Nano-SiO2 induces apoptosis via activation of p53 and Bax mediated by oxidative stress in human hepatic cell line

Numerical investigations of translocation characteristics of nano-silica lunar dust across pulmonary surfactant monolayer

The interactions between nano-silica lunar dust (NSLD) on the moon surface and pulmonary surfactant (PS) monolayer will pose risks to astronaut health in future manned lunar exploration missions, but the specifics of these interactions are unknown. This study investigates them using the coarse-grained molecular dynamics method considering different sizes (5, 10, and 15 nm) and shapes (sphere, ellipsoid, and cube), with special focus on the unique morphology of NSLDs with bugles. The key findings are as follows: (1) The 10 nm and 15 nm NSLDs embed in the PS monolayer through the major sphere of spherical-type, major ellipsoid of ellipsoidal-type, or one edge of cubic-type NSLDs upon contact the PS monolayer. (2) Adsorbed NSLDs cause a higher Sz value (ASz > 0.84), while embedded NSLDs cause a lower Sz value (0.47 < ASz < 0.83) that decreases with an increase in the number of bulges. (3) The embedding process absorbs 50-342 dipalmitoylphosphatidylcholine (DPPC) molecules, reducing the PS monolayer area by 0.21%-6.05%. NSLDs with bulges absorb approximately 9-126 additional DPPC molecules and cause a 0.05%-3.22% reduction in the PS monolayer area compared to NSLDs without bulges. (4) NSLDs move obliquely or vertically within the PS monolayer, displaying two distinct stages with varying velocities. Their movement direction and speed are influenced by the increasing complexity of NSLD with more bulges on them. In general, larger NSLDs with sharper shapes and increasing complex morphology of more bulges cause more significant damages to the PS monolayer. These findings have implications for safeguarding astronaut health in future manned lunar exploration missions.

Effect of Silica in the Manufacture of Autologous Serum Eye Drops on Corneal Stromal Cells

PURPOSE

The aim of this study was to evaluate the effect of serum clot activator, silica (SiO 2 ), which may be used for making autologous serum eye drops, on human corneal fibroblasts.

METHODS

Cultured human corneal fibroblasts were exposed to 10%, 20%, and 30% silica for 1, 6, and 24 hours; methyl thiazolyl tetrazolium-based colorimetric assay was performed to determine the survival rate of fibroblasts and lactate dehydrogenase leakage assay to assess the cytotoxicity. The apoptotic response was evaluated by flow cytometric analysis and fluorescence staining with Annexin V and propidium iodide. Cellular morphology was evaluated by inverted phase-contrast light microscopy and electron microscopy.

RESULTS

The survival rate of human corneal fibroblasts and cytotoxicity showed both dose-dependent and time-dependent responses. The fluorescent micrograph and flow cytometry showed that as the exposure time increased, more cells underwent apoptosis or necrosis after treatment with 30% silica. When observed with light and electron microscopy, the number of corneal fibroblasts decreased and they were more detached from the dish. In addition, damaged corneal fibroblasts showed degenerative changes after exposure to 30% silica.

CONCLUSIONS

Silica showed dose-dependent and time-dependent toxicity in human corneal fibroblasts. It is safer to keep the blood in tubes without a clot activator when manufacturing autologous serum eye drops to prevent possible corneal cytotoxicity.

Stability-Enhanced Cisplatin Gold Nanoparticles As Therapeutic Anticancer Agents

Using dendron chemistry, we developed stability enhanced, carboxylate surface modified (negatively charged dendron) AuNPs (Au-NCD). Since the carboxylate surface of Au-NCD is optimal for complexation with cisplatin (Pt) moieties, we further synthesized Pt loaded Au-NCD (Au-NCD/Pt) to serve as potential therapeutic anticancer agents. The size distribution, zeta potential and surface plasmon resonance of both Au-NCDs and Au-NCD/Pt were characterized via dynamic light scattering, scanning transmission electron microscopy and ultraviolet-visible spectrophotometry. Surface chemistry, Pt uptake, and Pt release were evaluated using inductively coupled plasma-mass spectrometry and X-ray photoelectron spectroscopy. Colloidal stability in physiological media over a wide pH range (1 to 13) and shelf-life stability (up to 6 months) were also assessed. Finally, the cytotoxicity of both Au-NCD and Au-NCD/Pt to Chinese hamster ovary cells (CHO K1; as a normal cell line) and to human lung epithelial cells (A549; as a cancer cell line) were evaluated. The results of these physicochemical and functional cytotoxicity studies with Au-NCD/Pt demonstrated that the particles exhibited superlative colloidal stability, cisplatin uptake and in vitro anticancer activity despite low amounts of Pt release from the conjugate.

Fermentation of Inula britannica using Lactobacillus plantarum SY12 increases of epigallocatechin gallate and attenuates toxicity

This study aimed to increase epigallocatechin gallate (EGCG) levels and attenuate the toxicity in Inulabritannica by fermentation using Lactobacillus plantarum SY12. The optimal medium was composed of 10 g of I. britannica, 4 g of xylose, 5 g of soytone, and 5 g of beef extract. The predicted value of EGCG was 237.327 μg/mL. To investigate damage in HepG2 cell lines by I. britannica extracts (IE) or fermented I. britannica extracts (FIE), cell viability, mitochondria membrane potential, the expression of apoptosis and autophagy genes, and chemical composition were measured. FIE increased cell viability, regulation of the gene expression (decreased p53, p62, p-ERK 1/2, and p-p38; increased CDK2 and CDK4) compared with IE. These results were explained by an increase in 1,3-dicaffeoylquinic acid and a decrease in 1-O-caffeoylquinic acid, 1-O-acetylbritannilactone, and ergolide in FIE. In conclusion, these results indicated that fermentation can mitigate the toxicity in I. britannica.

In Vivo Toxicity of Oral Administrated Nano-SiO2: Can Food Additives Increase Apoptosis?

Nano-silicon dioxide (nano-SiO2) has a great deal of application in food packaging, as antibacterial food additives, and in drug delivery systems but this nanoparticle, despite its wide range of utilizations, can generate destructive effects on organs such as the liver, kidney, and lungs. This study is aimed at investigating the toxicological effects of nano-SiO2 through apoptotic factors. For this purpose, 40 female rats in 4 groups (n = 10) received 300, 600, and 900 mg/kg/day of nano-SiO2 at 20-30 nm size orally for 20 days. Relative expression of Caspase3, Bcl-2, and BAX genes in kidney and liver was evaluated in real time-PCR. The results indicated the overexpression of BAX and Caspase3 genes in the liver and kidney in groups receiving 300 and 900 mg/kg/day of nano-SiO2. Bcl-2 gene was up-regulated in the liver and kidney at 600 mg/kg/day compared to the control group. Overexpression of the Bcl-2 gene in the kidney in 300 and 900 mg/kg/day recipient groups was observed (P ≤ 0.05). Histopathological examination demonstrated 600 mg/kg/day hyperemia in the kidney and lungs. In addition, at 900 mg/kg/day were distinguished scattered necrosis and hyperemia in the liver. The rate of epithelialization in the lungs increased. The nano-SiO2 at 300 and 900 mg/kg/day can induce more cytotoxicity in the liver and lung after oral exposure. However, cytotoxicity of nano-SiO2 at 600 mg/kg/day in the kidney and lung was noticed. Hence, the using of nano-SiO2 as an additive and food packaging should be more considered due to their deleterious effects.

Nanotechnology in agriculture: a review of genotoxic studies of nanopesticides in animal cells

Agriculture has been and still is one of the most influential primary operations in economic history worldwide. Its social, cultural, and political impact allows the progression and survival of humanity. Sustaining the supply of primary resources is crucial for the future. Therefore, the development of new technologies applied to agrochemicals is growing to obtain better food quality faster. Recently, nanotechnology has gained strength in this field in the last decade, mainly because of the presumed benefits that will carry with it compared with the current commercial presentations, like the decrease of risk in non-target organisms. The harm of pesticides is commonly associated with unwanted effects on human health, some with long-term genotoxic effects. Therefore, it would be relevant to set the existence of a risk or a benefit of the nanopesticides from a genotoxic point of view, comparing against those without this technology. Although some studies are concerned with its genotoxicity in live aquatic organisms, few focus on human in vitro models. Several studies conclude that some of them can induce oxidative stress, leading to DNA damage or cell death. However, there is still much to investigate to establish an accurate and complete assessment. In this review, we aim to give an overview of the genotoxic effect caused by nanopesticides in animal cells and a guide to the evolution of this topic, offering a base and critical review to facilitate future research.

