perovskite-type structure were prepared by a microwave-assisted colloidal method. Lanthanum nitrate, cobalt nitrate, and ethylenediamine were used as precursors and ethyl alcohol as solvent. The thermal decomposition of the precursors leads to the formation of LaCoO3from a temperature of 500°C. The structural, morphological, and compositional properties of LaCoO3nanoparticles were studied in this work by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and atomic force microscopy (AFM). Pellets were manufactured in order to test the gas sensing properties of LaCoO3powders in carbon monoxide (CO) and propane (C3H8) atmospheres. Agglomerates of nanoparticles with high connectivity, forming a porous structure, were observed from SEM and TEM analysis. LaCoO3pellets presented a high sensitivity in both CO and C3H8at different concentrations and operating temperatures. As was expected, sensitivity increased with the gas concentration and operation temperature increase.

Mesoporous CoSb2O6nanoparticles, synthesized through a nonaqueous method (using cobalt nitrate, antimony trichloride, ethylenediamine, and ethanol as a solvent), were tested to establish their sensitivity to CO and C3H8atmospheres at relatively low temperatures. The precursor material was dried at 200°C and calcined at 600°C. X-ray diffraction and scanning electron microscopy were employed to verify the existence of crystal phases (P42/mnm) and the morphology of this trirutile-type CoSb2O6oxide. Pyramidal and cubic shaped crystals (average size: 41.1 nm), embedded in the material’s surface, were identified. Mesopores (average size: 6.5 nm) on the nanoparticles’ surface were observed by means of transmission electron microscopy. The best sensitivity of the CoSb2O6in a CO atmosphere was at the relatively low temperatures of 250 and 350°C, whereas, in a C3H8atmosphere, the sensitivity increased uniformly with temperature. These results encourage using the CoSb2O6nanoparticles as gas sensors.

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