Amorphous Silica Nanoparticles Research Articles

Evidence-Based Prediction of Cellular Toxicity for Amorphous Silica Nanoparticles.

Developing a generalized model for a robust prediction of nanotoxicity is critical for designing safe nanoparticles. However, complex toxicity mechanisms of nanoparticles in biological environments, such as biomolecular corona formation, prevent a reliable nanotoxicity prediction. This is exacerbated by the potential evaluation bias caused by internal validation, which is not fully appreciated. Herein, we propose an evidence-based prediction method for distinguishing between cytotoxic and noncytotoxic nanoparticles at a given condition by uniting literature data mining and machine learning. We illustrate the proposed method for amorphous silica nanoparticles (SiO2-NPs). SiO2-NPs are currently considered a safety concern; however, they are still widely produced and used in various consumer products. We generated the most diverse attributes of SiO2-NP cellular toxicity to date, using >100 publications, and built predictive models, with algorithms ranging from linear to nonlinear (deep neural network, kernel, and tree-based) classifiers. These models were validated using internal (4124-sample) and external (905-sample) data sets. The resultant categorical boosting (CatBoost) model outperformed other algorithms. We then identified 13 key attributes, including concentration, serum, cell, size, time, surface, and assay type, which can explain SiO2-NP toxicity, using the Shapley Additive exPlanation values in the CatBoost model. The serum attribute underscores the importance of nanoparticle-corona complexes for nanotoxicity prediction. We further show that internal validation does not guarantee generalizability. In general, safe SiO2-NPs can be obtained by modifying their surfaces and using low concentrations. Our work provides a strategy for predicting and explaining the toxicity of any type of engineered nanoparticles in real-world practice.

47 Safe-by-Design Advanced Materials: A case Study on Paint Formulation

Abstract Paint formulations are complex mixtures of both dissolved and particulate components, both organic and inorganic. Amorphous silica nanoparticles are included to make the paint layer dirt-repellent. Over entire life cycle of the paints containing such silica nanoparticles, however, their complex multicomponent composition may raise several concerns as to their hazard when exposed to humans and environment, notably due to the potential release of the incorporated nano-objects. To mitigate such concerns, several Safe-by-Design target specifications can be performed to provide revised/modified paint formulations with reduced potential risk. Within EU H2020 funded project, HARMLESS (grant agreement 953183), a specific industrial case study focuses on worker exposure measurement at the industrial production site of silane modified silica nanoparticles and consumer exposure measurement during sanding of the painted surfaces containing such silica nanoparticles. First results indicate that the tested paint samples (with and without silica nanoparticles) have strong tendencies to generate airborne nano-objects during their sanding. However, the fraction of silica in the overall chemical composition of the airborne nano-objects is currently being investigated. A fraction of the dust generated during the paint sanding is being analysed for its hazard via advanced in vitro approaches combined with a battery of toxicological endpoint analyses. Based on the results, if the exposure concentration of silica nanoparticles is found to be exceeding its nano reference value (i.e. 40,000 cm-3 TWA) and exhibits deleterious biological impact, the size and surface of silica nanoparticles will be modulated accordingly by keeping an optimum balance between their functionality and risk

