Oxidative stress in the brain of mice caused by translocated nanoparticulate TiO2 delivered to the abdominal cavity

Neuroprotective potential of Betulinic acid against TIO2NP induced neurotoxicity in zebrafish

Betulinic acid (BA) is a natural triterpenoid extracted from Bacopa monnieri. BA has been reported to be used as a neuroprotective agent, but their molecular mechanisms are still unknown. Therefore, in this study, we attempted to investigate the precise mechanism of BA for its protective effect against Titanium dioxide nanoparticles (TiO2NP) induced neurotoxicity in zebrafish. Hence, our study observation showed that 10 µg/ml dose of TiO2NP caused a rigorous behavioral deficit in zebrafish. Further, biochemical analysis revealed TiO2NP significantly decreased GSH, and SOD, and increased MDA, AChE, TNF-α, IL-1β, and IL-6 levels, suggesting it triggers oxidative stress and neuroinflammation. However, BA at doses of 2.5,5,10 mg/kg improved behavioral as well as biochemical changes in zebrafish brain. Moreover, BA also significantly raised the levels of DA, NE, 5-HT, and GABA and decreased glutamate levels in TiO2NP-treated zebrafish brain. Our histopathological analysis proved that TiO2NP causes morphological changes in the brain. These changes were expressed by increasing pyknotic neurons, which were dose-dependently reduced by Betulinic acid. Likewise, BA upregulated the levels of NRF-2 and HO-1, which can reduce oxidative stress and neuroinflammation. Thus, our study provides evidence for the molecular mechanism behind the neuroprotective effect of Betulinic acid. Rendering to the findings, we can consider BA as a suitable applicant for the treatment of AD-like symptoms.

Titanium corrosion products from dental implants and their effect on cells and cytokine release: A review

INTRODUCTION

Titanium is considered to be an inert material owing to the ability of the material to form a passive titanium oxide layer. However, once the titanium oxide layer is lost, it can lead to exposure of the underlying titanium substructure and can undergo corrosion.

SUMMARY

The article explores the role of titanium ions and particles from dental implants on cells, cytokine release, and on the systemic redistribution of these particles as well as theories proposed to elucidate the effects of these particles on peri-implant inflammation based on evidence from in-vitro, human, and animal studies. Titanium particles and ions have a pro-inflammatory and cytotoxic effect on cells and promote the release of pro-inflammatory mediators like cytokines. Three theories to explain etiopathogenesis have been proposed, one based on microbial dysbiosis, the second based on titanium particles and ions and the third based on a synergistic effect between microbiome and titanium particles on the host.

CONCLUSION

There is clear evidence from in-vitro and limited human and animal studies that titanium particles released from dental implants have a detrimental effect on cells directly and through the release of pro-inflammatory cytokines. Future clinical and translational studies are required to clarify the role of titanium particles and ions in peri-implant inflammation and the etiopathogenesis of peri-implantitis.

Nervous system exposure of different classes of nanoparticles: A review on potential toxicity and mechanistic studies

Nanoparticles (NPs) are generally defined as very small particles in the size range of 1-100 nm. Due to the rapid development of modern society, many new materials have been developed. The widespread use of NPs in medical applications, the food industry and the textile industry has led to an increase in NPs in the environment and the possibility of human contact, which poses a serious threat to human health. The nervous system plays a leading role in maintaining the integrity and unity of the body and maintaining a harmonious balance with the external environment. Therefore, based on two categories of organic and inorganic NPs, this paper systematically summarizes the toxic effects and mechanisms of NPs released into the nervous system. The results showed that exposure to NPs may damage the nervous system, decrease learning and cognitive ability, and affect embryonic development. Finally, a remediation scheme for NPs entering the body via the environment is also introduced. This scheme aims to reduce the neurotoxicity caused by NPs by supplementing NPs with a combination of antioxidant and anti-inflammatory compounds. The results provide a valuable reference for future research in this field.

The effects of TiO2, ZnO, IONs and Al2O3 metallic nanoparticles on the CYP1A1 and NBN transcripts in rat liver

Introduction

Metal oxide nanoparticles are currently used widely in many aspects of human and animal life with broad prospects for biomedical purposes. The present work was carried out to investigate the effects of orally administrated TiO2NPs, ZnONPs, IONs and Al2O3NPs on the mRNA expression level of CYP 1A1 and NBN in the rat liver.

Materials and Methods

Four groups of male Albino rats were given their respective treatment orally for 60 days in a dose of 1/20 of the LD50 TiO2NPs (600 mg/Kg b.wt/day), ZnONPs (340 mg/Kg b.wt/day), IONs (200 mg/kg b.wt/day) and Al2O3NPs (100 mg/Kg b.wt/day) and a fifth group served as a control group.

Rresults

The mRNA level of CYP 1A1 and NBN showed up-regulation in all the NPs-treated groups relative to the control group. ZnONPs group recorded the highest expression level while the TiO2NPs group showed the lowest expression level transcript. Conclusion:The toxic effects produced by these nanoparticles were more pronounced in the case of zinc oxide, followed by aluminum oxide, iron oxide nanoparticles and titanium dioxide, respectively.

Curcumin-ZnO conjugated nanoparticles confer neuroprotection against ketamine-induced neurotoxicity

BACKGROUND

Nanotechnology and its application to manipulate herbal compounds to design new neuroprotective agents to manage neurotoxicity has recently increased. Cur-ZnO conjugated nanoparticles were synthesized and used in an experimental model of ketamine-induced neurotoxicity.

METHODS

Cur-ZnO conjugated nanoparticles were chemically characterized, and the average crystalline size was determined. Forty-nine adult mice were divided into seven groups of seven animals each. Normal saline was given to control mice (group 1). Ketamine (25 mg/kg) was given to a second group. A third group of mice was given ketamine (25 mg/kg) in combination with curcumin (40 mg/kg), while mice in groups 4, 5, and 6 received ketamine (25 mg/kg) plus Cur-ZnO nanoparticles (10, 20, and 40 mg/kg). Group 7 received only ZnO (5 mg/kg). All doses were ip for 14 days. Hippocampal mitochondrial quadruple complex enzymes, oxidative stress, inflammation, and apoptotic characteristics were assessed.

RESULTS

Cur-ZnO nanoparticles and curcumin decreased lipid peroxidation, GSSG content, IL-1β, TNF-α, and Bax levels while increasing GSH and antioxidant enzymes like GPx, GR, and SOD while increasing Bcl-2 level and mitochondrial quadruple complex enzymes in ketamine treatment groups.

CONCLUSION

The neuroprotective properties of Cur-ZnO nanoparticles were efficient in preventing ketamine-induced neurotoxicity in the mouse brain. The nanoparticle form of curcumin (Cur-ZnO) required lower doses to produce neuroprotective effects against ketamine-induced toxicity than conventional curcumin.

Neurotoxicity of Titanium Dioxide Nanoparticles: A Comprehensive Review

The increasing use of titanium dioxide nanoparticles (TiO2 NPs) across various fields has led to a growing concern regarding their environmental contamination and inevitable human exposure. Consequently, significant research efforts have been directed toward understanding the effects of TiO2 NPs on both humans and the environment. Notably, TiO2 NPs exposure has been associated with multiple impairments of the nervous system. This review aims to provide an overview of the documented neurotoxic effects of TiO2 NPs in different species and in vitro models. Following exposure, TiO2 NPs can reach the brain, although the specific mechanism and quantity of particles that cross the blood-brain barrier (BBB) remain unclear. Exposure to TiO2 NPs has been shown to induce oxidative stress, promote neuroinflammation, disrupt brain biochemistry, and ultimately impair neuronal function and structure. Subsequent neuronal damage may contribute to various behavioral disorders and play a significant role in the onset and progression of neurodevelopmental or neurodegenerative diseases. Moreover, the neurotoxic potential of TiO2 NPs can be influenced by various factors, including exposure characteristics and the physicochemical properties of the TiO2 NPs. However, a systematic comparison of the neurotoxic effects of TiO2 NPs with different characteristics under various exposure conditions is still lacking. Additionally, our understanding of the underlying neurotoxic mechanisms exerted by TiO2 NPs remains incomplete and fragmented. Given these knowledge gaps, it is imperative to further investigate the neurotoxic hazards and risks associated with exposure to TiO2 NPs.

