Zinc-doped cerium oxide nanoparticles: Sol-gel synthesis, characterization, and investigation of their in vitro cytotoxicity effects

Biogenesis of bacterial cellulose/xanthan/CeO2NPs composite films for active food packaging

The increasing significance of biopolymer-based food packaging can be attributed to its biodegradability and independence from petroleum-derived materials. Concurrently, metal oxide nanoparticles (NPs) have gained prominence as effective antimicrobial agents against both wild-type and antibiotic-resistant microbes. In this study, cerium oxide or ceria, CeO2, nanoparticles with an average diameter of 50 nm were synthesized via a green method utilizing Vibrio sp. VLC cell lysate supernatant. The synthesized CeO2 NPs displayed remarkable antimicrobial properties, inhibiting the growth of Escherichia coli and Staphylococcus aureus by 93.7 % and 98 %, respectively. To enhance the potential of bacterial cellulose (BC) for advanced applications, we developed a BC/xanthan/CeO2 nanocomposite using both ex situ and in situ techniques. The integration of CeO2 NPs within the nanocomposite structure not only improved the inherent properties of BC, but also rendered it suitable for use in active food packaging systems. The nanocomposite exhibited no significant cytotoxicity on the human dermal fibroblast (HDF) cells, confirming its safety. Nanocomposites containing biogenically synthesized CeO2 NPs demonstrated exceptional efficacy for reducing microbial contamination. Bread samples coated with nanocomposite films displayed no signs of microbial growth. These results support the application of BC/xanthan/CeO2 nanocomposites as suitable and effective coating materials for antimicrobial food packaging applications.

Incorporation of hydroxyapatite and cerium oxide nanoparticle scaffold as an antibacterial filler matrix for biomedical applications

Managing bone healing is essential for preventing problems such as non-union, bacterial infection, structural instability, psychological, and physical damage in patients. The need to use antibiotics less often has prompted researchers to look at possible substitutes, such as nanoparticles. In this investigation, we choose to employ cerium oxide nanoparticles due to their unique antibacterial properties based on redox reactions. The cerium oxide-hydroxyapatite composite was synthesized, calcined, and ball-milled to create a fine CeO2-HA powder. Luffa cylindrica sponge was used to prepare the scaffold, and X-ray diffraction (XRD) and scanning electron microscopy (SEM) were used to investigate the structural and morphological features. Rapid upregulation of osteogenesis marker genes confirmed that CeO2-HA nanoparticles in the scaffolds promoted osteoblast cell proliferation and osteogenic differentiation. The cell viability test was conducted by MTT assay. When the CeO2-HA composite was cultured with S. aureus, it showed signs of having more antibacterial efficacy than pure HA.

Green Facile Synthesis of Silver-Doped Zinc Oxide Nanoparticles and Evaluation of Their Effect on Drug Release

Silver doped zinc oxide nanoparticles (ZANPs) were synthesized by the gelatin mediated and polymerized sol-gel method, and a calcination temperature of 700 °C was applied for 2 h. X-ray diffraction (XRD), FESEM, TGA, DSC, and EDS were performed to study the structure of the prepared nano-powders. Both cubic silver and hexagonal ZnO diffraction peaks were detected in the XRD patterns. The XRD results, analyzed by the size strain plot (SSP) and Scherrer methods, showed that the crystalline sizes of these nanoparticles increased as the Ag concentration increased. The results were observed via transition electron microscopy (TEM), where the particle size of the prepared samples was increased in the presence of silver. Catechin was chosen as a drug model and was loaded into the hydrogels for release studies. The drug content percentage of catechin in the hydrogels showed a high loading of the drug, and the highest rate was 98.59 ± 2.11%, which was attributed to the Zn0.97Ag0.03O hydrogels. The swelling of the samples and in vitro release studies were performed. The results showed that Zn0.91Ag0.09O showed the highest swelling ratio (68 ± 3.40%) and, consequently, the highest release (84 ± 2.18%) within 300 min. The higher amount of silver ions in the hydrogel structure causes it to enhance the osmotic pressure of the inner structure and increases the relaxation of the structure chain.