63 A Case for Amorphous Silica Nanoparticle Exposure in the Development of Chronic Kidney Disease of Unknown Etiology

Abstract We have hypothesized that sugarcane burning in developing countries contributes to an endemic kidney pathology in agricultural workers called chronic kidney disease of an unknown etiology (CKDu). Elemental analysis shows that sugarcane stalks contain a high percentage of amorphous silica (SiO2). Therefore, we hypothesized that burning of sugarcane generates silica nanoparticles (SiNPs) that present an inhalation hazard to these agricultural workers. To determine if SiNPs are present in sugarcane ash and kidney biopsies from agricultural workers, we utilized single particle inductively coupled plasma mass spectrometry and found SiNPs, which ranged in size from 190-212 nm, in sugarcane ash. In a small cohort of CKDu patients from El Salvador and Mexico, we found a significant increase in the number of SiNPs in their kidney biopsies within a similar size range as observed in sugarcane ash. Additionally, Wistar rats exposed to sugarcane ash intranasally for 24 weeks developed focal injury in the tubulointerstitium and glomeruli with deposition of SiNPs in the kidney. To further determine the cellular effects of SiNPs, we exposed human proximal convoluted tubule (PCT) cells to sugarcane ash, de-silicated ash, or sugarcane ash derived SiNPs. Despite not being directly cytotoxic to PCT cells at 24 hrs, SiNPs were taken up and generated reactive oxygen species. Vimentin staining confirmed PCT cells underwent epithelial-mesenchymal transition (EMT) following treatment with ash or SiNPs but not with de-silicated ash. These findings suggest SiNPs present in sugarcane ash are capable of driving EMT in PCT cells potentially contributing to a CKDu phenotype.

Extraction and Physicochemical Characterization of Highly-pure Amorphous Silica Nanoparticles from Locally Available Dunes Sand

This study synthesized highly pure silica nanoparticles from the northeast Algerian Sahara dunes sand as a low-cost silica source using a simple and environmentally friendly method. The silica nanoparticles were extracted using a sodium silicate solution as a precursor without employing any additive agents. The extracted silica’s crystalline structure, chemical composition, chemical bonding, microstructure, elemental analysis, thermal analysis, and optical characteristics were investigated. The X-ray diffraction patterns demonstrate the amorphous nature of the extracted silica. Furthermore, the X-ray fluorescence spectroscopy (XRF) and energy dispersive X-ray (EDX) results prove the high purity of the extracted silica (99% SiO2). However, the Fourier-transform infrared spectroscopy (FTIR) results corroborate the presence of silanol and siloxane groups. According to the SEM image analysis, the produced silica has an average particle size in the range of nanometers. Thermal analysis (TGA/DTA) exhibited the high thermal stability of the silica, and the optical band gap energy for silica nanoparticles was determined to be 3.75 eV. Therefore, dunes sand is an alternative source for developing high-purity silica nanoparticles, which have great potential for advanced material applications.

Key Role of Choline Head Groups in Large Unilamellar Phospholipid Vesicles for the Interaction with and Rupture by Silica Nanoparticles.

For highly abundant silica nanomaterials, detrimental effects on proteins and phospholipids are postulated as critical molecular initiating events that involve hydrogen-bonding, hydrophobic, and/or hydrophilic interactions. Here, large unilamellar vesicles with various well-defined phospholipid compositions are used as biomimetic models to recapitulate membranolysis, a process known to be induced by silica nanoparticles in human cells. Differential analysis of the dominant phospholipids determined in membranes of alveolar lung epithelial cells demonstrates that the quaternary ammonium head groups of phosphatidylcholine and sphingomyelin play a critical and dose-dependent role in vesicle binding and rupture by amorphous colloidal silica nanoparticles. Surface modification by either protein adsorption or by covalent coupling of carboxyl groups suppresses the disintegration of these lipid vesicles, as well as membranolysis in human A549 lung epithelial cells by the silica nanoparticles. Furthermore, molecular modeling suggests a preferential affinity of silanol groups for choline head groups, which is also modulated by the pH value. Biomimetic lipid vesicles can thus be used to better understand specific phospholipid-nanoparticle interactions at the molecular level to support the rational design of safe advanced materials.

Human dendritic cell maturation induced by amorphous silica nanoparticles is Syk-dependent and triggered by lipid raft aggregation

