Amorphous nanosilica induced toxicity, inflammation and innate immune responses: A critical review

Ultra-high performance concrete alleviates ecotoxicological effects in aquatic organisms

With the advancement of cementitious material technologies, ultra-high performance concretes incorporating nano- and(or) micro-sized particle materials have been developed; however, their environmental risks are still poorly understood. This study investigates the ecotoxicological effects of ultra-high performance concrete (UC) leachate by comparing with that of the conventional concrete (CC) leachate. For this purpose, a dynamic leaching test and a battery test with algae, water flea, and zebrafish were performed using standardized protocols. The conductivity, concentration of inorganic elements (Al, K, Na, and Fe), and total organic concentration were lower in the UC leachate than in the CC leachate. The EC50 values of the CC and UC leachates were 44.9 % and >100 % in algae, and 8.0 % and 63.1 % in water flea, respectively. All zebrafish exposed to the CC and UC leachates survived. A comprehensive evaluation of the ecotoxicity of the CC and UC leachate based on the toxicity classification system (TCS) showed that their toxicity classification was "highly acute toxicity" and "acute toxicity", respectively. Based on the hazard quotient and principal component analysis, Al and(or) K could be significant factors determining the ecotoxicity of concrete leachate. Furthermore, the ecotoxicity of UC could not be attributed to the use of silica-based materials or multi-wall carbon nanotubes. This study is the first of its kind on the ecotoxicity of UC leachate in aquatic environments, and the results of this study can be used to develop environment-friendly UC.

Fibrin Network and Platelets Densities in Platelet-Rich Fibrin (PRF) Membranes Produced from Plastic Tubes Without Additives: A New Approach to PRF Clinical Use

Background/Purpose

The present study aimed to investigate plastic tubes without additives as alternatives to glass and silica-coated plastic tubes, in the production of PRF membranes.

Materials and Methods

Nine blood samples were collected from eight volunteers (n = 8) separated into three groups, according to tube material: glass, silica-coated plastic, and plastic without additives. In each group, the samples were centrifuged using different relative centrifugation forces: L-PRF (700 g/12 min), A-PRF (200 g/14 min), and A-PRF + (200 g/8 min). The generated membranes were evaluated by histomorphometry, considering the fibrin network, platelet aggregates, and cellular morphology, by light microscopy. The ultrastructural cellular morphology integrity was evaluated by transmission electron microscopy.

Results

The L-PRF (p < 0.019) and A-PRF (p < 0.001) membranes showed a significantly lower fibrin network density in plastic tubes without additives compared to glass and silica-coated plastic tubes. Plastic tubes without additives revealed a significantly higher platelet percentage, regardless of the protocol (p < 0.005). In all groups, TEM analysis showed preserved normal morphological ultrastructure, maintaining the integrity of cellular components.

Conclusion

Plastic tubes without additives offer a viable alternative for producing PRF membranes. They exhibited a higher platelet density and demonstrated fibrin network and cellular morphology similar to those of glass and silica-coated plastic tubes, irrespective of the centrifugation protocol.

Hyaluronic acid/silicon nanoparticle scaffold induces proliferation and differentiation of mouse spermatogonial stem cells transplanted to epididymal adipose tissue

Spermatogonia stem cells (SSCs) are a unique cell population maintaining male spermatogenesis during life, through their potential for proliferation and differentiation. The application of silicon nanoparticles (SNs) and hyaluronic acid (HA) to induce the differentiation of SSCs seems promising. Herein, we investigate the effect of SN and HA scaffolds on the progression of SSCs spermatogenesis in mice. Initially SSCs were isolated from healthy immature mice and cultured on prepared scaffolds (HA, SN, and HA/SN) in a 3D culture system. Then viability of SSCs cultured on scaffolds was examined using MTT assay and Acridine Orange staining. Then SSCs cultured on scaffolds were transplanted into epididymal adipose tissue (EAT) in mature mice and the result was studied by H&E and IHC staining 8 weeks after transplantation. MTT and Acridine Orange analysis revealed that among three different scaffolds HA/SN based scaffold causes considerable toxicity on SSCs (P < 0.05) while H&E staining showed that culture of SSCs on HA, SN, and HA/SN scaffolds has a positive effect on the progression of SSCs spermatogenesis after transplantation into EAT. IHC staining identified TP1, TEKT1, and PLZF as crucial biomarkers in the spermatogenesis development of SSCs transplanted to EAT. According to the presence of these biomarkers in different experimental groups, we found the most spermatogenesis development in SSCs cultured on HA/SN scaffold (PLZF, P < 0.01) (TEKT1, P < 0.01) (TP1, P < 0.001). Our study showed that, although the cytotoxic effect of the HA/SN scaffold decreases the viability rate of SSCs; however, SSCs that survive on HA/SN scaffold showed more ability to progress in spermatogenesis after transplantation into EAT.

