Epidermal Penetration of Gold Nanoparticles and Its Underlying Mechanism Based on Human Reconstructed 3D Episkin Model

Nanomaterials are widely used in diverse aspects, and their translocation behavior through the skin would be helpful in understanding the corresponding exposure risks. To reveal how surface functionalization of nanoparticles influences the skin penetration, three kinds of gold nanoparticles (GNPs) with negatively, neutrally, and positively charged surfaces, that is, cetyltrimethylammonium bromide-coated GNPs (CTAB@GNP), polyvinylpyrrolidone-coated GNPs (PVP@GNP), and citrate-coated GNPs (Citrate@GNP), were studied using human reconstructed 3D Episkin model. The measurement of Au distribution in diverse layers of the Episkin model indicated that all three GNPs could penetrate through the epidermis, wherein CTAB@GNP with positive surface charges exhibited the highest efficiency in skin penetration. The upward osmosis of the medium proteins confirmed the occurrence of skin permeation induced by GNP treatment, and the lipid network in the stratum corneum was also altered as the consequence of GNP exposure. When compared to Citrate@GNP and PVP@GNP, CTAB@GNP significantly compromised the tight junction of keratinocytes, causing paracellular penetration of nanoparticles. The existence of cytoplasmic gold showed the transcytosis pathway through endocytosis and exocytosis processes was the main epidermic penetration behavior of the tested GNPs. The study on GNP penetration process through the 3D Episkin model has, on one hand, offered a promising approach to evaluate the translocation process of nanoparticles across the skin, and, on the other hand, provided mechanism explanation for diverse penetration behaviors of GNPs with different surface charges. The findings herein would be of great help in nanotechnology improvement and nanosafety evaluation

Silica Nanoparticles Promote the Megakaryocyte Maturation and Differentiation: Potential Implications for Hematological Homeostasis

Silica nanoparticles (SiO2 NPs) have been widely applied in diverse areas, thus causing the extensive release through multiple routes. Their toxicological effects, especially for the disturbance in hematological homeostasis, have raised public concern. Considering the detrimental role of excessive platelets in many cardiovascular diseases, the regulation of platelet formation offers a unique aspect for studying the blood compatibility of nanomaterials. In this study, the effects of SiO2 NPs with four sizes (80, 120, 200, and 400 nm) were investigated on the maturation and differentiation of the megakaryocytes into platelets. The results showed that SiO2 NPs promoted megakaryocyte development as manifested by the occurrence of irregular cell morphology, enlargement of cell size, increases in DNA content and DNA ploidy, and formation of spore-like protrusions. The expression of megakaryocyte-specific antigen (CD41a) was up-regulated, due to SiO2 NP treatments. The correlation analysis of SiO2 NP size with the above test bioindicators showed that the smaller the SiO2 NPs were, the stronger effects they induced. Moreover, exposure to SiO2 NPs induced the up-regulation of both GATA-1 and FLI-1, while the transcriptional expressions of aNF-E2 and fNF-E2 remained unchanged. The significant positive correlation of GATA-1 and FLI-1 with megakaryocytic maturation and differentiation suggested their crucial roles in the SiO2 NP-promoted effect. The finding herein provided new insight into the potential health risk of SiO2 NPs by perturbing the platelet-involved hematological homeostasis

Perfluorooctyl Iodide Stimulates Steroidogenesis in H295R Cells via a Cyclic Adenosine Monophosphate Signaling Pathway

Perfluorinated iodine alkanes (PFIs) are used widely in the organic fluorine industry. Increased production of PFIs has caused environmental health concerns. To evaluate the potential endocrine-disrupting effect of PFIs, we investigated the effects of perfluorooctyl iodide (PFOI) on steroidogenesis in human adrenocortical carcinoma cells (H295R). Levels of aldosterone, cortisol, 17β-estradiol, and testosterone were measured in H295R culture medium upon treatment with perfluorooctanoic acid (PFOA) and PFIs. Expression of 10 steroidogenic genes (<i>StAR</i>, <i>HMGR</i>, <i>CYP11A1</i>, <i>3βHSD2</i>, <i>17βHSD</i>, <i>CYP17</i>, <i>CYP21</i>, <i>CYP11B1</i>, <i>CYP11B2</i>, and <i>CYP19</i>) was measured by real-time polymerase chain reaction. Levels of cyclic adenosine monophosphate (cAMP) and adenylate cyclase (AC) activity were measured to understand the underlying mechanism of steroidogenic perturbations. Levels of production of aldosterone, cortisol, and 17β-estradiol were elevated significantly, and the level of testosterone generation decreased upon treatment with 100 μM PFOI. Similar to the effect induced by forskolin (AC activator), expression of all 10 genes involved in the synthesis of steroid hormones was upregulated significantly upon exposure to 100 μM PFOI. PFOA had no effect on steroid hormone production or steroidogenic gene expression even though it is highly structurally similar with PFOI. Therefore, the terminal -CF₂I group in PFOI could be a critical factor for mediation of steroidogenesis. PFOI increased AC activity and cAMP levels in H295R cells, which implied an underlying mechanism for the disturbance of steroidogenesis. These data suggest that PFOI may act as an AC activator, thereby stimulating steroidogenesis by activating a cAMP signaling pathway

