Synthesis, Characterization and Magnetic Hyperthermia of Monodispersed Cobalt Ferrite Nanoparticles for Cancer Therapeutics.

Magnetic nanoparticles such as cobalt ferrite are investigated under clinical hyperthermia conditions for the treatment of cancer. Cobalt ferrite nanoparticles (CFNPs) synthesized by the thermal decomposition method, using nonionic surfactant Triton-X100, possess hydrophilic polyethylene oxide chains acting as reducing agents for the cobalt and iron precursors. The monodispersed nanoparticles were of 10 nm size, as confirmed by high-resolution transmission electron microscopy (HR-TEM). The X-ray diffraction patterns of CFNPs prove the existence of cubic spinel cobalt ferrites. Cs-corrected scanning transmission electron microscopy-high-angle annular dark-field imaging (STEM-HAADF) of CFNPs confirmed their multi-twinned crystallinity due to the presence of atomic columns and defects in the nanostructure. Magnetic measurements proved that the CFNPs possess reduced remnant magnetization (MR/MS) (0.86), which justifies cubic anisotropy in the system. Microwave-based hyperthermia studies performed at 2.45 GHz under clinical conditions in physiological saline increased the temperature of the CFNP samples due to the transformation of radiation energy to heat. The specific absorption rate of CFNPs in physiological saline was 68.28 W/g. Furthermore, when triple-negative breast cancer cells (TNBC) in the presence of increasing CFNP concentration (5 mg/mL to 40 mg/mL) were exposed to microwaves, the cell cytotoxicity was enhanced compared to CFNPs alone.

Formation of carbon nanodots with different spin states in mechanically processed mixtures of ZnO with carbon nanoparticles: an electron paramagnetic resonance study.

Mixtures of zinc oxide with carbon nanoparticles, ZnO + xC (x = 0.1%, 1% and 3% by weight), were subjected to mechanical processing (MP) in a hermetically sealed grinding chamber. Using electron paramagnetic resonance (EPR) spectroscopy, we monitored the evolution of spin centers in CNPs. While the initial CNPs were EPR silent, their short-duration MP (tMP) gave rise to emergence of low-intensity carbon signal. Increasing the sample temperature at tMP > 9 min induced CNP oxidation, which lead to a dramatic increase in the intensity of C signal. The oxidation process also manifested itself in the appearance of a photoluminescence (PL) band at ∼2.8 eV, which is characteristic for carbon nanodots with an average size of ∼2.7 nm. A limited amount of oxygen in the grinding chamber lead to different ways of carbon nanodot oxidation, depending on carbon content in the samples, which in turn influenced the characteristics of C EPR signals observed. The number of spins calculated per one CNP (NSOP) was found to depend on carbon content in ZnO + xC samples. Based on a detailed analysis of EPR spectral lines, we suggest the existence of a broad variety of relaxation mechanisms for forming C paramagnetic centers.

Synthesis and Characterization of Bimetallic Ni50Pt50 Catalyst Supported on SiO2 for N2O Decomposition.

Nanometallic and bimetallic catalyst of Ni, Pt and Ni50Pt50 were studied by the decompositions of N2O. The catalyst were prepared by incipient wetness impregnation of the silica with low superficial area of 50 m2/g supported with aqueous solution of the metal precursors, for Pt H2Pt Cl6 x 6H2O was used and for Ni, Ni(NO3)2 was used to a total metal loading of 1% wt. Catalyst were oxidized for 2 hours at 400 degrees C with O2, then the samples were reduced for 30 minutes with N2 and 2 hours with H2, all at the same temperature. The catalyst was characterized by Transmission Electron Microscopy (TEM), High Angular Annular Dark Field (HAADF), High Resolution Transmission Electron Microscopy (HR-TEM) and Termoprogramed Reduction (TPR). The mean particle sizes obtained by TEM and HAADF were about 12.5 nm for Ni/SiO2, 2.8 nm for Pt/SiO2 and 3.5 nm Ni50Pt50/SiO2 catalysts respectability. HR-TEM and HAADF analysis showed differences between Ni and Pt catalysts displaying mainly cuboctahedral shapes. Stepped surface defects were found in the Ni50Pt50/SiO2 catalyst. Finally Ni50Pt50/SiO2 was more active than Pt/SiO2 and Ni/SiO2 catalysts for the decomposition of N2O.