Quercetin Mitigates Oxidative Stress, Inflammation, Apoptosis, and Histopathological Alterations Induced by Chronic Titanium Dioxide Nanoparticle Exposure in the Rat Spleen

Titanium dioxide nanoparticles (nano-TiO2) have become widespread but are accompanied by various health concerns. Quercetin (QT), a naturally occurring flavonoid in fruits and vegetables, exhibits potent antioxidant properties. This research examined the toxic impacts of nano-TiO2 on the structure and function of the spleen in adult male rats and assessed the possible protective effects of QT. A set of randomly grouped rats was established, consisting of a control group, a QT group (50 mg/kg/day), a nano-TiO2 group (300 mg/kg/day), and a QT-nano-TiO2 group. These substances were orally administered to the respective groups for 90 days. Nano-TiO2 significantly induced oxidative stress in the spleen, leading to reduced levels of serum immunoglobulins. Additionally, there was a notable increase in the expression of apoptotic markers and proinflammatory cytokines. These biochemical disturbances were accompanied by morphological changes in the spleens of rats exposed to nano-TiO2. However, coadministration of QT and nano-TiO2 effectively mitigated most nano-TiO2-induced alterations in the spleen, including apoptotic and proinflammatory responses, antioxidant imbalance, serum immunoglobulin levels, and histopathological changes. It can be concluded that QT has the potential to function as a protective agent against the detrimental impacts of nano-TiO2 on the spleen by improving the antioxidant defense mechanism and modulating the apoptotic and inflammatory responses.

Combination of epigallocatechin 3 gallate and curcumin improves D-galactose and normal-aging associated memory impairment in mice

Previously, we observed curcumin improves aging-associated memory impairment in D-galactose (D-gal) and normal-aged (NA) mice. Evidence showed that multiple agents can be used in managing aging-induced memory dysfunction, drawn by the contribution of several pathways. Curcumin and Epigallocatechin 3 gallate (EGCG) combination substantially reduced the oxidative stress that commonly mediates aging. This study examined the combined effect of EGCG and curcumin on memory improvement in two recognized models, D-gal and normal-aged (NA) mice. The co-administration of EGCG and curcumin significantly (p < 0.05) increased retention time detected by passive avoidance (PA) and freezing response determined in contextual fear conditioning (CFC) compared to the discrete administration of EGCG or curcumin. Biochemical studies revealed that the combination of EGCG and curcumin remarkably ameliorated the levels (p < 0.05) of glutathione, superoxide dismutase, catalase, advanced oxidation protein products, nitric oxide, and lipid peroxidation compared to the monotherapy of EGCG or curcumin in mice hippocampi. The behavioral and biochemical studies revealed that the combination of EGCG and curcumin showed better improvement in rescuing aging-associated memory disorders in mice. EGCG and curcumin combination could serve as a better choice in managing aging-related memory disorders.

Amelioration of CCl4-induced oxidative stress and hepatotoxicity by Ganoderma lucidum in long evans rats

Liver disease is a serious health problem affecting people worldwide at an alarming rate. The present study aimed to investigate the protective effects of Ganoderma lucidum against CCl₄-induced liver toxicity in rats. The experimental Long Evans rats were divided into five groups, of which four groups were treated with carbon tetrachloride (CCl₄). Among the CCl₄ treated groups, one of the groups was treated with silymarin and two of them with ethanolic extract of G. lucidum at 100 and 200 mg/Kg body weight. The oxidative stress parameters and endogenous antioxidant enzyme concentrations were assessed by biochemical tests. Liver enzymes ALT, AST, and ALP were determined spectrophotometrically. Histopathological examinations were carried out to assess hepatic tissue damage and fibrosis. Reverse transcription PCR (RT-PCR) was performed to determine the expression of IL-1β, IL-6, IL-10, TNF-α, and TGF-β genes. Gas Chromatography-Mass Spectroscopy (GC-MS) analysis revealed that G. lucidum is rich in several phytochemicals including 6-Octadecanoic acid (55.81%), l-( +)-Ascorbic acid 2,6-dihexadecanoate (18.72%), Cis-11-Eicosenamide (5.76%), and Octadecanoic acid (5.26%). Treatment with the G. lucidum extract reduced the elevated ALT, AST, ALP levels, and cellular oxidative stress markers and increased the endogenous antioxidant levels. Histopathology observations revealed that the inflammation, infiltration of immune cells, and aberration of collagen fibers in the hepatocytes were altered by the G. lucidum treatment. The increased expression of inflammatory cytokines TNF-α, TGF-β, IL-1 β, and IL-6 were markedly suppressed by G. lucidum extract treatment. G. lucidum also prevented the suppression of protective IL-10 expression by CCl₄. This study strongly suggests that G. lucidum extract possesses significant hepatoprotective activity as evidenced by reduced oxidative stress and inflammation mediated by suppression in inflammatory cytokine expression and increased protective IL-10 cytokine expression.

Combined exposure to titanium dioxide and tetracycline induces neurotoxicity in zebrafish

In aquatic environment, engineered materials may inevitably interact with the coexisted organic pollutants, which affect their bioavailability and toxicity. In this contribution, the combined impacts of tetracycline (TC) and titanium dioxide nanoparticles (TiO₂ NPs) on the neurodevelopment of zebrafish larvae were investigated, and the underlying mechanisms were further elucidated. Firstly, it was confirmed that the co-existence of TC would increase the size and decrease the zeta potential of TiO₂ NPs. Following, developmental indicators and motor behaviors were investigated. Our results indicated that co-exposure to TC and TiO₂ NPs exhibited enhanced embryonic malformation rates and abnormal nervous system development in zebrafish embryos. Meanwhile, the locomotor behavior was increased upon treatment of TC and TiO₂ NP. Further, pathway enrichment analyses of transcriptomic sequencing provided detailed information that either lipid metabolism or PPAR signaling pathway were significantly affected in the co-exposure group. Also, TC + TiO₂ NP exposure significantly changed the mRNA expression of neural development-related genes and up-regulated the expression levels of neurotransmitters like 5-hydroxytryptamine, dopamine, acetylcholinesterase, and γ-aminobutyric acid. Taken together, our results demonstrated that the co-exposure of TC and TiO₂ NPs had the potential to cause neurotoxicity in zebrafish embryos.

Therapeutic Applications of Mesenchymal Stem Cell Loaded with Gold Nanoparticles for Regenerative Medicine

In the present study, the various concentrations of AuNP (1.25, 2.5, 5, 10 ppm) were prepared to investigate the biocompatibility, biological performances and cell uptake efficiency via Wharton's jelly mesenchymal stem cells and rat model. The pure AuNP, AuNP combined with Col (AuNP-Col) and FITC conjugated AuNP-Col (AuNP-Col-FITC) were characterized by Ultraviolet-visible spectroscopy (UV-Vis), Fourier-transform infrared spectroscopy (FTIR) and Dynamic Light Scattering (DLS) assays. For in vitro examinations, we explored whether the Wharton's jelly MSCs had better viability, higher CXCR4 expression, greater migration distance and lower apoptotic-related proteins expression with AuNP 1.25 and 2.5 ppm treatments. Furthermore, we considered whether the treatments of 1.25 and 2.5 ppm AuNP could induce the CXCR4 knocked down Wharton's jelly MSCs to express CXCR4 and reduce the expression level of apoptotic proteins. We also treated the Wharton's jelly MSCs with AuNP-Col to investigate the intracellular uptake mechanisms. The evidence demonstrated the cells uptake AuNP-Col through clathrin-mediated endocytosis and the vacuolar-type H⁺-ATPase pathway with good stability inside the cells to avoid lysosomal degradation as well as better uptake efficiency. Additionally, the results from in vivo examinations elucidated the 2.5 ppm of AuNP attenuated foreign body responses and had better retention efficacy with tissue integrity in animal model. In conclusion, the evidence demonstrates that AuNP shows promise as a biosafe nanodrug delivery system for development of regenerative medicine coupled with Wharton's jelly MSCs.

