In vitro study on influence of nano particles of CuO on CA1 pyramidal neurons of rat hippocampus potassium currents

Nanoparticle formulations: A smart era of advanced treatment with nanotoxicological imprints on the human body

In the modern era, nanoparticles are the preferred dosage form, and maximum research is going on in the field of nanoparticle formulations. But as they are so small, nanoparticles are able to slip through the body's defenses and cause damage to the organs and tissues deep inside. In recent years, most researchers have focused solely on the therapeutic value of drugs or, at times, the performance of dosage forms, but few have given toxicity studies equal weight in their research. This review demonstrates that nanoparticle formulations are not suitable from a safety standpoint. So, researchers should be focused on alternative formulations like nanoemulsion, nanogel, and other liquids as well as semisolid formulations.

Molecular dynamics simulation on surface modification of quantum scaled CuO nano-clusters to support their experimental studies

Interest in nanoparticle modification using functional chemicals has increased rapidly, as it allows more freedom of physiochemical tuning of the nanoparticle’s surface into biomedically oriented and designated properties. However, the observation and detection of the thin molecular layers on the nanoparticle surface are very challenging under current analytical facilities. The focus of this research is to demonstrate fundamental interactions between the surface treated nanoparticles and their host liquid media using lab-based experimentation and simulation. In this research, investigation has been carried out on analyzing the surface compatibility and the diffusivity of modified CuO nanoparticles (CuONPs) with short-chain carboxylate-terminated molecules in biofluids. Moreover, during the current Covid-19 pandemic, the Cu/CuONPs have proved effective in killing SARS-CoV1/2 and other airborne viruses. This research was conducted at the molecular level with joint consideration of experimental and simulation studies for characterization of variables. Experimental tests conducted using Fourier Transform Infrared (FTIR) spectroscopy demonstrated several spectral ranges of interest, specifically, detection of three major carboxylate attachments (i.e., 1667–1609 cm⁻¹, 1668–1557 cm⁻¹, etc.) were found. From simulation, similar attachment styles were observed by the LAMMPS simulation package that mimicked similar agglomerations with a predicted diffusion coefficient as recorded to be 2.28E−9 m²/s. Viscosities of modified nanofluids were also compared with unmodified nanofluids for defining aggregation kinetics.

Hippocampal toxicity of metal base nanoparticles. Is there a relationship between nanoparticles and psychiatric disorders?

Metal base nanoparticles are widely produced all over the world and used in many fields and products such as medicine, electronics, cosmetics, paints, ceramics, toys, kitchen utensils and toothpastes. They are able to enter the body through digestive, respiratory, and alimentary systems. These nanoparticles can also cross the blood brain barrier, enter the brain and aggregate in the hippocampus. After entering the hippocampus, they induce oxidative stress, neuro-inflammation, mitochondrial dysfunction, and gene expression alteration in hippocampal cells, which finally lead to neuronal apoptosis. Metal base nanoparticles can also affect hippocampal neurogenesis and synaptic plasticity that both of them play crucial role in memory and learning. On the one hand, hippocampal cells are severely vulnerable due to their high metabolic activity, and on the other hand, metal base nanoparticles have high potential to damage hippocampus through variety of mechanisms and affect its functions. This review discusses, in detail, nanoparticles' detrimental effects on the hippocampus in cellular, molecular and functional levels to reveal that according to the present information, which types of nanoparticles have more potential to induce hippocampal toxicity and psychiatric disorders and which types should be more evaluated in the future studies.

Deficiency of the CYLD Impairs Fear Memory of Mice and Disrupts Neuronal Activity and Synaptic Transmission in the Basolateral Amygdala

Fear learning and memory are crucial for animal survival. Abnormal fear memory is a hallmark of many neuropsychiatric disorders. Appropriate neuronal activation and excitability in the basolateral amygdala (BLA) are necessary for the formation of fear memory. The gene cylindromatosis (Cyld), which encodes a lysine-63 deubiquitinase, is expressed in several brain regions including the amygdala. The functions of the cylindromatosis protein (CYLD) in the regulation of the neuronal activity, neural circuits and fear memory, remain largely unknown, however. Here, we report that Cyld knockout impairs amygdala-dependent tone-cued fear memory. The number of c-Fos⁺ neurons responding to the tone-cued fear test was reduced in the BLA of Cyld^–/– mice, suggesting that the absence of CYLD causes aberrant neuronal activation. We found that this aberrant neuronal activation in the BLA of Cyld^–/– mice may relate to the decreased excitability of principal neurons. Another possibility of aberrant neuronal activation could be the impaired excitatory synaptic transmission in the BLA of Cyld^–/– mice. Specifically, both the frequency of spontaneous excitatory postsynaptic currents and the amplitude of miniature excitatory postsynaptic currents in BLA principal neurons were decreased. In addition, Cyld mutation caused an increase in both the frequency of miniature inhibitory postsynaptic currents in principal neurons and the number of parvalbumin⁺ interneurons, consistent with excessive local circuit inhibition in the BLA of Cyld^–/– mice. Taken together, these results suggest that CYLD deficiency disrupts the neuronal activity and synaptic transmission in the BLA of mice which may contribute to the impaired fear memory observed in Cyld^–/– mice.

