Structural, optical and enhanced antibacterial activities of ZnO and (Co, Fe) co-doped ZnO nanoparticles by sol-gel combustion method

Therapeutic Potential of Sol-Gel ZnO Nanocrystals: Anticancer, Antioxidant, and Antimicrobial Tri-Action

Zinc oxide nanocrystals (ZnO NCs) hold great promise in nanomedicine with fascinating multifunctional properties. We investigated the therapeutic potential of sol-gel synthesized ZnO NCs with crystal sizes of 52.65 and 25.11 nm, focusing on their anticancer effects on HepG2 and HT29 cells, antioxidant properties, and antimicrobial activity. Both samples displayed a hexagonal wurtzite ZnO structure, wherein the crystal sizes diminished with lower calcination temperatures according to X-ray diffraction. The scanning electron microscopy analysis revealed that lowering the calcination temperature resulted in a decrease in the grain size of the ZnO NCs, as expected. This reduction in grain size combined with a decrease in crystal size resulted in a significant 40% reduction in the reflectance of the ZnO NCs in UV-vis-NIR spectroscopy. It was also observed that the ZnO NCs calcined at higher temperatures exhibited larger particle sizes with a reduced surface area mean of 69.30 μm and a stable negative zeta potential of -11.2 mV. In contrast, the ZnO NCs calcined at lower temperatures exhibited a larger surface area mean of 34.56 μm and a positive zeta potential of +10 mV. In both cell lines, the cytotoxic potential was found to be higher in HepG2 cells. Specifically, when ZnO nanocrystals (NCs) with a crystal size of 52.65 nm were used, the lowest cell viability was observed at a concentration of 5.74 μg/mL. Based on oxidative stress index values, a lower crystal size of ZnO NCs displayed greater effectiveness in HT29 cells, while a higher crystal size of ZnO NCs had pronounced effects in HepG2 cells. Moreover, both ZnO NCs exhibited significant antimicrobial activity against Gram-positive bacteria (Enterococcus faecalis and Staphylococcus aureus) and Candida parapsilopsis fungus. These findings emphasize sol-gel ZnO NCs' potential as versatile agents in nanomedicine, spurring research on targeted cancer therapies and antimicrobial innovations.

Reduced TiO2 Nanotubes/Silk Fibroin/ZnO as a Promising Hybrid Antibacterial Coating

The current research aims to elucidate the influence of reduction process of TiO2 nanostructures on the surface properties of a bioinspired Ti modified implant, considering that the interface between a biomaterial surface and the living tissue plays an important role for this interaction. The production of reduced TiO2 nanotubes (RNT) with lower band gap is optimized and their performance is compared with those of simple TiO2 nanotubes (NT). The more conductive surfaces provided by the presence of RNT on Ti, allow a facile deposition of silk fibroin (SF) film using the electrochemical deposition method. This hybrid film is then functionalized with ZnO nanoparticles, to improve the antibacterial effect of the coating. The modified Ti surface is evaluated in terms of surface chemistry, morphology and roughness, wettability, surface energy, surface charge and antibacterial properties. Surface analysis such as SEM, AFM, FTIR and contact angle measurements were performed to obtain topographical features and wettability. FT-IR analysis confirms that SF was effectively attached to TiO2 nanotubes surfaces. The electrochemical deposition of SF and SF-ZnO reduced the interior diameter of nanotubes from ~85 nm to approx. 50-60 nm. All modified surfaces have a hydrophilic character.

Green synthesis of ZnO nanoparticles from ball moss (Tillandsia recurvata) extracts: characterization and evaluation of their photocatalytic activity

Green synthesis (GS), referred to the synthesis using bioactive agents such as plant materials, microorganisms, and various biowastes, prioritizing environmental sustainability, has become increasingly relevant in international scientific practice. The availability of plant resources expands the scope of new exploration opportunities, including the evaluation of new sources of organic extracts, for instance, to the best of our knowledge, no scientific articles have reported the synthesis of zinc oxide nanoparticles (ZnO NPs) from organic extracts of T. recurvata, a parasitic plant very common in semiarid regions of Mexico.This paper presents a greener and more efficient method for synthesizing ZnO NPs using T. recurvata extract as a reducing agent. The nanoparticles were examined by different techniques such as UV-vis spectroscopy, X-ray diffraction, scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), and BET surface analysis. The photocatalytic and adsorptive effect of ZnO NPs was investigated against methylene blue (MB) dye in aqueous media under sunlight irradiation considering an equilibrium time under dark conditions. ZnO nanoparticles were highly effective in removing MB under sunlight irradiation conditions, showing low toxicity towards human epithelial cells, making them promising candidates for a variety of applications. This attribute fosters the use of green synthesis techniques for addressing environmental issues.This study also includes the estimation of the supported electric field distributions of ZnO NPs in their individual spherical or rounded shapes and their randomly oriented organization, considering different diameters, by simulating their behavior in the visible wavelength range, observing resonant enhancements due to the strong light-matter interaction around the ZnO NPs boundaries.

Green inspired synthesis of zinc oxide nanoparticles using Silybum marianum (milk thistle) extract and evaluation of their potential pesticidal and phytopathogens activities

BACKGROUND

The green approaches for the synthesis of nanoparticles are gaining significant importance because of their high productivity, purity, low cost, biocompatibility, and environmental friendliness.

METHODS

The aim of the current study is the green synthesis of zinc oxide nanoparticles (ZnO-NPs) using seed extracts of Silybum marianum, which acts as a reducing and stabilizing agent. central composite design (CCD) of response surface methodology (RSM) optimized synthesis parameters (temperature, pH, reaction time, plant extract, and salt concentration) for controlled size, stability, and maximum yields of ZnO-NPs. Green synthesized ZnO-NPs was characterized using UV-visible spectroscopy and Zetasizer analyses.