Adverse effects and underlying mechanism of amorphous silica nanoparticles in liver

Amorphous silica nanoparticles (SiNPs) have been widely used and mass-producted due to its unique properties. With the life cycle of SiNPs-based products, SiNPs are further released into the air, soil, surface water and sediment, resulting in an increasing risk to humans. SiNPs could enter into the human body through vein, respiratory tract, digestive tract or skin. Moreover, recent evidences have showed that, regardless of exposure pathways, SiNPs could even be traced in liver, which is gradually considered as one of the main organs that SiNPs accumulate. Increasing evidences supported the link between SiNPs exposure and adverse liver effects. However, the research models are diverse and the molecular mechanisms have not been well integrated. In this review, the liver-related studies of SiNPs in vivo and in vitro were screened from the PubMed database by systematic retrieval method. We explored the interaction between SiNPs and the liver, and especially proposed a framework of SiNPs-caused liver toxicity, considering AOP Wiki and existing studies. We identified increased reactive oxygen species (ROS) as a molecular initiating event (MIE), oxidative stress, endoplasmic reticulum stress, lysosome disruption and mitochondrial dysfunction as subsequent key events (KEs), which gradually led to adverse outcomes (AOs) containing liver dysfunction and liver fibrosis through a series of key events about cell inflammation and death such as hepatocyte apoptosis/pyroptosis, hepatocyte autophagy dysfuncton and hepatic macrophages pyroptosis. To our best knowledge, this is the first AOP proposed on SiNPs-related liver toxicity. In the future, more epidemiological studies need to be performed and more biomarkers need to be explored to improve the AOP framework for SiNPs-associated liver toxicity.

Indirect mediators of systemic health outcomes following nanoparticle inhalation exposure

The growing field of nanoscience has shed light on the wide diversity of natural and anthropogenic sources of nano-scale particulates, raising concern as to their impacts on human health. Inhalation is the most robust route of entry, with nanoparticles (NPs) evading mucociliary clearance and depositing deep into the alveolar region. Yet, impacts from inhaled NPs are evident far outside the lung, particularly on the cardiovascular system and highly vascularized organs like the brain. Peripheral effects are partly explained by the translocation of some NPs from the lung into the circulation; however, other NPs largely confined to the lung are still accompanied by systemic outcomes. Omic research has only just begun to inform on the complex myriad of molecules released from the lung to the blood as byproducts of pulmonary pathology. These indirect mediators are diverse in their molecular make-up and activity in the periphery. The present review examines systemic outcomes attributed to pulmonary NP exposure and what is known about indirect pathological mediators released from the lung into the circulation. Further focus was directed to outcomes in the brain, a highly vascularized region susceptible to acute and longer-term outcomes. Findings here support the need for big-data toxicological studies to understand what drives these health outcomes and better predict, circumvent, and treat the potential health impacts arising from NP exposure scenarios.

Influence of Critical Parameters on Cytotoxicity Induced by Mesoporous Silica Nanoparticles

Mesoporous Silica Nanoparticles (MSNs) have received increasing attention in biomedical applications due to their tuneable pore size, surface area, size, surface chemistry, and thermal stability. The biocompatibility of MSNs, although generally believed to be satisfactory, is unclear. Physicochemical properties of MSNs, such as diameter size, morphology, and surface charge, control their biological interactions and toxicity. Experimental conditions also play an essential role in influencing toxicological results. Therefore, the present study includes studies from the last five years to statistically analyse the effect of various physicochemical features on MSN-induced in-vitro cytotoxicity profiles. Due to non-normally distributed data and the presence of outliers, a Kruskal–Wallis H test was conducted on different physicochemical characteristics, including diameter sizes, zeta-potential measurements, and functionalisation of MSNs, based on the viability results, and statistical differences were obtained. Subsequently, pairwise comparisons were performed using Dunn’s procedure with a Bonferroni correction for multiple comparisons. Other experimental parameters, such as type of cell line used, cell viability measurement assay, and incubation time, were also explored and analysed for statistically significant results.

Nanomaterial reinforced composite for biomedical implants applications: a mini-review

There is heavy demand for suitable implant materials with improved mechanical and biological properties. Classically, the demand was catered by conventional materials like metals, alloys, and polymer-based materials. Recently, nanomaterial reinforced composites have played a significant role in replacing conventional materials due to their excellent properties such as biocompatibility, bioactivity, high strength to weight ratio, long life, corrosion & wear resistance, and tailor-ability. Herein, we composed a systematic focus review on the role of nanoparticles in the form of composite materials for the advancements in orthopedic implants. Several nano materials-based reinforcements have been reviewed with various matrix materials, including metals, alloys, ceramics, composites, and polymers for biomedical implant applications. Moreover, the improved biological properties, mechanical properties, and other functionalities like infection resistance, drug delivery at the target, sensing, and detection of bone diseases, and corrosion & wear resistance are elaborated. At last, a particular focus has been given to the un-resolved challenges in orthopedic implant development.

Identifying the Molecular Mechanisms and Types of Cell Death Induced by bio- and pyr-Silica Nanoparticles in Endothelial Cells

The term "nanosilica" refers to materials containing ultrafine particles. They have gained a rapid increase in popularity in a variety of applications and in numerous aspects of human life. Due to their unique physicochemical properties, SiO₂ nanoparticles have attracted significant attention in the field of biomedicine. This study aimed to elucidate the mechanism underlying the cellular response to stress which is induced by the exposure of cells to both biogenic and pyrogenic silica nanoparticles and which may lead to their death. Both TEM and fluorescence microscopy investigations confirmed molecular changes in cells after treatment with silica nanoparticles. The cytotoxic activity of the compounds and intracellular RNS were determined in relation to HMEC-1 cells using the fluorimetric method. Apoptosis was quantified by microscopic assessment and by flow cytometry. Furthermore, the impact of nanosilica on cell migration and cell cycle arrest were determined. The obtained results compared the biological effects of mesoporous silica nanoparticles extracted from Urtica dioica L. and pyrogenic material and indicated that both types of NPs have an impact on RNS production causing apoptosis, necrosis, and autophagy. Although mesoporous silica nanoparticles did not cause cell cycle arrest, at the concentration of 50 μg/mL and higher they could disturb redox balance and stimulate cell migration.

Facilitation of adhesion and spreading of endothelial cells on silicone oxide-coated dacron material by microwave-excited low-pressure plasma

Objectives

Autologous transplants are still the means of choice for bypass surgery. In addition to good tolerability, there is a reduced thrombogenicity and fewer neointima hyperplasia compared to artificial materials. However, since viable transplants are limited, attempts are being made to improve existing artificial vascular prosthesis material. Next to the reduction of thrombogenicity, a rapid endothelialization of the vascular graft should reduce intimal hyperplasia and thus prevent stenoses. The effect of newly developed silicon oxide coatings on the growth of endothelial cells was therefore the goal of this work in a cell culture study.

Methods

A woven, uncoated polyethylene terephthalate (PET) vessel prosthesis was used. The coating process was carried out in a low-pressure plasma reactor in a multi-step process. After preparation of the vacuum chamber hexamethyldisiloxane (HDMSO) with oxygen was evaporated using argon plasma. By this an approx. 1 nm thin adhesion promoter layer was separated from plasma and HMDSO. The silicone oxide barrier layer was applied to the PET vessel samples. The carbon content of the layer could be selectively altered by changing the HMDSO oxygen flow ratio, resulting in coatings of 100 nm, 500 nm, and 1,000 nm. In addition, two different oxygen-to-HMDSO ratios were used. To achieve a carbon coating as low as possible, the ratio was set to 200:1. A carbon-rich layer was obtained with the 1:1 setting. The various coatings were then examined for their surface texture by scanning electron microscopy (SEM) as well as by cell culture experiments for cell viability and growth using EA.hy 926 cells.

Results

SEM showed no changes in the surface morphology; however a layer thickness of 1,000 nm showed peeled off coating areas. Alamar blue assays showed a significantly higher metabolic activity (p=0.026) for the coating 500 nm, ratio 200:1 compared to untreated control samples and a significantly lower metabolic activity (p=0.037) of the coating 500 nm, ratio 1:1 compared to the coating 500 nm, ratio 200:1. This underlines the apparent tendency of the 1:1 coating to inhibit the metabolic activity of the cells, while the 200:1 coating increases the activity. Fluorescence microscopy after calcein acetoxymethyl ester (AM) staining showed no significant difference between the different coatings and the uncoated PET material. However, a tendency of the increased surface growth on the coating 500 nm, ratio 200:1, is shown. The coatings with the ratio 1:1 tend to be less densely covered.

Conclusions

The results of this work indicate a great potential in the silicon coating of vascular prosthesis material. The plasma coating can be carried out easy and gently. Cell culture experiments demonstrated a tendency towards better growth of the cells on the 200:1 ratio coating and a poorer growth on the carbon-rich coating 1:1 compared to the uncoated material. The coating with silicon oxide with a thickness of 500 nm and an oxygen-HMDSO ratio of 200:1, a particularly low-carbon layer, appears to be a coating, which should therefore be further investigated for its effects on thrombogenicity and intimal hyperplasia.

