Wanderson de Souza

Graphene oxide-silver nanoparticle (GO-AgNP) nanocomposites have attracted interest due to the ability of graphene oxide to act as a support for silver nanoparticles and thereby influence their physicochemical and in vitro biological behavior; however, comparative studies integrating physicochemical characterization with cytotoxicity assessment in human cell models remain limited. This study aimed to synthesize a GO-AgNP hybrid and evaluate its effects, along with pristine GO and free AgNPs, in human retinal (ARPE-19), glioblastoma (U-87 MG), and hepatic (HepG2) cell models. GO was prepared using a Hummers method, while AgNPs and GO-AgNPs were synthesized via a tannic-acid/citrate reduction route. The materials were characterized by UV-Vis, Raman, FTIR, AFM, SEM/TEM, ICP OES, and spICP-MS. Cytotoxicity was assessed after 72 h using MTT and LDH assays across all three cell models, and IC₅₀ values were determined for HepG2 cells. Physicochemical analyses confirmed successful AgNP nucleation on GO sheets, evidenced by the emergence of the 418 nm plasmonic band, reduction of the AD/AG Raman ratio, attenuation and shifting of oxygen-related FTIR bands, and uniformly dispersed AgNPs with a mean diameter of ~ 47 nm. Biologically, GO remained largely biocompatible, whereas free AgNPs induced strong, dose-dependent metabolic impairment and membrane damage. GO-AgNPs exhibited an intermediate and cell-type-dependent toxicity pattern, with strong attenuation of AgNP effects in ARPE-19 cells, partial attenuation in U-87 MG cells, and a moderate reduction in HepG2 cells. In HepG2, IC₅₀ values followed the expected potency order: AgNP (5.3 µg/mL), GO-AgNP (33.4 µg/mL), while GO did not reach 50% inhibition within the tested concentration range. The synthesized GO-AgNP nanocomposites display well-defined structural features and substantially reduced cytotoxicity compared with free AgNPs, although the extent of attenuation varies by cell lineage. These findings indicate that GO anchoring modulates silver bioactivity in a cell-type-dependent manner under the present in vitro conditions.

Synthetic amorphous silica (SAS, E551) is one of the most widely used food additives, yet uncertainties remain regarding the potential biological effects of its nanoscale fraction. In this study, we performed a metrologically aligned in vitro assessment of food-grade SAS nanoparticles (NPs) in human digestive tract cell models. Detailed physicochemical characterization confirmed their amorphous structure and high purity (EDS, XRD), while dispersion protocols generated two size distributions: ultrasonication (Dispersion A, ~ 238–299 nm) and stirring (Dispersion B, ~ 1300–1600 nm). Dynamic light scattering (DLS) revealed colloidal instability in culture media, with zeta potential decreasing from − 26 mV (water) to ~–9 mV (DMEM). Human colorectal epithelial cells (Caco-2) and gingival fibroblasts (HGF) were exposed to 19.8–200 µg/mL SAS for 72 h. Cell viability remained above 75% in MTT assays, and real-time impedance (xCELLigence) confirmed stable proliferation curves comparable to controls. No increase in intracellular reactive oxygen species was observed, although transmission electron microscopy revealed endocytic uptake with particles confined to cytoplasmic vesicles. Cytokine analysis showed only discrete, dose-dependent modulations, with an increase in MCP-1 (HGF) and VEGF (Caco-2) only at the lower concentration. Scanning electron microscopy (SEM) demonstrated concentration-dependent ultrastructural changes, ranging from elongation of microvilli at 19.8 µg/mL to disorganization of the apical surface at 200 µg/mL. These findings indicate that food-grade SAS does not induce acute cytotoxicity under the tested conditions but can trigger sub-cytotoxic and adaptative morphological and secretory alterations in gastrointestinal cells. Our results emphasize the critical role of dispersion protocols in nanotoxicology and support evidence-based regulation of E551, highlighting the need for chronic and immunological studies to refine its safety profile.

Silicon dioxide nanoparticles (SiO₂ NPs) are widely used to manufacture products for human consumption. However, their large-scale use in many fields poses risks to industrial workers. In this study, we investigated the cytotoxic and inflammatory potential of SiO₂ NPs in the human cell line A549, representing the human alveolar epithelium. The NPs were characterized using energy-dispersive x-ray spectroscopy coupled with scanning electron microscopy, x-ray diffraction, transmission electron microscopy, dispersion, and dynamic light scattering. The effects on A549 cells were monitored by cell adhesion and proliferation using electrical impedance, as well as cell viability, apoptosis, necrosis, and secretion of multiple inflammatory mediators. SiO₂ NPs did not alter the adhesion and proliferation of A549 cells but led to cell death by apoptosis at the highest concentrations tested. SiO₂ NP impacted the secretion of pro-inflammatory (tumor necrosis factor-α, interleukin (IL)-8, monocyte chemoattractant protein-1, eotaxin, regulated upon activation, normal T cell expressed and secreted, vascular growth factor, granulocyte–macrophage colony-stimulating factor, and granulocyte-colony stimulating factor) and anti-inflammatory (IL-1ra and IL-10) mediators. These results indicate that, even with little impact on cell viability, SiO₂ NPs can represent a silent danger, owing to their influence on inflammatory mediator secretion and unbalanced local homeostasis.