RESULTS

The Zetasizer confirmed that green synthesized ZnO-NPs were 51.80 nm in size and monodispersed in nature. The UV-visible results revealed a large band gap energy in the visible region at 360.5 nm wavelength. The bioactivities of green synthesized ZnO-NPs, including antifungal, antibacterial, and pesticidal, were also evaluated. Data analysis confirmed that these activities were concentration dependent. Bio-synthesized ZnO-NPs showed higher mortality towards Tribolium castaneum of about 78 ± 0.57% after 72 h observation as compared to Sitophilus oryzae, which only displayed 74 ± 0.57% at the same concentration and time intervals. Plant-mediated ZnO-NPs also showed high potential against pathogenic gram-positive bacteria (Clavibacter michiganensis), gram-negative bacteria (Pseudomonas syringae), and two fungal strains such as Fusarium oxysporum, and Aspergillums niger with inhibition zones of 18 ± 0.4, 25 ± 0.4, 21 ± 0.57, and 19 ± 0.4 mm, respectively.

CONCLUSION

The results of this study showed that Silybum marianum-based ZnO-NPs are cost-effective and efficient against crop pests.

Husk-like Zinc Oxide Nanoparticles Induce Apoptosis through ROS Generation in Epidermoid Carcinoma Cells: Effect of Incubation Period on Sol-Gel Synthesis and Anti-Cancerous Properties

This study effectively reports the influence of experimental incubation period on the sol-gel production of husk-like zinc oxide nanoparticles (ZNPs) and their anti-cancerous abilities. The surface morphology of ZNPs was studied with the help of SEM. With the use of TEM, the diameter range of the ZNPs was estimated to be ~86 and ~231 nm for ZNP^A and ZNP^B, prepared by incubating zinc oxide for 2 and 10 weeks, respectively. The X-ray diffraction (XRD) investigation showed that ZNPs had a pure wurtzite crystal structure. On prolonging the experimental incubation, a relative drop in aspect ratio was observed, displaying a distinct blue-shift in the UV-visible spectrum. Furthermore, RBC lysis assay results concluded that ZNP^A and ZNP^B both demonstrated innoxious nature. As indicated by MTT assay, reactive oxygen species (ROS) release, and chromatin condensation investigations against the human epidermoid carcinoma (HEC) A431 cells, ZNP^B demonstrated viable relevance to chemotherapy. Compared to ZNP^B, ZNP^A had a slightly lower IC₅₀ against A431 cells due to its small size. This study conclusively describes a simple, affordable method to produce ZNP nano-formulations that display significant cytotoxicity against the skin cancer cell line A431, suggesting that ZNPs may be useful in the treatment of cancer.

Nanorod-like Structure of ZnO Nanoparticles and Zn8O8 Clusters Using 4-Dimethylamino Benzaldehyde Liquid to Study the Physicochemical and Antimicrobial Properties of Pathogenic Bacteria

To study their physicochemical and antimicrobial properties, zinc oxide nanoparticles were synthesized using a simple chemical route and 4-dimethylaminobenzaldehyde (4DB) as an organic additive. ZnO nanoparticles were characterized with XRD analysis, which confirmed the presence of a hexagonal wurtzite structure with different crystalline sizes. The SEM morphology of the synthesized nanoparticles confirmed the presence of nanorods in both modifications of ZnO nanoparticles. EDS analysis proved the chemical composition of the synthesized samples via different chemical approaches. In addition, the optical absorption results indicated that the use of 4DB increased the band gap energy of the synthesized nanoparticles. The synthesized Zn₈O₈ and Zn₈O₈:4DB clusters were subjected to HOMO-LUMO analysis, and their ionization energy (I), electron affinity (A), global hardness (η), chemical potential (σ), global electrophilicity index (ω), dipole moment (μ), polarizability (α_tot), first-order hyperpolarizability (β_tot), and other thermodynamic properties were determined. Furthermore, the antimicrobial properties of the ZnO nanoparticles were studied against G+ (S. aureus and B. subtilis) and G- (K. pneumoniae and E. coli) bacteria in a nutrient agar according to guidelines of the Clinical and Laboratory Standards Institute (CLSI).

Facile and Novel Route for the Preparation of ZnO Nanoparticles with Different Cr Loadings for Opto-Photocatalysis Applications

The current article deals with the facile yet novel route to prepare zinc oxide (ZnO) nanoparticles with different weight percentages of chromium as a dopant. The impact of such dopant into the ZnO host lattice is explored in terms of the structural, vibrational, optical, and photocatalytic characteristics. The Bragg reflections in the X-ray diffraction displayed a phase pure wurtzite ZnO hexagonal system. The morphology reflects spherical-shaped ZnO particles in all the systems. The optical analysis ensured a good ultraviolet light absorption and a bandgap energy in the range of 3.30–3.24 eV. The principal Raman vibrations ensured the presence of the wurtzite ZnO crystal structure. The decolorization experiment of methyl green dye with pristine and various chromium-doped ZnO nanoparticles was conducted under the illumination of visible light. The obtained results showed that the incorporation of Cr in the framework significantly improved the photocatalytic performance of ZnO.

Effective role of Rb doping in controlling crystallization, crystal imperfections, microstructural, and morphological features of ZnO-NPs synthesized by Sol-Gel way

This article is dedicated to synthesizing pure ZnO and Rb-doped ZnO nanoparticles, RbxZn1-xO-NPs (x=0.0, 0.02, 0.04, 0.06 mol) using sol-gel technology. Synthesized samples have been characterized and studied utilizing X-ray...