Rice Husk Silica Liquid Protects Pancreatic β Cells from Streptozotocin-Induced Oxidative Damage

Type 2 diabetes mellitus is a complex multifactorial disease characterized by insulin resistance and dysfunction of pancreatic β-cells. Rice husk silica liquid (RHSL) is derived from rice husks and has not been explored in diabetes mellitus until now. Previous studies showed that rice husk is enriched with silica, and its silica nanoparticles are higher more biocompatible. To investigate the potential protective role of RHSL on pancreatic β cells, we utilized RIN-m5F pancreatic β cells and explored RHSL effect after streptozotocin (STZ)-stimulation. The recovery effects of RHSL were evaluated using flow cytometry, Western blotting, and immunofluorescence analysis. Results of our study showed that RHSL reversed the cell viability, insulin secretion, reactive oxygen species (ROS) production, and the change of mitochondria membrane potential (ΔΨm) in STZ-treated RIN-m5F cells. Moreover, the expression of phospho-receptor-interacting protein 3 (p-RIP3) and cleaved-poly (ADP-ribose) polymerase (PARP), phospho-mammalian target of rapamycin (p-mTOR), and sequestosome-1 (p62/SQSTM1) were significantly decreased, while the transition of light chain (LC)3-I to LC3-II was markedly increased after RHSL treatment in STZ-induced RIN-m5F cells. Interestingly, using autophagy inhibitors such as 3-methyladenine (3-MA) and chloroquine (CQ) both showed an increase in cleaved-PARP protein level, indicating apoptosis induction. Taken together, this study demonstrated that RHSL induced autophagy and alleviated STZ-induced ROS-mediated apoptosis in RIN-m5F cells.

Panax ginseng modulates oxidative stress, DNA damage, apoptosis, and inflammations induced by silicon dioxide nanoparticles in rats

Silicon dioxide nanoparticles (SiO₂ NPs) are extensively used in cosmetics, food, and drug delivery. The main mechanism of SiO₂ NPs toxicities depends on oxidative stress. Ginseng (Panax ginseng Meyer) is used in various medicinal applications because of its antioxidant efficiency. Therefore, the present study was carried out to investigate the possible combated role of ginseng against SiO₂ NPs toxicity in rat liver. Thirty-five male rats (160-180 g) were allocated into five groups of seven rats each, randomly. The first group was used as a control while groups 2, 3, 4, and 5 were treated orally with ginseng (Gin; 75 mg/kg, 1/10 LD₅₀ ), SiO₂ NPs, (200 mg/kg, 1/10 LD₅₀ ), Gin + SiO₂ NPs (protection group), and SiO₂ NPs + Gin (therapeutic group) for 5 weeks, respectively. Treatment with SiO₂ NPs increased lipid peroxidation, liver function enzymes, and decreased antioxidant enzymes (SOD, CAT, GPx, GST) activity and non-enzymatic antioxidant (GSH) level. SiO₂ NPs administration motivated liver apoptosis as revealed by the upregulation of the apoptotic genes, Bcl2-associated x protein (Bax), and Beclin 1 and downregulation of the anti-apoptotic gene, B-cell lymphoma 2 (Bcl2) as well as increase in DNA damage. Also, SiO₂ NPs administration caused inflammation as indicated by upregulation of the inflammation-related genes (interleukin 1 beta [IL1β], tumor necrosis factor-alpha [TNFα], nuclear factor kappa B [NFκB], cyclooxygenase 2 [Cox2], transforming growth factor-beta 1 [TGFβ1]) as well as cell cycle arrest in the G0/G1 phase of liver cells. Moreover, histopathological examination proved the biochemical and molecular perturbations occurred due to SiO₂ NPs toxicity. On the other hand, ginseng caused a significant modulation on the deleterious effects induced by SiO₂ NPs in rat liver. In conclusion, ginseng has a potent preventive effect than the therapeutic one and might be used in the treatment of SiO₂ NPs hepatotoxicity.

Behavioural alterations induced by chronic exposure to 10 nm silicon dioxide nanoparticles

Silicon dioxide nanoparticles (SiO2 NPs) are widely invested in medicine, industry, agriculture, consuming products, optical imaging agents, cosmetics, and drug delivery. However, the toxicity of these NPs on human health and the ecosystem have not been extensively studied and little information is available about their behavioural toxicities. The current study aimed to find out the behavioural alterations that might be induced by chronic exposure to 10 nm SiO2 NPs. BALB/C mice were subjected to 36 injections of SiO2 NPs (2 mg/kg Bw) and subjected to 11 neurobehavioural tests: elevated plus-maze test, elevated zero-maze test, multiradial maze test, open field test, hole-board test, light-dark box test, forced swimming test, tail-suspension test, Morris water-maze test, Y-maze test and multiple T-maze test. Treated mice demonstrated anxiety-like effect, depression tendency, behavioural despair stress, exploration and locomotors activity reduction with error induction in both reference and working memories. The findings may suggest that silica NPs are anxiogenic and could aggravate depression affecting memory, learning, overall activity and exploratory behaviour. Moreover, the findings may indicate that these nanomaterials (NMs) may induce potential oxidative stress in the body leading to neurobehavioural alterations with possible changes in the vital organ including the central nervous system.

Mechanical cues protect against silica nanoparticle exposure in SH-SY5Y neuroblastoma

The increasing appearance of engineered nanomaterials in broad biomedical and industrial sectors poses an escalating health concern from unintended exposure with unknown consequences. Routine in vitro assessments of nanomaterial toxicity are a vital component to addressing these mounting health concerns; however, despite the known role of cell-cell and cell-matrix contacts in governing cell survival, these physical interactions are generally ignored. Herein, we demonstrate that exposure to amorphous silica particles destabilizes mitochondrial membrane potential, stimulates reactive oxygen species (ROS) production and promotes cytotoxicity in SH-SY5Y human neuroblastoma through mechanisms that are potently matrix dependent, with SH-SY5Y cells plated on the softest matrix displaying a near complete recovery in viability compared to dose-matched cells plated on tissue-culture plastic. Cells on the softest matrix (3 kPa) further displayed a 50% reduction in ROS production and preserved mitochondrial membrane potential. The actin cytoskeleton is mechanosensitive and closely related to ROS production. SH-SY5Y cells exposed to a 100 μg/mL dose of 50 nm silica particles displayed distinct cytoskeletal aberrations and a 70% increase in cell stiffness. Overall, this study establishes that the mechanical environment can significantly impact silica nanoparticle toxicity in SH-SY5Y cells. The mechanobiochemical mechanisms behind this regulation, which are initiated at the cell-matrix interface to adjust cytoskeletal structure and intracellular tension, demand specific attention for a comprehensive understanding of nanotoxicity.

Tailoring of silica-based nanoporous pod by spermidine multi-activity

Ubiquitous in nature, polyamines (PAs) are a class of low-molecular aliphatic amines critically involved in cell growth, survival and differentiation. The polycation behavior is validated as a successful strategy in delivery systems to enhance oligonucleotide loading and cellular uptake. In this study, the chemical features and the functional roles of the PA spermidine are synergistically exploited in the synthesis and bioactive functionalization of SiO2-based structures. Inspired by biosilicification, the role of spermidine is assessed both as catalyst and template in a biomimetic one-pot synthesis of dense silica-based particles (SPs) and as a competitive agent in an interfacial reassembly strategy, to empty out SPs and generate spermidine-decorated hollow silica nanoporous pods (spd-SNPs). Spermidine bioactivity is then employed for targeting tumor cell over-expressed polyamine transport system (PTS) and for effective delivery of functional miRNA into melanoma cells. Spermidine decoration promotes spd-SNP cell internalization mediated by PTS and along with hollow structure enhances oligonucleotide loading. Accordingly, the functional delivery of the tumor suppressor miR-34a 3p resulted in intracellular accumulation of histone-complexed DNA fragments associated with apoptosis. Overall, the results highlight the potential of spd-SNP as a multi-agent anticancer therapy.

The Size-dependent Cytotoxicity of Amorphous Silica Nanoparticles: A Systematic Review of in vitro Studies

With the increasing production and application of engineered amorphous silica nanoparticles (aSiNPs), people have more opportunities to be exposed to aSiNPs. However, the knowledge of its adverse health effects and related mechanisms is still limited, compared with the well-studied crystalline micron-sized silica. Since small differences in the physical–chemical properties of nanoparticles could cause significant differences in the toxic effect, it is important to distinguish how these variations influence the outcoming toxicity. Notably, particle size, as one of the essential characterizations of aSiNPs, is relevant to its biological activities. Thus, the aim of this systematic review was to summarize the relationship between the particle size of aSiNPs and its adverse biological effects. In order to avoid the influence of complicated in vivo experimental conditions on the toxic outcome, only in vitro toxicity studies which reported on the cytotoxic effect of different sizes aSiNPs were included. After the systematic literature retrieval, selection, and quality assessment process, 76 eligible scientific papers were finally included in this review. There were 76% of the studies that concluded a size-dependent cytotoxicity of aSiNPs, in which smaller-sized aSiNPs possessed greater toxicity. However, this trend could be modified by certain influence factors, such as the synthetic method of aSiNPs, particle aggregation state in cell culture medium, toxicity endpoint detection method, and some other experimental conditions. The effects of these influence factors on the size-dependent cytotoxicity of aSiNPs were also discussed in detail in the present review.