BackgroundSynthetic amorphous silica nanoparticles (SAS-NPs) are widely employed in pharmaceutics, cosmetics, food and concretes. Workers and the general population are exposed daily via diverse routes of exposure. SAS-NPs are generally recognized as safe (GRAS) by the Food and Drug Administration, but because of their nanoscale size and extensive uses, a better assessment of their immunotoxicity is required. In the presence of immune “danger signals”, dendritic cells (DCs) undergo a maturation process resulting in their migration to regional lymph nodes where they activate naive T-cells. We have previously shown that fumed silica pyrogenic SAS-NPs promote the two first steps of the adaptative immune response by triggering DC maturation and T-lymphocyte response, suggesting that SAS-NPs could behave as immune “danger signals”. The present work aims to identify the mechanism and the signalling pathways involved in DC phenotype modifications provoked by pyrogenic SAS-NPs. As a pivotal intracellular signalling molecule whose phosphorylation is associated with DC maturation, we hypothesized that Spleen tyrosine kinase (Syk) may play a central role in SAS-NPs-induced DC response.ResultsIn human monocyte-derived dendritic cells (moDCs) exposed to SAS-NPs, Syk inhibition prevented the induction of CD83 and CD86 marker expression. A significant decrease in T-cell proliferation and IFN-γ, IL-17F and IL-9 production was found in an allogeneic moDC:T-cell co-culture model. These results suggested that the activation of Syk was necessary for optimal co-stimulation of T-cells. Moreover, Syk phosphorylation, observed 30 min after SAS-NP exposure, occurred upstream of the c-Jun N-terminal kinase (JNK) Mitogen-activated protein kinases (MAPK) and was elicited by the Src family of protein tyrosine kinases. Our results also showed for the first time that SAS-NPs provoked aggregation of lipid rafts in moDCs and that MβCD-mediated raft destabilisation altered Syk activation.ConclusionsWe showed that SAS-NPs could act as an immune danger signal in DCs through a Syk-dependent pathway. Our findings revealed an original mechanism whereby the interaction of SAS-NPs with DC membranes promoted aggregation of lipid rafts, leading to a Src kinase-initiated activation loop triggering Syk activation and functional DC maturation.

Microstructural engineering of zeolite membranes through composite seed layers

MFI membranes were synthesized using composite seeds consisting of zeolite nanocrystals and amorphous silica nanoparticles. The weight compositions of zeolite and silica particles were tuned to 100/0, 75/25, 50/50, and 25/75, respectively, which were then deposited as seed layers on porous alumina support through rubbing. At the seeded growth condition at 135 °C for 24 h, the film thickness of zeolite membranes grown from 4 different seed layers was similar to 3 μm, along with preferential crystal orientation to (h 0 h) direction. The upper parts of the zeolite membrane shared comparable film characteristics independent of seed composition, according to FCOM images of the MFI membranes. On the other hand, the zeolite membrane prepared from a seed layer of 75 wt% zeolite and 25 wt% silica particles had the greatest N2/SF6 gas selectivity of >175 and N2 gas permeance of >3300 GPU. Porosimetry also showed that there are fewer non-zeolite pathways in the zeolite membrane. Such results were attributed to differences in silica loading in the seed layer, where the silica species effectively altered the microstructure of zeolite membranes. The grain size of zeolite membranes increases as silica particle loading increases, reducing the chance of non-zeolitic defects occurring at grain boundaries. The composite seed with a silica loading of 25% was particularly successful because it did not inhibit the intergrowth of zeolite seed crystals while sacrificing slight N2 gas permanence. Thus, adding silica nanoparticles to the seed layer can help reduce non-zeolite defects in MFI membranes, according to this research. Further research is needed to prove that this method can be applied to zeolite membranes with other zeolite frameworks.

Rice husk-derived mesoporous biogenic silica nanoparticles for gravity chromatography

Biogenic silica nanoparticle is a superb alternative to synthetic silica because of their highly active, polar, and porous nanostructure with a large interior area. Among the available agricultural bioresources, biogenic silica extracted from rice husks could be a simple, easily available, and cost-effective resource to use as the stationary phase for the column chromatographic technique. In the present study, highly pure amorphous biogenic silica nanoparticles (bSNPs) were synthesized using rice husk by a controlled combustion route followed by the sol-gel method. The bSNPs show better performance for the separation and isolation of ortho- and para-nitrophenol and nitroaniline. The outstanding performance of the as-synthesized bSNPs is attributed to the high surface area, high porosity, and presence of Si–OH polar bonds. These preliminary findings imply that rice husk, an agricultural waste, could be an alternative source of silica and applicable as a stationary phase in column chromatography.

