A Comparative Study of the Toxicity of Polyethylene Glycol-Coated Cobalt Ferrite Nanospheres and Nanoparticles

Cobalt ferrite as an electromagnetically boosted metal oxide hetero-Fenton catalyst for water treatment

The cobalt ferrite Fenton catalysts were obtained by the flow co-precipitation method. FTIR, XRD, and Mössbauer spectroscopy confirmed the spinel structure. The crystallite size of the as-synthesized sample is 12 nm, while the samples annealed at 400 and 600 °C have crystallite sizes of 16 and 18 nm, respectively. The as-synthesized sample has a grain size of 0.1-5.0 μm in size, while the annealed samples have grain sizes of 0.5 μm-15 μm. The degree of structure inversion ranges from 0.87 to 0.97. The catalytic activity of cobalt ferrites has been tested in the decomposition of hydrogen peroxide and the oxidation of caffeine. The annealing of the CoFe₂O₄ increases its catalytic activity in both model reactions, with the optimal annealing temperature being 400 °C. The reaction order has been found to increase with increasing H₂O₂ concentration. Electromagnetic heating accelerates the catalytic reaction more than 2 times. As a result, the degree of caffeine decomposition increases from 40% to 85%. The used catalysts have insignificant changes in crystallite size and distribution of cations. Thus, the electromagnetically heated cobalt ferrite can be a controlled catalyst in water purification technology.

The potential of surface nano-engineering in characteristics of cobalt-based nanoparticles and biointerface interaction with prokaryotic and human cells

Cobalt-based nanoparticles (CBNPs) have recently received great attention in biomedical studies; however, the possible biotoxicity of these nanoparticles (NPs) has remained a foremost concern that should be addressed. As surface functionalization is one of the helpful proposed solutions, we aimed to apply Lipoamino acids (LAAs) as a coating agent to improve biocompatibility. To this purpose, cobalt oxide, cobalt ferrite, and iron oxide nanoparticles (IONs) were synthesized with and without 2-amino-hexadecanoic acid coating to assess the impacts of LAA coating on characteristics and biocompatibility of CBNPs in human cells and compare with IONs, a widely used magnetic NPs in biomedicine. Antibacterial activities of NPs were evaluated against four Gram-negative and Gram-positive bacteria species to assess their biointerface interaction with prokaryotic cells. In addition, the antibacterial activities of synthesized NPs were compared to silver NPs, one of the widely used antimicrobial NPs and standard antibiotics (ampicillin). The structural characteristics properties of NPs were analyzed using TEM, FE-SEM, EDS, FTIR, XRD, and VSM. These NPs exhibited sphere-like to polygon-like morphology with desirable mean size. CBNPs displayed dose-dependent cytotoxicity and antimicrobial activities against human cell lines and all tested microbial species, as well as more cytotoxicity and bacterial inhibition compared to IONs. Besides, the results revealed that LAA coating could significantly improve the biocompatibility and antibacterial activity of NPs while impacting magnetic properties. To sum up, it seems that surface functionalization could provide more potent tools for bioapplications with improving biocompatibility and bacterial inhibition of CBNPs, though; further studies are needed in this regard.

Structural characteristics, cation distribution, and elastic properties of Cr3+ substituted stoichiometric and non-stoichiometric cobalt ferrites

