Properties Of Cobalt Nanoparticles Research Articles

RETRACTED ARTICLE: Novel green synthesis and antioxidant, cytotoxicity, antimicrobial, antidiabetic, anticholinergics, and wound healing properties of cobalt nanoparticles containing Ziziphora clinopodioides Lam leaves extract

The aim of the experiment was a green synthesis of cobalt nanoparticles from the aqueous extract of Ziziphora clinopodioides Lam (CoNPs) and assessment of their cytotoxicity, antioxidant, antifungal, antibacterial, and cutaneous wound healing properties. The synthesized CoNPs were characterized using different techniques including UV–Vis., FT-IR spectroscopy, X‐ray diffraction (XRD), energy dispersive X-ray spectrometry (EDS), scanning electron microscopy (SEM), and transmission electron microscopy (TEM). According to the XRD analysis, 28.19 nm was measured for the crystal size of NPs. TEM and SEM images exhibited a uniform spherical morphology and average diameters of 29.08 nm for the biosynthesized nanoparticles. Agar diffusion tests were done to determine the antibacterial and antifungal characteristics. Minimum inhibitory concentration (MIC), minimum bactericidal concentration (MBC), and minimum fungicidal concentration (MFC) were specified by macro-broth dilution assay. CoNPs indicated higher antibacterial and antifungal effects than many standard antibiotics (p ≤ 0.01). Also, CoNPs prevented the growth of all bacteria at 2–4 mg/mL concentrations and removed them at 2–8 mg/mL concentrations (p ≤ 0.01). In the case of antifungal effects of CoNPs, they inhibited the growth of all fungi at 1–4 mg/mL concentrations and destroyed them at 2–16 mg/mL concentrations (p ≤ 0.01). The synthesized CoNPs had great cell viability dose-dependently and indicated this method was nontoxic. DPPH free radical scavenging test was done to assess the antioxidant potentials, which revealed similar antioxidant potentials for CoNPs and butylated hydroxytoluene. In vivo experiment, after creating the cutaneous wound, the rats were randomly divided into six groups: untreated control, treatment with Eucerin basal ointment, treatment with 3% tetracycline ointment, treatment with 0.2% Co(NO3)2 ointment, treatment with 0.2% Z. clinopodioides ointment, and treatment with 0.2% CoNPs ointment. These groups were treated for 10 days. For histopathological and biochemical analysis of the healing trend, a 3 × 3 cm section was prepared from all dermal thicknesses at day 10. Use of CoNPs ointment in the treatment groups substantially raised (p ≤ 0.01) the wound contracture, hydroxyl proline, hexosamine, hexuronic acid, fibrocyte, and fibrocytes/fibroblast rate and remarkably decreased (p ≤ 0.01) the wound area, total cells, neutrophil, and lymphocyte compared to other groups. In conclusion, CoNPs can be used as a medical supplement owing to their non-cytotoxic, antioxidant, antibacterial, antifungal, and cutaneous wound healing effects. Additionally, the novel nanoparticles (Co(NO3)2 and CoNPs) were good inhibitors of the α-glycosidase, and cholinesterase enzymes.

A DFT+U study of the oxidation of cobalt nanoparticles: Implications for biomedical applications

Nanomaterials – magnetic nanoparticles in particular have been shown to have significant potential in cancer theranostics, where iron oxides are commonly the materials of choice. While biocompatibility presents an advantage, the low magnetisation is a barrier to their widespread use. As a result, highly magnetic cobalt nanoparticles are attracting increasing attention as a promising alternative. Precise control of the physiochemical properties of such magnetic systems used in biomedicine is crucial, however, it is difficult to test their behaviour in vivo. In the present work, density functional theory calculations with the Dudarev approach (DFT+U) have been used to model the adsorption of oxygen on low Miller index surfaces of the hexagonal phase of cobalt. In vivo conditions of temperature and oxygen partial pressure in the blood have been considered, and the effects of oxidation on the overall properties of cobalt nanoparticles are described. It is shown that oxygen adsorbs spontaneously on all surfaces with the formation of non-magnetic cobalt tetroxide, Co3O4, at body temperature, confirming that, despite their promising magnetic properties, bare cobalt nanoparticles would not be suitable for biomedical applications. Surface modifications could be designed to preserve their favourable characteristics for future utilisation.

A Dft+U Study of the Oxidation of Cobalt Nanoparticles: Implications for Biomedical Applications

Nanomaterials - magnetic nanoparticles in particular - have been shown to have significant potential in cancer theranostics, where iron oxides are commonly the materials of choice. While biocompatibility presents an advantage, the low magnetisation is a barrier to their widespread use. As a result, highly magnetic cobalt nanoparticles are attracting increasing attention as a promising alternative. Precise control of the physiochemical properties of such magnetic systems used in biomedicine is crucial, however, it is difficult to test their behaviour in vivo. In the present work, density functional theory calculations with the Dudarev approach (DFT+U) have been used to model the adsorption of oxygen on low Miller index surfaces of the hexagonal phase of cobalt. In vivo conditions of temperature and oxygen partial pressure in the blood have been considered, and the effects of oxidation on the overall properties of cobalt nanoparticles are described. It is shown that oxygen adsorbs spontaneously on all surfaces with the formation of non-magnetic cobalt tetroxide, Co3O4, at body temperature, confirming that, despite their promising magnetic properties, bare cobalt nanoparticles would not be suitable for biomedical applications. Surface modifications could be designed to preserve their favourable characteristics for future utilisation.

Ordered arrays and magnetic properties of cobalt nanoparticles

Monodisperse cobalt nanoparticles are produced by high-temperature thermal decomposition method. The influence of the size of nanoparticles, evaporation temperature, organic solvent, and concentration on the formation of the cobalt nanoparticles array is studied by transmission electron microscopy and ultraviolet absorption. Preliminary results of the cobalt nonoparticles magnetic properties are presented. These results lay a good foundation for the further study of the physical properties and the application in nanoscale devices of magnetic nanoparticles.

Preparation, structure, and magnetic properties of cobalt nanoparticles in carbon fibers

Samples of Co clusters embedded in a carbon fiber matrix have been prepared using a heat-treatment method of cellulose fibers with ion-absorbed cobalt cations. Depending on the heat-treatment temperature used, different cluster sizes have been obtained, ranging from superparamagnetic clusters (average size 10 nm) to ferromagnetic nanoparticles (size between 30 and 200 nm). The formation of graphite planes surrounding the nanoparticles has been observed.