The culprits of superoxide dismutase inactivation under size-dependent stress of ultrafine carbon black: Superoxide anion, genotoxicity and protein corona

As a critical component of atmospheric ultrafine particulates, ultrafine carbon black (UFCB) brings great exposure risk to organisms. At present, the action pathway and activity regulation mechanism of UFCB on functional proteins in vivo are not clear, and the size-dependent effects of UFCB during this process need to be elucidated. Superoxide dismutase (SOD), one of the most applied biomarkers to assess the environmental impact of pollutants, plays crucial roles in resistance to oxidative stress. Here, based on the inactivation of SOD (84.79 %, 86.81 % and 91.70 %) in primary mouse hepatocytes exposed to UFCB (13 nm, 50 nm and 95 nm), oxidative stress, genotoxicity and protein molecular studies were employed to elucidate the inactivation mechanisms. Results showed that inhibition of UFCB-mediated superoxide anion (O₂^-) contributed to a decrease in SOD activity. Furthermore, the significant increase in 8-hydroxy-2-deoxyguanosine content and the comet tail formation indicated the occurrence of DNA damage, supporting that concomitant aberrant transcriptional and protein translational under gene regulation should be responsible for SOD inactivation. At the molecular level, the constricted backbone, reduced content of α-helix and fluorescence sensitization all demonstrated that the attachment-type binding of SOD on UFCB to form the 'protein corona' disrupted protein structure. Enzyme activity assays indicated that SOD backbone tightening and helix decay resulted in decreased activity, which should be another reason for intracellular SOD inactivation. More importantly, the particle sizes of UFCB exert powerful influences on SOD inactivation mechanisms. Smaller UFCB (13 nm) induced more severe O₂^- inhibition and DNA damage, while UFCB_50nm with the best dispersity bound more SOD and induced stronger molecular toxicity, which are their different strengths in stressing SOD inactivation in hepatocytes. Our findings provide novel insights for exploring functional proteins activity and underscore a potentially size-dependent risk of nanoparticles.

Thermal stress and TiO2 nanoparticle-induced oxidative DNA damage and apoptosis in mouse hippocampus

Titanium dioxide (nano-TiO₂) is used abundantly in various industrial products and novel medical therapies. In addition, the impact of climate change on the health and safety will undoubtedly increase in the future. However, the effects of exposure to these nanoparticles and heat stress on hippocampal DNA damage and apoptosis remain unclear. This study was conducted to evaluate the DNA damage and apoptosis in the hippocampal tissue and the physiological responses in mice induced by intraperitoneal (i.p.) administration of TiO₂ nanoparticles (NPs) and heat stress for 14 consecutive days. The results showed that heat stress and TiO₂-NPs were induced in the mouse hippocampus that led to hippocampal reactive oxygen species generation, oxidative damage of DNA, and apoptosis in a partly dose-dependent manner, especially at very hot temperature. High doses of nanosized TiO₂ and severe heat stress significantly damaged the function of the hippocampus, as shown in the comet assay and apoptosis tests. The results of this study may provide data for appropriate measures to control and assess the risk of nano-TiO₂ and thermal stress hazards to human health, especially workers. Safety guidelines and policies should be considered when handling nanomaterials in a hot environment.

Melatonin Protects Against Titanium Oxide-Induced Neurotoxicity: Neurochemical, Neurobehavioral, and Histopathological Evidences

titania (titanium dioxide, TiO₂) is known to induce neurotoxicity and CNS dysfunctions. Numerous studies have explored the neuroprotective effects of melatonin against neurotoxicity. This study evaluates the potential of melatonin to protect against titania-induced neurotoxicity and the role of the Keap1/Nrf2/ARE signaling pathway. One group of animals were treated with Titania (0.045 and 0.075 g/rat) alone while the other with added melatonin (1 mg/kg and 3 mg/kg) and behavioral alterations were assessed using OFT (open field test). Neurochemical and histopathological changes were also studied in the hippocampus by analyzing kelch ECH associating protein 1 (Keap1), nuclear factor erythroid 2-related factor 2 (Nrf2), and antioxidant response element (ARE). It was seen that the animals with added Melatonin had improved behavioral scores in the OFT, like anxiety and motor dysfunction triggered by TiO₂. Melatonin also reduced lipid peroxidation, ROS, GSSG, IL1β, TNFα, Bax, and Keap1 levels, but boosted GSH, GPx, GR, SOD,IL10,IL4, Bcl2, Nrf2, and ARE levels and improved quadruple mitochondrial enzyme complex activity in titania-treated animals. Histopathological examination showed melatonin induced cytoprotection against vacuolization and necrosis in granular cells of DG and pyramidal cells of CA1 area of the hippocampus. In our study, pretreatment with melatonin reduced titania-induced neurotoxicity in the hippocampus through a mechanism potentially mediated by the Keap-1/Nrf2/ARE pathway.

The Use of Medicinal Plant-Derived Metallic Nanoparticles in Theranostics

In the quest to effectively diagnose and treat the diseases that afflict mankind, the development of a tool capable of simultaneous detection and treatment would provide a significant cornerstone for the survival and control of these diseases. Theranostics denotes a portmanteau of therapeutics and diagnostics which simultaneously detect and treat ailments. Research advances have initiated the advent of theranostics in modern medicine. Overall, theranostics are drug delivery systems with molecular or targeted imaging agents integrated into their structure. The application of theranostics is rising exponentially due to the urgent need for treatments that can be utilized for diagnostic imaging as an aid in precision and personalised medicine. Subsequently, the emergence of nanobiotechnology and the green synthesis of metallic nanoparticles (MNPs) has provided one such avenue for nanoscale development and research. Of interest is the drastic rise in the use of medicinal plants in the synthesis of MNPs which have been reported to be potentially effective in the diagnosis and treatment of diseases. At present, medicinal plant-derived MNPs have been cited to have broad pharmacological applications and have been studied for their potential use in the treatment and management of cancer, malaria, microbial and cardiovascular diseases. The subject of this article regards the role of medicinal plants in the synthesis of MNPs and the potential role of MNPs in the field of theranostics.

Curcumin improves D-galactose and normal-aging associated memory impairment in mice: In vivo and in silico-based studies

Aging-induced memory impairment is closely associated with oxidative stress. D-Galactose (D-gal) evokes severe oxidative stress and mimics normal aging in animals. Curcumin, a natural flavonoid, has potent antioxidant and anti-aging properties. There are several proteins like glutathione S-transferase A1 (GSTA1), glutathione S-transferase omega-1 (GSTO1), kelch-like ECH-associated protein 1 (KEAP1), beta-secretase 1 (BACE1), and amine oxidase [flavin-containing] A (MAOA) are commonly involved in oxidative stress and aging. This study aimed to investigate the interaction of curcumin to these proteins and their subsequent effect on aging-associated memory impairment in two robust animal models: D-Gal and normal aged (NA) mice. The aging mice model was developed by administering D-gal intraperitoneally (i.p). Mice (n = 64) were divided into the eight groups (8 mice in each group): Vehicle, Curcumin-Control, D-gal (100mg/kg; i.p), Curcumin + D-gal, Astaxanthin (Ast) + D-gal, Normal Aged (NA), Curcumin (30mg/kg Orally) + NA, Ast (20mg/kg Orally) + NA. Retention and freezing memories were assessed by passive avoidance (PA) and contextual fear conditioning (CFC). Molecular docking was performed to predict curcumin binding with potential molecular targets. Curcumin significantly increased retention time (p < 0.05) and freezing response (p < 0.05) in PA and CFC, respectively. Curcumin profoundly ameliorated the levels of glutathione, superoxide dismutase, catalase, advanced oxidation protein products, nitric oxide, and lipid peroxidation in mice hippocampi. In silico studies revealed favorable binding energies of curcumin with GSTA1, GSTO1, KEAP1, BACE1, and MAOA. Curcumin improves retention and freezing memory in D-gal and nature-induced aging mice. Curcumin ameliorates the levels of oxidative stress biomarkers in mice. Anti-aging effects of curcumin could be attributed to, at least partially, the upregulation of antioxidant enzymes through binding with GSTA1, GSTO1, KEAP1, and inhibition of oxidative damage through binding with BACE1 and MAOA.

Damaging effects of TiO2 nanoparticles on the ovarian cells of Bombyx mori

As a new type of biologically compatible material, TiO₂ NPs are widely used in the industry as additives, drug carriers, and components of skin care products. Due to their wide use, residual TiO₂ NPs in the environment are a safety concern that has attracted extensive attention. In this study, the ovarian cell line BmN of the model organism Bombyx mori was used to reveal the damaging effects of TiO₂ NPs exposure. The results demonstrated that TiO₂ NPs exhibited a dose-dependent effect on the relative cell viability, with significant toxic effects being observed above 20 mg/L. Oxidative damage analysis showed that ROS accumulated significantly in BmN cells after exposure to TiO₂ NPs (P ≤ 0.05) and induced DNA damage. Further analysis revealed that the transcriptional levels of key superoxide dismutase genes (SOD) decreased significantly, while the transcriptions of key genes of the MAPK/NF-κB signaling pathway (P38, MEK, ERK and REL) and the downstream inflammatory factor genes (IL6 and TNFSF5) were all significantly up-regulated (P ≤ 0.05). Overall, our results indicate that exposure to TiO₂ NPs leads to reduced transcription of antioxidant genes, accumulation of peroxides, and inflammation. These findings provide valuable data for the safety evaluation of environmental residues of TiO₂ NPs.

