Mononuclear Four-Coordinate Bis-Fluoride Bis-NHC Complexes of Chromium(II), Iron(II), and Cobalt(II).

The reaction between silylamido complexes of Cr(II), Fe(II), and Co(II) and IMes·2HF salt in the presence of IMes (IMes = 1,3-dimesitylimidazol-2-ylidene) led to isolation of Cr(IMes)2F2 (2-Cr), Fe(IMes)2F2 (2-Fe), and Co(IMes)2F2 (2-Co). X-ray structural studies revealed that 2-Cr adopts square planar geometry, while 2-Fe and 2-Co have distorted tetrahedral geometry. Magnetic susceptibility studies of 2-Cr, 2-Fe, and 2-Co were consistent with high-spin complexes, S = 2 for 2-Cr/2-Fe and S = 3/2 for 2-Co. We demonstrated that fluoride can be successfully exchanged for cyanide and azide using trimethylsilyl cyanide and trimethylsilyl azide (3-Fe and 4-Fe). DFT studies suggest that the preference of 2-Cr to adopt square planar geometry over tetrahedral is due to its d4 metal center, where four electrons fill the lower-lying d-orbitals.

Patchy Core/Shell, Magnetite/Silver Nanoparticles via Green and Facile Synthesis: Routes to Assure Biocompatibility.

Nanomedicine is entering a high maturity stage and is ready to reach full translation into the clinical practice. This is because of the ample spectrum of applications enabled by a large arsenal of nanostructured materials. In particular, bimetallic patchy core/shell nanoparticles offer tunable surfaces that allow multifunctional responses. Despite their attractiveness, major challenges regarding the environmental impact and biocompatibility of the obtained materials are yet to be solved. Here, we developed a green synthesis scheme to prepare highly biocompatible patchy core/shell magnetite/silver nanoparticles for biological and biomedical applications. The magnetite core was synthesized by the co-precipitation of ferric chloride and ferrous chloride in the presence of NaOH. This was followed by the patchy silver shell's growth by a green synthesis approach based on natural honey as a reducing agent. A purification process allowed selecting the target patchy nanoparticles and removing excess toxic reagents from the synthesis very efficiently. The obtained patchy magnetite/silver nanoparticles were characterized by UV-Vis spectrophotometry, dynamic light scattering (DLS), thermogravimetric analysis (TGA), Fourier transform infrared spectroscopy (FTIR), scanning electron microscope equipped with energy-dispersive spectroscopy (SEM + EDS), and transmission electron microscopy (TEM). The morphology, patchiness level, and size of the nanoparticles were determined via SEM and TEM. In addition, the spectrophotometric characterization confirmed the presence of the patchy silver coating on the surface of the magnetite core. The nanoparticles show high biocompatibility, as evidenced by low cytotoxicity, hemolytic effect, and platelet aggregation tendency. Our study also provides details for the conjugation of multiples chemistries on the surface of the patchy bimetallic nanoparticles, which might be useful for emerging applications in nanomedicine, where high biocompatibility is of the utmost importance.

PH-Responsive, Cell-Penetrating, Core/Shell Magnetite/Silver Nanoparticles for the Delivery of Plasmids: Preparation, Characterization, and Preliminary In Vitro Evaluation.

Over the past decade, gene therapies have attracted much attention for the development of treatments for various conditions, including cancer, neurodegenerative diseases, protein deficiencies, and autoimmune disorders. Despite the benefits of this approach, several challenges are yet to be solved to reach clinical implementation. Some of these challenges include low transfection rates, limited stability under physiological conditions, and low specificity towards the target cells. An avenue to overcome such issues is to deliver the therapies with the aid of potent cell-penetrating vectors. Non-viral vectors, such as nanostructured materials, have been successfully tested in drug and gene delivery. Here, we propose the development and in vitro evaluation of a nanostructured cell-penetrating vehicle based on core/shell, magnetite/silver nanoparticles. A subsequent conjugation of a pH-responsive polymer was used to assure that the vehicle can carry and release circular DNA. Additionally, the translocating peptide Buforin II was conjugated with the aid of a polyether amine polymer to facilitate translocation and endosome escape. The obtained nanobioconjugates (magnetite/silver-pDMAEMA-PEA-BUFII) were characterized by UV-Vis spectrophotometry, dynamic light scattering (DLS), thermogravimetric analysis (TGA), Fourier transform infrared spectroscopy (FTIR), scanning electron microscope equipped with energy dispersive spectroscopy (SEM+EDS), and transmission electron microscopy (TEM). They were also encapsulated in lecithin liposomes to form magnetoliposomes. The cell viability of Vero cells in the presence of the nanobioconjugates was above 95% and declined to 80% for the magnetoliposomes. The hemolytic tendency of nanobioconjugates and magnetoliposomes was below 10%, while the platelet aggregation approached that of the negative control (i.e., 35%). Cytoplasm coverage values of about 50% for both Vero and neuroblastoma cells confirmed significant cell penetration. Pearson's correlation coefficients for both cell lines allowed us to estimate 20-40% colocalization of the nanobioconjugates with lysotracker green, which implied high levels of endosomal escape. The developed vehicles were also capable of loading around 16% of the added DNA and releasing such cargo with 8% efficiency. The developed nanoplatform holds a significant promise to enable highly efficient gene therapies as it overcomes some of the major issues associated with their eventual translation to the pre-clinical and clinical scale.