Engineered nanoparticle-induced epigenetic changes: An important consideration in nanomedicine

Engineered nanoparticles (ENPs) are now being applied across a range of disciplines, and as a result numerous studies have now assessed ENP-related bioeffects. Among them, ENP-induced epigenetic changes including DNA methylation, histone modifications, and miRNA-mediated regulation of gene expression have recently attracted attention. In this review, we describe the diversity of ENP-induced epigenetic changes, focusing on their interplay with related functional biological events, especially oxidative stress, MAPK pathway activation, and inflammation. In doing so, we highlight the underlying mechanisms and biological effects of ENP-induced epigenetic changes. We also summarize how high-throughput technologies have helped to uncover ENP-induced epigenetic changes. Finally, we discuss future perspectives and the challenges related to ENP-induced epigenetic changes that still need to be addressed.

Toxicity Evaluation of Nanostructured Silica Orally Administered to Rats: Influence on Immune System Function

The experimental data on the oral toxicity of nanostructured amorphous silica (SiO₂), widely used in food supplements, pharmaceuticals, and cosmetics, in terms of its in vivo effect on the immune system, are contradictory. Therefore, this study aimed to assess the rat's immune function after SiO₂ oral administration. In the first experiment, SiO₂ was daily orally administered to Wistar rats for 92 days in doses of 0.1, 1.0, 10, and 100 mg/kg of body weight (bw). In the second 28-day experiment, SiO₂ in a dose of 100 mg/kg bw was daily orally administered to rats parenterally immunized with the food allergen ovalbumin (OVA) for the reproduction of systemic anaphylaxis reaction. Together with integral indices, we assessed intestinal permeability to protein macromolecules; hematology; CD45RA+, CD3+, CD4+, CD8+, and CD161a+ cells; cytokines TNF-α, IL-6, and IL-10; and IgG to OVA. The results obtained showed that SiO₂ has no effect on the severity of the anaphylactic reaction, but is capable inducing a toxic effect on the T-cell immune systems of rats. Estimated no observed adverse effect level NOAEL for SiO₂ ranges up to 100 mg/kg bw in terms of its daily consumption for 1-3 months. Using SiO₂ as a food additive should be the subject of regulation.

Proposing Urothelial and Muscle In Vitro Cell Models as a Novel Approach for Assessment of Long-Term Toxicity of Nanoparticles

Many studies evaluated the short-term in vitro toxicity of nanoparticles (NPs); however, long-term effects are still not adequately understood. Here, we investigated the potential toxic effects of biomedical (polyacrylic acid and polyethylenimine coated magnetic NPs) and two industrial (SiO₂ and TiO₂) NPs following different short-term and long-term exposure protocols on two physiologically different in vitro models that are able to differentiate: L6 rat skeletal muscle cell line and biomimetic normal porcine urothelial (NPU) cells. We show that L6 cells are more sensitive to NP exposure then NPU cells. Transmission electron microscopy revealed an uptake of NPs into L6 cells but not NPU cells. In L6 cells, we obtained a dose-dependent reduction in cell viability and increased reactive oxygen species (ROS) formation after 24 h. Following continuous exposure, more stable TiO₂ and polyacrylic acid (PAA) NPs increased levels of nuclear factor Nrf2 mRNA, suggesting an oxidative damage-associated response. Furthermore, internalized magnetic PAA and TiO₂ NPs hindered the differentiation of L6 cells. We propose the use of L6 skeletal muscle cells and NPU cells as a novel approach for assessment of the potential long-term toxicity of relevant NPs that are found in the blood and/or can be secreted into the urine.

Disturbed mitochondrial quality control involved in hepatocytotoxicity induced by silica nanoparticles

The extensive application of silica nanoparticles (SiNPs) brings about inevitable occupational, environmental, and even iatrogenic exposure for human beings. The liver, which is rich in mitochondria, is one of the target organs of SiNPs, but the underlying mechanisms by which these nanoparticles (NPs) interact with liver mitochondria and affect their functions still remain unclear. In the present study, we examined silicon nanoparticle (SiNP)-induced mitochondrial dysfunction, and further revealed its negative effects on mitochondrial quality control (MQC) in the human liver cell line L-02, including mitochondrial dynamics, mitophagy and biogenesis. Consequently, SiNPs induced cellular injury, accompanied by mitochondrial dysfunction, including mitochondrial reactive oxygen generation and mitochondrial membrane potential collapse. In line with the transmission electron microscopy (TEM)-observed abnormalities in the mitochondrial morphology and length distribution, a fission phenotype was manifested in the mitochondria of SiNP-exposed cells, and up-regulated DRP1 and FIS1, and down-regulated MFN1, were detected. Furthermore, the enhanced LC3II level, colocalization of the mitochondria and lysosomes, activated PINK1/Parkin signaling, and accumulated p62 in the SiNP-exposed cells suggested mitophagy disorder triggered by SiNPs. In addition, SiNPs inhibited mito-biogenesis, as evidenced by the reduced mitochondrial mass and mtDNA copy number, as well as the suppressed PGC1α-NRF1-TFAM signaling pathway. Overall, the study demonstrates that SiNPs trigger hepatocytotoxicity through interfering with the MQC process, bringing in excessive mitochondrial fission, mitophagy disorder and suppressed mito-biogenesis, leading to mitochondrial dysfunction and ensuing cell damage, and ultimately contributing to the occurrence and development of liver diseases. Our research could provide important experimental evidence related to safety assessments of SiNPs, especially in the field of biomedical applications.

Amorphous SiO2 nanoparticles promote cardiac dysfunction via the opening of the mitochondrial permeability transition pore in rat heart and human cardiomyocytes

Background

Silica nanoparticles (nanoSiO₂) are promising systems that can deliver biologically active compounds to tissues such as the heart in a controllable manner. However, cardiac toxicity induced by nanoSiO₂ has been recently related to abnormal calcium handling and energetic failure in cardiomyocytes. Moreover, the precise mechanisms underlying this energetic debacle remain unclear. In order to elucidate these mechanisms, this article explores the ex vivo heart function and mitochondria after exposure to nanoSiO₂.

Results

The cumulative administration of nanoSiO₂ reduced the mechanical performance index of the rat heart with a half-maximal inhibitory concentration (IC₅₀) of 93 μg/mL, affecting the relaxation rate. In isolated mitochondria nanoSiO₂ was found to be internalized, inhibiting oxidative phosphorylation and significantly reducing the mitochondrial membrane potential (ΔΨ_m). The mitochondrial permeability transition pore (mPTP) was also induced with an increasing dose of nanoSiO₂ and partially recovered with, a potent blocker of the mPTP, Cyclosporine A (CsA). The activity of aconitase and thiol oxidation, in the adenine nucleotide translocase, were found to be reduced due to nanoSiO₂ exposure, suggesting that nanoSiO₂ induces the mPTP via thiol modification and ROS generation. In cardiac cells exposed to nanoSiO₂, enhanced viability and reduction of H₂O₂ were observed after application of a specific mitochondrial antioxidant, MitoTEMPO. Concomitantly, CsA treatment in adult rat cardiac cells reduced the nanoSiO₂-triggered cell death and recovered ATP production (from 32.4 to 65.4%). Additionally, we performed evaluation of the mitochondrial effect of nanoSiO₂ in human cardiomyocytes. We observed a 40% inhibition of maximal oxygen consumption rate in mitochondria at 500 μg/mL. Under this condition we identified a remarkable diminution in the spare respiratory capacity. This data indicates that a reduction in the amount of extra ATP that can be produced by mitochondria during a sudden increase in energy demand. In human cardiomyocytes, increased LDH release and necrosis were found at increased doses of nanoSiO₂, reaching 85 and 48%, respectively. Such deleterious effects were partially prevented by the application of CsA. Therefore, exposure to nanoSiO₂ affects cardiac function via mitochondrial dysfunction through the opening of the mPTP.

Conclusion

The aforementioned effects can be partially avoided reducing ROS or retarding the opening of the mPTP. These novel strategies which resulted in cardioprotection could be considered as potential therapies to decrease the side effects of nanoSiO₂ exposure.