Silica Nanoparticles Shed Light on Intriguing Cellular Pathways in Human Tracheal Smooth Muscle Cells: Revealing COX-2/PGE2 Production through the EGFR/Pyk2 Signaling Axis

The use of manufactured silica nanoparticles (SiNPs) has become widespread in everyday life, household products, and various industrial applications. While the harmful effects of crystalline silica on the lungs, known as silicosis or chronic pulmonary diseases, are well understood, the impact of SiNPs on the airway is not fully explored. This study aimed to investigate the potential effects of SiNPs on human tracheal smooth muscle cells (HTSMCs). Our findings revealed that SiNPs induced the expression of cyclooxygenase-2 (COX-2) mRNA/protein and the production of prostaglandin E2 (PGE2) without causing cytotoxicity. This induction was transcription-dependent, as confirmed by cell viability assays and COX-2 luciferase reporter assays. Further analysis, including Western blot with pharmacological inhibitors and siRNA interference, showed the involvement of receptor tyrosine kinase (RTK) EGF receptor (EGFR), non-RTK Pyk2, protein kinase Cα (PKCα), and p42/p44 MAPK in the induction process. Notably, EGFR activation initiated cellular signaling that led to NF-κB p65 phosphorylation and translocation into the cell nucleus, where it bound and stimulated COX-2 gene transcription. The resulting COX-2 protein triggered PGE2 production and secretion into the extracellular space. Our study demonstrated that SiNPs mediate COX-2 up-regulation and PGE2 secretion in HTSMCs through the sequential activation of the EGFR/Pyk2/PKCα/p42/p44MAPKs-dependent NF-κB signaling pathway. Since PGE2 can have both physiological bronchodilatory and anti-inflammatory effects, as well as pathological pro-inflammatory effects, the increased PGE2 production in the airway might act as a protective compensatory mechanism and/or a contributing factor during airway exposure to SiNPs.

Multifunctional mesoporous silica nanoparticles for biomedical applications

Mesoporous silica nanoparticles (MSNs) are recognized as a prime example of nanotechnology applied in the biomedical field, due to their easily tunable structure and composition, diverse surface functionalization properties, and excellent biocompatibility. Over the past two decades, researchers have developed a wide variety of MSNs-based nanoplatforms through careful design and controlled preparation techniques, demonstrating their adaptability to various biomedical application scenarios. With the continuous breakthroughs of MSNs in the fields of biosensing, disease diagnosis and treatment, tissue engineering, etc., MSNs are gradually moving from basic research to clinical trials. In this review, we provide a detailed summary of MSNs in the biomedical field, beginning with a comprehensive overview of their development history. We then discuss the types of MSNs-based nanostructured architectures, as well as the classification of MSNs-based nanocomposites according to the elements existed in various inorganic functional components. Subsequently, we summarize the primary purposes of surface-functionalized modifications of MSNs. In the following, we discuss the biomedical applications of MSNs, and highlight the MSNs-based targeted therapeutic modalities currently developed. Given the importance of clinical translation, we also summarize the progress of MSNs in clinical trials. Finally, we take a perspective on the future direction and remaining challenges of MSNs in the biomedical field.