Influence of the Surface Functional Group Density on the Carbon-Nanotube-Induced α‑Chymotrypsin Structure and Activity Alterations

Because of the special properties of carbon nanotubes (CNTs), their applications have been introduced to many fields. The biosafety of these emerging materials is of high concern concomitantly. Because CNTs may initially bind with proteins in biofluids before they exert biological effects, it is of great importance to understand how the target proteins interact with these exogenous nanomaterials. Here we investigated the interaction between α-chymotrypsin (α-ChT) and carboxylized multiwalled CNTs in a simulated biophysical environment utilizing the techniques of fluorescence, UV–vis, circular dichroism spectroscopy, ζ potential, atomic force microscopy, and bicinchoninic acid analysis. It was demonstrated that CNTs interacted with α-ChT through electrostatic forces, causing a decrement in the α-helix and an increment in the β-sheet content of the protein. The protein fluorescence was quenched in a static mode. The increase in the surface modification density of CNTs enhanced the protein absorption and decreased the enzymatic activity correspondingly. α-ChT activity inhibition induced by CNTs with low surface modification density exhibited noncompetitive characteristics; however, a competitive feature was observed when CNTs with high surface modification density interacted with the protein. An increase of the ionic strength in the reaction buffer may help to reduce the interaction between CNTs and α-ChT because the high ionic strength may favor the release of the protein from binding on a CNT surface modified with functional groups. Accordingly, the functionalization density on the CNT surface plays an important role in the regulation of their biological effects and is worthy of concern when new modified CNTs are developed

Renal Clearable Ag Nanodots for in Vivo Computer Tomography Imaging and Photothermal Therapy

Albumin-stabilized Ag nanodots (ANDs) are prepared by a one-step biomineralization method. The highly crystallized nanodots have ultrasmall sizes (approximately 5.8 nm) and robust X-ray attenuation (5.7313 HU per mM Ag). The unlabeled ANDs are directly excreted from the body via the urine after in vivo X-ray computer tomography (CT) imaging application. ANDs could be used as CT imaging agents and effective photothermal therapy agents. Tumor growth inhibition reaches 90.2% after photothermal treatment with ANDs. ANDs are promising tools for in vivo CT imaging and clearable near-infrared-triggered theranostic agents

Sulfidation as a Natural Antidote to Metallic Nanoparticles Is Overestimated: CuO Sulfidation Yields CuS Nanoparticles with Increased Toxicity in Medaka (<i>Oryzias latipes</i>) Embryos

Sulfidation is considered as a natural antidote to toxicity of metallic nanoparticles (NPs). The detoxification contribution from sulfidation, however, may vary depending on sulfidation mechanisms. Here we present the dissolution–precipitation instead of direct solid-state-shell mechanism to illustrate the process of CuO-NPs conversion to CuS-NPs in aqueous solutions. Accordingly, the CuS-NPs at environmentally relevant concentrations showed much stronger interference on Japanese medaka (<i>Oryzias latipes</i>) embryo hatching than CuO-NPs, which was probably due to elevated free copper ions released from CuS-NPs, leading to significant increase in oxidative stress and causing toxicity in embryos. The larval length was significantly reduced by CuS-NPs, however, no other obviously abnormal morphological features were identified in the hatched larvae. Co-introduction of a metal ion chelator [ethylene diamine tetraacetic acid (EDTA)] could abolish the hatching inhibition induced by CuS-NPs, indicating free copper ions released from CuS-NPs play an important role in hatching interference. This work documents for the first time that sulfidation as a natural antidote to metallic NPs is being overestimated, which has far reaching implications for risk assessment of metallic NPs in aquatic environment

Synthetic Phenolic Antioxidants Cause Perturbation in Steroidogenesis in Vitro and in Vivo