Mechanism of copper nanoparticle toxicity in rainbow trout olfactory mucosa

Chemosensory perception is crucial for fish reproduction and survival. Direct contact of olfactory neuroepithelium to the surrounding environment makes it vulnerable to contaminants in aquatic ecosystems. Copper nanoparticles (CuNPs), which are increasingly used in commercial and domestic applications due their exceptional properties, can impair fish olfactory function. However, the molecular events underlying olfactory toxicity of CuNPs are largely unexplored. Our results suggested that CuNPs were bioavailable to olfactory mucosal cells. Using RNA-seq, we compared the effect of CuNPs and copper ions (Cu²⁺) on gene transcript profiles of rainbow trout (Oncorhynchus mykiss) olfactory mucosa. The narrow overlap in differential gene expression between the CuNP- and Cu²⁺-exposed fish revealed that these two contaminants exert their effects through distinct mechanisms. We propose a transcript-based conceptual model that shows that olfactory signal transduction, calcium homeostasis, and synaptic vesicular signaling were affected by CuNPs in the olfactory sensory neurons (OSNs). Neuroregenerative pathways were also impaired by CuNPs. In contrast, Cu²⁺ did not induce toxicity pathways and rather upregulated regeneration pathways. Both Cu treatments reduced immune system pathway transcripts. However, suppression of transcripts that were associated with inflammatory signaling was only observed with CuNPs. Neither oxidative stress nor apoptosis were triggered by Cu²⁺ or CuNPs in mucosal cells. Dysregulation of transcripts that regulate function, maintenance, and reestablishment of damaged olfactory mucosa represents critical mechanisms of toxicity of CuNPs. The loss of olfaction by CuNPs may impact survival of rainbow trout and impose an ecological risk to fish populations in contaminated environments.

Nano-CuO causes cell damage through activation of dose-dependent autophagy and mitochondrial lncCyt b-AS/ND5-AS/ND6-AS in SH-SY5Y cells

Metal copper oxide nanoparticles (nano-CuO) are under mass production and have been widely utilized in many fields including catalysis, gas sensors, semiconductor materials, etc. The broad applications of nano-CuO have increased the possibility of risk to incidental exposure to the environment, and therefore, an in-depth investigation of their effects on live cells is required. This study investigated the impact of the nano-CuO on SH-SY5Y cells, and findings showed that the ratio of LC3-II/LC3-I was significantly increased in SH-SY5Y cells when the cells were treated with nano-CuO. However, if the autophagy inhibitor Bafilomycin A1 (Baf A1) was co-treated, the ratio of LC3-II/LC3-I was further improved. These outcomes might indicate that autophagy flux was permanently elevated by adding nano-CuO. Further results found highly activated levels of long noncoding RNAs (lncRNAs) under nano-CuO treatment. The data illustrate a mechanism that nano-CuO can promote autophagy and activate lncCyt b-AS/ND5-AS/ND6-AS in SH-SY5Y cells and have critical implications for nanoparticle biomedical applications.

Exposure to CuO Nanoparticles Mediates NFκB Activation and Enhances Amyloid Precursor Protein Expression

Amyloid precursor protein (APP) is directly related to Aβ amyloidosis—a hallmark of Alzheimer’s disease (AD). However, the impact of environmental factors upon APP biology and Aβ amyloid pathology have not been well studied. The increased use of nanoparticles (NPs) or engineered nanomaterials (ENMs) has led to a growing body of evidence suggesting that exposure to metal/metal oxide NPs, such as Fe₂O₃, CuO, and ZnO, may contribute to the pathophysiology of neurodegenerative diseases such as AD through neuroinflammation. Our previous studies indicated that exposure to CuO nanoparticles (CuONPs) induce potent in vitro neurotoxicity. Herein, we investigated the effects on APP expression in neuronal cells exposed to different metal oxide NPs. We found a low dose of CuONPs effectively activated the NFκB signaling pathway and increased APP expression. Moreover, the inhibition of p65 expression using siRNA abolished CuONP-mediated APP expression, suggesting that NFκB-regulated APP expression in response to CuONP exposure may be associated with AD pathology.

