The inflammatory response to silver and titanium dioxide nanoparticles in the central nervous system

Recent developments in intranasal drug delivery of nanomedicines for the treatment of neuropsychiatric disorders

Neuropsychiatric disorders are multifaceted syndromes with confounding neurological explanations. It includes anxiety, depression, autism spectrum disorder, attention deficit hyperactivity disorder, schizophrenia, Tourette's syndrome, delirium, dementia, vascular cognitive impairment, and apathy etc. Globally, these disorders occupy 15% of all diseases. As per the WHO, India has one of the largest populations of people with mental illnesses worldwide. The blood-brain barrier (BBB) makes it extremely difficult to distribute medicine to target cells in the brain tissues. However, it is possible through novel advancements in nanotechnology, molecular biology, and neurosciences. One such cutting-edge delivery method, nose-to-brain (N2B) drug delivery using nanoformulation (NF), overcomes traditional drug formulation and delivery limitations. Later offers more controlled drug release, better bioavailability, improved patient acceptance, reduced biological interference, and circumvention of BBB. When medicines are delivered via the intranasal (IN) route, they enter the nasal cavity and go to the brain via connections between the olfactory and trigeminal nerves and the nasal mucosa in N2B. Delivering phytochemical, bioactive and synthetic NF is being investigated with the N2B delivery strategy. The mucociliary clearance, enzyme degradation, and drug translocations by efflux mechanisms are significant issues associated with N2B delivery. This review article discusses the types of neuropsychiatric disorders and their treatment with plant-derived as well as synthetic drug-loaded NFs administered via the IN-delivery system. In conclusion, this review provided a comprehensive and critical overview of the IN applicability of plant-derived NFs for psychiatric disorders.

The discovery of regional neurotoxicity-associated metabolic alterations induced by carbon quantum dots in brain of mice using a spatial metabolomics analysis

BACKGROUND

Recently, carbon quantum dots (CQDs) have been widely used in various fields, especially in the diagnosis and therapy of neurological disorders, due to their excellent prospects. However, the associated inevitable exposure of CQDs to the environment and the public could have serious severe consequences limiting their safe application and sustainable development.

RESULTS

In this study, we found that intranasal treatment of 5 mg/kg BW (20 µL/nose of 0.5 mg/mL) CQDs affected the distribution of multiple metabolites and associated pathways in the brain of mice through the airflow-assisted desorption electrospray ionization mass spectrometry imaging (AFADESI-MSI) technique, which proved effective in discovery has proven to be significantly alerted and research into tissue-specific toxic biomarkers and molecular toxicity analysis. The neurotoxic biomarkers of CQDs identified by MSI analysis mainly contained aminos, lipids and lipid-like molecules which are involved in arginine and proline metabolism, biosynthesis of unsaturated fatty acids, and glutamine and glutamate metabolism, etc. as well as related metabolic enzymes. The levels or expressions of these metabolites and enzymes changed by CQDs in different brain regions would induce neuroinflammation, organelle damage, oxidative stress and multiple programmed cell deaths (PCDs), leading to neurodegeneration, such as Parkinson's disease-like symptoms. This study enlightened risk assessments and interventions of QD-type or carbon-based nanoparticles on the nervous system based on toxic biomarkers regarding region-specific profiling of altered metabolic signatures.

CONCLUSION

These findings provide information to advance knowledge of neurotoxic effects of CQDs and guide their further safety evaluation.

The toxicological effects of nano titanium dioxide on target organs and mechanisms of toxicity

Nano-titanium dioxide (TiO2 NPs) is widely used for its extremely high stability, corrosion resistance, and photocatalytic properties and has penetrated into various fields of production and life. Assessing its toxicity to different organs should be a key part of preclinical toxicity assessment of TiO2 NPs, which is relatively incomprehensive yet. Therefore, this review focuses on the toxic effects of TiO2 NPs on various organs in mammals and biological mechanisms from different organs. The commonality of toxic effects on various target organs reflected in tissue structure damage and dysfunction, such as liver damage and dysfunction; pulmonary fibrosis; and renal impairment (including hematuria and nephritis); damage of brain tissue and neurons; alteration of intestinal villi; and weight loss. And effects on the reproductive system are affected by different sexes, including ovarian dysfunction, testicular development damage, and sperm viability reduction. We believe that the toxic mechanisms of TiO2 NPs in target organs have commonalities, such as oxidative stress, inflammatory responses, and organelle damage. However, different target organ toxicities also have their specificities. TiO2 NPs disturb the intestinal flora and cause undesirable changes in feces products. And in spleen are infiltration of neutrophils and lymphadenopathy and eventually immune deficiency. Although the toxic pathways are different, but there may be a close link between the different toxic pathways. In this article, the main manifestations of the toxic effects of titanium dioxide nanoparticles on major mammalian organs are reviewed, in order to provide basic data for their better application from a medical perspective.

Ag/TiO2 nanohybrids induce fibrosis-related epithelial-mesenchymal transition in lung epithelial cells and the influences of silver content and silver particle size

The controlled synthesis of silver nanoparticles (AgNPs) decorated TiO2 nanohybrids (Ag/TiO2) for photocatalysis has received considerable attention. These photocatalysts are widely used in environment and energy, resulting in human exposure through inhalation. Pure TiO2 is generally considered a low-toxic nanomaterial. However, little is known about the toxicity after AgNPs loading. In this study, silver-decorated TiO2 nanohybrids were controllably synthesized by the photodeposition method, and their toxic effects on murine lung and human lung epithelial cells were explored. As a result, silver loading significantly enhanced the effect of TiO2 photocatalyst on EMT in lung epithelial cells, potentially acting as a pro-fibrogenic effect in murine lung. Meanwhile, the increase in autophagy vacuoles, LC3-II marker, stub-RFP-sens-GFP-LC3 fluorescence assay, and LC3 turnover assay showed that silver loading also significantly increased autophagy flux. Furthermore, analysis of autophagy inhibition by 3-Methyladenine indicated that the promotion of EMT by silver loading was related to the increased autophagy flux. Intriguingly, the autophagy and EMT biological effects could be alleviated when the silver loading amount was reduced or silver particle size was increased, and the enhanced pro-fibrogenic effect was mitigated at the same time. This study supplemented safety information of Ag-decorated TiO2 nanohybrids and provided methods of controlled synthesis for reducing toxicity.

Long-term application of silver nanoparticles in dental restoration materials: potential toxic injury to the CNS

Silver nanoparticles (AgNPs) have durable and remarkable antimicrobial effects on pathogenic microorganisms, such as bacteria and fungi, in dental plaques. As such, they are widely added to dental restoration materials, including composite resins, denture bases, adhesives, and implants, to solve the problems of denture stomatitis, peri-implant inflammation, and oral infection caused by the long-term use of these dental restoration materials. However, AgNPs can be absorbed into the blood circulatory system through the nasal/oral mucosa, lungs, gastrointestinal tract, skin, and other pathways and then distributed into the lungs, kidneys, liver, spleen, and testes, thereby causing toxic injury to these tissues and organs. It can even be transported across the blood-brain barrier (BBB) and continuously accumulate in brain tissues, causing injury and dysfunction of neurons and glial cells; consequently, neurotoxicity occurs. Other nanomaterials with antibacterial or remineralization properties are added to dental restoration materials with AgNPs. However, studies have yet to reveal the neurotoxicity caused by dental restoration materials containing AgNPs. In this review, we summarize the application of AgNPs in dental restoration materials, the mechanism of AgNPs in cytotoxicity and toxic injury to the BBB, and the related research on the accumulation of AgNPs to cause changes of neurotoxicity. We also discuss the mechanisms of neurotoxicity caused by AgNPs and the mode and rate of AgNPs released from dental restorative materials added with AgNPs to evaluate the probability of neurotoxic injury to the central nervous system (CNS), and then provide a theoretical basis for developing new composite dental restoration materials. Mechanism of neurotoxicity caused by AgNPs: AgNPs in the blood circulation enter the brain tissue after being transported across the BBB through transendothelial cell pathway and paracellular transport pathway, and continuously accumulate in brain tissue, causing damage and dysfunction of neurons and glial cells which ultimately leads to neurotoxicity. The uptake of AgNPs by neurons, astrocytes and microglia causes damage to these cells. AgNPs with non-neurotoxic level often increases the secretion of a variety of cytokines, up-regulates the expression of metallothionein in glial cells, even up-regulates autophagy and inflammation response to protect neurons from the toxic damage of AgNPs. However, the protective effect of glial cells induced by AgNPs exposure to neurotoxic levels is insufficient, which leads to neuronal damage and dysfunction and even neuronal programmed cell death, eventually cause neurotoxicity.