Impact of gold nanoparticles (AuNPs) on eosinophils isolated from male and female individuals

It is well established that some differences exist between the male and female immune systems. Despites this, a sex-based analysis is not frequently performed in most scientific published reports. Knowing that inflammation is a common undesired effect observed resulting from nanoparticle (NP) exposure, we investigate here how in vitro treatment of gold NPs with a primary size of 20 and 70 nm (AuNP20 and AuNP70, respectively) will alter the biology of human eosinophils isolated from men and women blood. We found that treatment of AuNP70, but not AuNP20, significantly delay apoptosis only in eosinophils isolated from women. AuNPs were found to decrease eosinophil phagocytosis, however, significance was only observed in AuNP20-induced eosinophils isolated from women. The production of IL-8 was significantly increased in response to both AuNPs but only in eosinophils isolated from men and the production of IL-1β was increased in AuNPs-induced eosinophils, although significance was observed only in AuNP70-induced eosinophils isolated from women. We conclude that future studies investigating the toxicity of AuNPs (or other NPs) should include a sex-based analysis, especially if the tested NPs have potential medical applications knowing the increased interest in the development of personalized precision medicine.

Impact of gold nanoparticles (AuNPs) in human neutrophils in vitro and in leukocytes attraction in vivo: A sex-based analysis

Some differences exist between the male and female immune systems. Despite this, a sex-based analysis is not frequently performed in most studies. Knowing that inflammation is a common undesired effect observed resulting from nanoparticle (NP) exposure, we investigate here how gold NPs with a primary size of 20 (AuNP20) and 70 nm (AuNP70) will alter the biology of polymorphonuclear neutrophil cells (PMNs) isolated from men and women as well as their potential pro-inflammatory effect in vivo in male and female mice. We found that AuNP20 significantly delay apoptosis only in PMN isolated from men. The production of interleukin (IL)- 8 by PMNs was increased by both AuNPs regardless of sex although significance was only observed in AuNP20-induced PMNs. Using the murine air pouch model of inflammation, AuNPs did not induce a neutrophilic infiltration regardless of sex. In conclusion, AuNPs could differently alter the biology of PMNs according to sex.

The current status of stimuli-responsive nanotechnologies on orthopedic titanium implant surfaces

With the continuous innovation and breakthrough of nanomedical technology, stimuli-responsive nanotechnology has been gradually applied to the surface modification of titanium implants to achieve brilliant antibacterial activity and promoted osteogenesis. Regarding to the different physiological and pathological microenvironment around implants before and after surgery, these surface nanomodifications are designed to respond to different stimuli and environmental changes in a timely, efficient, and specific way/manner. Here, we focus on the materials related to stimuli-responsive nanotechnology on titanium implant surface modification, including metals and their compounds, polymer materials and other materials. In addition, the mechanism of different response types is introduced according to different activation stimuli, including magnetic, electrical, photic, radio frequency and ultrasonic stimuli, pH and enzymatic stimuli (the internal stimuli). Meanwhile, the associated functions, potential applications and developing prospect were discussion.

Closing the Nutrient Loop-The New Approaches to Recovering Biomass Minerals during the Biorefinery Processes

The recovery of plant mineral nutrients from the bio-based value chains is essential for a sustainable, circular bioeconomy, wherein resources are (re)used sustainably. The widest used approach is to recover plant nutrients on the last stage of biomass utilization processes-e.g., from ash, wastewater, or anaerobic digestate. The best approach is to recover mineral nutrients from the initial stages of biomass biorefinery, especially during biomass pre-treatments. Our paper aims to evaluate the nutrient recovery solutions from a trans-sectorial perspective, including biomass processing and the agricultural use of recovered nutrients. Several solutions integrated with the biomass pre-treatment stage, such as leaching/bioleaching, recovery from pre-treatment neoteric solvents, ionic liquids (ILs), and deep eutectic solvents (DESs) or integrated with hydrothermal treatments are discussed. Reducing mineral contents on silicon, phosphorus, and nitrogen biomass before the core biorefinery processes improves processability and yield and reduces corrosion and fouling effects. The recovered minerals are used as bio-based fertilizers or as silica-based plant biostimulants, with economic and environmental benefits.