Silica nanoparticles and variety: their efficacy and interaction on the tomato fruit worm ( Helicoverpa armigera hubner) population infesting tomato (Solanum lycopersicum L.)

Field experiments were conducted at the Teaching and Research Farms of the University of Maiduguri and Mohamet Lawan College of Agriculture, Maiduguri, Nigeria to determine the effects of silica nanoparticles and tomato variety on the tomato fruit worm (Helicoverpa armigera Hübner) (Lepidoptera: Noctuidae). The treatments each replicated thrice were factorially combined and laid out in a split-plot design with four tomato varieties namely: UC-82, Dan Syria, Roma VF and Tima and three concentrations of amorphous silica nanoparticles (1000 ppm, 2000 ppm and 3000 ppm) and cypermethrin (as a check). Insecticides were applied during the fruiting stage at 7 days interval for 8 weeks. Larval holes and marketable fruit yield were recorded. Silica nanoparticles at 3000 ppm resulted in fewer larval population (39.25) at p < 0.05 with a resultant decrease in number of damaged fruits (36.58) as compared to lower doses of 1000 ppm and 2000 ppm. Cypermethrin also gave minimum population of larvae (39.12). In all tested varieties, Roma VF had the lowest larval population (28.79). Variety Roma VF in combination with both cypermethrin and silica nanoparticle at 3000 ppm resulted in lower larval population (19.67) and (28.67) respectively. These results show that silica nanoparticle at 3000 ppm acting together with Roma VF appreciably controls H. armigera in tomato, making both practices important components of IPM against this larval pest.

Comparative Evaluation of the Effects of Amorphous Silica Nanoparticles on the Erythrocytes of Wistar Normotensive and Spontaneously Hypertensive Rats.

Silica nanoparticles (SiNPs) are one of the most widely used nanomaterials. SiNPs can encounter erythrocytes and hypertension is strongly linked to abnormalities in the functional and structural characteristics of erythrocytes. As little is known about the combinatorial effect of SiNP-hypertension interactions on erythrocytes, the aim of this work was to study the effects triggered by hypertension on SiNPs induced hemolysis and the pathophysiological mechanism underlying it. We compared the interaction of amorphous 50 nm SiNPs at various concentrations (0.2, 1, 5 and 25 µg/mL) with erythrocytes of normotensive (NT) and hypertensive (HT) rats in vitro. Following incubation of the erythrocytes, SiNPs induced significant and dose-dependent increase in hemolysis. Transmission electron microscopy revealed erythrocyte deformity in addition to SiNPs taken up by erythrocytes. The erythrocyte susceptibility to lipid peroxidation was significantly increased. The concentration of reduced glutathione, and activities of superoxide dismutase, and catalase were significantly increased. SiNPs significantly increased intracellular Ca2+. Likewise, the concentration of the cellular protein annexin V and calpain activity was enhanced by SiNPs. Concerningly, all the tested parameters were significantly enhanced in erythrocytes from HT rats compared to NT rats. Our results collectively demonstrate that hypertension can potentially exacerbate the in vitro effect induced by SiNPs.

A facile cost-effective electrolyte-assisted approach and comparative study towards the Greener synthesis of silica nanoparticles.