Synthetic phenolic antioxidants (SPAs) are closely correlated with human life due to their extensive usages, and increasing concerns have been raised on their biosafety. The previous controversial findings caused continuous debates on their potential endocrine disrupting effects. In the present study, four commonly used SPAs, including butylated hydroxyanisole (BHA), butylated hydroxytoluene (BHT), <i>tert</i>-butyl hydroquinone (TBHQ) and 2,2′-methylenebis­(6-<i>tert</i>-butyl-4-methylphenol) (AO2246), were investigated for their estrogenic effects, and the results from in vitro screening assays showed SPAs themselves had negligible estrogen receptor binding affinities. Nevertheless, significant increase in E₂ secretion was observed in H295R cells treated with SPAs, especially for BHA. The transcriptional levels of steroidogenic enzymes, including StAR, 3βHSD, CYP11B1, and CYP11B2 were up-regulated via the mediation of protein kinase A (PKA) signaling pathway. In vivo experiment confirmed that waterborne exposure to BHA disturbed E₂ and testosterone (T) levels in zebrafish gonad, thus causing potential estrogenic effects through the regulation of hypothalamic-pituitary–gonadal-liver axis (HPGL-axis). Accordingly, this study has provided new insights for SPA-induced endocrine disrupting effects. Considering the allowable maximum level of individual BHA or in combination with TBHQ and BHT in foodstuffs (200 mg kg^–1), the perturbation in steroidogenesis observed for relatively low concentrations of SPAs would need more public attention

Permission to Enter Cell by Shape: Nanodisk vs Nanosphere

Changing polystyrene nanoparticles from three-dimensional spherical shape to two-dimensional disk shape promotes their cell surface binding with significant reduction of cell uptake. As a result of lower cell uptake, nanodisks show very little perturbations on cell functions such as cellular ROS generation, apoptosis and cell cycle progression compared to nanospheres. Therefore, disk-shaped nanoparticles may be a promising template for developing cell membrane-specific and safer imaging agents for a range of biomedical applications such as molecular imaging, tissue engineering, cell tracking, and stem cell separation

Structure-Dependent Hematological Effects of Per- and Polyfluoroalkyl Substances on Activation of Plasma Kallikrein–Kinin System Cascade

Per- and polyfluoroalkyl substances (PFASs) are a global concern because of their ubiquitous occurrence and high persistence in human blood, and increasing amounts of unidentified fluorinated compounds are now becoming new exposure issues. This study aims to investigate the structure-related effects of PFASs on the activation of the plasma kallikrein-kinin system (KKS). The effects of 20 PFASs and the related long-chain aliphatic compounds were screened, and their binding affinities for the initial zymogen, Hagmen factor XII (FXII) in the KKS, were evaluated by molecular docking analysis. PFASs were demonstrated to activate the KKS in a structure-dependent mode. More specifically, PFASs with longer carbon chain length, higher fluorine atom substitution degree, and terminal acid group exhibited relatively higher activities in activating the KKS. The binding affinities of PFASs with FXII determined their capabilities for inducing KKS activation. The alternative binding modes of PFASs with FXII, together with van der Waals and hydrogen bonds, specifically accommodated the distinctive chemical structures. To our knowledge, PFASs, for the first time, were found to induce the activation of the KKS in plasma, and their chemical structure-related effects would be extremely important for risk assessment on emerging PFASs in addition to the listing in Stockholm Convention

Graphene Enhances Cellular Proliferation through Activating the Epidermal Growth Factor Receptor

Graphene has promising applications in food packaging, water purification, and detective sensors for contamination monitoring. However, the biological effects of graphene are not fully understood. It is necessary to clarify the potential risks of graphene exposure to humans through diverse routes, such as foods. In the present study, graphene, as the model nanomaterial, was used to test its potential effects on the cell proliferation based on multiple representative cell lines, including HepG2, A549, MCF-7, and HeLa cells. Graphene was characterized by Raman spectroscopy, particle size analysis, atomic force microscopy, and transmission electron microscopy. The cellular responses to graphene exposure were evaluated using flow cytometry, 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide, and alamarBlue assays. Rat cerebral astrocyte cultures, as the non-cancer cells, were used to assess the potential cytotoxicity of graphene as well. The results showed that graphene stimulation enhanced cell proliferation in all tested cell cultures and the highest elevation in cell growth was up to 60%. A western blot assay showed that the expression of epidermal growth factor (EGF) was upregulated upon graphene treatment. The phosphorylation of EGF receptor (EGFR) and the downstream proteins, ShC and extracellular regulating kinase (ERK), were remarkably induced, indicating that the activation of the mitogen-activated protein kinase (MAPK)/ERK signaling pathway was triggered. The activation of PI3 kinase p85 and AKT showed that the PI3K/AKT signaling pathway was also involved in graphene-induced cell proliferation, causing the increase of cell ratios in the G2/M phase. No influences on cell apoptosis were observed in graphene-treated cells when compared to the negative controls, proving the low cytotoxicity of this emerging nanomaterial. The findings in this study revealed the potential cellular biological effect of graphene, which may give useful hints on its biosafety evaluation and the further exploration of the bioapplication