Chitosan attenuated the neurotoxicity-induced titanium dioxide nanoparticles in brain of adult rats

In the current study, we aimed to investigate the neurotoxic effect of oral titanium dioxide nanoparticles (TiO₂ NPs) as well as the possible neuroprotective effect of carboxymethyl chitosan in adult rats for 14 days. The results revealed that TiO₂ NPs inhibited the activity of the acetylcholine esterase enzyme and the levels of serotonin, dopamine, and norepinephrine neurotransmitters. Additionally, it induced neuro-oxidative stress and neuroinflammation via an elevation in MDA levels and IL-6, while GSH concentration, as well as GPx and GST activities, were decreased. TiO₂ NPs induced neuronal apoptosis through upregulation of the expression of caspase-8 and -9 that was further confirmed by increasing caspases-3 and -8 proteins in the hippocampus, cerebral cortex, and cerebellum. The expression of the immediate-early gene BDNF was increased in response to TiO₂ NPs, while that of Arc was reduced. Chitosan significantly attenuated the TiO₂ NPs-induced neurotoxicity regarding AChE, serotonin, MDA, GSH, GPx, GST, IL-6, caspases-8, -9, and -3. Chitosan inhibited the expression of Arc and alleviated the effect of TiO₂ NPs on BDNF expression. Collectively, TiO₂ NPs induced neurotoxicity via their action on vital neuronal biomarkers that might in turn cause brain dysfunction. Despite the neuroprotection of chitosan, its inhibitory effect on Arc expression should be considered.

A Perspective on Reproductive Toxicity of Metallic Nanomaterials

Nanotechnological tools have been greatly exploited in all possible fields. However, advancement of nanotechnology has raised concern about their adverse effects on human and environment. These deleterious effects cannot be ignored and need to be explored due to safety purpose. Several recent studies have demonstrated possible health hazard of nanoparticles on organism. Moreover, studies showed that toxicity of metallic nanomaterial could also lead to reproductive toxicity. Various deleterious effects have demonstrated decreased sperm motility, increased abnormal spermatozoa, altered sperm count, and altered sperm morphology. Morphological and ultrastructural changes also have been reported due to the accumulation of these nanomaterials in reproductive organs. Nonetheless, studies also suggest crossing of metallic nanoparticles through blood testes barrier and generation of oxidative stress which plays major role in reproductive toxicity. In the present study, we have incorporated updated information by gathering all available literature about various metallic nanomaterials and risk related to reproductive system.

Acute titanium dioxide nanoparticles exposure impaired spatial cognitive performance through neurotoxic and oxidative mechanisms in Wistar rats

CONTEXT

Titanium dioxide nanoparticles (TiO2-NPs) are used in many commercial products. However, their effects on human and animal organism remained to be clarified.

OBJECTIVE

The present study aimed to investigate the effects of TiO2-NPs on the behavioural performance, monoamine neurotransmitters and oxidative stress in the rat brain.

MATERIAL AND METHODS

Rats were injected intravenously with a single dose of TiO2-NPs (20 mg/kg body weight) and were subjected to cognitive and emotional tests using Morris water maze and elevated plus maze.

RESULTS

Cognitive capacity as well as the emotional reactivity were significantly disrupted, in TiO2-NPs-administered rats compared to control group. These behavioural effects were correlated with changes in brain neurotransmitter contents reflected by a significant increase in dopamine and a decrease in serotonin levels. TiO2-NPs also induced oxidative stress in the brain manifested by increased levels of H2O2 and malondialdehyde, associated with antioxidant enzymes activities disturbance, in particular, superoxide dismutase and catalase activities. Moreover, TiO2-NPs administration caused histological damages in the brain tissue with abundant lymphocytic clusters, capillary dilations, vascular congestion and oedema.

CONCLUSIONS

Acute intravenous injection of TiO2-NPs impaired behaviour performances through brain biochemical and structural changes and precautions should be taken to their usage in food additive and medical applications.

Current and Advanced Nanomaterials in Dentistry as Regeneration Agents: An Update

In modern dentistry, nanomaterials have strengthened their foothold among tissue engineering strategies for treating bone and dental defects due to a variety of reasons, including trauma and tumors. Besides their finest physiochemical features, the biomimetic characteristics of nanomaterials promote cell growth and stimulate tissue regeneration. The single units of these chemical substances are small-sized particles, usually between 1 to 100 nm, in an unbound state. This unbound state allows particles to constitute aggregates with one or more external dimensions and provide a high surface area. Nanomaterials have brought advances in regenerative dentistry from the laboratory to clinical practice. They are particularly used for creating novel biomimetic nanostructures for cell regeneration, targeted treatment, diagnostics, imaging, and the production of dental materials. In regenerative dentistry, nanostructured matrices and scaffolds help control cell differentiation better. Nanomaterials recapitulate the natural dental architecture and structure and form functional tissues better compared to the conventional autologous and allogenic tissues or alloplastic materials. The reason is that novel nanostructures provide an improved platform for supporting and regulating cell proliferation, differentiation, and migration. In restorative dentistry, nanomaterials are widely used in constructing nanocomposite resins, bonding agents, endodontic sealants, coating materials, and bioceramics. They are also used for making daily dental hygiene products such as mouth rinses. The present article classifies nanostructures and nanocarriers in addition to reviewing their design and applications for bone and dental regeneration.

Pomegranate juice reverses AlCl3-Induced neurotoxicity and improves learning and memory in female mice

BACKGROUND

Aluminum is a neurotoxic element that can accumulate in the brain and cause neurodegenerative disorders. In addition, the antioxidants found in pomegranate juice (PJ) are much more than those existing in other fruits. It was proven to provide protection against neurodegenerative diseases.

OBJECTIVES

This experiment aimed to clarify the amelioration efficiency of PJ against aluminum chloride-induced neurobehavioral and biochemical disorders in female mice.

METHODS

The female mice were given oral administrations for 35 days as follows. The control group received tap water, the PJ groups received 20% and 40% pomegranate juice, the aluminum chloride (AlCl₃) group was treated with 400 mg/kg AlCl₃, and the last two groups received AlCl₃ + 20% PJ and AlCl₃ + 40% PJ, respectively. The neurobehavioral features were assessed by shuttle box, T-maze, and Morris water maze devices. Furthermore, the neurotransmitters and oxidative indicators in the brains of the female mice were determined at the end of experiment.

RESULTS

Significant effects of AlCl₃ were observed on female mice in the body weight, during the behavioral tasks (shuttle box, T-maze, and Morris water maze), and in neurotransmitters and oxidative stress parameters. Pomegranate juice, especially at low concentrations, induced remarkable improvements in body weight, spatial memory and learning during T-maze, Morris water maze and shuttle box tasks, as well as in neurotransmitters and oxidative biomarkers in the AlCl₃-treated female mice.

CONCLUSION

PJ reversed AlCl₃-induced neurotoxicity and improved learning and memory in female mice. However, PJ contains a group of antioxidants that may be considered double-edged swords in the cellular redox status especially at high doses.

Potential neurotoxicity of titanium implants: Prospective, in-vivo and in-vitro study

Titanium dioxide (TiO₂) is a frequently used biomaterial, particularly in orthopedic and dental implants, and it is considered an inert and benign compound. This has resulted in toxicological scrutiny for TiO₂ in the past decade, with numerus studies showing potential pathologic downstream effects. Herein we describe case report of a 77-year-old male with subacute CNS dysfunction, secondary to breakdown of a titanium-based carotid stent and leading to blood levels 1000 times higher (3 ppm) than the reported normal. We prospectively collected tissues adjacent to orthopedic implants and found a positive correlation between titanium concentration and time of implant in the body (r = 0.67, p < 0.02). Rats bearing titanium implants or intravascularly treated with TiO₂ nanoparticles (TiNP) exhibited memory impairments. A human blood-brain barrier (BBB) in-vitro model exposed to TiNP showed paracellular leakiness, which was corroborated in-vivo with the decrease of key BBB transcripts in isolated blood vessels from hippocampi harvested from TiNP-treated mice. Titanium particles rapidly internalized into brain-like endothelial cells via caveolae-mediated endocytosis and macropinocytosis and induced pro-inflammatory reaction with increased expression of pro-inflammatory genes and proteins. Immune reaction was mediated partially by IL-1R and IL-6. In summary, we show that high levels of titanium accumulate in humans adjacent to orthopedic implants, and our in-vivo and in-vitro studies suggest it may be neurotoxic.