Structural, elastic and cation distribution properties have been investigated on stoichiometric and non-stoichiometric cobalt ferrites. Crystal structure, formation of spinel type ferrite, chemical bonding, cation distribution, and thermal properties of two series of Cr3+ substituted stoichiometric and non-stoichiometric various cobalt ferrites with general formula Co1-x Cr x Fe2O4 (S1), and Co1+x Cr x Fe2-x O4 (S2) were reported. Samples are synthesized by the solid-state reaction technique via planetary ball milling. X-ray diffraction (XRD) analysis confirms the formation of a single phase cubic spinel structure with the space group Fd3̄m. Rietveld refinement results show that Cr occupies both the tetrahedral (A-site) and octahedral sites (B-site). The experimental lattice parameters show increasing trends for both the series with increase of Cr content. The cation-anion vacancies, chemical bonding, and the displacement of oxygen have been evaluated to understand the effect of Cr substitution and how the non-stoichiometry affects the physical and chemical properties of the material. The crystallite size is found to be the decreasing value with an increase of Cr concentration for both series of samples. Specific vibrational modes from the FTIR spectra suggest a gradual change of inversion of the ferrite lattice with the increase of Cr concentration which is also evident from Rietveld refinement data. The elastic properties analysis reveals that the synthesized samples for both series are ductile in nature. The non-stoichiometric structure with excess Co2+ may pave a new way to realize the lowering of Curie temperature of ferrite that is expected to improve the magnetocaloric properties.

Retraction Note to: A Comparative Study of the Toxicity of Polyethylene Glycol-Coated Cobalt Ferrite Nanospheres and Nanoparticles

An amendment to this paper has been published and can be accessed via the original article.

A review on nanotoxicity and nanogenotoxicity of different shapes of nanomaterials

Nanomaterials (NMs) generally display fascinating physical and chemical properties that are not always present in bulk materials; therefore, any modification to their size, shape, or coating tends to cause significant changes in their chemical/physical and biological characteristics. The dramatic increase in efforts to use NMs renders the risk assessment of their toxicity highly crucial due to the possible health perils of this relatively uncharted territory. The different sizes and shapes of the nanoparticles are known to have an impact on organisms and an important place in clinical applications. The shape of nanoparticles, namely, whether they are rods, wires, or spheres, is a particularly critical parameter to affect cell uptake and site-specific drug delivery, representing a significant factor in determining the potency and magnitude of the effect. This review, therefore, intends to offer a picture of research into the toxicity of different shapes (nanorods, nanowires, and nanospheres) of NMs to in vitro and in vivo models, presenting an in-depth analysis of health risks associated with exposure to such nanostructures and benefits achieved by using certain model organisms in genotoxicity testing. Nanotoxicity experiments use various models and tests, such as cell cultures, cores, shells, and coating materials. This review article also attempts to raise awareness about practical applications of NMs in different shapes in biology, to evaluate their potential genotoxicity, and to suggest approaches to explain underlying mechanisms of their toxicity and genotoxicity depending on nanoparticle shape.

Curcumin-Loaded Nanoparticles with Low-Intensity Focused Ultrasound-Induced Phase Transformation as Tumor-Targeted and pH-Sensitive Theranostic Nanoplatform of Ovarian Cancer

We have developed a simple and versatile nanoplatform using pH-sensitive ferritin nanocages co-loaded with the anticancer drug curcumin (Cur) and liquid fluorocarbon perfluorohexane (PFH) inside the core and conjugated tumor-targeting molecule FA outside the shell referred to as FA-FCP. The synthesized FA-FCP has an average particle diameter of 47 nm, with stable and favorable physicochemical properties in different media, and high biocompatibility and biosafety in vivo and in vitro. Under the conditions of low-intensity focused ultrasound (LIFU) and at pH = 5.0, FA-FCP released a large amount of drugs (53.2%) in 24 h. After 4 min of LIFU (7 W) treatment, FA-FCP provided contrast-enhanced ultrasound imaging capabilities at pH = 5.0. Due to FA receptor-mediated endocytosis, FA-FCP could efficiently enter the cells and further relocate to lysosomes. Eighteen hours after injection of FA-FCP, the tumor was stimulated by LIFU, resulting in a contrast-enhanced ultrasound image. In vivo and in vitro experiments showed that the combined use of FA-FCP and LIFU had significant tumor treatment effects. Based on the results, it was concluded that FA-FCP combined with the external LIFU and the endogenic acidic environment can have powerful theranostic functions and provide a novel type of non-invasive and integrated tumor theranostic option.