Nowadays, silica nanoparticles are gaining tremendous importance because of their wide applications across different domains such as drug delivery, chromatography, biosensors, and chemosensors. The synthesis of silica nanoparticles generally requires a high percentage composition of organic solvent in an alkali medium. The eco-friendly synthesis of silica nanoparticles in bulk amounts can help save the environment and is cost-effective. Herein, efforts have been made to minimize the concentration of organic solvents used during synthesis via the addition of a low concentration of electrolytes, e.g., NaCl. The effects of electrolytes and solvent concentrations on nucleation kinetics, particle growth, and particle size were investigated. Ethanol was used as a solvent in various concentrations, ranging from 60% to 30%, and to optimize and validate the reaction conditions, isopropanol and methanol were also utilized as solvents. The concentration of aqua-soluble silica was determined using the molybdate assay to establish reaction kinetics, and this approach was also utilized to quantify the relative concentration changes in particles throughout the synthesis. The prime feature of the synthesis is the reduction in organic solvent usage by up to 50% using 68 mM NaCl. The surface zeta potential was reduced after the addition of an electrolyte, which made the condensation process faster and helped reaching the critical aggregation concentration in a shorter time. The effect of temperature was also monitored, and we obtained homogeneous and uniform nanoparticles by increasing the temperature. We found that it is possible to tune the size of the nanoparticles by changing the concentration of electrolytes and the temperature of the reaction using an eco-friendly approach. The overall cost of the synthesis can also be reduced by ∼35% by adding electrolytes.

Survival, growth, behavior, hematology and serum biochemistry of mice under different concentrations of orally administered amorphous silica nanoparticle

Silica nanoparticles (SiNPs) are used extensively in consumer products and biomedical research basically due to ease of production and low cost. However, insufficient literature is reported regarding the toxicity and biocompatibility of SiNPs. The present study aimed to investigate the potential role of amorphous SiNPs on survival, growth, behavioral alterations, hematology and serum biochemistry of mice at four concentrations (control, 50, 100 and 150mg/kg/day) of an oral supplementation for a period of 3 months. Signs of toxicity (lethargy, nausea, coma, tremors, vomiting and diarrhea, etc.) were noted at 9:00am and 9:00pm (twice a day) and the body weight of each of these mice was measured every week. The data were subjected to mean, standard deviation (S.D). Moreover, One-Way Analysis of Variance (ANOVA) and Dunnett's test were applied for analysis of statistical significance between groups by using SPSS software, version 20. All the mice survived with minor alterations in behavior and no significant weight changes were observed during the stipulated time period. Complete blood count (CBC) analysis indicated non-significant (P≥0.05) systemic dysfunctions of organ systems. However, there was elevation in the level of AST and ALT in the analysis of serum biochemistry, while the values of all other examined parameters were not-significant (P≥0.05). The study concluded that orally administered large silica nanoparticles up to the dose level of 150mg/kg/day are nontoxic for the in vivo use in mice.

Surface Heterogeneity in Amorphous Silica Nanoparticles Evidenced from Tapping AFM–IR Nanospectroscopy

In this work, we propose to evaluate and validate an emerging spectroscopic space-resolved technique: atomic force microscopy coupled with infrared spectroscopy (AFM-IR) for inorganic materials in tapping mode at the nanoscale. For this aim, a preliminary investigation of sample preparation techniques was done and the stability of tapping AFM-IR spectra was evaluated on reference samples [poly(methyl methacrylate) and silica]. It was concluded that for a homogeneous polymer, it is possible to compare AFM-IR spectra with conventional Fourier-transform infrared (FTIR) spectra obtained in transmission. When an inorganic solid is considered, AFM-IR spectra are different from the global FTIR spectrum which indicates that the AFM-IR technique probes a volume which is not representative of global composition, that is, the external surface layer. Moreover, local infrared spectra recorded in the tapping mode of the external surface are significantly different depending on the analyzed regions of the same particle and between particles of the amorphous silica, implying surface heterogeneity. The AFM-IR technique allows surface description of amorphous inorganic materials at the nanoscale and opens new frontiers in the characterization of functional nanoscale and crystalline materials.

Impact of non-thermal plasma on SiO2 nano particles synthesized by rice husk

Silicon dioxide (SiO2) is the most plentiful mineral in the world. Plants are the basis of this mineral. In recent periods, with the development of nanotechnology, silica nano particles have been establish new applications in solar cell. Rice husk and straw are rich causes of silica. In this study, amorphous silica nano particles were made from RH by chemical reduction method, and the surface of the material is improved by using DC glow discharge plasma. The synthesized samples were characterized by FTIR,XRD,EDAX,UV , FESEM and the results of both plasma treated and untreated samples were compared.

