Superparamagnetic Iron Oxide Nanoparticle Nanodevices Based on Fe3O4 Coated by Megluminic Ligands for the Adsorption of Metal Anions from Water

Optimization of iron oxide nanoparticles for MRI-guided magnetic hyperthermia tumor therapy: reassessing the role of shape in their magnetocaloric effect

Superparamagnetic iron oxide nanoparticles have hogged the limelight in different fields of nanotechnology. Surprisingly, notwithstanding the prominent role played as agents in magnetic hyperthermia treatments, the effects of nanoparticle size and shape on the magnetic hyperthermia performance have not been entirely elucidated yet. Here, spherical or cubical magnetic nanoparticles synthesized by a thermal decomposition method with the same magnetic and hyperthermia properties are evaluated. Interestingly, spherical nanoparticles displayed significantly higher magnetic relaxivity than cubic nanoparticles; however, comparable differences were not observed in specific absorption rate (SAR), pointing out the need for additional research to better understand the connection between these two parameters. Additionally, the as-synthetized spherical nanoparticles showed negligible cytotoxicity and, therefore, were tested in vivo in tumor-bearing mice. Following intratumoral administration of these spherical nanoparticles and a single exposure to alternating magnetic fields (AMF) closely mimicking clinical conditions, a significant delay in tumor growth was observed. Although further in vivo experiments are warranted to optimize the magnetic hyperthermia conditions, our findings support the great potential of these nanoparticles as magnetic hyperthermia mediators for tumor therapy.

A Cu(ii) complex supported on Fe3O4@SiO2 as a magnetic heterogeneous catalyst for the reduction of environmental pollutants

Today, the presence of pollutants in the environment has become one of the serious problems and concerns of human beings. To eliminate these pollutants, researchers have made many efforts. One of the most important of these efforts is the reduction of such contaminants in the presence of effective catalysts. Two of the most important and widespread types of these pollutants are nitro compounds and organic dyes. In this paper, we report the synthesis of an efficient and reusable magnetic catalyst using Fe3O4@SiO2 core-shell nanoparticles (NPs), N-(4-bromophenyl)-N'-benzoylthiourea, and copper(ii). Specifically, the Cu(ii)-N-(4-bromophenyl)-N'-benzoylthiourea complex supported on Fe3O4-core magnetic NPs (CM)/SiO2-shell (SS) (CM@SS-BBTU-Cu(ii)) has been prepared. CM@SS-BBTU-Cu(ii) was characterized by FT-IR (Fourier transform infrared spectroscopy), XRD (X-ray diffraction), TEM (transmission electron microscopy), HRTEM (high resolution transmission electron microscopy), FFT (fast Fourier transform), VSM (vibrating sample magnetometry), TG-DTA (thermogravimetry-differential thermal analysis), STEM (scanning transmission electron microscopy), EDS (energy-dispersive X-ray spectroscopy), and elemental mapping. The synthesized CM@SS-BBTU-Cu(ii) was applied for the reduction of 4-nitrophenol (4-NP), Congo red (CR), and methylene blue (MB) in the presence of NaBH4 (sodium borohydride) at room temperature. CM@SS-BBTU-Cu(ii) can be recycled and reused 5 times. Our results displayed that the performance of the catalyst was not significantly reduced by recycling.

Chain-Breaking Antioxidant and Peroxyl Radical Trapping Activity of Phenol-Coated Magnetic Iron Oxide Nanoparticles

Superparamagnetic iron oxide nanoparticles (SPION) are important materials for biomedical applications, and phenol capping is a common procedure to passivate their surface. As phenol capped SPION have been reported to behave as antioxidants, herein, we investigate the mechanism underlying this activity by studying the reaction with alkyl peroxyl (ROO^•) radicals. SPION were prepared by coprecipitation of Fe(II) and Fe(III), using phenolic antioxidants (gallic acid, Trolox and nordihydroguaiaretic acid) as post-synthesis capping agents and by different purification procedures. The reactivity of ROO^• was investigated by inhibited autoxidation studies, using styrene as an oxidizable substrate (solvent MeCN, 30 °C) and azo-bis(isobutyronitrile) as a radical initiator. While unprotected, bare SPION behaved as prooxidant, accelerating the O₂ consumption of styrene autoxidation, phenol capping provided a variable antioxidant effect that was dependent upon the purification degree of the material. Thoroughly washed SPION, containing from 7% to 14% (w/w) of phenols, had a low reactivity toward peroxyl radicals, while SPION with a higher phenol content (46% to 55%) showed a strong radical trapping activity. Our results indicate that the antioxidant activity of phenol-capped SPION can be caused by its release in a solution of weakly bound phenols, and that purification plays a major role in determining the properties of these materials.