Titanium dioxide nanoparticles: revealing the mechanisms underlying hepatotoxicity and effects in the gut microbiota

Numerous studies in recent years have questioned the safety of oral exposure to titanium dioxide nanoparticles (TiO2 NPs). TiO2 NPs are not only likely to accumulate in the gastrointestinal tract, but they are also found to penetrate the body circulation and reach distant organs. The liver, which is considered to be a target organ for nanoparticles, is of particular concern. TiO2 NPs accumulate in the liver and cause oxidative stress and inflammatory reactions, resulting in pathological damage. The impact of TiO2 NPs on liver aspartate aminotransferase (AST) and alanine aminotransferase (ALT) was studied using a meta-analysis. According to the findings, TiO2 NPs exposure can cause an elevation in AST and ALT levels in the blood. Furthermore, TiO2 NPs are eliminated mostly through feces, and their lengthy residence in the gut exposes them to microbiota. The gut microbiota is also dysbiotic due to titanium dioxide's antibacterial capabilities. This further leads to changes in the amount of microbiota metabolites, which can reach the liver with blood circulation and trigger hepatotoxicity through the gut-liver axis. This review examines the gut-liver axis to assess the effects of gut microbiota dysbiosis on the liver to provide suggestions for assessing the gut-hepatotoxicity of TiO2 NPs.

Application of Inorganic Nanomaterials in Cultural Heritage Conservation, Risk of Toxicity, and Preventive Measures

Nanotechnology has allowed for significant progress in architectural, artistic, archaeological, or museum heritage conservation for repairing and preventing damages produced by deterioration agents (weathering, contaminants, or biological actions). This review analyzes the current treatments using nanomaterials, including consolidants, biocides, hydrophobic protectives, mechanical resistance improvers, flame-retardants, and multifunctional nanocomposites. Unfortunately, nanomaterials can affect human and animal health, altering the environment. Right now, it is a priority to stop to analyze its advantages and disadvantages. Therefore, the aims are to raise awareness about the nanotoxicity risks during handling and the subsequent environmental exposure to all those directly or indirectly involved in conservation processes. It reports the human-body interaction mechanisms and provides guidelines for preventing or controlling its toxicity, mentioning the current toxicity research of main compounds and emphasizing the need to provide more information about morphological, structural, and specific features that ultimately contribute to understanding their toxicity. It provides information about the current documents of international organizations (European Commission, NIOSH, OECD, Countries Normative) about worker protection, isolation, laboratory ventilation control, and debris management. Furthermore, it reports the qualitative risk assessment methods, management strategies, dose control, and focus/receptor relationship, besides the latest trends of using nanomaterials in masks and gas emissions control devices, discussing their risk of toxicity.

Biogenic silver NPs alleviate LPS-induced neuroinflammation in a human fetal brain-derived cell line: Molecular switch to the M2 phenotype, modulation of TLR4/MyD88 and Nrf2/HO-1 signaling pathways, and molecular docking analysis

Silver nanoparticles (AgNPs) have inconsistent findings against inflammation. Although a wealth of literature on the beneficial effects of green-synthesized AgNPs has been published, a detailed mechanistic study of green AgNPs on the protective effects against lipopolysaccharide (LPS)-induced neuroinflammation using human microglial cells (HMC3) has not yet been reported. For the first time, we studied the inhibitory effect of biogenic AgNPs on inflammation and oxidative stress induced by LPS in HMC3 cells. X-ray photoelectron spectroscopy, Fourier-transform infrared spectroscopy, and transmission electron microscopy were used to characterize AgNPs produced from honeyberry. Co-treatment with AgNPs significantly reduced mRNA expressions of inflammatory molecules such as interleukin (IL)-6 and tumor necrosis factor-α, while increasing the expressions of anti-inflammatory markers such as IL-10 and transforming growth factor (TGF)-β. HMC3 cells were also switched from M1 to M2, as shown by lower expression of M1 markers such as cluster of differentiation (CD)80, CD86, and CD68 and higher expression of M2 markers such as CD206, CD163, and triggering receptors expressed on myeloid cells (TREM2). Furthermore, AgNPs inhibited LPS-induced toll-like receptor (TLR)4 signaling, as evidenced by decreased expression of myeloid differentiation factor 88 (MyD88) and TLR4. In addition, AgNPs reduced the production of reactive oxygen species (ROS) and enhanced the expression of nuclear factor-E2-related factor 2 (Nrf2) and heme oxygenase-1 (HO-1), while decreasing the expression of inducible nitric oxide synthase. The docking score of the honeyberry phytoconstituents ranged from -14.93 to - 4.28 KJ/mol. In conclusion, biogenic AgNPs protect against neuroinflammation and oxidative stress by targeting TLR4/MyD88 and Nrf2/HO-1 signaling pathways in a LPS-induced in vitro model. Biogenic AgNPs could be utilized as potential nanomedicine against LPS-induced inflammatory disorders.

Nanomaterials and Their Impact on the Immune System

Nanomaterials have been the focus of intensive development and research in the medical and industrial sectors over the past several decades. Some studies have found that these compounds can have a detrimental impact on living organisms, including their cellular components. Despite the obvious advantages of using nanomaterials in a wide range of applications, there is sometimes skepticism caused by the lack of substantial proof that evaluates potential toxicities. The interactions of nanoparticles (NPs) with cells of the immune system and their biomolecule pathways are an area of interest for researchers. It is possible to modify NPs so that they are not recognized by the immune system or so that they suppress or stimulate the immune system in a targeted manner. In this review, we look at the literature on nanomaterials for immunostimulation and immunosuppression and their impact on how changing the physicochemical features of the particles could alter their interactions with immune cells for the better or for the worse (immunotoxicity). We also look into whether the NPs have a unique or unexpected (but desired) effect on the immune system, and whether the surface grafting of polymers or surface coatings makes stealth nanomaterials that the immune system cannot find and get rid of.

Sleep matters: Neurodegeneration spectrum heterogeneity, combustion and friction ultrafine particles, industrial nanoparticle pollution, and sleep disorders-Denial is not an option

Sustained exposures to ubiquitous outdoor/indoor fine particulate matter (PM_2.5), including combustion and friction ultrafine PM (UFPM) and industrial nanoparticles (NPs) starting in utero, are linked to early pediatric and young adulthood aberrant neural protein accumulation, including hyperphosphorylated tau (p-tau), beta-amyloid (Aβ_{1 - 42}), α-synuclein (α syn) and TAR DNA-binding protein 43 (TDP-43), hallmarks of Alzheimer's (AD), Parkinson's disease (PD), frontotemporal lobar degeneration (FTLD), and amyotrophic lateral sclerosis (ALS). UFPM from anthropogenic and natural sources and NPs enter the brain through the nasal/olfactory pathway, lung, gastrointestinal (GI) tract, skin, and placental barriers. On a global scale, the most important sources of outdoor UFPM are motor traffic emissions. This study focuses on the neuropathology heterogeneity and overlap of AD, PD, FTLD, and ALS in older adults, their similarities with the neuropathology of young, highly exposed urbanites, and their strong link with sleep disorders. Critical information includes how this UFPM and NPs cross all biological barriers, interact with brain soluble proteins and key organelles, and result in the oxidative, endoplasmic reticulum, and mitochondrial stress, neuroinflammation, DNA damage, protein aggregation and misfolding, and faulty complex protein quality control. The brain toxicity of UFPM and NPs makes them powerful candidates for early development and progression of fatal common neurodegenerative diseases, all having sleep disturbances. A detailed residential history, proximity to high-traffic roads, occupational histories, exposures to high-emission sources (i.e., factories, burning pits, forest fires, and airports), indoor PM sources (tobacco, wood burning in winter, cooking fumes, and microplastics in house dust), and consumption of industrial NPs, along with neurocognitive and neuropsychiatric histories, are critical. Environmental pollution is a ubiquitous, early, and cumulative risk factor for neurodegeneration and sleep disorders. Prevention of deadly neurological diseases associated with air pollution should be a public health priority.