Moderate maternal separation mitigates the altered synaptic transmission and neuronal activation in amygdala by chronic stress in adult mice

Exposure to moderate level of stress during the perinatal period helps the organisms to cope well with stressful events in their later life, an effect known as stress inoculation. Amygdala is one of the kernel brain regions mediating stress-coping in the brain. However, little is known about whether early life stress may affect amygdala to have its inoculative effect. Here, we observed that moderate maternal separation (MS) from postnatal day 3 to day 21 (D3–21, 1 h per day) significantly alleviated the increased anxiety-like behavior induced by chronic social defeat stress (CSDS) in adulthood, suggesting an obvious inoculative effect of moderate MS. Further studies revealed that MS prevented CSDS-evoked augmentation of glutamatergic transmission onto principal neurons (PNs) in the basolateral amygdala (BLA) by inhibiting presynaptic glutamate release. By contrast, it did not affect GABAergic transmission in BLA PNs, as indicated by unaltered frequency and amplitude of miniature inhibitory postsynaptic currents (mIPSCs). Moreover, the CSDS-induced increase of neuronal excitability was also mitigated by MS in BLA PNs. In conclusion, our results suggest that MS may have its inoculative effect through alleviating the influences of later life stress on the glutamatergic transmission and neuronal activity in amygdala neurons.

Effect of Titanium Particles on the Voltage-Gated Potassium Channel Currents in Trigeminal Root Ganglion Neurons

PURPOSE

Titanium (Ti) is the key material used in dental implants because of its excellent biocompatibility. But wear and corrosion Ti particles had been widely reported to induce inflammation and promote bone absorption. However, little information is known about the damage of Ti particles on neurons.

MATERIALS AND METHODS

Trigeminal root ganglion (TRG) neurons were exposed to Ti particles (<5 μm). The electrophysiological properties of 2 main subtypes of voltage-gated potassium channels (VGPCs) (KA and KV) were examined by whole-cell patch-clamp techniques.

RESULT

With the presence of 0.25 mg/mL Ti particles, amplitudes of IK, A and IK, V were both obviously inhibited. For IK, A, the activation V1/2 shifted to the depolarizing direction with an increased k value, whereas the inactivation V1/2 showed obvious hyperdepolarizing shifts. For IK, V, 0.5 mg/mL Ti particles produced a depolarizing shift of activation V1/2 with a slower activation rate. No significant changes of its inactivation kinetics were found.

CONCLUSION

Titanium (Ti) particles might alter the electrophysiological properties of VGPCs on TRG neurons, which are likely to further influence the excitability of neurons.

Acute exposure to zinc oxide nanoparticles critically disrupts operation of the respiratory neural network in neonatal rat

Due to their extremely small size that gives them unique physicochemical properties, nanoparticles (NPs) are used in the production of everyday materials. However, NPs can accumulate in body organs and could cause various diseases. Moreover, NPs that cross biological membranes such as the blood-brain barrier can aggregate in the brain and potentially produce neuronal damage. Although studies have reported the effects of diverse NPs on the bioelectrical properties of individual neurons, their potential influences on the operation of whole neuronal networks have not been documented. Here, we aimed to evaluate the effects of an acute exposure to zinc oxide (ZnO) NPs on the central neural networks responsible for mammalian respiratory rhythm generation. Using an isolated ex vivo brainstem-spinal cord preparation from neonatal rat in which the circuitry for the central respiratory command remained intact, we show that ZnO NPs accelerate, then profoundly disrupt respiratory-related activity produced by the pre-Bötzinger complex (preBötC) responsible for inspiratory rhythm generation. Consequently, a sudden and definitive cessation of respiratory-related activity occurs in ZnO NPs-exposed preparations. Part of these effects is related to zinc ions released from NPs. Using brainstem slice preparations containing the preBötC network, whole-cell patch-clamp recordings revealed that ZnO NPs depolarize preBötC inspiratory neurons and affect their bioelectrical properties by reducing the amplitude of action potentials, thereby leading to a depression of intra-network activity and the ultimate termination of respiratory rhythmogenesis. These findings support the conclusion that ZnO NPs may have deleterious effects on the central respiratory centers of newborn mammals.

Nano-CuO impairs spatial cognition associated with inhibiting hippocampal long-term potentiation via affecting glutamatergic neurotransmission in rats

Manufactured metal nanoparticles and their applications are continuously expanding because of their unique characteristics while their increasing use may predispose to potential health problems. Several studies have reported the adverse effects of copper oxide nanoparticles (nano-CuO) relative to ecotoxicity and cell toxicity, whereas little is known about the neurotoxicity of nano-CuO. The present study aimed to examine its effects on spatial cognition, hippocampal function, and the possible mechanisms. Male Wistar rats were used to establish an animal model, and nano-CuO was administered at a dose of 0.5 mg/kg/day for 2 weeks. The Morris water maze (MWM) test was employed to evaluate learning and memory. The long-term potentiation (LTP) from Schaffer collaterals to the hippocampal CA1 region, and the effects of nano-CuO on synases were recorded in the hippocampal CA1 neurons of rats. MWM test showed that learning and memory abilities were impaired significantly by nano-CuO ( p < 0.05). The LTP test demonstrated that the field excitatory postsynaptic potential (fEPSP) slopes were significantly lower in nano-CuO-treated groups compared with the control group ( p < 0.01). Furthermore, the data of whole-cell patch-clamp experiments showed that nano-CuO markedly depressed the frequencies of both spontaneous excitatory postsynaptic currents (sEPSCs) and miniature EPSCs (mEPSCs), indicating an effect of nano-CuO on inhibiting the release frequency of glutamate presynapticly ( p < 0.01). Meanwhile, the amplitudes of both sEPSC and mEPSC were significantly reduced in nano-CuO-treated animals, which suggested that the effect of nano-CuO modulates postsynaptic receptor kinetics ( p < 0.01). Paired pulse facilitation (PPF) ( p < 0.05) and the expression of NR2A, but not NR2B, of N-methyl-d-aspartate (NMDA) subunits ( p < 0.05), were decreased significantly. In conclusion, nano-CuO impaired glutamate transmission presynapticly and postsynapticly, which may contribute importantly to diminished LTP and other induced cognitive deficits.