Controlled Tyrosine Kinase Inhibitor Delivery to Liver Cancer Cells by Gate-Capped Mesoporous Silica Nanoparticles

Hepatocellular carcinoma is the most common type of primary malignancy in the liver and one of the most common types of cancer worldwide. Its readily increasing mortality rate highlights the urgent need for the development of efficient therapeutic strategies. Tyrosine kinase inhibitors (TKIs) such as sorafenib and sunitinib are used as efficient angiogenesis inhibitors for this purpose. However, despite their pharmacological effects, their transfer into clinical practice is characterized by their poor aqueous solubility and accumulation in off-target tissues, resulting in unfavorable side effects. Here, we report a nanocomposite made of amine-functionalized mesoporous silica nanocomposites (MSNs) that are surface-coated with cerium oxide nanoparticles (CNPs) for the controlled delivery and release of TKIs. Amine-functionalized MSNs were prepared using a sol-gel method and loaded with TKIs. To trap drug molecules into the mesoporous structure, CNPs were covalently conjugated to the surface of MSNs. The synthesis and functionalization steps were controlled using different characterization methods, confirming the desired morphology and structure, the identity of functional groups on the surface, successful coating, and appropriate loading efficiency. Under physiological conditions, CNP-capped MSNs demonstrated a sustained drug release over time as a result of CNPs' gatekeeping effect on the payloads. Strong cellular interactions with different liver cancer cells and enhanced cellular uptake were also observed in vitro for the gate-capped MSNs. Internalization of nanocomposites induced cell death via the production of reactive oxygen species, and subsequent activation of apoptosis pathways. This study demonstrates that gate-capped MSNs are promising chemotherapeutic vehicles characterized by a sustained drug release profile and high cellular internalization.

Bi-functional nature of nanoceria: pro-drug and drug-carrier potentiality towards receptor-mediated targeting of doxorubicin

The bifunctional nature of nanoceria as pro-drug and vehicle for the site-specific targeted delivery of DOX is achieved with CeO₂–(DOX–FA) nanoconjugates towards MFC-7 cells.

Microarray-assisted size-effect study of amorphous silica nanoparticles on human bronchial epithelial cells

Amorphous silica nanoparticles (SiNPs) are not only abundant in nature, but also the second largest engineering nanomaterials in terms of annual output. Respiratory exposure is the main route for SiNPs to enter the human body. A large number of studies have focused on the respiratory toxicity of SiNPs and demonstrated that SiNPs could induce pulmonary tissue damage, inflammation, fibrosis, and even the malignant transformation of bronchial epithelial cells, while the size-dependent toxicity of SiNPs and their underlying biological mechanisms remain unclear. In this regard, a transcriptomics study would be conductive to gaining a better understanding of the toxic mechanism. In the present study, microarray analysis was performed to investigate the genome-wide transcriptional alteration induced by different sizes of SiNPs in human primary bronchial epithelial cells (BEAS-2B). To determine the effect of the particle size on the toxicity, nanoparticles of two sizes (41 nm and 61 nm) and submicron particles of one size (206 nm) were introduced. The bioinformatics analysis results indicated that: (1) the number of differentially expressed genes in the three SiNP-treated groups increased with the particle size decreasing; (2) the genes involved in the immune and inflammatory response, gene expression, signal transduction, endoplasmic reticulum stress, oxidative stress, cell metabolism, and cell proliferation were gradually upregulated with the particle size decreasing, while the genes related to the morphological development of the respiratory system were gradually downregulated with the particle size decreasing; (3) the modes of action of the two nanoparticles overlapped with each other to some degree, and there existed many different modes compared to those from the submicron particles; (4) both the silica nanoparticles affected the pathways associated with the cell entry of silica nanoparticles, autophagy and lysosomal dysfunction, endoplasmic reticulum stress, inflammatory response, DNA damage, and gene expression, as well as apoptotic resistance and cancer. To the best of our knowledge, this is the first study that has reported the alteration trend of gene expression profiles with the change in silica particle size. Our study provides a great deal of information on the toxic mechanisms underlying the respiratory toxicity induced by SiNPs, and can also serve as an experimental basis for the toxicity and safety evaluation of silica nanoparticles.

Cytotoxic effect of silica nanoparticles against hepatocellular carcinoma cells through necroptosis induction

Hepatocellular carcinoma (HCC) is a common cancer that affects people worldwide with high morbidity and mortality, and its resistance to current chemotherapeutic drugs is a serious concern. Cytotoxicity of silica nanoparticles (Nano-SiO₂) towards cancer cells has been reported previously, but the specific mechanism is not fully clear. In this study, Nano-SiO₂ showed a remarkable cytotoxic effect against HCC cells, regardless of whether the cells were drug resistant or not. Further study showed that Nano-SiO₂ treatment leads to cell cycle arrest, apoptosis enhancement and necroptosis induction in the HCC cells. RNA-seq data, together with bioinformatics analysis, revealed that a series of genes involved in cancer cell death could be regulated by Nano-SiO₂, among which ZBP-1 was up-regulated the most by Nano-SiO₂ treatment. The siRNA based experiments demonstrated that ZBP-1 might play a key role in mediating Nano-SiO₂ cytotoxic functions against HCC cells. These results have evidently signified the anti-tumor potential of Nano-SiO₂ in the treatment of HCC.

The effects of nickel oxide nanoparticles on structural changes, heme degradation, aggregation of hemoglobin and expression of apoptotic genes in lymphocytes

Nickel oxide nanoparticles (NiO NPs) have received great interests in medical and biotechnological applications. However, their adverse impacts against biological systems have not been well-explored. Herein, the influence of NiO NPs on structural changes, heme degradation and aggregation of hemoglobin (Hb) was evaluated by UV-visible (Vis) spectroscopy, circular dichroism (CD) spectroscopy, fluorescence spectroscopy, transmission electron microscopy (TEM), and molecular modeling investigations. Also, the morphological changes and expression of Bax/Bcl-2 mRNA in human lymphocyte cell exposed to NiO NPs were assayed by DAPI staining and quantitative real-time PCR (qPCR), respectively. The UV-Vis study depicted that NiO NPs resulted in the displacement of aromatic residues and heme groups and production of the pro-aggregatory species. Intrinsic and Thioflavin T (ThT) fluorescence studies revealed that NiO NPs resulted in heme degradation and amorphous aggregation of Hb, respectively, which the latter result was also confirmed by TEM study. Moreover, far UV-CD study depicted that NiO NPs lead to substantial secondary structural changes of Hb. Furthermore, near UV-CD displayed that NiO NPs cause quaternary conformational changes of Hb as well as heme displacement. Molecular modelling study also approved that NiO NPs resulted in structural alterations of Hb and heme deformation. Moreover, morphological and genotoxicity assays revealed that the DNA fragmentation and expression ratio of Bax/Bcl-2 mRNA increased in lymphocyte cells treated with NiO NPs for 24 hr. In conclusion, this study indicates that NiO NPs may affect the biological media and their applications should be limited.Communicated by Ramaswamy H. Sarma.

Silica Nanoparticles Provoke Cell Death Independent of p53 and BAX in Human Colon Cancer Cells

Several in vitro studies have suggested that silica nanoparticles (NPs) might induce adverse effects in gut cells. Here, we used the human colon cancer epithelial cell line HCT116 to study the potential cytotoxic effects of ingested silica NPs in the presence or absence of serum. Furthermore, we evaluated different physico-chemical parameters important for the assessment of nanoparticle safety, including primary particle size (12, 70, 200, and 500 nm) and surface modification (-NH2 and -COOH). Silica NPs triggered cytotoxicity, as evidenced by reduced metabolism and enhanced membrane leakage. Automated microscopy revealed that the silica NPs promoted apoptosis and necrosis proportional to the administered specific surface area dose. Cytotoxicity of silica NPs was suppressed by increasing amount of serum and surface modification. Furthermore, inhibition of caspases partially prevented silica NP-induced cytotoxicity. In order to investigate the role of specific cell death pathways in more detail, we used isogenic derivatives of HCT116 cells which lack the pro-apoptotic proteins p53 or BAX. In contrast to the anticancer drug cisplatin, silica NPs induced cell death independent of the p53-BAX axis. In conclusion, silica NPs initiated cell death in colon cancer cells dependent on the specific surface area and presence of serum. Further studies in vivo are warranted to address potential cytotoxic actions in the gut epithelium. The unintended toxicity of silica NPs as observed here could also be beneficial. As loss of p53 in colon cancer cells contributes to resistance against anticancer drugs, and thus to reoccurrence of colon cancer, targeted delivery of silica NPs could be envisioned to also deplete p53 deficient tumor cells.

Acute Exposure to SiO2 Nanoparticles Affects Protein Synthesis in Bergmann Glia Cells

Attractive due to an alleged high biocompatibility, silica nanoparticles have been widely used in the field of nanomedicine; however, their proven capacity to induce the synthesis and release of pro-inflammatory cytokines in several cellular models has raised concern about their safety. Glutamate, the main excitatory amino acid transmitter triggers a wide variety of signal transduction cascades that regulate protein synthesis at transcriptional and translational levels. A stimulus-dependent dynamic change in the protein repertoire in neurons and glia cells is the molecular framework of higher brain functions. Within the cerebellum, Bergmann glia cells are the most abundant non-neuronal cells and span the entire molecular layer of the cerebellar cortex, wrapping the synapses in this structure. Taking into consideration the functional role of Bergmann glia in terms of the recycling of glutamate, lactate supply to neurons, and prevention of neurotoxic insults, we decided to investigate the possibility that silica nanoparticles affect Bergmann glia and by these means alter the major excitatory neurotransmitter system in the brain. To this end, we exposed cultured chick cerebellar Bergmann glia cells to silica nanoparticles and measured [³⁵S]-methionine incorporation into newly synthesized polypeptides. Our results demonstrate that exposure of the cultured cells to silica nanoparticles exerts a time- and dose-dependent modulation of protein synthesis. Furthermore, altered patterns of eukaryotic initiation factor 2 alpha and eukaryotic elongation factor 2 phosphorylation were present upon nanoparticle exposure. These results demonstrate that glia cells respond to the presence of this nanomaterial modifying their proteome, presumably in an effort to overcome any plausible neurotoxic effect.