Amorphous silica nanoparticles caused lung injury through the induction of epithelial apoptosis via ROS/Ca2+/DRP1-mediated mitochondrial fission signaling

The adverse effects of amorphous silica nanoparticles (SiNPs) exposure on the respiratory system were increasingly recognized, however, its potential pathogenesis still remains not fully elucidated. So, this study aimed to explore its effects on pulmonary injury, and to investigate related mechanisms. Histological investigations illustrated SiNPs triggered the lung injury, mainly manifested as alveolar structure destruction, collagen deposition, and mitochondrial ultrastructural injury. In particular, SiNPs greatly enhanced pulmonary ROS and TUNEL positive rate in lungs, both of which were positively correlated with lung impairments. Further, the underlying mechanisms were investigated in cultured human bronchial epithelial cells (16HBE). Consistent with the in vivo findings, SiNPs caused the impairments on mitochondrial structure, as well as the activation of ROS generation and oxidative injury. Upon SiNPs stimuli, mitochondrial respiration was greatly inhibited, while Ca2+ overload in cytosol and mitochondria owing to ER calcium release was noticed, resulting in mitochondrial-dependent epithelial apoptosis. More importantly, mitochondrial dynamics was imbalanced toward a fission type, as evidenced by upregulated DRP1 and its phosphorylation at Ser616 (DRP1s616), while downregulated DRP1s637, and also MFN1, MFN2. Mechanistic investigations revealed that the activation of ROS/Ca2+ signaling promoted DRP1-mediated mitochondrial fission by SiNPs, forming a vicious cycle, and ultimately contributing to apoptosis in 16HBE. In summary, our results disclosed SiNPs caused pulmonary injury through the induction of epithelial apoptosis via a ROS/Ca2+/DRP1-mediated mitochondrial fission axis.

SOC-IV-03 Amorphous silica nanoparticles effects on human dendritic cells promote the T-cell response to the pneumallergen Bet v 1a

SOC-IV-03 Amorphous silica nanoparticles effects on human dendritic cells promote the T-cell response to the pneumallergen Bet v 1a

Atomistic study of the effect of grain size and reinforcement particle on mechanical behavior of magnesium / silica nanocomposite

In the present study, the atomistic simulations were carried out to investigate the mechanical properties and deformation mechanisms of nanocrystalline magnesium with different grain sizes. Also, the effect of reinforcement particle position and structure on the mechanical behavior of nanocrystalline magnesium / (amorphous/crystalline) silica nanocomposite under uniaxial compression loading was studied by using the molecular dynamics method. Firstly, eight structure with the mean grain sizes from 5 to 24 nm of nanocrystalline magnesium were constructed using the Voronoi tessellation method, and used to study the deformation mechanism. The simulation results showed that the sample with an average grain size of 14 nm had the optimum mean flow stress. Furthermore, by increasing the average grain size to values close to coarse-grained structures (> 25 nm), an increasing in the dislocation density and elastic modulus was observed. Moreover, there are two distinct deformation mechanisms activated by decreasing grain size. The first one, the dislocation-dominated deformation mechanism, belonged to large average grain size (≥ 14 nm) samples, and the second one, the grain boundary sliding deformation mechanism, was observed in small grain-sized simulation samples. In the following, nanocrystalline Mg nanocomposite simulation samples with different amorphous silica nanoparticle positions were studied, and it was observed that the presence of nanoparticle in the triple junction among three grains had the main effect on the strength of nanocomposites compared to the samples with nanoparticle at the grain boundary or inside the grain. Accordingly, the maximum strength and fracture strain was observed in the simulation samples with nanoparticles in the triple junctions. The investigated structures showed that the partial dislocations and aggregation of FCC structure stacking faults as lamella structure defects were observed in all simulated nanocomposite samples. Also, the local atomic shear strain contour obtained by simulation of nanocrystalline magnesium reinforced by amorphous and crystalline silica nanoparticles showed different responses of amorphous and crystalline nanoparticles during compression loading. Furthermore, amorphous and crystalline silica with the same size have different effects on the mechanical properties of the magnesium: in which, amorphous silica not only increases the ultimate compressive strength but also increases the strain before fracture compared to crystalline silica. The results of this research can expand the use of amorphous ceramic nanoparticles as reinforcement instead of crystalline ceramic nanoparticles in the development of nanocomposite materials.