Label-free and dynamic monitoring of cytotoxicity to the blood-brain barrier cells treated with nanometre copper oxide

A cytotoxicity study was conducted with a primary culture of the nervous system cells, including brain microvascular endothelial cells (BMECs) and astrocytes, which are important components of the blood-brain barrier. The real-time cell analysis (RTCA) was used to determine the cytotoxicity of copper-oxide nanoparticles (CuO NPs). The IC50 values of CuO NPs in astrocytes and BMECs were determined by the RTCA at different exposure times and were used as base values for further research. DNA damage after exposure to CuO NPs for 3 and 24 h was assessed using comet assay at the IC50 obtained from RTCA. The onset time of cytotoxicity induced by CuO NPs was 2 and 2-4 h post-exposure in BMECs and astrocytes, respectively. Furthermore, the degree of cytotoxicity induced by exposure to CuO NPs for 24-48 h in the BMECs and astrocytes was similar. Treatment with CuO NPs at 1/2*IC50 and 1/5*IC50 for 3 h induced genotoxicity in both cells as assessed by a measurement of DNA damage, although no cytotoxicity was observed. However, significant DNA damage was observed at all concentrations of CuO NPs used in this study, when the treatment time was 24 h.

Neurotoxicity of Copper

Copper is an essential trace metal that is required for several important biological processes, however, an excess of copper can be toxic to cells. Therefore, systemic and cellular copper homeostasis is tightly regulated, but dysregulation of copper homeostasis may occur in disease states, resulting either in copper deficiency or copper overload and toxicity. This chapter will give an overview on the biological roles of copper and of the mechanisms involved in copper uptake, storage, and distribution. In addition, we will describe potential mechanisms of the cellular toxicity of copper and copper oxide nanoparticles. Finally, we will summarize the current knowledge on the connection of copper toxicity with neurodegenerative diseases.

Application of dental nanomaterials: potential toxicity to the central nervous system

Nanomaterials are defined as materials with one or more external dimensions with a size of 1-100 nm. Such materials possess typical nanostructure-dependent properties (eg, chemical, biological, optical, mechanical, and magnetic), which may differ greatly from the properties of their bulk counterparts. In recent years, nanomaterials have been widely used in the production of dental materials, particularly in light polymerization composite resins and bonding systems, coating materials for dental implants, bioceramics, endodontic sealers, and mouthwashes. However, the dental applications of nanomaterials yield not only a significant improvement in clinical treatments but also growing concerns regarding their biosecurity. The brain is well protected by the blood-brain barrier (BBB), which separates the blood from the cerebral parenchyma. However, in recent years, many studies have found that nanoparticles (NPs), including nanocarriers, can transport through the BBB and locate in the central nervous system (CNS). Because the CNS may be a potential target organ of the nanomaterials, it is essential to determine the neurotoxic effects of NPs. In this review, possible dental nanomaterials and their pathways into the CNS are discussed, as well as related neurotoxicity effects underlying the in vitro and in vivo studies. Finally, we analyze the limitations of the current testing methods on the toxicological effects of nanomaterials. This review contributes to a better understanding of the nano-related risks to the CNS as well as the further development of safety assessment systems.

SILAC-based quantitative proteomic analysis of human lung cell response to copper oxide nanoparticles

Copper (II) oxide (CuO) nanoparticles (NP) are widely used in industry and medicine. In our study we evaluated the response of BEAS-2B human lung cells to CuO NP, using Stable isotope labeling by amino acids in cell culture (SILAC)-based proteomics and phosphoproteomics. Pathway modeling of the protein differential expression showed that CuO NP affect proteins relevant in cellular function and maintenance, protein synthesis, cell death and survival, cell cycle and cell morphology. Some of the signaling pathways represented by BEAS-2B proteins responsive to the NP included mTOR signaling, protein ubiquitination pathway, actin cytoskeleton signaling and epithelial adherens junction signaling. Follow-up experiments showed that CuO NP altered actin cytoskeleton, protein phosphorylation and protein ubiquitination level.

Engineered nanoparticles. How brain friendly is this new guest?