Nanoparticle Effects on Stress Response Pathways and Nanoparticle-Protein Interactions

Nanoparticles (NPs) are increasingly used in a wide variety of applications and products; however, NPs may affect stress response pathways and interact with proteins in biological systems. This review article will provide an overview of the beneficial and detrimental effects of NPs on stress response pathways with a focus on NP-protein interactions. Depending upon the particular NP, experimental model system, and dose and exposure conditions, the introduction of NPs may have either positive or negative effects. Cellular processes such as the development of oxidative stress, the initiation of the inflammatory response, mitochondrial function, detoxification, and alterations to signaling pathways are all affected by the introduction of NPs. In terms of tissue-specific effects, the local microenvironment can have a profound effect on whether an NP is beneficial or harmful to cells. Interactions of NPs with metal-binding proteins (zinc, copper, iron and calcium) affect both their structure and function. This review will provide insights into the current knowledge of protein-based nanotoxicology and closely examines the targets of specific NPs.

Integrative proteomics and metabolomics approach to elucidate metabolic dysfunction induced by silica nanoparticles in hepatocytes

Silica nanoparticles (SiNPs) are derived from manufactured materials and the natural environment, and they cause detrimental effects on human health via various exposure routes. The liver is proven to be a key target organ for SiNP toxicity; however, the mechanisms causing toxicity remain largely uncertain. Here, we investigated the effects of SiNPs on the metabolic spectrum in hepatocytes via integrative analyses of proteomics and metabolomics. First, a proteomic analysis was used to screen for critical proteins (including RPL3, HSP90AA1, SOD, PGK1, GOT1, and PNP), indicating that abnormal protein synthesis, protein misfolding, oxidative stress, and metabolic dysfunction may contribute to SiNP-induced hepatotoxicity. Next, metabolomic data demonstrated that SiNPs caused metabolic dysfunction by altering vital metabolites (including glucose, alanine, GSH, CTP, and ATP). Finally, a systematic bioinformatic analysis of protein-metabolite interactions showed that SiNPs disturbed glucose metabolism (glycolysis and pentose phosphate pathways, amino acid metabolism (alanine, aspartate, and glutamate), and ribonucleotide metabolism (purine and pyrimidine). These metabolic dysfunctions could exacerbate oxidative stress and lead to liver injury. Moreover, SOD, TKT, PGM1, GOT1, PNP, and NME2 may be key proteins for SiNP-induced hepatotoxicity. This study revealed the metabolic mechanisms underlying SiNP-induced hepatotoxicity and illustrated that integrative omics analyses can be a powerful approach for toxicity evaluations and risk assessments of nanoparticles.

Pulmonary Toxicity of Silica Linked to Its Micro- or Nanometric Particle Size and Crystal Structure: A Review

Silicon dioxide (SiO2) is a mineral compound present in the Earth’s crust in two mineral forms: crystalline and amorphous. Based on epidemiological and/or biological evidence, the pulmonary effects of crystalline silica are considered well understood, with the development of silicosis, emphysema, chronic bronchitis, or chronic obstructive pulmonary disease. The structure and capacity to trigger oxidative stress are recognized as relevant determinants in crystalline silica’s toxicity. In contrast, natural amorphous silica was long considered nontoxic, and was often used as a negative control in experimental studies. However, as manufactured amorphous silica nanoparticles (or nanosilica or SiNP) are becoming widely used in industrial applications, these paradigms must now be reconsidered at the nanoscale (<100 nm). Indeed, recent experimental studies appear to point towards significant toxicity of manufactured amorphous silica nanoparticles similar to that of micrometric crystalline silica. In this article, we present an extensive review of the nontumoral pulmonary effects of silica based on in vitro and in vivo experimental studies. The findings of this review are presented both for micro- and nanoscale particles, but also based on the crystalline structure of the silica particles.