Damage to the Blood Brain Barrier Structure and Function from Nano Titanium Dioxide Exposure Involves the Destruction of Key Tight Junction Proteins in the Mouse Brain

Numerous studies have proven that nano titanium dioxide (nano TiO₂) can accumulate in animal brains, where it damages the blood brain barrier (BBB); however, whether this process involves destruction of tight junction proteins in the mouse brain has not been adequately investigated. In this study, mice were exposed to nano TiO₂ for 30 consecutive days, and then we used transmission electron microscopy to observe the BBB ultrastructure and the Evans blue assay to evaluate the permeability of the BBB. Our data suggested that nano TiO₂ damaged the BBB ultrastructure and increased BBB permeability. Furthermore, we used immunofluorescence and Western blotting to examine the expression of key tight junction proteins, including Occludin, ZO-1, and Claudin-5 in the mouse brain. Our data showed that nano TiO₂ reduced Occludin, ZO-1 and Claudin-5 expression. Taken together, nano TiO₂-induced damage to the BBB structure and function may involve the destruction of key tight junction proteins.

Air Pollution Neurotoxicity in the Adult Brain: Emerging Concepts from Experimental Findings

Epidemiological studies are associating elevated exposure to air pollution with increased risk of Alzheimer's disease and other neurodegenerative disorders. In effect, air pollution accelerates many aging conditions that promote cognitive declines of aging. The underlying mechanisms and scale of effects remain largely unknown due to its chemical and physical complexity. Moreover, individual responses to air pollution are shaped by an intricate interface of pollutant mixture with the biological features of the exposed individual such as age, sex, genetic background, underlying diseases, and nutrition, but also other environmental factors including exposure to cigarette smoke. Resolving this complex manifold requires more detailed environmental and lifestyle data on diverse populations, and a systematic experimental approach. Our review aims to summarize the modest existing literature on experimental studies on air pollution neurotoxicity for adult rodents and identify key gaps and emerging challenges as we go forward. It is timely for experimental biologists to critically understand prior findings and develop innovative approaches to this urgent global problem. We hope to increase recognition of the importance of air pollution on brain aging by our colleagues in the neurosciences and in biomedical gerontology, and to support the immediate translation of the findings into public health guidelines for the regulation of remedial environmental factors that accelerate aging processes.

Effect of Saffron Extract on the Hepatotoxicity Induced by Copper Nanoparticles in Male Mice

Background: Nanotechnology application has widespread use in many products. Copper nanoparticles (CuNPs) are widely used in industrial applications. The present study was conducted to investigate the effect of the ethanolic saffron extract (ESE) as a natural antioxidant on the hepatotoxicity induced by CuNPs in male mice. Methods: The characterization of CuNPs was determined using ultraviolet–visible absorption spectroscopy, particle size analysis, zeta potential, Fourier-transform infrared spectroscopy, and electron microscope. The effect of saffron on the hepatotoxicity induced by CuNPs in mice was evaluated by evaluating the survival rate of the mice, oxidative stress, antioxidant capacity, DNA evaluation, as well as its effect on the histology and transmission electron microscope of the liver. Results: The results revealed that all parameters were affected in a dose-dependent manner by CuNPs. These effects have been improved when the treatment of CuNPs is combined with ethanolic saffron extract. Conclusions: We can conclude that saffron and its bioactive crocin portion can prevent CuNP-induced oxidative liver damage. This substance should be useful as a new pharmacological tool for oxidative stress prevention.

Au-TiO2 nanoparticles exposure induced oxidative stress and neurotoxicity in rat

CONTEXT

The Au-TiO2NPs have a wide range of applications and can easily enter the cells. Due to their properties, they can cause toxicity.

OBJECTIVE

It was aimed to test the toxic effects of Au-TiO2 NPs in the brain, heart, kidney and liver of rats in this work.

MATERIALS AND METHODS

All used rats in this work were treated using diverse concentrations (doses) of NPs (100 and 200 mg/kg bw) for 21 days. SOD, CAT, AChE activities and MDA, H2O2, NO contents were evaluated in different organs.

RESULTS

The Au-TiO2 NPs exposure induced biochemical changes in different organs of rats in view of oxidative stress and neurotoxicity by the alteration of the activity of the enzyme of neurotransmitter (AChE activity).

CONCLUSION

The Au-TiO2 NPs have the potential to interact with rat's biochemical status and cause undesirable effects. One of those damaging effects was oxidative stress and neurotoxicity.

CLINICAL SIGNIFICANCE

The study signifies the impact of usage of Au-TiO2 NPs in the medical field for further exploration.

Effects of Au/TiO2 metallic nanoparticles on Unio ravoisieri: assessment through an oxidative stress and toxicity biomarkers

Several studies have been performed on the effects of nanoparticles on aquatic life. However, most of them investigated marine organisms, not freshwater organisms. This study investigated biomarker responses after exposure for 48 h and 7 days to newly made gold and titanium dioxide (Au/TiO₂) metallic nanoparticles (MNPs) (100 and 200 μg·L^-1) using the freshwater bivalve mussel Unio ravoisieri. Biochemical analysis of the gills and digestive glands showed induction of oxidative stress following exposure of the bivalve to Au/TiO₂ MNPs. After 2 or 7 days of exposure to Au/TiO₂ MNPs, both utilized concentrations of Au/TiO₂ MNPs induce an overproduction of H₂O₂. Catalase and glutathione S-transferase activities and the malonedialdehyde content significantly increased in the presence of Au/TiO₂ MNPs, depending on the concentration and target organ. In contrast, acetylcholinesterase activity was significantly inhibited, indicating a discernible disturbance of the cholinergic system in the presence of Au/TiO₂ MNPs. The behavior of the freshwater mussel was altered by reducing the clearance rate. Therefore, U. ravoisieri can be used as a model species in laboratory studies to mirror the presence of MNPs, and the biomarker approach is important for detecting the effects of Au/TiO₂ MNPs. In addition, digestive gland is the target organ of Au/TiO₂NPs contamination.

Tissue-specific genotoxicity and antioxidant imbalance of titanium dioxide nanoparticles (NPTiO2) and inorganic lead (PbII) in a neotropical fish species

The aquatic environment is the major recipient of wastes containing nanoparticles and other contaminants. Titanium dioxide nanoparticles (NPTiO₂) are one of the most produced and used nanoparticle worldwide. This study investigated the toxicity of NPTiO₂, as well as the toxicity interaction between NPTiO₂ and lead (Pb), in response to genetic and biochemical biomarkers using freshwater fish Rhamdia quelen, as an animal model. The results showed genotoxicity in blood and kidney tissues. No effect of NPTiO₂ alone or in co-exposure with Pb on liver genotoxicity were observed. Alterations in the antioxidant hepatic enzymes activities, as well as alterations in glutathione levels indicated that NPTiO₂ alone or in co-exposure with Pb can cause antioxidant imbalance. The lipid peroxidation was also raised after exposure to NPTiO₂. In general, the results of this study indicated that both NPTiO₂ alone and their co-exposure with Pb are capable of producing significant toxic effects in short-term exposure.