In the last 30 years, the use of engineered nanoparticles (NPs) has progressively increased in many industrial and medical applications. In therapy, NPs may allow more effective cellular and subcellular targeting of drugs. In diagnostic applications, quantum dots are exploited for their optical characteristics, while superparamagnetic iron oxides NPs are used in magnetic resonance imaging. NPs are used in semiconductors, packaging, textiles, solar cells, batteries and plastic materials. Despite the great progress in nanotechnologies, comparatively little is known to date on the effects that exposure to NPs may have on the human body, in general and specifically on the brain. NPs can enter the human body through skin, digestive tract, airways and blood and they may cross the blood-brain barrier to reach the central nervous system. In addition to the paucity of studies describing NP effects on brain function, some of them also suffer of insufficient NPs characterization, inadequate standardization of conditions and lack of contaminant evaluation, so that results from different studies can hardly be compared. It has been shown in vitro and in vivo in rodents that NPs can impair dopaminergic and serotoninergic systems. Changes of neuronal morphology and neuronal death were reported in mice treated with NPs. NPs can also affect the respiratory chain of mitochondria and Bax protein levels, thereby causing apoptosis. Changes in expression of genes involved in redox pathways in mouse brain regions were described. NPs can induce autophagy, and accumulate in lysosomes impairing their degradation capacity. Cytoskeleton and vesicle trafficking may also be affected. NPs treated animals showed neuroinflammation with microglia activation, which could induce neurodegeneration. Considering the available data, it is important to design adequate models and experimental systems to evaluate in a reliable and controlled fashion the effects of NPs on the brain, and generate data representative of effects on the human brain, thereby useful for developing robust and valid nanosafety standards.

Perturbation of physiological systems by nanoparticles

Nanotechnology is having a tremendous impact on our society. However, societal concerns about human safety under nanoparticle exposure may derail the broad application of this promising technology. Nanoparticles may enter the human body via various routes, including respiratory pathways, the digestive tract, skin contact, intravenous injection, and implantation. After absorption, nanoparticles are carried to distal organs by the bloodstream and the lymphatic system. During this process, they interact with biological molecules and perturb physiological systems. Although some ingested or absorbed nanoparticles are eliminated, others remain in the body for a long time. The human body is composed of multiple systems that work together to maintain physiological homeostasis. The unexpected invasion of these systems by nanoparticles disturbs normal cell signaling, impairs cell and organ functions, and may even cause pathological disorders. This review examines the comprehensive health risks of exposure to nanoparticles by discussing how nanoparticles perturb various physiological systems as revealed by animal studies. The potential toxicity of nanoparticles to each physiological system and the implications of disrupting the balance among systems are emphasized.

Intracellular gold nanoparticles increase neuronal excitability and aggravate seizure activity in the mouse brain

Due to their inert property, gold nanoparticles (AuNPs) have drawn considerable attention; their biological application has recently expanded to include nanomedicine and neuroscience. However, the effect of AuNPs on the bioelectrical properties of a single neuron remains unknown. Here we present the effect of AuNPs on a single neuron under physiological and pathological conditions in vitro. AuNPs were intracellularly applied to hippocampal CA1 neurons from the mouse brain. The electrophysiological property of CA1 neurons treated with 5- or 40-nm AuNPs was assessed using the whole-cell patch-clamp technique. Intracellular application of AuNPs increased both the number of action potentials (APs) and input resistance. The threshold and duration of APs and the after hyperpolarization (AHP) were decreased by the intracellular AuNPs. In addition, intracellular AuNPs elicited paroxysmal depolarizing shift-like firing patterns during sustained repetitive firings (SRF) induced by prolonged depolarization (10 sec). Furthermore, low Mg²⁺-induced epileptiform activity was aggravated by the intracellular AuNPs. In this study, we demonstrated that intracellular AuNPs alter the intrinsic properties of neurons toward increasing their excitability, and may have deleterious effects on neurons under pathological conditions, such as seizure. These results provide some considerable direction on application of AuNPs into central nervous system (CNS).

Neurotoxicity of nanoscale materials

Nanotechnology has been applied in consumer products and commercial applications, showing a significant impact on almost all industries and all areas of society. Significant evidence indicates that manufactured nanomaterials and combustion-derived nano-materials elicit toxicity in humans exposed to these nanomaterials. The interaction of the engineered nanomaterials with the nervous system has received much attention in the nanotoxicology field. In this review, the biological effects of metal, metal oxide, and carbon-based nanomaterials on the nervous system are discussed from both in vitro and in vivo studies. The translocation of the nanoparticles through the blood–brain barrier or nose to brain via the olfactory bulb route, oxidative stress, and inflammatory mechanisms of nanomaterials are also reviewed.

