Controlled synthesis of dense MgFe 2 O 4 nanospheres by ultrasonic spray pyrolysis technique: Effect of ethanol addition to precursor solvent

Efficient catalytic activity of NiO and CeO2 films in benzoic acid removal using ozone

This research focuses on the synthesis of NiO and CeO2 thin films using spray pyrolysis for the removal of benzoic acid using ozone as an oxidant. The results indicate that the addition of CeO2 films significantly enhances the mineralization of benzoic acid, achieving a rate of over 80% as the CeO2 films react with ozone to produce strong oxidant species, such as hydroxyl radicals, superoxide radicals, and singlet oxygen as demonstrated by the presence of quenchers in the reaction system. The difference in catalytic activity between NiO and CeO2 films was analyzed via XPS technique; specifically, hydroxyl oxygen groups in the CeO2 film were greater in number than those in the NiO film, thus benefitting catalytic oxidation as these species are considered active oxidation sites. The effects of nozzle-substrate distances and deposition time during the synthesis of the films on benzoic acid removal efficiency were also explored. Based on XRD characterization, it was established that the NiO and CeO2 films were polycrystalline with a cubic structure. NiO spherical nanoparticles were well-distributed on the substrate surface, while some pin holes and overgrown clusters were observed in the CeO2 films according to the SEM results. The stability of the CeO2 films after five consecutive cycles confirms their reusability. The retrieval of films is easy because it does not require additional separation methods, unlike the catalyst in powder form. The obtained results indicate that the CeO2 films have potential application in pollutant removal from water through catalytic ozonation.

Mg(1-x)CuxFe2O4 superparamagnetic nanoparticles as nano-radiosensitizer agents in radiotherapy of MCF-7 human breast cancer cells

Magnesium-doped copper spinel ferrite superparamagnetic nanoparticles (Mg_(1-x)Cu_xFe₂O₄ SPMNPs, 0.2 ≤ x ≤ 0.8) were successfully synthesized by a hydrothermal method. The cytotoxicity effects and cell viability of MCF-7 on human breast cancer cells pre and post exposure to the Mg_1-xCu_xFe₂O₄ SPMNPs at different concentrations of 0.1, 1, 10 and 100 μg ml^-1 under radiotherapy were studied by MTT (3-[4,5-dimethylthiazol-2-yl]-2, 5-diphenyltetrazolium bromide) assay. Here, x-ray diffraction, scanning electron microscopy, atomic force microscopy, UV-visible spectrophotometry, Fourier transform infrared spectroscopy and vibrating-sample magnetometry were evaluated for the crystal structure, morphology, optical and magnetic property of the Mg_(1-x)Cu_xFe₂O₄ SPMNPs. The results showed that the Mg_(1-x)Cu_xFe₂O₄ SPMNPs all at x values had no significant cytotoxicity at concentrations of 0.1,1 and 10 μg ml^-1, but were enhanced by increasing of Cu content. Furthermore, cell destruction of MCF-7 human breast cancer cells post exposure to Mg_(1-x)Cu_xFe₂O₄ SPMNPs under x-ray irradiation was enhanced by increasing the Cu content and concentration. Superparamagnetic properties of the Mg_(1-x)Cu_xFe₂O₄ SPMNPs cause their localization and elimination, by only an external magnetic field. In conclusion, the Mg_(1-x)Cu_xFe₂O₄ SPMNPs with optimum values of x = 0.2 (10 μg ml^-1) and x = 0.6 (1 μg ml^-1) can be considered as a nano-radiosensitizer because of the synergistic treatment effect without cytotoxicity on the MCF-7 cells.

Magnetic Nanoparticles as MRI Contrast Agents

Iron oxide nanoparticles (IONPs) have emerged as a promising alternative to conventional contrast agents (CAs) for magnetic resonance imaging (MRI). They have been extensively investigated as CAs due to their high biocompatibility and excellent magnetic properties. Furthermore, the ease of functionalization of their surfaces with different types of ligands (antibodies, peptides, sugars, etc.) opens up the possibility of carrying out molecular MRI. Thus, IONPs functionalized with epithelial growth factor receptor antibodies, short peptides, like RGD, or aptamers, among others, have been proposed for the diagnosis of various types of cancer, including breast, stomach, colon, kidney, liver or brain cancer. In addition to cancer diagnosis, different types of IONPs have been developed for other applications, such as the detection of brain inflammation or the early diagnosis of thrombosis. This review addresses key aspects in the development of IONPs for MRI applications, namely, synthesis of the inorganic core, functionalization processes to make IONPs biocompatible and also to target them to specific tissues or cells, and finally in vivo studies in animal models, with special emphasis on tumor models.