Coenzyme Q10 and Silymarin Reduce CCl4-Induced Oxidative Stress and Liver and Kidney Injury in Ovariectomized Rats—Implications for Protective Therapy in Chronic Liver and Kidney Diseases

Oxidative stress is one of the key factors in the pathophysiology of liver disease. The present study aimed to evaluate the potential impact of two antioxidants, namely coenzyme Q10 (CoQ10) and silymarin, on carbon tetrachloride (CCl₄)-induced oxidative stress and hepatic damage in ovariectomized rats. Female Long Evans rats were divided into six groups (n = 6): control, CCl₄, CCl₄ + CoQ10 (200 mg/kg), CCl₄ + silymarin (140 mg/kg), Control + CoQ10, and Control + silymarin. Plasma and tissues from liver and kidney were analyzed for oxidative stress parameters and antioxidant enzyme activities using biochemical assays. Infiltration of inflammatory cells and fibrosis were assessed by histological staining of tissue sections. Both CoQ10 and silymarin significantly lowered serum alanine aminotransferase (ALT), aspartate aminotransferase (AST), and alkaline phosphatase (ALP) levels that were detected to be higher in CCl₄ rats compared to controls. Significant reduction in CCl₄-induced elevated levels of oxidative stress markers malondialdehyde (MDA), nitric oxide (NO), and advanced protein oxidation product (APOP) was observed with both antioxidants. However, in control rats, CoQ10 and silymarin did not produce a significant effect. Histological analysis revealed that CCl₄ markedly increased the level of inflammatory cells infiltration and fibrosis in liver and kidney tissues, but this was significantly reduced in CCl₄ + CoQ10 and CCl₄ + silymarin groups. Taken together, our results suggest that CoQ10 and silymarin can protect the liver against oxidative damage through improved antioxidant enzyme activities and reduced lipid peroxidation. Thus, supplementation of the aforementioned antioxidants may be useful as a therapeutic intervention to protect liver health in chronic liver diseases.

Toxic effects of TiO2 NPs in the blood-milk barrier of the maternal dams and growth of offspring

Titanium dioxide nanoparticles (TiO₂ NPs) are amongst the most frequently used nanomaterial in everyday consumer products, and their widespread applications have raised concerns of the consequent deleterious effects on human health, particularly to vulnerable populations, such as lactating females remains elusive. Therefore, this study was initiated to investigate the detrimental effects and toxic mechanisms induced by TiO₂ NPs in maternal dams and offspring during the lactation period. Dams were randomly divided into three groups. The water (Control; Group I) and TiO₂ NPs (100 mg/kg; Group II) were orally administered from postnatal day 1-20, respectively. The results indicated that TiO₂ NPs could cause toxicity in the dams, such as pathological damages to mammary gland tissues. The excessive accumulation of TiO₂ NPs could induce oxidative stress in the mammary gland, leading to the dysfunctional blood-milk barrier; besides, TiO₂ NPs could also be transferred to offspring via breastfeeding, causing abnormal development of infant. We further accessed the possible underlying molecular mechanism; for this, we orally administered TiO₂ NPs with vitamin E (100 mg/kg; Group III). The results revealed that toxicity induced by TiO₂ NPs was rescued. Collectively, this study presented the deleterious pathological effects of oral exposure to TiO₂ NPs in the mammary gland tissues and blood-milk barrier via the production of reactive oxygen species (ROS) in dams and developmental concerns in offspring. However, the administration of VE could mitigate the toxic effects induced by the TiO₂ NPs.

Molecular mechanism of mice gastric oxidative damage induced by nanoparticulate titanium dioxide

Background

Nanoparticulate titanium dioxide (Nano-TiO₂) has been widely used in food industry, and it has been demonstrated to have adverse effects on mice and human stomach, but its mechanism is rarely concerned. The aim of this study is to determine the effects of nano-TiO₂ on the stomach and confirm the role of oxidative stress and apoptosis in the mice gastric damage caused by nano-TiO₂, as well as its molecular mechanisms.

Methods

Mice were continuously exposed to nano-TiO₂ with 1.25, 2.5 and 5 mg/kg bw by intragastric administration for 9 months in the present study. The ultrastructure, levels of reactive oxygen species (ROS) and peroxides, activities of antioxidant enzymes and mitochondria-related enzymes, ATP contents as well as apoptosis-related factors expression in mice stomach were examined.

Results

Oxidative stress, apoptosis and nano-TiO₂ aggregation were found in gastric mucosal smooth muscle cells after nano-TiO₂ exposure. Nano-TiO₂ exposure also resulted in the over-production of ROS and peroxides, decrease of ATP production and activities of antioxidant enzymes and mitochondria-related ATPases, upregulation of apoptosis-related factors including γH2AX, Cyt c, caspase 3, and p-JNK expression, and down-regulation of Bcl-2 expression in mice stomach.

Conclusions

The gastric toxicity of mice induced by chronic exposure to low dose nano-TiO₂ may be associated with oxidative stress and mitochondria-mediated apoptosis in mice.

Nano-scaled materials may induce severe neurotoxicity upon chronic exposure to brain tissues: A critical appraisal and recent updates on predisposing factors, underlying mechanism, and future prospects

Owing to their tremendous potential, the inference of nano-scaled materials has revolutionized many fields including the medicine and health, particularly for development of various types of targeted drug delivery devices for early prognosis and successful treatment of various diseases, including the brain disorders. Owing to their unique characteristic features, a variety of nanomaterials (particularly, ultra-fine particles (UFPs) have shown tremendous success in achieving the prognostic and therapeutic goals for early prognosis and treatment of various brain maladies such as Alzheimer's disease, Parkinson's disease, brain lymphomas, and other ailments. However, serious attention is needful due to innumerable after-effects of the nanomaterials. Despite their immense contribution in optimizing the prognostic and therapeutic modalities, biological interaction of nanomaterials with various body tissues may produce severe nanotoxicity of different organs including the heart, liver, kidney, lungs, immune system, gastro-intestinal system, skin as well as nervous system. However, in this review, we have primarily focused on nanomaterials-induced neurotoxicity of the brain. Following their translocation into different regions of the brain, nanomaterials may induce neurotoxicity through multiple mechanisms including the oxidative stress, DNA damage, lysosomal dysfunction, inflammatory cascade, apoptosis, genotoxicity, and ultimately necrosis of neuronal cells. Our findings indicated that rigorous toxicological evaluations must be carried out prior to clinical translation of nanomaterials-based formulations to avoid serious neurotoxic complications, which may further lead to develop various neuro-degenerative disorders.

C-reactive Protein Signaling and Chromosomal Abnormalities in Nanotoxicity Induced via Different Doses of TiO2 (80 nm) Boost Liver Function

The wide application of nanotechnology merits the need to clarify their nanotoxicity. In vivo studies have raised concerns about the toxicity of titanium dioxide nanoparticles (TiO₂ NPs), but there are limited data on chromosomal abnormalities induced in hepatic tissue. In this article, the toxicity of three IP doses of TiO₂ NPs (80 nm) (50, 250, and 500 mg/kg) through three time intervals (up to 7, 15, and 45 days) on liver tissue was assessed. Hepatic catalase (CAT), glutathione (GSH), nitric oxide (NOx), and malondialdehyde (MDA) levels varied with the administered dose and exposure time of TiO₂ NPs. As a result, TiO₂ NPs caused a statistically significant decrease in hepatic CAT and GSH activities and a significant alleviation in MDA and NOx levels (p < 0.05), suggesting that the liver exposed to these various doses of TiO₂ NPs suffered from severe oxidative stress. The extent of depletion of antioxidant enzymes and the elevation of MDA and NOx in the liver exposed to the highest dose and duration of TiO₂ NPs 500 mg for 45 days was the greatest, suggesting that the toxicity might be dose and time dependent. Further, C-reactive protein (CRP) as an inflammatory marker was also alleviated, in addition to the apparent chromosomal aberration and liver pathologies including necrotic and fibrotic hepatocytes after exposure to 250 and 500 mg/kg of TiO₂ NPs for 14 and 45 days that were deduced. Hence, nanotechnology-based industries are growing rapidly leading to large-scale production of engineered nanoparticles. They contribute to increased chances of human NPs exposure and health risk.

Alterations in structure of biomolecules using ATR-FTIR and histopathological variations in brain tissue of Channa punctatus exposed to 2Naphthalene sufonate

2Naphthalene sulfonate (2NS) is an intermediate compound used in textile industries. Being nonbiodegradable, the concerns regarding its biotoxicity have risen. In the present investigation the toxic effects of 2NS were analyzed with the help of Attenuated Total Reflection Fourier Transform Infrared (ATR-FTIR), which was used to monitor changes in the vibrational modes of functional groups within the biomolecules. After calculating LD _50, one half of LD ₅₀ i.e. 0.33 mg/15 g b.w. was intraperitoneally administrated and the brain tissue was collected for investigation after 96 h of exposure. The spectra observed revealed the significant differences in absorbance and areas between control and treated groups reflecting the change in proteins, lipids and nucleic acid due to toxicity induced by 2NS. In addition, protein secondary structure analysis was focused in this study, which reveals alterations in α helix and β sheet structure after 2NS intoxication. Histopathology of brain was also studied, which reveals changes in the histology of brain in group treated with 2NS. In conclusion, the study highlighted the application of ATR-FTIR and histopathology for toxicity assessment.