Estimating the modulatory effects of nanoparticles on neuronal circuits using computational upscaling

BACKGROUND

Beside the promising application potential of nanotechnologies in engineering, the use of nanomaterials in medicine is growing. New therapies employing innovative nanocarrier systems to increase specificity and efficacy of drug delivery schemes are already in clinical trials. However the influence of the nanoparticles themselves is still unknown in medical applications, especially for complex interactions in neural systems. The aim of this study was to investigate in vitro effects of coated silver nanoparticles (cAgNP) on the excitability of single neuronal cells and to integrate those findings into an in silico model to predict possible effects on neuronal circuits.

METHODS

We first performed patch clamp measurements to investigate the effects of nanosized silver particles, surrounded by an organic coating, on excitability of single cells. We then determined which parameters were altered by exposure to those nanoparticles using the Hodgkin-Huxley model of the sodium current. As a third step, we integrated those findings into a well-defined neuronal circuit of thalamocortical interactions to predict possible changes in network signaling due to the applied cAgNP, in silico.

RESULTS

We observed rapid suppression of sodium currents after exposure to cAgNP in our in vitro recordings. In numerical simulations of sodium currents we identified the parameters likely affected by cAgNP. We then examined the effects of such changes on the activity of networks. In silico network modeling indicated effects of local cAgNP application on firing patterns in all neurons in the circuit.

CONCLUSION

Our sodium current simulation shows that suppression of sodium currents by cAgNP results primarily by a reduction in the amplitude of the current. The network simulation shows that locally cAgNP-induced changes result in changes in network activity in the entire network, indicating that local application of cAgNP may influence the activity throughout the network.

Uptake and toxicity of copper oxide nanoparticles in cultured primary brain astrocytes

To test for consequences of an exposure of brain cells to copper oxide nanoparticles (CuO-NPs), we synthesised and characterised dimercaptosuccinate-coated CuO-NPs. These particles had a diameter of around 5 nm as determined by transmission electron microscopy, while their average hydrodynamic diameter in aqueous dispersion was 136 ± 4 nm. Dispersion in cell-culture medium containing 10% fetal calf serum increased the hydrodynamic diameter to 178 ± 12 nm and shifted the zeta potential of the particles from -49 ± 7 mV (in water) to -10 ± 3 mV. Exposure of cultured primary brain astrocytes to CuO-NPs increased the cellular copper levels and compromised the cell viability in a time-, concentration- and temperature-dependent manner. Application of CuO-NPs in concentrations above 100 µM copper (6.4 µg/ml) severely compromised the viability of the cells, as demonstrated by a lowered 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide reduction capacity, a lowered cellular lactate dehydrogenase activity and an increased membrane permeability for the fluorescent dye propidium iodide. Copper internalisation as well as cell toxicity of astrocytes exposed to CuO-NPs were similar to that observed for cells that had been incubated with copper salts. The CuO-NP-induced toxicity was accompanied by an increase in the generation of reactive oxygen species (ROS) in the cells. Both, ROS formation and cell toxicity in CuO-NP-treated astrocytes, were lowered in the presence of the cell-permeable copper chelator tetrathiomolybdate. These data demonstrate that CuO-NPs are taken up by cultured astrocytes and suggest that excess of internalised CuO-NPs cause cell toxicity by accelerating the formation of ROS.

The effect of nanoparticle uptake on cellular behavior: disrupting or enabling functions?

Nanoparticles (NPs) are materials with overall dimensions in the nanoscale range. They have unique physicochemical properties, and have emerged as important players in current research in modern medicine. In the last few decades, several types of NPs and microparticles have been synthesized and proposed for use as contrast agents for diagnostics and imaging and for drug delivery; for example, in cancer therapy. Yet specific targeting that will improve their delivery still represents an unsolved challenge. The mechanism by which NPs enter the cell has important implications not only for their fate but also for their impact on biological systems. Several papers in the literature discuss the potential risks related to NP exposure, and more recently the concept that even sublethal doses of NPs may elicit a cell response has been proposed. In this review, we intend to present an overall view of cell mechanisms that may be perturbed by cell-NP interaction. Published data, in fact, emphasize that NPs should no longer be viewed only as simple carriers for biomedical applications, but that they can also play an active role in mediating biological effects.

Toxicity of copper oxide nanoparticle suspensions to aquatic biota

Toxicity effects induced by nanosuspensions of CuO (<50 nm; Sigma-Aldrich) on macrophytic algae cells of Nitellopsis obtusa (96-h median lethal concentration [LC50]), microphytic algae Chlorella (30-min median inhibitory concentration [IC50]), shrimp Thamnocephalus platyurus (24-h LC50), and rotifer Brachionus calyciflorus (24-h LC50) were investigated. No substantial differences between the effects of nonsonicated and sonicated nCuO suspensions were observed. The particle size distribution analysis accomplished by the laser diffraction technique at suspension concentration from 3 to 100 mg/L revealed rapid (within 5 min) reagglomeration of the particles after the sonication. The observed adverse effects on N. obtusa cells may be attributed to nanoparticles per se, but not to ionic Cu, because neither chemical analysis nor biological testing (algae survival in the supernatants of suspensions) confirmed the presence of cupric ions in toxic amounts. Contrary to ionic Cu form, nCuO delayed the initial phase of N. obtusa cell membrane depolarization. Lethality tests with rewash demonstrated that the least used 5-min exposure in 100 mg/L nCuO sonicated suspension induced 70% mortality in charophyte cells after 8 d, whereas the rewash after a short exposure to a noticeably toxic concentration of Cu(2+) prevented cell mortality. The obtained data suggested the possible influence of a thick charophyte cell wall on the dynamics of nanotoxicity effects.