Improvement of the antioxidant activity of thyme essential oil against biosynthesized titanium dioxide nanoparticles-induced oxidative stress, DNA damage, and disturbances in gene expression in vivo

BACKGROUND

Titanium dioxide nanoparticles (TiO₂-NPs) are widely utilized in medicine and industry; however, their safety in biological organisms is still unclear. In this study, we determined the bioactive constitutes of thyme essential oil (TEO) and utilized the nanoemulsion technique to improve its protective efficiency against oxidative stress, genotoxicity, and DNA damage of biosynthesized titanium dioxide nanoparticles (TiO₂-NPs).

METHODS

TEO nanoemulsion (TEON) was prepared using whey protein isolate (WPI). Sixty male Sprague-Dawley rats were divided into six groups and treated orally for 21 days including the control group, TEO, or TEON- treated groups (5 mg/kg b.w), TiO₂-NPs-treated group (50 mg/kg b.w) and the groups received TiO₂-NPs plus TEO or TEON. Blood and tissues samples were collected for different assays.

RESULTS

The GC-MS analysis identified 17 bioactive compounds in TEO and thymol and carvacrol were the major compounds. TEON was irregular with average particles size of 230 ± 3.7 nm and ζ-potential of -24.17 mV. However, TiO2-NPs showed a polygonal shape with an average size of 50 ± 2.4 nm and ζ-potential of -30.44 mV. Animals that received TiO2-NPs showed severe disturbances in liver and kidney indices, lipid profile, oxidant/antioxidant indices, inflammatory cytokines, gene expressions, increased DNA damage, and pathological changes in hepatic tissue. Both TEO and TEON showed potential protection against these hazards and TEON was more effective than TEO.

CONCLUSION

The nanoemulsion of TEO enhances the oil bioactivity, improves its antioxidant characteristics, and protects against oxidative damage and genotoxicity of TiO2-NPs.

Nanogels as Novel Nanocarrier Systems for Efficient Delivery of CNS Therapeutics

Nanogels have come out as a great potential drug delivery platform due to its prominently high colloidal stability, high drug loading, core-shell structure, good permeation property and can be responsive to environmental stimuli. Such nanoscopic drug carriers have more excellent abilities over conventional nanomaterials for permeating to brain parenchyma in vitro and in vivo. Nanogel-based system can be nanoengineered to bypass physiological barriers via non-invasive treatment, rendering it a most suitable platform for the management of neurological conditions such as neurodegenerative disorders, brain tumors, epilepsy and ischemic stroke, etc. Therapeutics of central nervous system (CNS) diseases have shown marked limited site-specific delivery of CNS by the poor access of various drugs into the brain, due to the presences of the blood-brain barrier (BBB) and blood-cerebrospinal fluid barrier (BCSFB). Hence, the availability of therapeutics delivery strategies is considered as one of the most major challenges facing the treatment of CNS diseases. The primary objective of this review is to elaborate the newer advances of nanogel for CNS drugs delivery, discuss the early preclinical success in the field of nanogel technology and highlight different insights on its potential neurotoxicity.

Nanoparticle Effects on Stress Response Pathways and Nanoparticle-Protein Interactions

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

A protective role of autophagy in fine airborne particulate matter-induced apoptosis in LN-229 cells

Air pollution is a public health threat and global epidemiological studies have shown that ambient air pollutants are closely related to various poor health conditions, including neurodegenerative diseases. Here, we evaluated the toxic effects and the underlying mechanisms of fine airborne particulate matter (PM2.5) on human glioblastoma LN-229 cells. Our results showed that exposure of LN-229 cells to PM2.5 (≥ 200 μg/mL) significantly reduced cell viability. PM2.5 exposure increased autophagy, apoptosis, and ROS production in the cells. Pre-treatment with a ROS scavenger, catalase, or depletion of mtDNA (ρ0 cells) abolished PM2.5-induced autophagy and apoptosis. PM2.5 exposure also activated MAPK signals in cells, which were blocked by catalase pre-treatment or mtDNA depletion. Furthermore, inhibition of JNK, but not ERK1/2 or p38, attenuated PM2.5-induced autophagy and apoptosis in cells. Finally, suppression of autophagy with Bafilomycin A1 or Beclin 1 siRNA exacerbated PM2.5-induced apoptosis, indicating a protective role of autophagy against PM2.5-induced apoptosis. Our results demonstrated that exposure of LN-229 cells to PM2.5 caused autophagy and apoptosis through PM2.5-induced ROS generation, mainly by mitochondria, and JNK activation. Autophagy may have a transient protective response in PM2.5-induced apoptosis. These findings have important implications for understanding the potential neurotoxicity of PM2.5.

Silver nanoparticles induced hippocampal neuronal damage involved in mitophagy, mitochondrial biogenesis and synaptic degeneration

Silver nanoparticles (AgNPs) could accumulate in the central nervous system (CNS) and induce neurotoxicity for their widespread use in industry and medicine. Mitochondria are vulnerable to toxicity of AgNPs, however, their role in the neurotoxicity remains unclear. This study aimed to evaluate AgNPs-induced synaptic degeneration in mouse hippocampal neurons (at a dose of 12-120 mg/kg BW via intravenous injection), and to further investigate mechanism of mitophagy, mitochondrial biogenesis process in the neurotoxicity. The results indicated that AgNPs accumulated in mouse hippocampal neurons and induced neurological deficits of learning and memory, which involved in synaptic degeneration accompanied with mitochondrial damage. Mechanistically, AgNPs exposure increased protein expression of PTEN-induced kinase 1 (PINK1), Parkin and inhibited peroxisome proliferator-activated receptor coactivator 1 alpha (PGC-1α) protein expression, caused disturbed mitophagy and mitochondrial biogenesis. AgNPs also induced synaptic damage by increasing the protein expression of synaptophysin and decreasing PSD95, MAP2 protein expression. AgNPs exposure even promoted protein expression of amyloid precursor protein (APP) using in amyloid-β (Aβ) cleavage. Furthermore, AgNPs induced hippocampal neuronal synaptic degeneration, mitophagy and mitochondrial biogenesis is dependent on particle-specific AgNPs rather than released silver ions. Our research could provide insights into the regulatory mechanisms of AgNPs-induced neurotoxicity. This study will shed the light of neurotoxicological evaluation of nanoparticles and possible early warning of biomedical applications.

Metallic Engineered Nanomaterials and Ocular Toxicity: A Current Perspective

The ocular surface, comprised of the transparent cornea, conjunctiva, and protective tear film, forms a protective barrier defending deeper structures of the eye from particulate matter and mechanical trauma. This barrier is routinely exposed to a multitude of naturally occurring and engineered nanomaterials (ENM). Metallic ENMs are particularly ubiquitous in commercial products with a high risk of ocular exposure, such as cosmetics and sunscreens. Additionally, there are several therapeutic uses for metallic ENMs owing to their attractive magnetic, antimicrobial, and functionalization properties. The increasing commercial and therapeutic applications of metallic ENMs come with a high risk of ocular exposure with poorly understood consequences to the health of the eye. While the toxicity of metallic ENMs exposure has been rigorously studied in other tissues and organs, further studies are necessary to understand the potential for adverse effects and inform product usage for individuals whose ocular health may be compromised by injury, disease, or surgical intervention. This review provides an update of current literature on the ocular toxicity of metallic ENMs in vitro and in vivo, as well as the risks and benefits of therapeutic applications of metallic ENMs in ophthalmology.

Targeted Delivery Platforms for the Treatment of Multiple Sclerosis

Multiple sclerosis (MS) is a neurodegenerative condition of the central nervous system (CNS) that presents with varying levels of disability in patients, displaying the significance of timely and effective management of this complication. Though several treatments have been developed to protect nerves, comprehensive improvement of MS is still considered an essential bottleneck. Therefore, the development of innovative treatment methods for MS is one of the core research areas. In this regard, nanoscale platforms can offer practical and ideal approaches to the diagnosis and treatment of various diseases, especially immunological disorders such as MS, to improve the effectiveness of conventional therapies. It should be noted that there is significant progress in the development of neuroprotective strategies through the implementation of various nanoparticles, monoclonal antibodies, peptides, and aptamers. In this study, we summarize different particle systems as well as targeted therapies, such as antibodies, peptides, nucleic acids, and engineered cells for the treatment of MS, and discuss their potential in the treatment of MS in the preclinical and clinical stages. Future advances in targeted delivery of medical supplies may offer new strategies for complete recovery as well as practical treatment of progressive forms of MS.