Antagonistic effect of co-exposure to short-multiwalled carbon nanotubes and benzo[a]pyrene in human lung cells (A549)

In theenvironment, co-exposure to short-multiwalled carbon nanotubes (S-MWCNTs) and polycyclic aromatic compounds (PAHs) has been reported. In the co-exposure condition, the adsorption of PAHs onto MWCNTs may reduce PAHs toxic effect. The objective of this study was to investigate the cytotoxicity of S-MWCNTs and benzo[a]pyrene (B[a]P) individually, and in combination in human lung cell lines (A549). The adsorption of B[a]P onto MWCNTs was measured spectrometrically. In vitro toxicity was assessed through cell viability, reactive oxygen species (ROS) generation, apoptosis, and 8-hydroxy-2'-deoxyguanosine (8-OHdG) generation experiments. The S-MWCNTs demonstrated cytotoxicity through the generation of ROS, apoptosis, and 8-OHdG in A549 cells. Co-exposure to S-MWCNTs and B[a]P demonstrated a significant reduction in ROS generation and apoptosis compared with the sum of their separate toxic effects at the same concentrations. Decreasing the bioavailability of B[a]P by MWCNT interaction is the probable reason for the antagonistic effects of the co-exposure condition. The findings of this study will contribute to a better understanding of the health effects of co-exposures to air pollutants and could be a starting point for modifying future health risk assessments.

The fate and oxidative stress of different sized SiO2 nanoparticles in zebrafish (Danio rerio) larvae

Nanoparticle such as silicon dioxide nanoparticles (nano-SiO₂) are extensively produced and applied in society. Hence there is an increasing concern about their exposure and toxicity to human and wildlife. To understand the effects of sizes of NPs on their bioavailability and toxicity, zebrafish (Danio rerio) embryos (2 h post-fertilization, hpf) were exposed to 25, 50 and 100 mg/L of 15 or 30 nm nano-SiO₂ for 5 days respectively. The results showed that SiO₂ could be readily uptaken by zebrafish, and the accumulation of SiO₂ was significantly higher in 15 nm treatments groups compared to 30 nm nano-SiO₂ treated groups. Furthermore, exposure to 15 nm nano-SiO₂ at the concentration of 100 mg/L resulted in more significant changes in reactive oxygen species (ROS) levels, perturbation of lipid peroxidative and antioxidant system than the same concentration of 30 nm nano-SiO₂, indicating small sized nano-SiO₂ evoked severer oxidative stress in zebrafish larvae. In addition, the more significant up-regulation of transcription of genes related to oxidative stress (e.g., nrf2 and sod1) in 15 nm nano-SiO₂ at the 100 mg/L treatments groups provided more evidence for this speculation. Given the above, 15 nm nano-SiO₂ were more likely to enter and accumulate in zebrafish larvae, thus causing more serious oxidative stress in vivo. These results may provide additional information on the fate and toxicities of different sizes of NPs.

Enhancing singlet oxygen generation in semiconducting polymer nanoparticles through fluorescence resonance energy transfer for tumor treatment

Photosensitizers (PSs) are of particular importance for efficient photodynamic therapy (PDT). Challenges for PSs simultaneously possessing strong light-absorbing ability, high 1O2 generation by effective intersystem crossing from the singlet to the triplet state, good water-solubility and excellent photostability still exist. Reported here are a new kind of dual-emissive semiconducting polymer nanoparticles (SPNs) containing fluorescent BODIPY derivatives and near-infrared (NIR) phosphorescent iridium(iii) complexes. In the SPNs, the BODIPY units serve as the energy donors in the fluorescence resonance energy transfer (FRET) process for enhancing the light absorption of the SPNs. The NIR emissive iridium(iii) complexes are chosen as the energy acceptors and efficient photosensitizers. The ionized semiconducting polymers can easily self-assemble to form hydrophilic nanoparticles and homogeneously disperse in aqueous solution. Meanwhile, the conjugated backbone of SPNs provides effective shielding for the two luminophores from photobleaching. Thus, an excellent overall performance of the SPN-based PSs has been realized and the high 1O2 yield (0.97) resulting from the synergistic effect of BODIPY units and iridium(iii) complexes through the FRET process is among the best reported for PSs. In addition, owing to the phosphorescence quenching of iridium(iii) complexes caused by 3O2, the SPNs can also be utilized for O2 mapping in vitro and in vivo, which assists in the evaluation of the PDT process and provides important instructions in early-stage cancer diagnosis.

Necrotic, apoptotic and autophagic cell fates triggered by nanoparticles

Nanomaterials have gained a rapid increase in use in a variety of applications that pertain to many aspects of human life. The majority of these innovations are centered on medical applications and a range of industrial and environmental uses ranging from electronics to environmental remediation. Despite the advantages of NPs, the knowledge of their toxicological behavior and their interactions with the cellular machinery that determines cell fate is extremely limited. This review is an attempt to summarize and increase our understanding of the mechanistic basis of nanomaterial interactions with the cellular machinery that governs cell fate and activity. We review the mechanisms of NP-induced necrosis, apoptosis and autophagy and potential implications of these pathways in nanomaterial-induced outcomes. Abbreviations: Ag, silver; CdTe, cadmium telluride; CNTs, carbon nanotubes; EC, endothelial cell; GFP, green fluorescent protein; GO, graphene oxide; GSH, glutathione; HUVECs, human umbilical vein endothelial cells; NP, nanoparticle; PEI, polyethylenimine; PVP, polyvinylpyrrolidone; QD, quantum dot; ROS, reactive oxygen species; SiO2, silicon dioxide; SPIONs, superparamagnetic iron oxide nanoparticles; SWCNT, single-walled carbon nanotubes; TiO2, titanium dioxide; USPION, ultra-small super paramagnetic iron oxide; ZnO, zinc oxide.

Nanoparticles induce apoptosis via mediating diverse cellular pathways

With a special size and structure, nanoparticles (NPs) have excellent application prospects in various fields and are widely used in the biomedicine, cosmetics and chemical industries nowadays. However, there have been some reports on the biosafety of this new type of material, pointing out its cytotoxicity in inducing apoptosis. With different physicochemical properties in size, shape, surface charge, and ligand, NPs exhibit different biocompatibilities when interacting with different cells. Therefore, a comprehensive and deep study into the proapoptotic mechanism of NPs is necessary. In the present review, we summarize the NP-triggered apoptotic signal pathways in detail and highlight some important functional molecules involved. We hope our findings and perspectives provide a new direction for the sound development of nanotechnology in the future.

Montelukast attenuates rotenone-induced microglial activation/p38 MAPK expression in rats: Possible role of its antioxidant, anti-inflammatory and antiapoptotic effects

Montelukast (MK),a cysteinyl leukotriene (CysLT1) receptor antagonist, latterly exhibited a remarkable neuroprotective activity in various neurodegenerative disorders. This study aims to elucidate the neuroprotective effect of MK in rotenone-induced Parkinson's disease(PD) model in rats. Ninety six male rats were split into four groups: vehicle control (0.2 ml/kg/48 h, sc), MK (10 mg/kg/day, ip), rotenone (1.5 mg/kg/48 h, sc.) and rotenone pretreated with MK. Rotenone treatment led to significant reduction in motor functioning and elevation in oxidative stress markers. Additionally, upregulation of p38 mitogen-activated protein kinase (p38 MAPK) and CysLT1 receptor expressions were anchored with enhanced striatal microglial activation generating a severe neuro-inflammatory milieu. Furthermore, an augmentation in p53 expression and cleaved caspases-3 activity increased apoptotic neurodegeneration synchronized with reduction of striatal tyrosine hydroxylase (TH) content. Changes in neuronal morphology was also noted. MK administration significantly mitigated motor impairment and rise in oxidative stress mediators. As well, the anti-inflammatory activity of MK was manifested by hindering the principal controller of inflammatory pathway, nuclear factor-kappa B, followed by its downstream pro-inflammatory cytokines (tumor necrosis factor-alpha and interleukin-1 beta), by attenuating striatal microglial activation and hampering the expression of both p38 MAPK and CysLT1. Moreover, MK revealed a decline in p53 expression with its downstream cleaved caspases-3 which resulted in preservation of striatal TH terminals as verified by increased striatal TH content and improvement in the histopathological changes incited by rotenone. In conclusion, MK endowed neuroprotective effects in rotenone-induced PD animal model via attenuation of microglial cell activation and p38 MAPK expression.