Grape Seed Proanthocyanidin Extract Mitigates Titanium Dioxide Nanoparticle (TiO2-NPs)-Induced Hepatotoxicity Through TLR-4/NF-κB Signaling Pathway

With the progress of nanotechnology, the adverse effects of nanoscale materials are receiving much attention. Inhibition of toll-like receptor 4 (TLR-4)/nuclear factor kappa B (NF-κB) signaling is a hallmark for downregulating the expression of many inflammatory genes implicated in oxidative stress. Therefore, the present study aimed to demonstrate the influence of grape seed proanthocyanidin extract (GSE) on the hepatic TLR-4/ NF-κB signaling pathway in TiO₂-NP-induced liver damage in rats. Forty male Albino rats were divided into 4 groups (n = 10): G1 was used as a control, G2 received TiO₂-NPs (500 mg/kg/day orally) from the 17th to 30th day (acute toxicity), G3 received GSE (75 mg/kg/day orally) for 30 days, and G4 pre- and co-treated with GSE (for 30 days) and TiO₂-NPs (from the 17th to 30th day), with the aforementioned doses. TiO₂-NPs induced severe hepatic injury that was indicated by biochemical alterations in serum liver markers (acetylcholinesterase, ALT, ALP, total proteins, albumin, and direct bilirubin), oxidative stress indicators (MDA, GSH, and catalase), and histopathological alterations as well. Moreover, TiO₂-NPs triggered an inflammatory response via the upregulation of TLR-4, NF-κB, NIK, and TNF-α mRNA expressions. Pre- and co-treatments with GSE alleviated the detrimental effects of TiO₂-NPs which were enforced by the histopathological improvements. These results indicated that GSE effectively protected against TiO₂-NP-induced hepatotoxicity via the inhibition of TLR-4/NF-κB signaling and hence suppressed the production of pro inflammatory cytokines such as TNF-α and improved the antioxidant status of the rats.

Moringa seed extract alleviates titanium oxide nanoparticles (TiO2-NPs)-induced cerebral oxidative damage, and increases cerebral mitochondrial viability

To investigate the influence of Moringa seed extract (MSE) on the cerebral Nrf2/NQO1 signaling in TiO₂-NPs-induced brain damage, 80 male albino rats were divided into four groups (n = 20); group I was used as a control, group II received TiO₂-NPs (500 mg/kg b.w/day orally) for 14 days, group III received MSE (100 mg/kg b.w/day orally) for 30 days, and group IV received MSE an hour before TiO₂-NPs administration with the same doses as before. Administration of TiO₂-NPs was started on the 17th day for both groups (II) and (IV). Administration of MSE significantly increased the cerebral mitochondrial viability and Nrf2 level with a simultaneous increase of NQO1 mRNA expression. This designates a powerful antioxidant effect of MSE which is indicated by a significant reduction of INOS expression, MDA, TOS, OSI levels, and DNA fragmentation % with a significant increase of GSH concentration, SOD activities, and TAC. MSE possesses an anti-inflammatory effect by a significant reduction of IL-1β and TNF-α levels, and anti-apoptotic effect manifested by a significant reduction of caspase-3 and Fas levels. In harmonization, dopamine, serotonin concentrations, and acetylcholinesterase activities return back to normal as compared to control group. These results were confirmed by the histopathological features which were alleviated with MSE administration. In conclusion, Nrf2 plays a pivotal role in the mechanism of TiO₂-NPs cerebral toxicity and MSE as a Nrf2 activator can provide a powerful cerebroprotective effect, whereas MSE increased the Nrf2 expression and consequently restore the antioxidant activity of brain cells by increasing NQO1 gene expression and cerebral mitochondrial viability as well as inhibition of pro-inflammatory and apoptotic mediators.

Toxicity assessment of reduced graphene oxide and titanium dioxide nanomaterials on gram-positive and gram-negative bacteria under normal laboratory lighting condition

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Bacterial growth curve deviates from its normal pattern after the exposure to nanoparticles.

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Cell wall structure of Gram-positive and Gram-negative bacteria played the major factor contribute to its toxicity effect towards nanoparticles exposure.

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Smaller particle had greater impact on the bacterial growth.

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E. coli and B. subtilis cells suffered from morphological changes upon nanoparticles exposure.

Toxicity effect of reduced graphene oxide (rGO) and titanium dioxide (TiO₂) nanomaterials (NMs) on Gram-positive (Bacillus subtilis) and Gram-negative (Escherichia coli) bacteria was assessed. For both strains, study demonstrated that the toxicity was time and concentration dependent which led to reduction in growth rate and cell death. Upon NMs exposure, an instantaneous cell death in E. coli culture was observed. This is in contrast with B. subtilis, in which the culture growth remained in the log phase; however their growth rate constant, μg was reduced by ∼70%. The discrepancy between E. coli and B. subtilis was due to strain-specific response upon contact with NMs. TEM, SEM and EDX analysis revealed direct physical surface-surface interaction, as evidence from the adherence of NMs on the cell surface.

Neurotoxicology of Nanomaterials

The remarkable advances coming about through nanotechnology promise to revolutionize many aspects of modern life; however, these advances come with a responsibility for due diligence to ensure that they are not accompanied by adverse consequences for human health or the environment. Many novel nanomaterials (having at least one dimension <100 nm) could be highly mobile if released into the environment and are also very reactive, which has raised concerns for potential adverse impacts including, among others, the potential for neurotoxicity. Several lines of evidence led to concerns for neurotoxicity, but perhaps none more than observations that inhaled nanoparticles impinging on the mucosal surface of the nasal epithelium could be internalized into olfactory receptor neurons and transported by axoplasmic transport into the olfactory bulbs without crossing the blood-brain barrier. From the olfactory bulb, there is concern that nanomaterials may be transported deeper into the brain and affect other brain structures. Of course, people will not be exposed to only engineered nanomaterials, but rather such exposures will occur in a complex mixture of environmental materials, some of which are incidentally generated particles of a similar inhalable size range to engineered nanomaterials. To date, most experimental studies of potential neurotoxicity of nanomaterials have not considered the potential exposure sources and pathways that could lead to exposure, and most studies of nanomaterial exposure have not considered potential neurotoxicity. Here, we present a review of potential sources of exposures to nanoparticles, along with a review of the literature on potential neurotoxicity of nanomaterials. We employ the linked concepts of an aggregate exposure pathway (AEP) and an adverse outcome pathway (AOP) to organize and present the material. The AEP includes a sequence of key events progressing from material sources, release to environmental media, external exposure, internal exposure, and distribution to the target site. The AOP begins with toxicant at the target site causing a molecular initiating event and, like the AEP, progress sequentially to actions at the level of the cell, organ, individual, and population. Reports of nanomaterial actions are described at every key event along the AEP and AOP, except for changes in exposed populations that have not yet been observed. At this last stage, however, there is ample evidence of population level effects from exposure to ambient air particles that may act similarly to engineered nanomaterials. The data give an overall impression that current exposure levels may be considerably lower than those reported experimentally to be neurotoxic. This impression, however, is tempered by the absence of long-term exposure studies with realistic routes and levels of exposure to address concerns for chronic accumulation of materials or damage. Further, missing across the board are "key event relationships", which are quantitative expressions linking the key events of either the AEP or the AOP, making it impossible to quantitatively project the likelihood of adverse neurotoxic effects from exposure to nanomaterials or to estimate margins of exposure for such relationships.

Derivation of whole blood biomonitoring equivalents for titanium for the interpretation of biomonitoring data

Biomonitoring equivalents (BEs) have been increasingly applied for biomonitoring purposes by regulatory bodies worldwide. The present report describes the development of a BE for titanium based on a 4-step process: (i) identification of a critical study/point of departure (PoD) supporting an established oral exposure guidance value (OEGV);, (ii) review the available oral PK data and application of a pharmacokinetic model for titanium; (iii) selection of the most appropriate biomarker of exposure in a specific tissue and calculation of steady-state tissue levels corresponding to the PoD in the critical study; and (iv) derivation of BE value adjusting for the uncertainties considered in the original OEGV assessment. Using the above 4-step approach, a blood BE value of 32.5 μg titanium/L was derived. Key components of the analysis included a pharmacokinetic model developed by investigators at the Netherlands National Institute of Public Health (RIVM) and a two-year rodent bioassay of titanium conducted by the US National Cancer Institute. The most sensitive pharmacokinetic parameter involved in the current BE derivation is the oral absorption factor of 0.02%. The provisional BE proposed in this article may be updated as new information on the pharmacokinetics of titanium becomes available.

