Impact of nanoparticles on neuron biology: current research trends

Navigating Neurotoxicity and Safety Assessment of Nanocarriers for Brain Delivery: Strategies and Insights

Nanomedicine, an area that uses nanomaterials for theragnostic purposes, is advancing rapidly, particularly in the detection and treatment of neurodegenerative diseases. The design of nanocarriers can be optimized to enhance drug bioavailability and targeting to specific organs, improving therapeutic outcomes. However, clinical translation hinges on biocompatibility and safety. Nanocarriers can cross the blood-brain barrier (BBB), potentially causing neurotoxic effects through mechanisms such as oxidative stress, DNA damage, and neuroinflammation. Concerns about their accumulation and persistence in the brain make it imperative to carry out a nanotoxicological risk assessment. Generally, this involves identifying exposure sources and routes, characterizing physicochemical properties, and conducting cytotoxicity assays both in vitro and in vivo. The lack of a specialized regulatory framework creates substantial gaps, making it challenging to translate findings across development stages. Additionally, there is a pressing need for innovative testing methods due to constraints on animal use and the demand for high-throughput screening. This review examines the mechanisms of nanocarrier-induced neurotoxicity and the challenges in risk assessment, highlighting the impact of physicochemical properties and the advantages and limitations of current neurotoxicity evaluation models. Future perspectives are also discussed. Additional guidance is crucial to improve the safety of nanomaterials and reduce associated uncertainty. STATEMENT OF SIGNIFICANCE: Nanocarriers show tremendous potential for theragnostic purposes in neurological diseases, enhancing drug targeting to the brain, and improving biodistribution and pharmacokinetics. However, their neurotoxicity is still a major field to be explored, with only 5% of nanotechnology-related publications addressing this matter. This review focuses on the issue of neurotoxicity and safety assessment of nanocarriers for brain delivery. Neurotoxicity-relevant exposure sources, routes, and molecular mechanisms, along with the impact of the physicochemical properties of nanomaterials, are comprehensively described. Moreover, the different experimental models used for neurotoxicity evaluation are explored at length, including their main advantages and limitations. To conclude, we discuss current challenges and future perspectives for a better understanding of risk assessment of nanocarriers for neurobiomedical applications.

Gold Nanoparticles in Neurological Diseases: A Review of Neuroprotection

This review explores the diverse applications of gold nanoparticles (AuNPs) in neurological diseases, with a specific focus on Alzheimer's disease (AD), Parkinson's disease (PD), and stroke. The introduction highlights the pivotal role of neuroinflammation in these disorders and introduces the unique properties of AuNPs. The review's core examines the mechanisms by which AuNPs exert neuroprotection and anti-neuro-inflammatory effects, elucidating various pathways through which they manifest these properties. The potential therapeutic applications of AuNPs in AD are discussed, shedding light on promising avenues for therapy. This review also explores the prospects of utilizing AuNPs in PD interventions, presenting a hopeful outlook for future treatments. Additionally, the review delves into the potential of AuNPs in providing neuroprotection after strokes, emphasizing their significance in mitigating cerebrovascular accidents' aftermath. Experimental findings from cellular and animal models are consolidated to provide a comprehensive overview of AuNPs' effectiveness, offering insights into their impact at both the cellular and in vivo levels. This review enhances our understanding of AuNPs' applications in neurological diseases and lays the groundwork for innovative therapeutic strategies in neurology.

Recognition and detection technology for microplastic, its source and health effects

Microplastic (MP) is ubiquitous in the environment which appeared as an immense intimidation to human and animal health. The plastic fragments significantly polluted the ocean, fresh water, food chain, and other food items. Inadequate maintenance, less knowledge of adverse influence along with inappropriate usage in addition throwing away of plastics items revolves present planet in to plastics planet. The present study aims to focus on the recognition and advance detection technologies for MPs and the adverse effects of micro- and nanoplastics on human health. MPs have rigorous adverse effect on human health that leads to condensed growth rates, lessened reproductive capability, ulcer, scrape, and oxidative nervous anxiety, in addition, also disturb circulatory and respiratory mechanism. The detection of MP particles has also placed emphasis on identification technologies such as scanning electron microscopy, Raman spectroscopy, optical detection, Fourier transform infrared spectroscopy, thermo-analytical techniques, flow cytometry, holography, and hyperspectral imaging. It suggests that further research should be explored to understand the source, distribution, and health impacts and evaluate numerous detection methodologies for the MPs along with purification techniques.