A perspective on persistent toxicants in veterans and amyotrophic lateral sclerosis: identifying exposures determining higher ALS risk

Multiple studies indicate that United States veterans have an increased risk of developing amyotrophic lateral sclerosis (ALS) compared to civilians. However, the responsible etiological factors are unknown. In the general population, specific occupational (e.g. truck drivers, airline pilots) and environmental exposures (e.g. metals, pesticides) are associated with an increased ALS risk. As such, the increased prevalence of ALS in veterans strongly suggests that there are exposures experienced by military personnel that are disproportionate to civilians. During service, veterans may encounter numerous neurotoxic exposures (e.g. burn pits, engine exhaust, firing ranges). So far, however, there is a paucity of studies investigating environmental factors contributing to ALS in veterans and even fewer assessing their exposure using biomarkers. Herein, we discuss ALS pathogenesis in relation to a series of persistent neurotoxicants (often emitted as mixtures) including: chemical elements, nanoparticles and lipophilic toxicants such as dioxins, polycyclic aromatic hydrocarbons and polychlorinated biphenyls. We propose these toxicants should be directly measured in veteran central nervous system tissue, where they may have accumulated for decades. Specific toxicants (or mixtures thereof) may accelerate ALS development following a multistep hypothesis or act synergistically with other service-linked exposures (e.g. head trauma/concussions). Such possibilities could explain the lower age of onset observed in veterans compared to civilians. Identifying high-risk exposures within vulnerable populations is key to understanding ALS etiopathogenesis and is urgently needed to act upon modifiable risk factors for military personnel who deserve enhanced protection during their years of service, not only for their short-term, but also long-term health.

Environmental Nanoparticles Reach Human Fetal Brains

Anthropogenic ultrafine particulate matter (UFPM) and industrial and natural nanoparticles (NPs) are ubiquitous. Normal term, preeclamptic, and postconceptional weeks(PCW) 8–15 human placentas and brains from polluted Mexican cities were analyzed by TEM and energy-dispersive X-ray spectroscopy. We documented NPs in maternal erythrocytes, early syncytiotrophoblast, Hofbauer cells, and fetal endothelium (ECs). Fetal ECs exhibited caveolar NP activity and widespread erythroblast contact. Brain ECs displayed micropodial extensions reaching luminal NP-loaded erythroblasts. Neurons and primitive glia displayed nuclear, organelle, and cytoplasmic NPs in both singles and conglomerates. Nanoscale Fe, Ti, and Al alloys, Hg, Cu, Ca, Sn, and Si were detected in placentas and fetal brains. Preeclamptic fetal blood NP vesicles are prospective neonate UFPM exposure biomarkers. NPs are reaching brain tissues at the early developmental PCW 8–15 stage, and NPs in maternal and fetal placental tissue compartments strongly suggests the placental barrier is not limiting the access of environmental NPs. Erythroblasts are the main early NP carriers to fetal tissues. The passage of UFPM/NPs from mothers to fetuses is documented and fingerprinting placental single particle composition could be useful for postnatal risk assessments. Fetal brain combustion and industrial NPs raise medical concerns about prenatal and postnatal health, including neurological and neurodegenerative lifelong consequences.

Regenerative rehabilitation with conductive biomaterials for spinal cord injury

The individual approaches of regenerative medicine efforts alone and rehabilitation efforts alone have not yet fully restored function after severe spinal cord injury (SCI). Regenerative rehabilitation may be leveraged to promote regeneration of the spinal cord tissue, and promote reorganization of the regenerated neural pathways and intact spinal circuits for better functional recovery for SCI. Conductive biomaterials may be a linchpin that empowers the synergy between regenerative medicine and rehabilitation approaches, as electrical stimulation applied to the spinal cord could facilitate neural reorganization. In this review, we discuss current regenerative medicine approaches in clinical trials and the rehabilitation, or neuromodulation, approaches for SCI, along with their respective translational limitations. Furthermore, we review the translational potential, in a surgical context, of conductive biomaterials (e.g., conductive polymers, carbon-based materials, metallic nanoparticle-based materials) as they pertain to SCI. While pre-formed scaffolds may be difficult to translate to human contusion SCIs, injectable composites that contain blended conductive components and can form within the injury may be more translational. However, given that there are currently no in vivo SCI studies that evaluated conductive materials combined with rehabilitation approaches, we discuss several limitations of conductive biomaterials, including demonstrating safety and efficacy, that will need to be addressed in the future for conductive biomaterials to become SCI therapeutics. Even so, the use of conductive biomaterials creates a synergistic opportunity to merge the fields of regenerative medicine and rehabilitation and redefine what regenerative rehabilitation means for the spinal cord. STATEMENT OF SIGNIFICANCE: For spinal cord injury (SCI), the individual approaches of regenerative medicine and rehabilitation are insufficient to fully restore functional recovery; however, the goal of regenerative rehabilitation is to combine these two disparate fields to maximize the functional outcomes. Concepts similar to regenerative rehabilitation for SCI have been discussed in several reviews, but for the first time, this review considers how conductive biomaterials may synergize the two approaches. We cover current regenerative medicine and rehabilitation approaches for SCI, and the translational advantages and disadvantages, in a surgical context, of conductive biomaterials used in biomedical applications that may be additionally applied to SCI. Furthermore, we identify the current limitations and translational challenges for conductive biomaterials before they may become therapeutics for SCI.

TGF-β1/SMADs signaling involved in alleviating inflammation induced by nanoparticulate titanium dioxide in BV2 cells

There are increasing safety concerns accompanying the widespread use of nanoparticulate titanium dioxide (nano-TiO₂). It has been demonstrated that nano-TiO₂ can cross the blood-brain barrier and enter the brain, causing damage to the nervous system, consisting mainly of neuroinflammation and neuronal apoptosis. Several studies have linked the TGF-β1/SMADs signaling to the development of inflammatory response in various organs. However, no studies have connected the induction of microglial inflammation by nano-TiO₂ to this signaling. Therefore, this study aimed to investigate the role of TGF-β1/SMADs signaling in microglia inflammatory response induced by nano-TiO₂. The results showed that nano-TiO₂ increased the secretions of pro-inflammatory cytokines (IL-1α, IL-6, and TNF-α) and decreased the expressions of TGF-β1 and SMAD1/2/3 proteins in BV2 cells. When TGF-β1/SMADs signaling was inhibited, the inflammatory effect induced by nano-TiO₂ increased, suggesting a suppressive effect of this signaling on the inflammation. In addition, exogenous TGF-β1 upregulated the expressions of TGF-β1 and SMADs1/2/3 proteins as well as decreased the secretions of pro-inflammatory cytokines (IL-1α, IL-6, and TNF-α) compared to BV2 cells treated with only nano-TiO₂. Our results suggest that nano-TiO₂ may inhibit the TGF-β1/SMADs signaling by suppressing the intracellular secretion of active TGF-β1, leading to microglial activation and the induction or exacerbation of inflammatory responses.

Synthesis of encapsulated fish oil using whey protein isolate to prevent the oxidative damage and cytotoxicity of titanium dioxide nanoparticles in rats

Fish oil exhibited several beneficial effects on human health; however, its applications face several challenges such as its effects on the organoleptic properties of food and its susceptibility to oxidation. Titanium dioxide NPs (TiO₂-NPs) are utilized widely in pharmaceutical and food applications although there are some reports about their oxidative damage to living organisms. The current work was undertaken to identify fatty acids content in mullet fish oil, encapsulation, and characterization of the oil, and to assess the protective efficiency of the encapsulated mullet fish oil (EMFO) against the oxidative damage and genotoxicity of TiO₂-NPs in rats. Sixty female Sprague-Dawley rats were distributed to 6 groups and treated for 21 days included the control group; TiO₂-NPs-treated group (50 mg/kg b.w); the groups treated with EMFO (50 or 100 mg/kg b.w) and the groups received TiO₂-NPs plus EMFO at the low or high dose. Samples of blood, liver, and kidney were taken for different assays and histological studies. The GC-FID analysis showed that a total of 14 different fatty acids were found in Mullet fish oil included 41.4% polyunsaturated fatty acids (PUFAs), 31.1% monounsaturated fatty acids (MUFAs), and 25.1% saturated fatty acids (SFAs). The structure of EMFO was spherical with an average diameter of 234.5 nm and a zeta potential of -6.24 mV and was stable up to 10 days at 25 °C with EE of 81.08%. The PV of EMFO was decreased at 5 days then increased at 15 days; however, TBARS was increased throughout the storage time over 15 days. The biological evaluation showed that TiO₂-NPs disturb the hepato-nephro functions, lipid profile, inflammatory cytokines, oxidative stress markers, antioxidant enzymes activity, and their corresponding gene expression along with severe pathological alterations in both hepatic and renal tissue. Co-administration of EMFO induced a strong antioxidant role, and the high level could normalize the majority of the parameters tested and the histological picture of the hepatic and renal tissues. These results pointed out that the encapsulation technology enhances the protective role of EMFO against oxidative stress and genotoxicity of TiO₂-NPs through the prevention of ω-3 PUFAs oxidation and controlling their release.