Inhibitory effect of tungsten carbide nanoparticles on voltage-gated potassium currents of hippocampal CA1 neurons

The effects of tungsten carbide nanoparticles (nano-WC) on the properties of voltage-dependent potassium currents and evoked action potentials were studied in the hippocampal CA1 pyramidal neurons of rats at the ages of postnatal days 10-14 using the whole-cell patch-clamp technique. The results indicated that: (1) the amplitudes of transient outward potassium current (I(A)) and delayed rectifier potassium current (I(K)) were significantly decreased by 10(-7) g/ml nano-WC, while the current-voltage curves of I(A) and I(K) were significantly decreased by nano-WC from +10 to +90 mV. (2) Nano-WC produced a depolarizing shift in the steady-state activation curve of I(A) and I(K) with increased slope factors, and delayed the recovery of I(A) from inactivation, but no significant effects were found on the inactivation of I(A). (3) Nano-WC prolonged the evoked action potential duration and lowered the firing rate. These results suggest that 10(-7) g/ml nano-WC can decrease the amplitudes of I(A) and I(K) currents by reducing the opening number of voltage-gated potassium channels and delaying the recovery of I(A) from inactivation, which indicate that nano-WC has the potential neurotoxicity.

The inhibitory effects of nano-Ag on voltage-gated potassium currents of hippocampal CA1 neurons

The application of the nano-sized materials continues to grow at a rapid rate in the fields of medicine, biotechnology, and environmental technology. Voltage-gated potassium currents play a key role in excitable cellular viability and function, especially in the central nervous system. The aim of this study was to investigate the actions of silver nano-particles (nano-Ag) on voltage-activated potassium currents in hippocampal CA1 neurons using whole cell patch-clamp technique. The hydrodynamic mean diameter of nano-Ag (10(-5) g mL(-1) ) was 223.9 nm in artificial cerebrospinal fluid (ACSF). Both types, transient potassium (I(A) ) and delayed rectifier potassium (I(K) ) current amplitudes were inhibited by the nano-Ag (10(-5) g mL(-1) ). The nano-Ag particles produced a hyperpolarizing shift in the activation-voltage curve of I(K) and inactivation-voltage curve of I(A) and also delayed the recovery of I(A) from inactivation. The results suggest that nano-Ag may have potential to alter the excitability of neurons by depressing the potassium channels.

Modeling the effects of nanoparticles on neuronal cells: from ionic channels to network dynamics

Engineered nanoparticles (NPs) offer great application potential in various fields, for example the chemical industry, energy management or medical sciences. Nanoparticles are increasingly being incorporated into daily products. But what happens, if living organisms are exposed to those NPs? Their ability to move seemingly barrier-free in organic tissue could be both beneficial and harmful. Even though research concerning nanotoxicity has already begun, there are still many open questions to be addressed. In this report, we propose a computational model applying the steady-state Hodgkin-Huxley-equations and the Differential Evolution Algorithm for fitting the model to the data of patch-clamp measurements carried out by our group: Coated silvernanoparticles (Ag-Nano) in different concentrations were applied to single chromaffin cells while measuring the ionic currents in the whole-cell configuration. Compared to controls, significant differences in sodium-currents were observed after the application of NPs. Using the computational model, we could evaluate the parameters which model the change in behavior of neuronal cells due to the addition of Ag-Nano. This can ultimately give insight to underlying mechanisms. An integration to model the dynamic behavior of neuronal networks exposed to NP is easily conceivable using this technique.

Risks from accidental exposures to engineered nanoparticles and neurological health effects: a critical review

There are certain concerns regarding the safety for the environment and human health from the use of engineered nanoparticles (ENPs) which leads to unintended exposures, as opposed to the use of ENPs for medical purposes. This review focuses on the unintended human exposure of ENPs. In particular, possible effects in the brain are discussed and an attempt to assess risks is performed.

Animal experiments have shown that investigated ENPs (metallic nanoparticles, quantum dots, carbon nanotubes) can translocate to the brain from different entry points (skin, blood, respiratory pathways). After inhalation or instillation into parts of the respiratory tract a very small fraction of the inhaled or instilled ENPs reaches the blood and subsequently secondary organs, including the CNS, at a low translocation rate. Experimental in vivo and in vitro studies have shown that several types of ENPs can have various biological effects in the nervous system. Some of these effects could also imply that ENPs can cause hazards, both acutely and in the long term. The relevance of these data for risk assessment is far from clear. There are at present very few data on exposure of the general public to either acute high dose exposure or on chronic exposure to low levels of air-borne ENPs. It is furthermore unlikely that acute high dose exposures would occur. The risk from such exposures for damaging CNS effects is thus probably very low, irrespective of any biological hazard associated with ENPs.