Exploring the Influence of Synthesis Parameters on the Optical Properties for Various CeO2 NPs

Cerium oxide (CeO₂) nanoparticles were synthesized with a chemical precipitation method in different experimental conditions using cerium nitrate hexahydrate (Ce(NO₃)₃·6H₂O) as a precursor, modifying the solution pH, the reaction time, and Co atoms as dopants, in order to tune the band gap energy values of the prepared samples. The physical characteristics of the synthesized ceria nanoparticles were evaluated by Fourier transform infrared (FT-IR) spectroscopy, X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), UV–Vis analyses and photoluminescence measurements. XRD data revealed a pure cubic fluorite structure of CeO₂ NPs, the estimation of crystallite sizes by Scherrer’s formula indicates the formation of crystals with dimensions between 11.24 and 21.65 nm. All samples contain nearly spherical CeO₂ nanoparticles, as well as cubic, rhomboidal, triangular, or polyhedral nanoparticles that can be identified by TEM images. The optical investigation of CeO₂ samples revealed that the band gap energy values are between 3.18 eV and 2.85 eV, and, after doping with Co atoms, the E_g of samples decreased to about 2.0 eV. In this study, we managed to obtain CeO₂ NPs with E_g under 3.0 eV by only modifying the synthesis parameters. In addition, by doping with Co ions, the band gap energy value was lowered to 2.0 eV. This aspect leads to promising results that provide an encouraging approach for future photocatalytic investigations.

Nanoantioxidants: Pioneer Types, Advantages, Limitations, and Future Insights

Free radicals are generated as byproducts of normal metabolic processes as well as due to exposure to several environmental pollutants. They are highly reactive species, causing cellular damage and are associated with a plethora of oxidative stress-related diseases and disorders. Antioxidants can control autoxidation by interfering with free radical propagation or inhibiting free radical formation, reducing oxidative stress, improving immune function, and increasing health longevity. Antioxidant functionalized metal nanoparticles, transition metal oxides, and nanocomposites have been identified as potent nanoantioxidants. They can be formulated in monometallic, bimetallic, and multi-metallic combinations via chemical and green synthesis techniques. The intrinsic antioxidant properties of nanomaterials are dependent on their tunable configuration, physico-chemical properties, crystallinity, surface charge, particle size, surface-to-volume ratio, and surface coating. Nanoantioxidants have several advantages over conventional antioxidants, involving increased bioavailability, controlled release, and targeted delivery to the site of action. This review emphasizes the most pioneering types of nanoantioxidants such as nanoceria, silica nanoparticles, polydopamine nanoparticles, and nanocomposite-, polysaccharide-, and protein-based nanoantioxidants. This review overviews the antioxidant potential of biologically synthesized nanomaterials, which have emerged as significant alternatives due to their biocompatibility and high stability. The promising nanoencapsulation nanosystems such as solid lipid nanoparticles, nanostructured lipid carriers, and liposome nanoparticles are highlighted. The advantages, limitations, and future insights of nanoantioxidant applications are discussed.

Engineered defects in cerium oxides: tuning chemical reactivity for biomedical, environmental, & energy applications

Nanocrystalline cerium oxide (nanoceria) is a rare earth oxide with a complex surface chemistry. This material has seen substantial investigation in recent years in both fundamental and applied studies due largely to more precise characterization of the unique surface structures, which mediate its pronounced redox activity. In particular, oxygen storage/buffering capacities have been thoroughly correlated with synthesis and processing condition effects on other material features such as surface (micro-) faceting, reconstruction, and (extent of) hydration. Key material features such as these modulate nanoceria redox performance by changing the crystal microenvironment. In this review, we present nanoengineering methods, which have produced increased nanoceria performance in biomedical, energy, and catalysis applications. The impact of combined/cooperative theoretical and experimental studies are highlighted throughout.