The TLR4/NFκB-Dependent Inflammatory Response Activated by LPS Is Inhibited in Human Macrophages Pre-Exposed to Amorphous Silica Nanoparticles

Amorphous silica nanoparticles (ASNP) are present in a variety of products and their biological effects are actively investigated. Although several studies have documented pro-inflammatory effects of ASNP, the possibility that they also modify the response of innate immunity cells to natural activators has not been thoroughly investigated. Here, we study the effects of pyrogenic ASNP on the LPS-dependent activation of human macrophages differentiated from peripheral blood monocytes. In macrophages, 24 h of pre-exposure to non-cytotoxic doses of ASNP markedly inhibited the LPS-dependent induction of pro-inflammatory (TNFα, IL-6) and anti-inflammatory cytokines (IL-10). The inhibitory effect was associated with the suppression of NFκB activation and the increased intracellular sequestration of the TLR4 receptor. The late induction of glutamine synthetase (GS) by LPS was also prevented by pre-exposure to ASNP, while GS silencing did not interfere with cytokine secretion. It is concluded that (i) macrophages exposed to ASNP are less sensitive to LPS-dependent activation and (ii) GS induction by LPS is likely secondary to the stimulation of cytokine secretion. The observed interference with LPS effects may point to a dampening of the acute inflammatory response after exposure to ASNP in humans.

In Situ Detection of Nanotoxicity in Living Cells Based on Multiple miRNAs Probed by a Peptide Functionalized Nanoprobe

The potential toxicity of nanoparticles, especially for clinically applicable ones, has become a critical concern. Technologies that can in situ-evaluate the toxicity of nanoparticles with high sensitivity are urgently needed. In this study, a facile strategy was developed for sensitive detection on the nanotoxicity of nanoparticles with low toxicity or a low dose. A functional nanoprobe loaded with molecular beacons was constructed to realize in situ evaluation of the nanotoxicity through probing multiple miRNAs in nanoparticle-exposed living cells. Being composed of protamine complexed with molecular beacons for miRNA detection and decorated by TAT and KALA peptides, the dual-peptide functionalized nanoprobe can efficiently deliver molecular beacons into living cells to realize the real-time monitoring of early biomarkers (miR-21 and miR-221) to evaluate nanotoxicity. Using mesoporous silica nanoparticles (MSNs) with different surface modifications as typical representatives of low toxic nanoparticles, we demonstrate that our nanoprobe can sensitively detect miRNA changes in cells under diverse exposure conditions, that is, MSN-NH₂ exhibits the strongest capability to upregulate miR-21 and miR-221, and the upregulation is exposure dose- and time-dependent. Our approach is much more sensitive as compared with conventional methods to study cytotoxicity such as 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay, cell morphology observation, and reactive oxygen species (ROS) assay. This study paves a path for effective and facile nanotoxicity evaluation and provides insights into the biological impacts of MSNs.

Nanophysical Mapping of Inflammasome Activation by Nanoparticles via Specific Cell Surface Recognition Events

Silica nanoparticles (SiNP) trigger a range of innate immune responses in relevant essential organs, such as the liver and the lungs. Inflammatory reactions, including NLRP3 inflammasome activation, have been linked to particulate materials; however, the molecular mechanisms and key actors remain elusive. Although many receptors, including several scavenger receptors, were suggested to participate in SiNP cellular uptake, mechanistic evidence of their role on innate immunity is lacking. Here we present an atomic force microscopy-based approach to physico-mechanically map the specific interaction occurring between nanoparticles and scavenger receptor A1 (SRA1) in vitro on living lung epithelial cells. We find that SiNP recognition by SRA1 on human macrophages plays a key role in mediating NLRP3 inflammasome activation, and we identify cellular mechanical changes as clear indicators of inflammasome activation in human macrophages, greatly advancing our knowledge on the interplay among nanomaterials and innate immunity.