Elimination of oxidative stress and genotoxicity of biosynthesized titanium dioxide nanoparticles in rats via supplementation with whey protein-coated thyme essential oil

The green synthesis of metal nanoparticles is growing dramatically; however, the toxicity of these biosynthesized particles against living organisms is not fully explored. Therefore, this study was designed to synthesize and characterize TiO₂-NPs, encapsulation and characterization thyme essential oil (ETEO), and determination of the bioactive constituents of ETEO using GC-MS and evaluate their protective role against TiO₂-NPs-induced oxidative damage and genotoxicity in rats. Six groups of rats were treated orally for 30 days including the control group, TiO₂-NPs (300 mg/kg b.w)-treated group, ETEO at low (50 mg/kg b.w) or high dose (100 mg/kg b.w)-treated groups, and TiO₂-NPs plus ETEO at the two doses-treated groups. Blood and tissues were collected for different assays. The GC-MS results indicated the presence of 21 compounds belonging to phenols, terpene derivatives, and heterocyclic compounds. The synthesized TiO₂-NPs were 45 nm tetragonal particles with a zeta potential of -27.34 mV; however, ETEO were 119 nm round particles with a zeta potential of -28.33 mV. TiO₂-NPs administration disturbs the liver and kidney markers, lipid profile, cytokines, oxidative stress parameters, the apoptotic and antioxidant hepatic mRNA expression, and induced histological alterations in the liver and kidney tissues. ETEO could improve all these parameters in a dose-dependent manner. It could be concluded that ETEO is a promising candidate for the protection against TiO₂-NPs and can be applied safely in food applications.

Functional state of the myometrium of rats under chronic in vivo effect of nanostructured ZnO and ТіО2 materials

The specificities of the structure and blood supply of the uterus facilitate a considerable accumulation of nanosized xenobiotics, including nanoparticles of metal oxides, in its tissues. Numerous in vitro and in vivo experiments demonstrated that nanoparticles of metal oxides (ZnO and TiO2) have significant cytotoxic activity, caused by oxidative stress induction. However, there is no information about the impact of these nanomaterials on the functional state of the myometrium under chronic exposure on the organism. Tenzometric methods and mechanokinetic analysis were used in our work to investigate the contractile activity of the myometrium of non-pregnant rats. The contractile activity was either spontaneous or induced by oxytocin (the uterotonic hormone) and acetylcholine (the agonist of muscarinic choline receptors) under chronic peroral intake of the ZnO and TiO2 aqueous nanocolloids into the organism. It was found that after burdening of rats with ZnO and ТіО2 aqueous nanocolloids there were no changes in the pacemaker-dependent mechanisms forming the frequency of spontaneous contractions in the myometrium, but there was a considerably induced increase in the AU index of contractions. It was shown that during the oxytocin-induced excitation of the myometrium under both chronic and short-term burdening of the rats with ZnO and TiO2 aqueous nanocolloids, the mechanisms that regulate the intracellular concentration of Ca2+ ions are the target for the nanomaterials. When the rats were burdened with ZnO aqueous nanocolloids for 6 months, during cholinergic excitation there was hyperstimulation of both M3-receptor-dependent mechanisms of Са2+ ions intake via the potential-governed Са2+-channels of L-type into the smooth muscles of the myometrium, and M2-receptor-dependent mechanisms, controlling the intracellular concentration of these cations. Thus, the regularities and mechanisms of the change in the functioning of uterine smooth muscles under chronic intake of the ZnO and TiO2 aqueous nanocolloids were determined in this study.

Potential toxicity of nanoparticles on the reproductive system animal models: A review

Over the past two decades, nanotechnology has been involved in an array of applications in various fields, including diagnostic kits, disease treatment, drug manufacturing, drug delivery, and gene therapy. But concerns about the toxicity of nanoparticles have greatly hindered their use; also, due to their increasing use in various industries, all members of society are exposed to the toxicity of these nanoparticles. Nanoparticles have a negative impact on various organs, including the reproductive system. They also can induce abortion in women, reduce fetal growth and development, and can damage the reproductive system and sperm morphology in men. In some cases, it has been observed that despite the modification of nanoparticles in composition, concentration, and method of administration, there is still damage to the reproductive organs. Therefore, understanding how nanoparticles affect the reproductive system is of very importance. In several studies, the nanoparticle toxicity effect on the genital organs has been investigated at the clinical and molecular levels using the in vivo and in vitro models. This study reviews these investigations and provides important data on the toxicity, hazards, and safety of nanoparticles in the reproductive system to facilitate the optimal use of nanoparticles in the industry.

ZnO and TiO2 Nanocolloids: State of Mechanisms that Regulating the Motility of the Gastrointestinal Tract and the Hepatobiliary System

Using the transmission electron microscopy (TEM)/high-resolution TEM (HRTEM) and selected area electron diffraction (SAED) methods, it was shown that the nanocolloids of ZnO contain hydrolyzed ZnO nanoparticles (NPs). Typically, the nanocrystalline ZnO/Zn(OH)2 core is covered by an amorphous shell of zinc hydroxides, preventing the encapsulated crystal core from dissolving. Similar studies were carried out with TiO2 nanocolloids. It was found that burdening of rats for 30 days with a ZnO aqueous nanocolloid (AN) was accompanied by a narrowing of the amplitude range, a decrease (increase) in the frequency of spontaneous contractions (SCs), and an inhibition of the efficiency indices for smooth muscles (SMs) of the antrum and cecum. Under longer (100 days) burdening of rats with AN of ZnO, there was a tendency toward restoring the above parameters. In terms of the value and the direction of changes in most parameters for SCs of SMs, the effects (30 days) of TiO2 AN differed from those for ZnO AN and were almost the same in the case of their long-term impact. It was found that mostly M2-cholinoreceptor-dependent mechanisms of regulating the intracellular concentration of Ca2+ were sensitive to the effect of ZnO and TiO2 ANs. The molecular docking demonstrated that ZnO and TiO2 NPs did not compete with acetylcholine for the site of binding to M3 and M2 cholinoreceptors but may impact the affinity of orthosteric ligands to M2 cholinoreceptors. The studies showed that burdening rats with ZnO and TiO2 ANs was also accompanied by changes in the activity state of both intracellular enzymes and the ion transport systems for Na+, K+, and Ca2+, related to the processes of bile secretion, via the plasma membrane of hepatocytes.

Silver Nanostructures: Limited Sensitivity of Detection, Toxicity and Anti-Inflammation Effects

Nanosilver with sizes 1–100 nm at least in one dimension is widely used due to physicochemical, anti-inflammatory, anti-angiogenesis, antiplatelet, antifungal, anticancer, antibacterial, and antiviral properties. Three modes of the nanosilver action were suggested: “Trojan horse”, inductive, and quantum mechanical. The Ag⁺ cations have an affinity to thiol, amino, phosphate, and carboxyl groups. Multiple mechanisms of action towards proteins, DNA, and membranes reduce a risk of pathogen resistance but inevitably cause toxicity for cells and organisms. Silver nanoparticles (AgNP) are known to generate two reactive oxygen species (ROS)-superoxide (•O₂⁻) and hydroxyl (•OH) radicals, which inhibit the cellular antioxidant enzymes (superoxide dismutase, catalase, and glutathione peroxidase) and cause mechanical damage of membranes. Ag⁺ release and replacement by electrolyte ions with potential formation of insoluble AgCl result in NP instability and interactions of heavy metals with nucleic acids and proteins. Protein shells protect AgNP core from oxidation, dissolution, and aggregation, and provide specific interactions with ligands. These nanoconjugates can be used for immunoassays and diagnostics, but the sensitivity is limited at 10 pg and specificity is restricted by binding with protective proteins (immunoglobulins, fibrinogen, albumin, and others). Thus, broad implementation of Ag nanostructures revealed limitations such as instability; binding with major blood proteins; damage of proteins, nucleic acids, and membranes; and immunosuppression of the majority of cytokines.