Harnessing filamentous phages for enhanced stroke recovery

Stroke poses a critical global health challenge, leading to substantial morbidity and mortality. Existing treatments often miss vital timeframes and encounter limitations due to adverse effects, prompting the pursuit of innovative approaches to restore compromised brain function. This review explores the potential of filamentous phages in enhancing stroke recovery. Initially antimicrobial-centric, bacteriophage therapy has evolved into a regenerative solution. We explore the diverse role of filamentous phages in post-stroke neurological restoration, emphasizing their ability to integrate peptides into phage coat proteins, thereby facilitating recovery. Experimental evidence supports their efficacy in alleviating post-stroke complications, immune modulation, and tissue regeneration. However, rigorous clinical validation is essential to address challenges like dosing and administration routes. Additionally, genetic modification enhances their potential as injectable biomaterials for complex brain tissue issues. This review emphasizes innovative strategies and the capacity of filamentous phages to contribute to enhanced stroke recovery, as opposed to serving as standalone treatment, particularly in addressing stroke-induced brain tissue damage.

Study of nerve cell regeneration on nanofibers containing cerium oxide nanoparticles in a spinal cord injury model in rats

Since the CNS is unable to repair itself via neuronal regeneration in adult mammals, alternative therapies need to be found. The use of cerium oxide nanoparticles to repair nerve damage could be a promising approach for spinal cord reconstruction. In this study, we constructed a scaffold containing cerium oxide nanoparticles (Scaffold-CeO₂) and investigated the rate of nerve cell regeneration in a rat model of spinal cord injury. The scaffold of gelatin and polycaprolactone was synthesized, and a gelatin solution containing cerium oxide nanoparticles was attached to the scaffold. For the animal study, 40 male Wistar rats were randomly divided into 4 groups (n = 10): (a) Control; (b) Spinal cord injury (SCI); (c) Scaffold (SCI + scaffold without CeO₂ nanoparticles); (d) Scaffold-CeO₂ (SCI + scaffold containing CeO₂ nanoparticles). After creation of a hemisection SCI, scaffolds were placed at the site of injury in groups c and d, and after 7 weeks the rats were subjected to behavioral tests and then sacrificed for preparation of the spinal cord tissue to measure the expression of G-CSF, Tau and Mag proteins by Western blotting and Iba-1 protein by immunohistochemistry. The result of behavioral tests confirmed motor improvement and pain reduction in the Scaffold-CeO₂ group compared to the SCI group. Decreased expression of Iba-1 and higher expression of Tau and Mag in the Scaffold-CeO₂ group compared to the SCI group could be the result of nerve regeneration caused by the scaffold containing CeONPs as well as relief of pain symptoms.

Analysis of Experimental Data on Changes in Various Structures and Functions of the Rat Brain following Intranasal Administration of Fe2O3 Nanoparticles

Particulate matter, including iron nanoparticles, is one of the constituents of ambient air pollution. We assessed the effect of iron oxide (Fe₂O₃) nanoparticles on the structure and function of the brain of rats. Electron microscopy showed Fe₂O₃ nanoparticles in the tissues of olfactory bulbs but not in the basal ganglia of the brain after their subchronic intranasal administration. We observed an increase in the number of axons with damaged myelin sheaths and in the proportion of pathologically altered mitochondria in the brains of the exposed animals against the background of almost stable blood parameters. We conclude that the central nervous system can be a target for toxicity of low-dose exposure to Fe₂O₃ nanoparticles.