Introduction: Periodontitis, affecting approximately 3.9 billion individuals globally, significantly impacts quality of life and has raised interest in its potential systemic effects. Sodium perborate, a common component in oral care products for biofilm control, is widely used, though concerns about its safety persist. This study aimed to evaluate the in vitro toxicity of six commercial oral care products and varying concentrations of sodium perborate, utilizing human gingival fibroblasts (HGF) and keratinocytes (HaCat) as cell models.Methods: Experiments were performed in both 2D monolayer and 3D cultures using MTT and electrical impedance assays, adhering to the manufacturer’s recommended exposure time of 30–60 s for product testing. For the reconstructed epidermis model, a prolonged exposure time of 42 min was applied, following the Organization for Economic Cooperation and Development (OECD) Test Guideline 439.Results: Results indicated that all products and sodium perborate at 1 mg/mL were cytotoxic in monolayer cultures. However, at concentrations relevant to commercial formulations (0.06 mg/mL sodium perborate), no significant toxicity was observed. In contrast, the 3D culture models, including spheroids and reconstructed epidermis, exhibited minimal to no cytotoxic effects for the commercial products, with sodium perborate showing no significant toxicity below 0.1 mg/mL. The reconstructed epidermis model, used as surrogate for oral mucosa, further confirmed that the products were non-irritating, in compliance with OECD TG 439 standards.Discussion: This study highlights the importance of considering exposure time, dosage, and cellular model when assessing the safety of oral care products. While 2D models are useful for preliminary screenings, 3D models provide a more physiologically relevant assessment, emphasizing the need for robust testing protocols to ensure product safety.

Mesenchymal stem cells (MSCs) have significant therapeutic potential and their use requires in-depth studies to better understand their effects. Labeling cells with superparamagnetic iron oxide nanoparticles allows real-time monitoring of their location, migration, and fate post-transplantation. This study aimed to investigate the efficacy and cytotoxicity of magnetic–fluorescent nanoparticles in human adipose tissue-derived mesenchymal stem cells (hADSCs). The efficacy of Molday ION rhodamine B (MIRB) labeling in hADSCs was evaluated and their biocompatibility was assessed using various techniques and differentiation assays. Prussian blue and fluorescence staining confirmed that 100% of the cells were labeled with MIRB and this labeling persisted for at least 3 days. Transmission electron microscopy revealed the internalization and clustering of the nanoparticles on the outer surface of the cell membrane. The viability assay showed increased cell viability 3 days after nanoparticle exposure. Cell counts were higher in the MIRB-treated group compared to the control group at 3 and 5 days and an increased cell proliferation rate was observed at 3 days post-exposure. Adipogenic, osteogenic, and chondrogenic differentiation was successfully achieved in all groups, with MIRB-treated cells showing an enhanced differentiation rate into adipocytes and osteocytes. MIRB was efficiently internalized by hADSCs but induced changes in cellular behavior due to the increased cell proliferation rate.

This study demonstrated the utility of real-time electrical impedance, utilizing the xCELLigence system to assess the cytotoxic effects of silver nanoparticles (AgNPs) and hydroxyapatite nanoparticles (HANPs) on A549 cells. Method validation confirmed the accuracy and reliability of cell index (CI) measurements. The NPs were thoroughly characterized to confirm their elemental composition, size, and morphology through energy dispersive spectroscopy, transmission electron microscopy, and dynamic light scattering. Cytotoxicity assays revealed a concentration-dependent response. Exposure to AgNPs resulted in a significant change in CI, with a pronounced increase followed by a sharp decrease in the first few hours after treatment at the highest concentration of 50 μg mL–1. This pattern suggested an initial cell response to AgNPs exposure, possibly indicating mechanisms such as apoptosis or necrosis, followed by a decrease in cell adhesion. Conversely, HANPs demonstrated a tendency to restore CI at higher concentrations (1-100 μg mL–1) before 48 h, suggesting a potential recovery in cell proliferation capacity. This underscores the diverse cell responses to NPs, emphasizing the sensitivity of the method in detecting subtle cytotoxic effects. These findings highlight the efficacy of real-time electrical impedance in dynamic nanoparticle cytotoxicity assessments, surpassing traditional assays. Adapting to high-throughput screening enhances nanomaterial safety evaluations.

CIÊNCIAS REGULATÓRIAS: NANOTECNOLOGIAS, REGULAÇÃO BASEADA EM EVIDÊNCIAS

Titanium (Ti) and its alloys are the most widely used metallic biomaterials in total joint replacement; however, increasing evidence supports the degradation of its surface due to corrosion and wear processes releasing debris (ions, and micro and nanoparticles) and contribute to particle-induced osteolysis and implant loosening. Cell-to-cell communication involving several cell types is one of the major biological processes occurring during bone healing and regeneration at the implant-bone interface. In addition to the internal response of cells to the uptake and intracellular localization of wear debris, a red flag is the ability of titanium dioxide nanoparticles (mimicking wear debris) to alter cellular communication with the tissue background, disturbing the balance between osseous tissue integrity and bone regenerative processes. This study aims to understand whether titanium dioxide nanoparticles (TiO₂ NPs) alter osteoblast-derived exosome (Exo) biogenesis and whether exosomal protein cargos affect the communication of osteoblasts with human mesenchymal stem/stromal cells (HMSCs). Osteoblasts are derived from mesenchymal stem cells coexisting in the bone microenvironment during development and remodelling. We observed that TiO₂ NPs stimulate immature osteoblast- and mature osteoblast-derived Exo secretion that present a distinct proteomic cargo. Functional tests confirmed that Exos derived from both osteoblasts decrease the osteogenic differentiation of HMSCs. These findings are clinically relevant since wear debris alter extracellular communication in the bone periprosthetic niche, contributing to particle-induced osteolysis and consequent prosthetic joint failure.