Oxidative stress and cell cycle arrest induced by short-term exposure to dustfall PM2.5 in A549 cells

It was reported that in vitro short-term exposure to PM_2.5 caused different lung diseases through inflammatory response, immune toxicity, oxidative stress, and genetic mutations. However, the complex molecular biological mechanism for its toxicity had not been fully elucidated. Therefore, the present study investigated the cytotoxicity, oxidative damage, mitochondria damage, apoptosis, and cell cycle arrest of NX and QH PM_2.5 in A549 cells. Further, cell cycle arrest-related gene levels in PM_2.5-induced A549 cells were also detected. Our results suggested that PM_2.5 reduced the cell viability in A549 cells. Simultaneously, excessive ROS decreased MMP levels and damaged mitochondrial membrane integrity and induced mitochondrial oxidative damage through the oxygen-dependent killer route, resulting in mitochondrial damage and cell apoptosis. Besides, the results also showed that PM_2.5 induced A549 cell cycle alteration in G2/M phase after co-culture for 24 h. G2/M phase arrest was induced by upregulation of p53 and p21 and downregulation of CDK1 mRNA expression. In addition, lncRNA Sox2ot might play an important role as the specific oncogenes and it participated in G2/M phase arrest by regulating the expression of EZH₂.

Global metabolomics approach in in vitro and in vivo models reveals hepatic glutathione depletion induced by amorphous silica nanoparticles

The present study aimed to investigate the mechanisms involved in amorphous silica nanoparticles (aSiNPs)-mediated hepatotoxicity through the evaluation of changes in global metabolomics in in vitro and in vivo systems. ¹H NMR-based non-targeted global metabolomics and biochemical approaches were conducted in an aSiNPs-treated human hepatoma cell line (HepG2) and in ICR mice liver. The non-targeted NMR-based metabolomic analysis, followed by pathway analysis, revealed the perturbation of glutathione metabolism and the depletion of the glutathione pool after aSiNPs treatment in both in vitro (HepG2 cells) and in vivo systems. The total glutathione level, glutathione-S-transferase enzyme activity, and antioxidant gene expression strongly corroborated the metabolomic analysis results. The in vitro results were further supported by the in vivo data, specifically for metabolites profiling (Pearson Correlation coefficient is 0.462 (p = 0.026)). Furthermore, the depletion of glutathione, the formation of NADPH oxidase-mediated reactive oxygen species, and oxidative stress were evident in aSiNPs-treated HepG2 cells. Overall, the suppression of glutathione metabolism and oxidative stress are among the principal causes of aSiNPs-mediated hepatotoxicity.

Interaction of silica nanoparticles with tau proteins and PC12 cells: Colloidal stability, thermodynamic, docking, and cellular studies

Study on the side effects of the nanoparticles (NPs) can provide useful information regarding their biological and medical applications. Herein, the colloidal stability of the silicon dioxide NPs (SiO₂ NPs) in the absence and presence of tau was investigated by TEM and DLS techniques. Afterwards, the thermodynamic parameters of interaction between SiO₂ NPs and tau were determined by fluorescence spectroscopy and docking studies. Finally, the cytotoxic effects of SiO₂ NPs on the viability of PC12 cells were investigated by MTT, AO/EB staining and flow cytometry assays. TEM, DLS, and zeta potential investigations revealed that tau can reduce the colloidal stability of SiO₂ NPs. Fluorescence spectroscopy study indicated that SiO₂ NPs bound to the tau with high affinity through hydrogen bonds and van der Waals interactions. Docking study also determined that Ser, Thr and Tyr residues provide a polar microenvironment for SiO₂ NPs/tau interaction. Cellular studies demonstrated that SiO₂ NPs can induce cell mortality through both apoptosis and necrosis mechanisms. Therefore, it may be concluded that the biological systems such as nervous system proteins can affect the colloidal stability of NPs and vice versa NPs in the biological systems can bind to proteins and cell membranes non-specifically and may induce toxicity.

Probing Cellular Processes Using Engineered Nanoparticles

Nanoparticles, the building blocks of nanotechnology, have been widely utilized in various biomedical applications, such as detection, diagnosis, imaging, and therapy. However, another emerging, albeit under-represented, area is the employment of nanoparticles as tools to understand cellular processes (e.g., oxidative stress-induced signaling cascades). Such investigations have enormous potential to characterize a disease from a different perspective and unravel some new features that otherwise would have remained a mystery. In this review, we summarize the intrinsic biological properties of unmodified as well surface modified nanoparticles and discuss how such properties could be utilized to interrogate biological processes and provide a perspective for future evolution of this field.

Combination of LC/MS and GC/MS based metabolomics to study the hepatotoxic effect of realgar nanoparticles in rats

Realgar nanoparticles (NPs) are increasingly used as therapeutic agents for their enhanced anti-proliferation effect and cytotoxicity on cancer cells. However, the alteration of particle size may enhance biological reactivity as well as toxicity. A LC/MS and GC/MS based metabolomics approach was employed to explore the mechanism of realgar NPs-induced hepatotoxicity and identify potential biomarkers. Male Sprague-Dawley rats were administrated intragastrically with realgar or realgar NPs at a dose of 1.0 g·kg^-1·d^-1 for 28 days and toxic effects of realgar NPs on liver tissues were examined by biochemical indicator analysis and histopathologic examination. Increased levels of serum enzymes and high hepatic steatosis were discovered in the realgar NPs treated group. Multivariate data analysis revealed that rats with realgar NPs-induced hepatotoxicity could be distinctively differentiated from the animals in the control and realgar treated groups. In addition, 21 and 32 endogenous metabolites were apparently changed in the serum and live extracts, respectively. Realgar NPs might induce free fatty acid and triglyceride accumulation, resulting in hepatotoxicity. In conclusion, the present study represents the first comprehensive LC/MS- and GC/MS-based metabolomics analysis of realgar NPs-induced hepatotoxicity, which may help further research of nanotoxicity.

In vivo investigation on the chronic hepatotoxicity induced by intraperitoneal administration of 10-nm silicon dioxide nanoparticles

Background

Silicon dioxide (silica) nanoparticles (SDNPs) are widely used in nanotechnology and medicine, but these nanomaterials may carry a high risk for human health while little is known about their toxicity.

Methods

We investigated the alterations in morphometry, biochemistry, hematology, histology of liver tissue and gene expression of drug-metabolizing enzymes induced by 10-nm SDNPs. Healthy male Wistar albino rats were exposed to 20, 35 and 50 repeated injections of SDNPs (2 mg/kg body weight). Whole blood, serum and plasma samples were used for hematological and biochemical analyses, whereas liver biopsies were processed for histopathological and gene expression alterations.

Results

In comparison with control rats, exposure to SDNPs lowered the body weight gain and liver index and increased the counts of white blood cells and platelets, but lowered the platelet larger cell ratio and plateletcrit. Levels of alkaline phosphatase, lactate dehydrogenase, low-density lipids, procalcitonin, aspartate aminotransferase and alanine aminotransferase, as well as potassium, phosphorus and iron concentrations, were increased. Histopathology revealed that SDNPs could induce hydropic degeneration, sinusoidal dilatation, hyperplasia of Kupffer cells, karyopyknosis and infiltration of inflammatory cells in the liver. SDNPs reduced the expression of 12 genes of drug-metabolizing enzymes significantly (p<0.05).

Conclusion

These results suggest that SDNPs could cause alterations in morphometry, biochemistry, hematology, liver tissues and the expression of drug-metabolizing enzyme genes.

Cellular pathways involved in silica nanoparticles induced apoptosis: A systematic review of in vitro studies

Silica nanoparticles (SiNPs) have been found to pass through biological barriers and get distributed in the human body. They induce cell apoptosis via various mechanisms in body organs. To understand these mechanisms, we carried out systematic review of in vitro studies on SiNPs-induced cell apoptosis. Office of Health Assessment and Translation approach for Systematic Review and Evidence Integration was used to identify 14 studies dating from the year 2000 to current. Four studies showed an increase in DNA damage, cell cycle arrest, proapoptotic factors and decrease in antiapoptotic factors resulting to apoptosis. Eight studies showed induction of mitochondrial dysfunction, Bax upregulation, Bcl-2 downregulation, and caspase-3, -7, -9 activities increase. Increase in FADD, TNFR1 and Bid proteins was observed in one study, while the other NO production and caspase-3 activity was increased. These studies found the potency of SiNPs to induce cell apoptosis through DNA damage, mitochondrial, tumor necrosis factor, and nitric oxide related pathways.