Superparamagnetic Iron Oxide Nanoparticles and Curcumin Equally Promote Neuronal Branching Morphogenesis in the Absence of Nerve Growth Factor in PC12 Cells

Regeneration of the damaged neurons in neurological disorders and returning their activities are two of the main purposes of neuromedicine. Combination use of specific nanoformulations with a therapeutic compound could be a good candidate for neuroregeneration applications. Accordingly, this research aims to utilize the combination of curcumin, as a neurogenesis agent, with dextran-coated superparamagnetic iron oxide nanoparticles (SPIONs) to evaluate their effects on PC12 cellsʹ neuronal branching morphogenesis in the absence of nerve growth factor. Therefore, the effects of each component alone and in combination form on the cytotoxicity, neurogenesis, and neural branching morphogenesis were evaluated using MTT assay, immunofluorescence staining, and inverted microscopy, respectively. Results confirmed the effectiveness of the biocompatible iron oxide nanoparticles (with a size of about 100 nm) in improving the percentage of neural branching (p < 0.01) in PC12 cells. In addition, the combination use of these nanoparticles with curcumin could enhance the effect of curcumin on neurogenesis (p < 0.01). These results suggest that SPIONs in combination with curcumin could act as an inducing factor on PC12 neurogenesis in the absence of nerve growth factor and could offer a novel therapeutic approach to the treatment of neurodegenerative diseases.

Light-to-Heat Converting ECM-Mimetic Nanofiber Scaffolds for Neuronal Differentiation and Neurite Outgrowth Guidance

The topological cues of fibrous scaffolds (in particular extracellular matrix (ECM)-mimetic nanofibers) have already proven to be a powerful tool for influencing neuronal morphology and behavior. Remote photothermal optical treatment provides additional opportunities for neuronal activity regulation. A combination of these approaches can provide “smart” 3D scaffolds for efficient axon guidance and neurite growth. In this study we propose two alternative approaches for obtaining biocompatible photothermal scaffolds: surface coating of nylon nanofibers with light-to-heat converting nanoparticles and nanoparticle incorporation inside the fibers. We have determined photoconversion efficiency of fibrous nanomaterials under near infrared (NIR) irradiation, as well as biocompatible photothermal treatment parameters. We also measured photo-induced intracellular heating upon contact of cells with a plasmonic surface. In the absence of NIR stimulation, our fibrous scaffolds with a fiber diameter of 100 nm induced an increase in the proportion of β3-tubulin positive cells, while thermal stimulation of neuroblastoma cells on nanoparticles-decorated scaffolds enhanced neurite outgrowth and promoted neuronal maturation. We demonstrate that contact guidance decorated fibers can stimulate directional growth of processes of differentiated neural cells. We studied the impact of nanoparticles on the surface of ECM-mimetic scaffolds on neurite elongation and axonal branching of rat hippocampal neurons, both as topographic cues and as local heat sources. We show that decorating the surface of nanofibers with nanoparticles does not affect the orientation of neurites, but leads to strong branching, an increase in the number of neurites per cell, and neurite elongation, which is independent of NIR stimulation. The effect of photothermal stimulation is most pronounced when cultivating neurons on nanofibers with incorporated nanoparticles, as compared to nanoparticle-coated fibers. The resulting light-to-heat converting 3D materials can be used as tools for controlled photothermal neuromodulation and as “smart” materials for reconstructive neurosurgery.

Comparison of the possible histopathological changes of the rat neonatal cerebellum induced by toxic and nontoxic doses of biological silver nanoparticles with chemical silver nanoparticles

INTRODUCTION

Today, due to the increasing application of silver nanoparticles in medical products, it is necessary to pay attention to the user's safety. There are three methods, namely, chemical, physical, and biological, used for the production of nanoparticles. Although the first two methods might introduce health hazards, the latter is hypothetically safe. In this study, we examined the histopathological changes in the cerebellum of neonatal Wistar rats induced by injection of toxic and nontoxic doses of silver nanoparticles, which were produced by green synthetic method and were compared with chemical silver nanoparticles.