Tragacanth-mediate synthesis of NiO nanosheets for cytotoxicity and photocatalytic degradation of organic dyes

In this study, NiO nanosheets have been manufactured using a co-precipitation approach that involved the usage of nickel nitrate (Ni (NO₃)₂.6H₂O) as the raw material and tragacanth in the role of a stabilizing agent. NiO nanosheets have been fabricated through the reduction of nickel nitrate solution that had been obtained by the application of aqueous extract of tragacanth, which is capable of functioning as a reducing and stabilizing agent. In the following, the physical and chemical properties of tragacanth-stabilized NiO nanosheets have been identified via FESEM, EDS, XRD, UV-Vis, and FT-IR techniques. According to the XRD pattern, these particular nanosheets have contained a cubic structure and group space Fm3m, along with the average size of about 18 to 43 nm that had been in agreement with the FESEM measurements. In addition, we have evaluated the photocatalytic activity of tragacanth-stabilized NiO nanosheets on the degradations of methylene blue (MB) and methyl orange (MO) dyes. The performed photocatalytic assessment has displayed that the nanosheets can degrade 82% of MO within 210 min and 60% of MB in 300 min. The cytotoxicity of tragacanth-stabilized NiO nanosheets on human Glioblastoma cancer (U87MG) cell lines has been investigated via the MTT assay, while it has been detected in the obtained results that the inhibitory concentration (IC₅₀) had been 125 µg/mL.

Metallic SPIONP/AgNP synthesis using a novel natural source and their antifungal activities

The green synthesis of nanoparticles (NPs) is important because of the favorable potential of plant biomolecules involved in the synthesis of NPs. This study aimed to provide a fast, easy, cheap, and environmentally friendly method for the synthesis of superparamagnetic iron oxide NPs (SPIONP) and silver nanoparticles (AgNPs) using Stachys lavandulifolia and an evaluation of their use as antifungal agents against Aspergillus niger and Fusarium solani. The physicochemical properties of AgNPs and SPIONPs were studied using FESEM, HRTEM, XRD, VSM, UV-Vis, and EDX spectroscopy. The sizes and morphologies of the AgNPs and SPIONPs, measured via electron microscopy, were 12.57 nm and 10.70 nm, respectively. Nanoparticles have previously been shown to have antifungal activities, and SPIONPs and AgNPs can show antifungal resistance. These NPs can be used as a substitute for widely used toxic fungicides to promote food safety and public health.

AgNPs and SPIONPs showed inhibitory effects against the radial growth of the mycelia of the pathogenic fungi A. niger and F. solani.

Green synthesis of labeled CeO2 nanoparticles with 99mTc and its biodistribution evaluation in mice

AIMS

The in vivo targeted diagnostic applications of biosynthetic Cerium oxide nanoparticles (CeO₂-NPs), prepared by applying chitosan as a stabilizer, was explored by evaluating the cytotoxicity through MTT assay on WEHI 164 cell line, the Hemolytic activity of CeO₂-NPs and biodistribution in rats.

MAIN METHODS

The CeO₂-NPs were characterized through the use of TGA/DTG, PXRD, FESEM, FTIR, and UV-Vis spectroscopy. The biodistribution of CeO₂-NPs were determined by directly labeled nanoparticles with Technetium-99 m (99mTc) radioisotope (99mTc-CeO₂-NPs). The labeling efficiency and stability of 99mTc-CeO₂-NPs were also measured with Instant Thin Layer Chromatography (ITLC) method. The saturation study was investigated by 1 mCi of 99mTc-CeO₂-NPs using different concentrations of WEHI 164 cells after 4 h of incubation. In vivo biodistribution study was performed by intravenous injection of 600 μCi/200 μL 99mTc-CeO₂-NPs through rat's tail.

KEY FINDINGS

CeO₂-NPs seemed to have a low cytotoxic effect on WEHI 164 cell line and did not result in hemolysis. The biodistribution of CeO₂-NPs has shown that a huge amount of 99mTc-CeO₂-NPs was amassed in the living human organs, including liver, lung, spleen, stomach, and thyroid which shows the in vivo stability of the labeled conjugate. Herein, we have developed a facile, economical, and greener synthetic procedure applying Chitosan template. This green approach is comparable to conventional methods that utilize hazardous materials which are would be a suitable alternative to circumvent synthetic issues related to these materials.

SIGNIFICANCE

The bio-applications of nano-sized CeO₂-NPs were explored to find new horizon to use nanotechnology as the diagnostic tool.