Suitability of the In Vitro Cytokinesis-Block Micronucleus Test for Genotoxicity Assessment of TiO2 Nanoparticles on SH-SY5Y Cells

Standard toxicity tests might not be fully adequate for evaluating nanomaterials since their unique features are also responsible for unexpected interactions. The in vitro cytokinesis-block micronucleus (CBMN) test is recommended for genotoxicity testing, but cytochalasin-B (Cyt-B) may interfere with nanoparticles (NP), leading to inaccurate results. Our objective was to determine whether Cyt-B could interfere with MN induction by TiO₂ NP in human SH-SY5Y cells, as assessed by CBMN test. Cells were treated for 6 or 24 h, according to three treatment options: co-treatment with Cyt-B, post-treatment, and delayed co-treatment. Influence of Cyt-B on TiO₂ NP cellular uptake and MN induction as evaluated by flow cytometry (FCMN) were also assessed. TiO₂ NP were significantly internalized by cells, both in the absence and presence of Cyt-B, indicating that this chemical does not interfere with NP uptake. Dose-dependent increases in MN rates were observed in CBMN test after co-treatment. However, FCMN assay only showed a positive response when Cyt-B was added simultaneously with TiO₂ NP, suggesting that Cyt-B might alter CBMN assay results. No differences were observed in the comparisons between the treatment options assessed, suggesting they are not adequate alternatives to avoid Cyt-B interference in the specific conditions tested.

Matlodextrin-cinnamon essential oil nanoformulation as a potent protective against titanium nanoparticles-induced oxidative stress, genotoxicity, and reproductive disturbances in male mice

Recently, bio-nanofabrication becomes one of the widest methods for synthesizing nanoparticles (NPs); however, there is scanty literature exploring the toxicity of these green NPs against living organisms. This study aimed to evaluate the potential protective role of encapsulated cinnamon oil (ECO) against titanium oxide nanoparticle (TiO2NP)-induced oxidative stress, DNA damage, chromosomal aberration, and reproductive disturbances in male mice. Sixty male Balb/c mice were distributed into six groups treated orally for 3 weeks and included control group, TiO2NP-treated group (25 mg/kg b.w), ECO at low or high dose-treated groups (50 or 100 mg/kg b.w), and the groups that received TiO2NPs plus ECO at a low or high dose. The results of GC-MS revealed the isolation of 21 compounds and the majority was cinnamaldehyde. The average size zeta potential of TiO2NPs and ECO were 28.9 and 321 nm and -33.97 and -17.35 mV, respectively. TiO2NP administration induced significant changes in liver and kidney function, decreased antioxidant capacity, and increased oxidative stress markers in liver and kidney, DNA damage in the hepatocytes, the number of chromosomal aberrations in the bone marrow and germ cells, and sperm abnormalities along with histological changes in the liver, kidney, and testis. Co-administration of TiO2NPs and ECO could alleviate these disturbances in a dose-dependent manner. It could be concluded that ECO is a promising and safe candidate for the protection against the health hazards of TiO2NPs.

The key role of autophagy in silver nanoparticle-induced BV2 cells inflammation and polarization

As the release of silver nanoparticles (AgNPs) in the environment continues to increase, great concerns have been raised about their potential toxicity to humans. It is urgent to assess the possible toxicity of AgNPs to the immune cells of the central nervous system due to the continuous accumulation of AgNPs in the brain. This study aimed to evaluate the neurotoxicity of AgNPs and the regulatory mechanism of autophagy in AgNPs-induced inflammation by using mouse microglia BV2 cell lines. AgNPs decreased the microglia cell activity in a concentration and time-dependent manner. The exposure of BV2 cells to AgNPs at a non-cytotoxic level of 5 μg/mL resulted in increase of pro-inflammatory cytokines and decrease of mRNA expression of anti-inflammatory cytokines. AgNPs exposure increased M1 markers of iNOS expression and decreased the expression of M2 markers of CD206 in a time-dependent manner. Meanwhile, the expression of inflammatory proteins IL-1β and NF-κB increased significantly. Additionally, AgNPs induced an increase in autophagosome and upregulation of LC3II, Beclin1, and p62 expression levels. Pretreatment by an autophagy inhibitor, 3-Methyladenine, caused more AgNPs-treated microglia to polarized into pro-inflammatory phenotypes. Inhibition of autophagy also increased the expression of inflammation-associated mRNA and proteins in BV2 cells. These results indicated that AgNPs could induce pro-inflammatory phenotypic polarization of microglia and the autophagy could play a key regulatory role in the pro-inflammatory phenotypic polarization of microglia induced by AgNPs.

Silver nanoparticles: Correlating particle size and ionic Ag release with cytotoxicity, genotoxicity, and inflammatory responses in human cell lines

The widespread use of silver nanoparticles (AgNPs), their many sources for human exposure, and the ability of AgNPs to enter organisms and induce general toxicological responses have raised concerns regarding their public health and environmental safety. To elucidate the differential toxic effects of polyvinylpyrrolidone-capped AgNPs with different primary particle sizes (i.e. 5, 50, and 75 nm), we performed a battery of cytotoxicity and genotoxicity assays and examined the inflammatory responses in two human cell lines (i.e. HepG2 and A549). Concentration-dependent decreases in cell proliferation and mitochondrial membrane potential and increases in cytokine (i.e. interleukin-6 and interleukin-8) excretion indicated disruption of mitochondrial function and inflammation as the main mediating factors of AgNPs-induced cytotoxicity. An incremental increase in genotoxicity with decreasing AgNPs diameter was noted in HepG2 cells, which was associated with S and G2/M accumulation and transcriptional activation of the GADD45α promoter as reflected by luciferase activity. Dose-related genetic damage, as indicated by Olive tail moment and micronucleus formation, was also observed in A549 cells, but these effects as well as the AgNPs-induced cytotoxicity were more associated with ionic Ag release from nanoparticles (NPs). In summary, the present study addressed different toxicity mechanisms of AgNPs, depending on the cell model, toxicological endpoint, particle size, and degree of Ag+ release from NPs. The results suggest that the GADD45α promoter-driven luciferase reporter cell system provided a rapid screening tool for the identification of genotoxic properties of NPs across a range of different sizes and concentrations.

Evaluation of the neurotoxic effects of engineered nanomaterials in C57BL/6J mice in 28-day oral exposure studies

In recent years, concerns have emerged about the potential neurotoxic effects of engineered nanomaterials (NMs). Titanium dioxide and silver are among the most widely used types of metallic NMs. We have investigated the effects of these NMs on behaviour and neuropathology in male and female C57BL/6J mice following 28-day oral exposure with or without a 14-day post-exposure recovery. The mice were fed ad libitum with food pellets dosed with 10 mg/g TiO₂, 2 mg/g polyvinylpyrrolidone-coated Ag or control pellets. Behaviour was evaluated by X-maze, open field, string suspension and rotarod tests. Histological alterations were analysed by immunohistochemistry and brain tissue homogenates were investigated for markers of oxidative stress, inflammation and blood-brain barrier disruption. Effects of the NMs on tyrosine and serine/threonine protein kinase activity in mouse brains were investigated by measuring kinase activity on peptide microarrays. Markers of inflammation, oxidative stress and blood-brain barrier integrity were not significantly affected in the male and female mice following exposure to Ag or TiO₂. Both types of NMs also revealed no consistent significant treatment-related effects on anxiety and cognition. However, in the Ag NM exposed mice altered motor performance effects were observed by the rotarod test that differed between sexes. At 1-week post-exposure, a diminished performance in this test was observed exclusively in the female animals. Cortex tissues of female mice also showed a pronounced increase in tyrosine kinase activity following 28 days oral exposure to Ag NM. A subsequent Inductively Coupled Plasma - Mass Spectrometry (ICP-MS) based toxicokinetic study in female mice revealed a rapid and persistent accumulation of Ag in various internal organs including liver, kidney, spleen and the brain up to 4 weeks post-exposure. In conclusion, our study demonstrated that subacute exposure to foodborne TiO₂ and Ag NMs does not cause substantial neuropathological changes in mice. However, the toxicokinetic and specific toxicodynamic findings indicate that long-term exposures to Ag NM can cause neurotoxicity, possibly in a sex-dependent manner.