On the structure-properties relationship of amorphous and crystalline silica nanoparticles reinforced magnesium matrix nanocomposites

In this study, the structure-properties relationship of magnesium matrix nanocomposites was studied. Using an accumulative extrusion (AE) process, the matrix was reinforced by adding 0.25, 0.5 and 1 wt% crystalline and amorphous silica nanoparticles separately. The mechanical behavior of nanocomposite strips was investigated by hardness and uniaxial compression tests. The results indicated that the Mg/0.5%SiO2-Am had the best room temperature compressive properties. An increase of 28.5% in compressive yield strength after extrusion and 235% after annealing was measured. Ultimate compressive strength (UCS) was increased by 20% without reduction in the nanocomposite ductility compared to the pure magnesium strip. FESEM and OM were used for microstructural analysis and revealed no visible cracks or distinct defects between magnesium layers after AE passes. It is found from the EDS analysis that the reinforcement distribution after the AE process was uniform with few agglomerates. Texture analysis using X-ray diffraction and EBSD after the AE process for samples reinforced with 0.5 wt% of amorphous and crystalline silica nanoparticles indicated a negligible difference in the basal plane orientation of the monolithic and nanocomposite magnesium strips after the AE process along extrusion direction. On the other hand, increasing the basal plane peak intensity after annealing for the sample reinforced with amorphous silica compared to the sample reinforced with crystalline silica indicated a weakening of basal texture. Furthermore, the EBSD analysis showed that amorphous silica nanoparticles are more effective than crystalline silica in grain refinement.

Eryptosis is an indicator of hematotoxicity in the risk assessment of environmental amorphous silica nanoparticles exposure: The role of macromolecule corona

Silica nanoparticles (SiO2 NPs) have been widely manufactured for various applications and unintentionally generated in various industrial processes. SiO2 NPs exposure is potentially hazardous to human health. Incremental evidence has indicated the presence of SiO2 NPs in systemic circulation, which warranted their interaction with blood components. Due to the obvious weakness of hemolysis in the risk assessment of environmental NPs, we for the first time use eryptosis as a sensitive indicator to assess the hematotoxicity of SiO2 NPs. In vitro results showed that the exposure of erythrocytes to pristine SiO2 NPs resulted in typical features of eryptosis, including oxidative stress, calcium influx, phosphatidylserine externalization and hemolysis. However, SiO2 NPs covered with mouse plasma (SiO2@MP) or grafted with polyvinylpyrrolidone (SiO2@PVP) did not stimulate eryptosis. Interestingly, neither bare nor macromolecule-decolorated SiO2 NPs caused eryptosis in our in vivo mouse model, highlighting the protective role of coronal proteins on the amelioration of SiO2 NPs-induced hematotoxicity. These results emphasized the influences of surface modification on the toxicity of environmental NPs.

A toxicological profile of silica nanoparticles.

Humans are regularly exposed to silica nanoparticles in environmental and occupational contexts, and these exposures have been implicated in the onset of adverse health effects. Existing reviews on silica nanoparticle toxicity are few and not comprehensive. There are natural and synthetic sources by which crystalline and amorphous silica nanoparticles are produced. These processes influence physiochemical properties, which are factors that can dictate toxicological effects. Toxicological assessment includes exposure scenario (e.g. environmental, occupational), route of exposure, toxicokinetics, and toxicodynamics. Broader considerations include pathology, risk assessment, regulation, and treatment after injury. This review aims to consolidate the most relevant and up-to-date research in these areas to provide an exhaustive toxicological profile of silica nanoparticles.