Nitric oxide synthase-mediated sub-chronic injury and recovery in the small intestine of mice after oral administration with halloysite nanotubes

Natural halloysite nanotubes (HNTs) with a hollow lumen have been widely applied in many fields, such as water purification, drug carriers, cosmetics, antibacterial, and scaffolds for tissue engineering. However, their in vivo toxicity is still largely unclear. The aim of this study is to evaluate sub-chronic oral toxicity of HNTs in the small intestine of mice. The results demonstrated that oral HNTs at low dose (5 mg/kg) for 30 days promoted mouse growth with no obvious adverse effect on the small intestine. The promotive effect on mouse growth disappeared after cessation of oral administration of HNTs. Oral HNTs at high dose (50 mg/kg) for 30 days induced aluminum (Al) and silicon (Si) accumulation and oxidative stress in the small intestine, which caused significant increases in the levels of cyclooxygenase-2 (COX-2) and nitric oxide synthase (iNOS) and inflammatory response and iNOS-mediated damages in the organ. Oral HNTs-induced changes in the small intestine at high dose were not observed after a 30-day recovery period. These findings provided the first evidence that oral HNTs-induced sub-chronic toxicity in the small intestine was reversible. The results suggest that HNTs at low concentration in environments have no adverse effect on mice, while there are health risks to mice under severe contamination by HNTs.

Insights into Theranostic Properties of Titanium Dioxide for Nanomedicine

Titanium dioxide (TiO2) nanostructures exhibit a broad range of theranostic properties that make them attractive for biomedical applications. TiO2 nanostructures promise to improve current theranostic strategies by leveraging the enhanced quantum confinement, thermal conversion, specific surface area, and surface activity. This review highlights certain important aspects of fabrication strategies, which are employed to generate multifunctional TiO2 nanostructures, while outlining post-fabrication techniques with an emphasis on their suitability for nanomedicine. The biodistribution, toxicity, biocompatibility, cellular adhesion, and endocytosis of these nanostructures, when exposed to biological microenvironments, are examined in regard to their geometry, size, and surface chemistry. The final section focuses on recent biomedical applications of TiO2 nanostructures, specifically evaluating therapeutic delivery, photodynamic and sonodynamic therapy, bioimaging, biosensing, tissue regeneration, as well as chronic wound healing.

Nanotechnology Scaffolds for Alveolar Bone Regeneration

In oral biology, tissue engineering aims at regenerating functional tissues through a series of key events that occur during alveolar/periodontal tissue formation and growth, by means of scaffolds that deliver signaling molecules and cells. Due to their excellent physicochemical properties and biomimetic features, nanomaterials are attractive alternatives offering many advantages for stimulating cell growth and promoting tissue regeneration through tissue engineering. The main aim of this article was to review the currently available literature to provide an overview of the different nano-scale scaffolds as key factors of tissue engineering for alveolar bone regeneration procedures. In this narrative review, PubMed, Medline, Scopus and Cochrane electronic databases were searched using key words like “tissue engineering”, “regenerative medicine”, “alveolar bone defects”, “alveolar bone regeneration”, “nanomaterials”, “scaffolds”, “nanospheres” and “nanofibrous scaffolds”. No limitation regarding language, publication date and study design was set. Hand-searching of the reference list of identified articles was also undertaken. The aim of this article was to give a brief introduction to review the role of different nanoscaffolds for bone regeneration and the main focus was set to underline their role for alveolar bone regeneration procedures.

Activation of Nrf2 by lead sulfide nanoparticles induces impairment of learning and memory

This study aimed to determine, using rats, the mechanism of action of PbS NPs, exposure to which results in persistent alterations in nervous system function. The results showed that PbS NPs significantly impaired learning and memory.

Neurotoxicity mediated by oxidative stress caused by titanium dioxide nanoparticles in human neuroblastoma (SH-SY5Y) cells

BACKGROUND

Titanium is widely used in biomedicine. Due to biotribocorrosion, titanium dioxide (TiO₂) nanoparticles (NPs) can be released from the titanium implant surface, enter the systemic circulation, and migrate to various organs and tissues including the brain. A previous study showed that 5 nm TiO₂ NPs reached the highest concentration in the brain. Even though TiO₂ NPs are believed to possess low toxicity, little is known about their neurotoxic effects. The aim of the study was to evaluate in vitro the effects of 5 nm TiO₂ NPs on a human neuroblastoma (SH-SY5Y) cell line.

METHODS

Cell cultures were divided into non-exposed and exposed to TiO₂ NPs for 24 h. The following were evaluated: reactive oxygen species (ROS) generation, apoptosis, cellular antioxidant response, endoplasmic reticulum stress and autophagy.

RESULTS

Exposure to TiO₂ NPs induced ROS generation in a dose dependent manner, with values reaching up to 10 fold those of controls (p < 0.001). Nrf2 nuclear localization and autophagy, also increased in a dose dependent manner. Apoptosis increased by 4- to 10-fold compared to the control group, depending on the dose employed.

CONCLUSIONS

Our results show that TiO₂ NPs cause ROS increase, induction of ER stress, Nrf2 cytoplasmic translocation to the nucleus and apoptosis. Thus, neuroblastoma cell response to TiO₂ NPs may be associated with an imbalance of the oxidative metabolism where endoplasmic reticulum-mediated signal pathway seems to be the main neurotoxic mechanism.

Exposure to PbSe Nanoparticles and Male Reproductive Damage in a Rat Model

PbSe nanoparticles (PbSe-NPs) attract ever-growing interest owing to their great promise in various fields. However, potential toxic effects of PbSe-NPs on male reproductive systems have not been reported. This study aimed to determine whether early-life exposure to PbSe-NPs could affect male reproductive systems and other related health effects in rats. The male rats were intraperitoneally injected with 10 mg/kg/week PbSe-NPs for 60 days followed by a series of reproductive-related analyses. We found that the nanoparticles could accumulate in testes in a size-dependent manner. Furthermore, accumulation of PbSe-NPs resulted in oxidative stress and disorder of normal serum sex hormones. Endoplasmic reticulum and mitochondria-mediated cell apoptosis were triggered via oxidative stress, as shown by upregulation of cytoplasmic Cyt-c, Bax, cleaved Caspase-3, GRP78, and Caspase-12. Notably, PbSe-NP administration led to reduction in the quantity and quality of sperm, which caused a great fertility decrease. In contrast, released Pb²⁺ from PbSe-NPs did not result in any testis toxicity and fertility declines. These results demonstrate that PbSe-NPs could cause severe reproductive toxicity in a size-dependent manner and these toxic effects should be responsible for PbSe-NPs themselves rather than released Pb²⁺. The application of PbSe-NPs might be a double-edged sword, and corresponding measures should be taken before use.

In deep evaluation of the neurotoxicity of orally administered TiO2 nanoparticles

Titanium dioxide nanoparticles were widely used in food as dietary supplements, in drugs, in toothpaste, ect. Few numbers of studies were interested to the neurotoxicity of TiO₂ NPs through oral pathway. The present study aims firstly to understand the connection between the physicochemical properties of TiO₂ NPs and their associated toxicological oral pathway by evaluation the colloidal stability of TiO₂ NPs over time in different media simulating physiological gastric, intestinal and serum conditions at 37 °C to be close to the oral administraton. Secondly, this study aims to evaluate the neurotoxicity of a subchronic intragastric administration of TiO₂ NPs to rats. Different doses of anatase TiO₂ NPs were administrated to Wistar rats every day for consecutives eight weeks. Titanium (Ti) content in brain, oxidative antioxidant biomarkers, lipid peroxidation, nitric oxide (NO) levels, tumor necrosis factor-alpha (TNF-α) levels, histophatological changes, degenerated and apoptosis neurons were investigated. Results suggested that TiO₂ NPs can reach the brain and cross the brain blood barrier (BBB) to been accumulated in the brain of rats causing cerebral oxidative stress damage, increasing NO levels and histopathological injury. At higher dose, we observed the most cerebral injury by the highest accumulation of Ti and by the remarkable increase of TNF-α besides to the most increase of degenerated and apoptosis neurons in the brain of exposed rats. TiO₂ NPs led to a neurotoxic damage accompanied by the increase of degenerated and apoptotic neurons in cerebral cortex.