Contribution of Particle-Induced Lysosomal Membrane Hyperpolarization to Lysosomal Membrane Permeabilization

Lysosomal membrane permeabilization (LMP) has been proposed to precede nanoparticle-induced macrophage injury and NLRP3 inflammasome activation; however, the underlying mechanism(s) of LMP is unknown. We propose that nanoparticle-induced lysosomal hyperpolarization triggers LMP. In this study, a rapid non-invasive method was used to measure changes in lysosomal membrane potential of murine alveolar macrophages (AM) in response to a series of nanoparticles (ZnO, TiO2, and CeO2). Crystalline SiO2 (micron-sized) was used as a positive control. Changes in cytosolic potassium were measured using Asante potassium green 2. The results demonstrated that ZnO or SiO2 hyperpolarized the lysosomal membrane and decreased cytosolic potassium, suggesting increased lysosome permeability to potassium. Time-course experiments revealed that lysosomal hyperpolarization was an early event leading to LMP, NLRP3 activation, and cell death. In contrast, TiO2- or valinomycin-treated AM did not cause LMP unless high doses led to lysosomal hyperpolarization. Neither lysosomal hyperpolarization nor LMP was observed in CeO2-treated AM. These results suggested that a threshold of lysosomal membrane potential must be exceeded to cause LMP. Furthermore, inhibition of lysosomal hyperpolarization with Bafilomycin A1 blocked LMP and NLRP3 activation, suggesting a causal relation between lysosomal hyperpolarization and LMP.

Cirrhotic Liver of Liver Transplant Recipients Accumulate Silver and Co-Accumulate Copper

Silver-based materials are widely used in clinical medicine. Furthermore, the usage of silver containing materials and devices is widely recommended and clinically approved. The impact on human health of the increasing use of silver nanoparticles in medical devices remains understudied, even though Ag-containing dressings are known to release silver into the bloodstream. In this study, we detected a widespread and sometimes significant silver accumulation both in healthy and sick liver biopsies, levels being statistically higher in patients with various hepatic pathologies. 28 healthy and 44 cirrhotic liver samples were investigated. The median amount of 0.049 ppm Ag in livers was measured in cirrhotic livers while the median was 0.0016 ppm for healthy livers (a more than 30-fold difference). The mean tissue concentrations of essential metals, Fe and Zn in cirrhotic livers did not differ substantially from healthy livers, while Cu was positively correlated with Ag. The serum levels of gamma-glutamyl transpeptidase (GGTP) was also positively correlated with Ag in cirrhotic livers. The increased Ag accumulation in cirrhotic livers could be a side effect of wide application of silver in clinical settings. As recent studies indicated a significant toxicity of silver nanoparticles for human cells, the above observation could be of high importance for the public health.

Toxic effect of titanium dioxide nanoparticles on corneas in vitro and in vivo

Titanium dioxide nanoparticles (TiO₂ NPs) are widely used in a variety of areas. However, TiO₂ NPs possess cytotoxicity which involves oxidative stress. Nuclear factor erythroid 2-related factor 2 (Nrf2) is a key molecule preventing cells from oxidative stress damage. In the current study, we explored the effect of Nrf2 signaling pathway in TiO₂ NPs-induced corneal endothelial cell injury. Firstly, we found TiO₂ NPs inhibited proliferation and damaged morphology and mitochondria of mouse primary corneal endothelial cells. Moreover, TiO₂ NPs-induced oxidative damage of mouse primary corneal endothelial cells was inhibited by antioxidant NAC by evaluating production of reactive oxygen species (ROS), malondialdehyde (MDA), and activities of superoxide dismutase (SOD) and glutathione peroxidase (GSH-Px). Next, flow cytometry analysis showed TiO₂ NPs promoted apoptosis and cell cycle G2/M phase arrest of mouse primary corneal endothelial cells. Further investigation suggested that Nrf2 signaling pathway activation and the downregulation of ZO-1, β-catenin and Na-K-ATPase were involved in TiO₂ NPs-induced mouse primary corneal endothelial cell injury. Our research highlighted the toxic effect of TiO₂ NPs on corneas in vitro and in vivo, providing an alternative insight into TiO₂ NPs-induced corneal endothelial cell injury.

Effect of silver nanoparticles (AgNPs) exposure on microRNA expression and global DNA methylation in endothelial cells EA.hy926

The aim of this study was to determine the effect of AgNPs on the epigenome of endothelial cells EA.hy926, including the levels of expression of microRNAs (miRNAs) and global DNA methylation patterns. In addition, evaluation of the expression of inflammatory genes and the levels of VCAM-1 protein (miRNA-126 target) was performed. The expression levels of analyzed miRNAs (microRNAs-126, 155 and 146) were reduced significantly and there were not observed changes in inflammatory gene expression. Regarding the levels of protein vascular cell adhesion molecule 1 (VCAM-1), they increase significantly to 0.5 μM AgNPs at 24 h of exposure. As far as DNA methylation is concerned, we found that AgNPs induce a state of global hyper-methylation. In conclusion, it was demonstrated that direct contact between AgNPs and endothelial cells resulted in the dysregulation of highly enriched and vastly functional miRNAs and DNA hypermethylation, that may have multiple effects on endothelium function and integrity.

Quadruple abnormal protein aggregates in brainstem pathology and exogenous metal-rich magnetic nanoparticles (and engineered Ti-rich nanorods). The substantia nigrae is a very early target in young urbanites and the gastrointestinal tract a key brainstem portal

Fine particulate air pollution (PM_2.5) exposures are linked with Alzheimer's and Parkinson's diseases (AD,PD). AD and PD neuropathological hallmarks are documented in children and young adults exposed lifelong to Metropolitan Mexico City air pollution; together with high frontal metal concentrations (especially iron)-rich nanoparticles (NP), matching air pollution combustion- and friction-derived particles. Here, we identify aberrant hyperphosphorylated tau, ɑ synuclein and TDP-43 in the brainstem of 186 Mexico City 27.29 ± 11.8y old residents. Critically, substantia nigrae (SN) pathology seen in mitochondria, endoplasmic reticulum and neuromelanin (NM) is co-associated with the abundant presence of exogenous, Fe-, Al- and Ti-rich NPs.The SN exhibits early and progressive neurovascular unit damage and mitochondria and NM are associated with metal-rich NPs including exogenous engineered Ti-rich nanorods, also identified in neuroenteric neurons. Such reactive, cytotoxic and magnetic NPs may act as catalysts for reactive oxygen species formation, altered cell signaling, and protein misfolding, aggregation and fibril formation. Hence, pervasive, airborne and environmental, metal-rich and magnetic nanoparticles may be a common denominator for quadruple misfolded protein neurodegenerative pathologies affecting urbanites from earliest childhood. The substantia nigrae is a very early target and the gastrointestinal tract (and the neuroenteric system) key brainstem portals. The ultimate neural damage and neuropathology (Alzheimer's, Parkinson's and TDP-43 pathology included) could depend on NP characteristics and the differential access and targets achieved via their portals of entry. Thus where you live, what air pollutants you are exposed to, what you are inhaling and swallowing from the air you breathe,what you eat, how you travel, and your occupational longlife history are key. Control of NP sources becomes critical.

Electrochemistry of Graphene Nanoplatelets Printed Electrodes for Cortical Direct Current Stimulation

Possible risks stemming from the employment of novel, micrometer-thin printed electrodes for direct current neural stimulation are discussed. To assess those risks, electrochemical methods are used, including cyclic voltammetry, square-wave voltammetry, and electrochemical impedance spectroscopy. Experiments were conducted in non-deoxidized phosphate-buffered saline to better emulate living organism conditions. Since preliminary results obtained have shown unexpected oxidation peaks in 0–0.4 V potential range, the source of those was further investigated. Hypothesized redox activity of printing paste components was disproven, supporting further development of proposed fabrication technology of stimulating electrodes. Finally, partial permeability and resulting electrochemical activity of underlying silver-based printed layers of the device were pointed as the source of potential tissue irritation or damage. Employing this information, electrodes with corrected design were investigated, yielding no undesired redox processes.