The situation is more complicated regarding chronic exposures, at low doses. The long term accumulation of ENPs can not be excluded. However, we do not have exposure data for the general public regarding ENPs. Although translocation to the brain via respiratory organs and the circulation appears to be very low, there remains a possibility that chronic exposures, and/or biopersistent ENPs, can influence processes within the brain that are triggering or aggravating pathological processes.

In general, the present state of knowledge is unsatisfactory for a proper risk assessment in this area. Crucial deficits include lack of exposure data, the absence of a proper dose concept, and that studies often fail in adequate description of the investigated ENPs.

A review of nanoparticle functionality and toxicity on the central nervous system

Although nanoparticles have tremendous potential for a host of applications, their adverse effects on living cells have raised serious concerns recently for their use in the healthcare and consumer sectors. As regards the central nervous system (CNS), research data on nanoparticle interaction with neurons has provided evidence of both negative and positive effects. Maximal application dosage of nanoparticles in materials to provide applications such as antibacterial and antiviral functions is approximately 0.1-1.0 wt%. This concentration can be converted into a liquid phase release rate (leaching rate) depending upon the host or base materials used. For example, nanoparticulate silver (Ag) or copper oxide (CuO)-filled epoxy resin demonstrates much reduced release of the metal ions (Ag(+) or Cu(2+)) into their surrounding environment unless they are mechanically removed or aggravated. Subsequent to leaching effects and entry into living systems, nanoparticles can also cross through many other barriers, such as skin and the blood-brain barrier (BBB), and may also reach bodily organs. In such cases, their concentration or dosage in body fluids is considered to be well below the maximum drug toxicity test limit (10(-5) g ml(-1)) as determined in artificial cerebrospinal solution. As this is a rapidly evolving area and the use of such materials will continue to mature, so will their exposure to members of society. Hence, neurologists have equal interests in nanoparticle effects (positive functionality and negative toxicity) on human neuronal cells within the CNS, where the current research in this field will be highlighted and reviewed.

A review of nanoparticle functionality and toxicity on the central nervous system

Although nanoparticles have tremendous potential for a host of applications, their adverse effects on living cells have raised serious concerns recently for their use in the healthcare and consumer sectors. As regards the central nervous system (CNS), research data on nanoparticle interaction with neurons has provided evidence of both negative and positive effects. Maximal application dosage of nanoparticles in materials to provide applications such as antibacterial and antiviral functions is approximately 0.1-1.0 wt%. This concentration can be converted into a liquid phase release rate (leaching rate) depending upon the host or base materials used. For example, nanoparticulate silver (Ag) or copper oxide (CuO)-filled epoxy resin demonstrates much reduced release of the metal ions (Ag(+) or Cu(2+)) into their surrounding environment unless they are mechanically removed or aggravated. Subsequent to leaching effects and entry into living systems, nanoparticles can also cross through many other barriers, such as skin and the blood-brain barrier (BBB), and may also reach bodily organs. In such cases, their concentration or dosage in body fluids is considered to be well below the maximum drug toxicity test limit (10(-5) g ml(-1)) as determined in artificial cerebrospinal solution. As this is a rapidly evolving area and the use of such materials will continue to mature, so will their exposure to members of society. Hence, neurologists have equal interests in nanoparticle effects (positive functionality and negative toxicity) on human neuronal cells within the CNS, where the current research in this field will be highlighted and reviewed.

Effect of melamine on potassium currents in rat hippocampal CA1 neurons

As an industrially synthesized chemical, melamine has been applied in a wide range of areas. However, many questions on the adverse effect and toxicity of melamine have been emerged, recently. In this investigation, the cytotoxicity of melamine on PC12 cells was evaluated. Furthermore, the effect of melamine on the transient outward potassium current (I(A)) and the delayed rectifier potassium current (I(K)) in hippocampal CA1 pyramidal neurons of rat was studied using whole-cell patch-clamp technique. The results showed that melamine-induced cell death in a concentration and time-dependent manner, and produced a concentration-dependent inhibition in amplitudes of I(A) and I(K) at any concentrations (5x10(-4), 5x10(-5), and 5x10(-6)g/ml). Moreover, at higher concentration (5x10(-4)g/ml), melamine had observable effects of the steady-state inactivation of I(A), that is melamine shifted inactivation curve of I(A) towards hyperpolarization. The spontaneous firing frequency was increased as well. These results suggest that the regulation of I(A) and I(K) induced by melamine would make neurons display aberrant firing properties and abnormal neuronal discharge, which could be a possible underlying mechanism for the melamine-induced neurotoxicity.