Silica Nanoparticles Inhibit Responses to ATP in Human Airway Epithelial 16HBE Cells

Because of their low cost and easy production, silica nanoparticles (SiNPs) are widely used in multiple manufacturing applications as anti-caking, densifying and hydrophobic agents. However, this has increased the exposure levels of the general population and has raised concerns about the toxicity of this nanomaterial. SiNPs affect the function of the airway epithelium, but the biochemical pathways targeted by these particles remain largely unknown. Here we investigated the effects of SiNPs on the responses of 16HBE14o- cultured human bronchial epithelial (16HBE) cells to the damage-associated molecular pattern ATP, using fluorometric measurements of intracellular Ca2+ concentration. Upon stimulation with extracellular ATP, these cells displayed a concentration-dependent increase in intracellular Ca2+, which was mediated by release from intracellular stores. SiNPs inhibited the Ca2+ responses to ATP within minutes of application and at low micromolar concentrations, which are significantly faster and more potent than those previously reported for the induction of cellular toxicity and pro-inflammatory responses. SiNPs-induced inhibition is independent from the increase in intracellular Ca2+ they produce, is largely irreversible and occurs via a non-competitive mechanism. These findings suggest that SiNPs reduce the ability of airway epithelial cells to mount ATP-dependent protective responses.

Multiple pathways of alveolar macrophage death contribute to pulmonary inflammation induced by silica nanoparticles

In our previous study, 20 nm-sized amorphous silica nanoparticles (20-SiNPs), but not 50 nm-sized amorphous silica nanoparticles (50-SiNPs), induced pulmonary inflammatory response in rats exposed repeatedly for 14 days (12.5, 25, and 50 μg/time, total six times). In this study, we tried to clarify the causes of different responses induced by both SiNPs using mice (12.5, 25, and 50 μg/lung) and mouse alveolar macrophage cells. When exposed to alveolar macrophage cells for 24 h, both SiNPs decreased cell viability and enhanced ROS generation compared to controls. The 20- and 50-SiNPs also formed giant and autophagosome-like vacuoles in the cytoplasm, respectively. Structural damage of organelles was more pronounced in 20-SiNPs-treated cells than in 50-SiNPs-treated cells, and an increased mitochondrial membrane potential and mitochondrial calcium accumulation were observed only in the 20-SiNPs-treated cells. Additionally, a single intratracheal instillation of both sizes of SiNPs to mice clearly elevated the relative proportion of neutrophils and inhibited differentiation of macrophages and expression of an adhesion molecule. Meanwhile, interestingly, the total number of pulmonary cells and the levels of pro-inflammatory mediators more notably increased in the lungs of mice exposed to 20-SiNPs compared to 50-SiNPs. Given that accumulation of giant vacuoles and dilation of the ER and mitochondria are key indicators of paraptosis, we suggest that 20-SiNPs-induced pulmonary inflammation may be associated with paraptosis of alveolar macrophages.

Flavonoid-Based Nanomedicines in Alzheimer's Disease Therapeutics: Promises Made, a Long Way To Go

Alzheimer's disease (AD) is characterized by the continuous decline of the cognitive abilities manifested due to the accumulation of large aggregates of amyloid-beta 42 (Aβ42), the formation of neurofibrillary tangles of hyper-phosphorylated forms of microtubule-associated tau protein, which may lead to many alterations at the cellular and systemic level. The current therapeutic strategies primarily focus on alleviating pathological symptoms rather than providing a possible cure. AD is one of the highly studied but least understood neurological problems and remains an unresolved condition of human brain degeneration. Over the years, multiple naturally derived small molecules, including plant products, microbial isolates, and some metabolic byproducts, have been projected as supplements reducing the risk or possible treatment of the disease. However, unfortunately, none has met the expected success. One major challenge for most medications is their ability to cross the blood-brain barrier (BBB). In past decades, nanotechnology-based interventions have offered an alternative platform to address the problem of the successful delivery of the drugs to the specific targets. Interestingly, the exciting interface of natural products and nanomedicine is delivering promising results in AD treatment. The potential applications of flavonoids, the plant-derived compounds best known for their antioxidant activities, and their amalgamation with nanomedicinal approaches may lead to highly effective therapeutic strategies for treating well-known neurodegenerative diseases. In the present review, we explore the possibilities and recent developments on an exciting combination of flavonoids and nanoparticles in AD.