Osteotropic Radiolabeled Nanophotosensitizer for Imaging and Treating Multiple Myeloma

Rapid liver and spleen opsonization of systemically administered nanoparticles (NPs) for in vivo applications remains the Achilles' heel of nanomedicine, allowing only a small fraction of the materials to reach the intended target tissue. Although focusing on diseases that reside in the natural disposal organs for nanoparticles is a viable option, it limits the plurality of lesions that could benefit from nanomedical interventions. Here we designed a theranostic nanoplatform consisting of reactive oxygen (ROS)-generating titanium dioxide (TiO2) NPs, coated with a tumor-targeting agent, transferrin (Tf), and radiolabeled with a radionuclide (89Zr) for targeting bone marrow, imaging the distribution of the NPs, and stimulating ROS generation for cell killing. Radiolabeling of TiO2 NPs with 89Zr afforded thermodynamically and kinetically stable chelate-free 89Zr-TiO2-Tf NPs without altering the NP morphology. Treatment of multiple myeloma (MM) cells, a disease of plasma cells originating in the bone marrow, with 89Zr-TiO2-Tf generated cytotoxic ROS to induce cancer cell killing via the apoptosis pathway. Positron emission tomography/X-ray computed tomography (PET/CT) imaging and tissue biodistribution studies revealed that in vivo administration of 89Zr-TiO2-Tf in mice leveraged the osteotropic effect of 89Zr to selectively localize about 70% of the injected radioactivity in mouse bone tissue. A combination of small-animal PET/CT imaging of NP distribution and bioluminescence imaging of cancer progression showed that a single-dose 89Zr-TiO2-Tf treatment in a disseminated MM mouse model completely inhibited cancer growth at euthanasia of untreated mice and at least doubled the survival of treated mice. Treatment of the mice with cold Zr-TiO2-Tf, 89Zr-oxalate, or 89Zr-Tf had no therapeutic benefit compared to untreated controls. This study reveals an effective radionuclide sensitizing nanophototherapy paradigm for the treatment of MM and possibly other bone-associated malignancies.

The interaction between nanoparticles-protein corona complex and cells and its toxic effect on cells

Once nanoparticles (NPs) contact with the biological fluids, the proteins immediately adsorb onto their surface, forming a layer called protein corona (PC), which bestows the biological identity on NPs. Importantly, the NPs-PC complex is the true identity of NPs in physiological environment. Based on the affinity and the binding and dissociation rate, PC is classified into soft protein corona, hard protein corona, and interfacial protein corona. Especially, the hard PC, a protein layer relatively stable and closer to their surface, plays particularly important role in the biological effects of the complex. However, the abundant corona proteins rarely correspond to the most abundant proteins found in biological fluids. The composition profile, formation and conformational change of PC can be affected by many factors. Here, the influence factors, not only the nature of NPs, but also surface chemistry and biological medium, are discussed. Likewise, the formed PC influences the interaction between NPs and cells, and the associated subsequent cellular uptake and cytotoxicity. The uncontrolled PC formation may induce undesirable and sometimes opposite results: increasing or inhibiting cellular uptake, hindering active targeting or contributing to passive targeting, mitigating or aggravating cytotoxicity, and stimulating or mitigating the immune response. In the present review, we discuss these aspects and hope to provide a valuable reference for controlling protein adsorption, predicting their behavior in vivo experiments and designing lower toxicity and enhanced targeting nanomedical materials for nanomedicine.

Nec-1 Attenuates Neurotoxicity Induced by Titanium Dioxide Nanomaterials on Sh-Sy5y Cells Through RIP1

Titanium dioxide nanomaterials are applied in numerous fields due to their splendid physicochemical characteristics, which in turn poses a potential threat to human health. Recently, numerous in vivo studies have revealed that titanium dioxide nanoparticles (TNPs) can be transported into animal brains after exposure through various routes. Absorbed TNPs can accumulate in the brain and may disturb neuronal cells, leading to brain dysfunction. In vitro studies verified the neurotoxicity of TNPs. The mechanisms underlying the neurotoxicity of TNPs remains unclear. Whether necroptosis is involved in the neurotoxicity of TNPs is unknown. Therefore, we performed an in vitro study and found that TNPs induced inflammatory injury in SH-SY5Y cells in a dose-dependent way, which was mitigated by necrostatin-1 (Nec-1) pretreatment. Since receptor-interacting protein kinase 1 (RIP1) is reported to be the target of Nec-1, we silenced it by siRNA. We exposed mutant and wild-type cells to TNPs and assessed inflammatory injury. Silencing RIP1 expression inhibited inflammatory injury induced by TNPs exposure. Taken together, Nec-1 ameliorates the neurotoxicity of TNPs through RIP1. However, more studies should be performed to comprehensively assess the correlation between the neurotoxicity of TNPs and RIP1.

Recent strategies and advances in the fabrication of nano lipid carriers and their application towards brain targeting

In last two decades, the lipid nanocarriers have been extensively investigated for their drug targeting efficiency towards the critical areas of the human body like CNS, cardiac region, tumor cells, etc. Owing to the flexibility and biocompatibility, the lipid-based nanocarriers, including nanoemulsion, liposomes, SLN, NLC etc. have gained much attention among various other nanocarrier systems for brain targeting of bioactives. Across different lipid nanocarriers, NLC remains to be the safest, stable, biocompatible and cost-effective drug carrier system with high encapsulation efficiency. Drug delivery to the brain always remains a challenging issue for scientists due to the complex structure and various barrier mechanisms surrounding the brain. The application of a suitable nanocarrier system and the use of any alternative route of drug administration like nose-to-brain drug delivery could overcome the hurdle and improves the therapeutic efficiency of CNS acting drugs thereof. NLC, a second-generation lipid nanocarrier, upsurges the drug permeation across the BBB due to its unique structural properties. The biocompatible lipid matrix and nano-size make it an ideal drug carrier for brain targeting. It offers many advantages over other drug carrier systems, including ease of manufacturing and scale-up to industrial level, higher drug targeting, high drug loading, control drug release, compatibility with a wide range of drug substances, non-toxic and non-irritant behavior. This review highlights recent progresses towards the development of NLC for brain targeting of bioactives with particular reference to its surface modifications, formulations aspects, pharmacokinetic behavior and efficacy towards the treatment of various neurological disorders like AD, PD, schizophrenia, epilepsy, brain cancer, CNS infection (viral and fungal), multiple sclerosis, cerebral ischemia, and cerebral malaria. This work describes in detail the role and application of NLC, along with its different fabrication techniques and associated limitations. Specific emphasis is given to compile a summary and graphical data on the area explored by scientists and researchers worldwide towards the treatment of neurological disorders with or without NLC. The article also highlights a brief insight into two prime approaches for brain targeting, including drug delivery across BBB and direct nose-to-brain drug delivery along with the current global status of specific neurological disorders.

Neurotoxicity of green- synthesized magnetic iron oxide nanoparticles in different brain areas of wistar rats

AIMS

The aim of the present study was to evaluate the toxicity of magnetic iron oxide nanoparticles (MIONs) which were synthesized using carob leaf extract on various brain areas of Wistar rats.

MAIN METHODS

Carob leaf synthesized-MIONs were characterized using different techniques: Dynamic Light Scattering (DLS), Transmission Electron Microscope (TEM), UV-vis spectrophotometer, Fourier Transform infrared (FTIR), X-Ray Diffraction (XRD) and Atomic Force Microscope (AFM). The toxicity of MIONs in vivo was evaluated by: monitoring rat's body weight, measuring iron content in different brain areas, evaluating some oxidative stress parameters, estimating acetylcholinesterase (AChE) in addition to histopathological investigations.

KEY FINDINGS

The present study demonstrated no body weight changes of MIONs- treated rats. According to the conditions of the present study, the hippocampus and striatum were the most affected areas and demonstrated neuronal degeneration due to MIONs exposure. MIONs treatment of Wistar rats, also affected the iron homeostasis in both striatum and midbrain by decreasing iron content in these areas. The least affected areas were thalamus and cerebellum. The histopathological examination of brain areas demonstrated moderate neuronal degeneration in hippocampus and striatum, mild neuronal degeneration in cortex and slight degeneration in hypothalamus and pons-medulla areas were detected.

SIGNIFICANCE

The results suggested that MIONs have a toxic impact on different brain areas and the effect varies according to the brain area.