Health care costs of antibiotic resistance to the community have been astounding over the last decade and require urgent attention. This calls for new alternatives, such as metal oxide nanomaterials, to be considered at a more extended level. Metal oxide nanomaterials have been exerting a pull-on deal with its complete applications in biological and pharmaceutical fields of nanobiotechnology. The present study addresses the synthesis of nanoparticles of the zirconium oxide (ZrO2) by a process that can be quickly, economically and industrially used to combat deadly pathogens. The biological activity of synthesized zirconium oxide nanoparticles against bacterial strains has been studied by using agar well diffusion method. Besides, DPPH (1,1-diphenyl-2-picryl hydrazyl) and a nitrous oxide-scavenging study, we have also studied the antioxidant ability of ZrO2 nanoparticles along with the anticancer activity. Importantly, our research demonstrated the antimicrobial activity of ZrO2 nanoparticles at different concentrations comparable to standard antibiotics against gram-positive bacteria (Staphylococcus aureus) and gram-negative bacteria (Klebsiella pneumonia), respectively. We believe that the synthesized ZrO2 nanoparticles demonstrated inhibitive activity against K. pneumoniae by the attraction of negatively charged K. pneumoniae cell wall against positively charged zirconium ions. Our findings suggest that synthesized multifunctional ZrO2 nanoparticles may be a successful candidate in health care systems.

Zirconium oxide (ZrO2) nanoparticles from antibacterial activity to cytotoxicity: A next-generation of multifunctional nanoparticles

How toxic is a non-toxic nanomaterial: Behaviour as an indicator of effect in Danio rerio exposed to nanogold.

Titanium dioxide nanoparticles (TiO2NPs) are increasingly used in consumer products, industrial and medical applications, raising concerns on their potential toxicity. The available in vitro and in vivo studies on these NPs show controversial results. Crystalline structure is the physicochemical characteristic that seems to influence mainly TiO2NPs toxicity, so its effect needs to be further studied. We aimed to study whether and how crystalline form influences potential cyto-genotoxic and inflammatory effects induced by two commercial TiO2NPs (TiO2-A, mainly anatase; TiO2-B, mainly rutile) in human alveolar A549 and bronchial BEAS-2B cells exposed to 1–40 µg/mL. Cell viability (WST-1), membrane damage (LDH release), IL-6, IL-8 and TNF-α release (ELISA) and direct/oxidative DNA damage (fpg-comet assay) were evaluated. Physicochemical characterization included analysis of crystalline form (TEM and XRD), specific surface area (BET), agglomeration (DLS) and Z-potential (ELS). Our results show that TiO2-A NPs induce in BEAS-2B cytotoxicity and a slight inflammation and in A549 slight oxidative effects, whereas TiO2-B NPs induce genotoxic/oxidative effects in both cell lines, revealing different toxicity mechanisms for the two tested NPs. In conclusion, our study confirms the influence of crystalline form on cellular response, also demonstrating the suitability of our in vitro model to screen early TiO2NPs effects.

Assessment of the Influence of Crystalline Form on Cyto-Genotoxic and Inflammatory Effects Induced by TiO2 Nanoparticles on Human Bronchial and Alveolar Cells.

Meta-analysis of in-vitro cytotoxicity evaluation studies of zinc oxide nanoparticles: Paving way for safer innovations.

This editorial aims to summarize the 14 scientific papers contributed to the Special Issue "Nanotoxicology and nanosafety 2.0 from the point of view of both toxicology and ecotoxicology".

The Recent Progress in Nanotoxicology and Nanosafety from the Point of View of Both Toxicology and Ecotoxicology.

The application of nanoparticles (NPs) in industry is on the rise, along with the potential for human exposure. While the toxicity of microscale equivalents has been studied, nanoscale materials exhibit different properties and bodily uptake, which limits the prediction ability of microscale models. Here, we examine the cytotoxicity of seven transition metal oxide NPs in the fourth period of the periodic table of the chemical elements. We hypothesized that NP-mediated cytotoxicity is a function of cell killing and suppression of cell proliferation. To test our hypothesis, transition metal oxide NPs were tested in a human lung cancer cell model (A549). Cells were exposed to a series of concentrations of TiO2, Cr2O3, Mn2O3, Fe2O3, NiO, CuO, or ZnO for either 24 or 48 h. All NPs aside from Cr2O3 and Fe2O3 showed a time- and dose-dependent decrease in viability. All NPs significantly inhibited cellular proliferation. The trend of cytotoxicity was in parallel with that of proliferative inhibition. Toxicity was ranked according to severity of cellular responses, revealing a strong correlation between viability, proliferation, and apoptosis. Cell cycle alteration was observed in the most toxic NPs, which may have contributed to promoting apoptosis and suppressing cell division rate. Collectively, our data support the hypothesis that cell killing and cell proliferative inhibition are essential independent variables in NP-mediated cytotoxicity.

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Fang Yao Stephen Hou

Papers

Differential Cytotoxicity Induced by Transition Metal Oxide Nanoparticles is a Function of Cell Killing and Suppression of Cell Proliferation.