Excess Manganese-Induced Apoptosis in Chicken Cerebrums and Embryonic Neurocytes

There were many studies about the effect of excess manganese (Mn) on nervous system apoptosis; however, Mn-induced apoptosis in chicken cerebrums and embryonic neurocytes was unclear. The purpose of this study was to investigate the effect of excess Mn on chicken cerebrum and embryonic neurocyte apoptosis. Seven-day-old Hyline male chickens were fed either a commercial diet or three levels of manganese chloride (MnCl₂)-added commercial diets containing 600-, 900-, and 1800-mg/kg-Mn diet, respectively. On the 30th, 60th, and 90th days, cerebrums were collected. Fertilized Hyline chicken eggs were hatched for 6-8 days and were selected. Embryonic neurocytes with 0, 0.5, 1, 1.5, 2, 2.5, and 3 mM Mn were collected and were cultured for 12, 24, 36, and 48 h, respectively. The following research contents were performed: superoxide dismutase (SOD) and total antioxidant capacity (T-AOC) activities; tumor protein p53 (p53), B cell lymphoma-2 (Bcl-2), B cell lymphoma extra large (Bcl-x), Bcl-2-associated X protein (Bax), Bcl-2 homologous antagonist/killer (Bak), fas, and caspase-3 messenger RNA (mRNA) expression; and morphologic observation. The results indicated that excess Mn inhibited SOD and T-AOC activities; induced p53, Bax, Bak, fas, and caspase-3 mRNA expression; and inhibited Bcl-2 and Bcl-x mRNA expression in chicken cerebrums and embryonic neurocytes. There were dose-dependent manners on all the above factors at all the time points and time-dependent manners on SOD activity of 1800-mg/kg-Mn group, T-AOC activity, and apoptosis-related gene mRNA expression in all the treatment groups in chicken cerebrums. Excess Mn induced chicken cerebrum and embryonic neurocyte apoptosis.

Silver nanoparticles of different sizes induce a mixed type of programmed cell death in human pancreatic ductal adenocarcinoma

Pancreatic ductal adenocarcinoma, with the high resistance to chemotherapeutic agents, remains the fourth leading cause of cancer-death in the world. Due to the wide range of biological activity and unique properties, silver nanoparticles (AgNPs) are indicated as agents with potential to overcome barriers involved in chemotherapy failure. Therefore, in our study we decided to assess the ability of AgNPs to kill pancreatic cancer cells, and then to identify the molecular mechanism underlying this effect. Moreover, we evaluated the cytotoxicity of AgNPs against non-tumor cell of the same tissue (hTERT-HPNE cells) for comparison. Our results indicated that AgNPs with size of 2.6 and 18 nm decreased viability, proliferation and caused death of pancreatic cancer cells in a size- and concentration-dependent manner. Ultrastructural analysis identified that cellular uptake of AgNPs resulted in apoptosis, autophagy, necroptosis and mitotic catastrophe. These alterations were associated with increased pro-apoptotic protein Bax and decreased level of anti-apoptotic protein Bcl-2. Moreover, AgNPs significantly elevated the level of tumor suppressor p53 protein as well as necroptosis- and autophagy-related proteins: RIP-1, RIP-3, MLKL and LC3-II, respectively.

In addition, we found that PANC-1 cells were more vulnerable to AgNPs-induced cytotoxicity compared to pancreatic non-tumor cells.

In conclusion, AgNPs by inducing mixed type of programmed cell death in PANC-1 cells, could provide a new therapeutic strategy to overcome chemoresistance in one of the deadliest human cancer.

Safety of Nonporous Silica Nanoparticles in Human Corneal Endothelial Cells

Nonporous silica nanoparticles (SiNPs) are promising drug carrier platforms for intraocular drug delivery. In this study, we investigated the safety of three different sizes of SiNPs (50, 100, and 150 nm) in a human corneal endothelial cell (HCEC) line, B4G12. The HCECs were exposed to different concentrations (0, 25, 50, and 100 µg/ml) of three sizes of SiNPs for up to 48 h. Cellular viability, autophagy, lactate dehydrogenase (LDH) assay, and mammalian target of rapamycin (mTOR) pathway activation were evaluated. Intracellular distribution of the SiNPs was evaluated with transmission electron microscopy (TEM). TEM revealed that the SiNPs were up-taken by the HCECs inside cytoplasmic vacuoles. No mitochondrial structural damage was observed. Both cellular viability and LDH level remained unchanged with up to 100 µg/mL of SiNP treatment. Autophagy showed a significant dose-dependent activation with 50, 100, and 150 nm SiNPs. However, the mTOR activation remained unchanged. Human corneal tissue culture with 100 µg/ml concentrations of SiNPs for 72 h revealed no significant endothelial toxicity. In vivo corneal safety of the SiNPs (0.05 ml intracameral injection, 200 mg/ml concentration) was also verified in rabbit models. These findings suggested that 50, 100, and 150 nm SiNPs did not induce acute significant cytotoxicity in corneal endothelial cells at concentrations up to 100 µg/mL. However, long-term toxicity of SiNPs remains unknown.

Toxicology of silica nanoparticles: an update

Large-scale production and use of amorphous silica nanoparticles (SiNPs) have increased the risk of human exposure to SiNPs, while their health effects remain unclear. In this review, scientific papers from 2010 to 2016 were systematically selected and sorted based on in vitro and in vivo studies: to provide an update on SiNPs toxicity and to address the knowledge gaps indicated in the review of Napierska (Part Fibre Toxicol 7:39, 2010). Toxicity of SiNPs in vitro is size, dose, and cell type dependent. SiNPs synthesized by wet route exhibited noticeably different biological effects compared to thermal route-based SiNPs. Amorphous SiNPs (particularly colloidal and stöber) induced toxicity via mechanisms similar to crystalline silica. In vivo, route of administration and physico-chemical properties of SiNPs influences the toxicokinetics. Adverse effects were mainly observed in acutely exposed animals, while no significant signs of toxicity were noted in chronically dosed animals. The correlation between in vitro and in vivo toxicity remains less well established mainly due to improper-unrealistic-dosing both in vitro and in vivo. In conclusion, notwithstanding the multiple studies published in recent years, unambiguous linking of physico-chemical properties of SiNPs types to toxicity, bioavailability, or human health effects is not yet possible.

The Effects of Silica Nanoparticles on Apoptosis and Autophagy of Glioblastoma Cell Lines

Silica nanoparticles (SiNPs) are one of the most commonly used nanomaterials in various medical applications. However, possible mechanisms of the toxicity caused by SiNPs remain unclear. The study presented here provides novel information on molecular and cellular effects of SiNPs in glioblastoma LBC3 and LN-18 cells. It has been demonstrated that SiNPs of 7 nm, 5–15 nm and 10–20 nm induce time- and dose-dependent cytotoxicity in LBC3 and LN-18 cell lines. In contrast to glioblastoma cells, we observed only weak reduction in viability of normal skin fibroblasts treated with SiNPs. Furthermore, in LBC3 cells treated with 5–15 nm SiNPs we noticed induction of apoptosis and necrosis, while in LN-18 cells only necrosis. The 5–15 nm SiNPs were also found to cause oxidative stress, a loss in mitochondrial membrane potential, and changes in the ultrastructure of the mitochondria in LBC3 cells. Quantitative real-time PCR results showed that in LBC3 cells the mRNA levels of pro-apoptotic genes Bim, Bax, Puma, and Noxa were significantly upregulated. An increase in activity of caspase-9 in these cells was also observed. Moreover, the activation of SiNP-induced autophagy was demonstrated in LBC3 cells as shown by an increase in LC3-II/LC3-I ratio, the upregulation of Atg5 gene and an increase in AVOs-positive cells. In conclusion, this research provides novel information concerning molecular mechanisms of apoptosis and autophagy in LBC3 cells.

Silica nanoparticles induced intrinsic apoptosis in neuroblastoma SH-SY5Y cells via CytC/Apaf-1 pathway

The present study was to investigate effects of Silica nanoparticles (SiNPs) on nervous system and explore potential mechanisms in human neuroblastoma cells (SH-SY5Y). Cytotoxicity was detected by cell viability and Lactate dehydrogenase (LDH) release. Flow cytometry analysis was applied to assess mitochondrial membrane potential (MMP) loss, intracellular Ca²⁺ and apoptosis. To clarify the mechanism of SiNPs-induced apoptosis, intrinsic apoptosis-related proteins were detected. Our results showed that SiNPs caused cytotoxicity, cell membrane damage and Ca²⁺ increase in a dose-dependent manner in SH-SY5Y cells. Both the mitochondrial membrane potential (MMP) loss and potential mitochondria damage resulted in Cyt C release to the cytoplasm. The elevated Cyt C and Apaf1 further triggered intrinsic apoptosis via executive molecular caspase-9 and caspase-3. The present study confirmed that SiNPs induced intrinsic apoptosis in neuroblastoma SH-SY5Y cells via CytC/Apaf-1 pathway and provided a better understanding of the potential toxicity induced by SiNPs on human neurocyte.