METHODS

This study was a laboratory interventional study performed on 25 Wistar rats in the Animal Laboratory of Islamic Azad University of Shahrood. These rats were divided into five groups of the control group, the group with nonpoisonous injection of chemical nanoparticles, the group with nonpoisonous injection of biological nanoparticles, the group with injection of poisonous chemical nanoparticles, and the group with injection of poisonous biological nanoparticles. The rats were impregnated by the males of the same race and the cerebellum of their offspring was studied after birth.

RESULTS

We found that the injection of nonpoisonous chemical nanoparticles caused hyperemia, inappropriate size, and dark cytoplasm in some Purkinje cells. Also, injection of poisonous chemical nanoparticles caused hyperemia and cellular dispersion in the molecular layer, caused abnormal shapes, and reduced the number of cells in Purkinje cells. However, injection of poisonous and nonpoisonous biological nanoparticles did not alter cerebellum cells nor did it cause any inflammation or hyperemia.

CONCLUSION

In contrast with chemical nanoparticles, biological nanoparticles have less significant effect on the cerebellum cells.

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

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

Therapeutic Potential of Magnetic Nanoparticle-Based Human Adipose-Derived Stem Cells in a Mouse Model of Parkinson's Disease

Parkinson's disease (PD) is a progressive neurodegenerative disease characterized by the loss of dopaminergic neurons in the substantia nigra. Several treatments for PD have focused on the management of physical symptoms using dopaminergic agents. However, these treatments induce various adverse effects, including hallucinations and cognitive impairment, owing to non-targeted brain delivery, while alleviating motor symptoms. Furthermore, these therapies are not considered ultimate cures owing to limited brain self-repair and regeneration abilities. In the present study, we aimed to investigate the therapeutic potential of human adipose-derived stem cells (hASCs) using magnetic nanoparticles in a 6-hydroxydopamine (6-OHDA)-induced PD mouse model. We used the Maestro imaging system and magnetic resonance imaging (MRI) for in vivo tracking after transplantation of magnetic nanoparticle-loaded hASCs to the PD mouse model. The Maestro imaging system revealed strong hASCs signals in the brains of PD model mice. In particular, MRI revealed hASCs distribution in the substantia nigra of hASCs-injected PD mice. Behavioral evaluations, including apomorphine-induced rotation and rotarod performance, were significantly recovered in hASCs-injected 6-OHDA induced PD mice when compared with saline-treated counterparts. Herein, we investigated whether hASCs transplantation using magnetic nanoparticles recovered motor functions through targeted brain distribution in a 6-OHDA induced PD mice. These results indicate that magnetic nanoparticle-based hASCs transplantation could be a potential therapeutic strategy in PD.

Chronic Inflammatory Diseases, Anti-Inflammatory Agents and Their Delivery Nanosystems

Inflammatory diseases, whether caused by excessive stress on certain tissues/parts of the body or arising from infections accompanying autoimmune or secondary diseases, have become a problem, especially in the Western world today. Whether these are inflammations of visceral organs, joints, bones, or the like, they are always a physiological reaction of the body, which always tries to eradicate noxious agents and restore tissue homeostasis. Unfortunately, this often results in damage, often irreversible, to the affected tissues. Nevertheless, these inflammatory reactions of the body are the results of excessive stress, strain, and the generally unhealthy environment, in which the people of Western civilization live. The pathophysiology and pathobiochemistry of inflammatory/autoimmune processes are being studied in deep detail, and pharmaceutical companies are constantly developing new drugs that modulate/suppress inflammatory responses and endogenous pro-inflammatory agents. In addition to new specifically targeted drugs for a variety of pro-inflammatory agents, a strategy can be found for the use of older drugs, which are formulated into special nanodrug delivery systems with targeted distribution and often modified release. This contribution summarizes the current state of research and development of nanoformulated anti-inflammatory agents from both conventional drug classes and experimental drugs or dietary supplements used to alleviate inflammatory reactions.

Targeted Delivery of Erythropoietin Hybridized with Magnetic Nanocarriers for the Treatment of Central Nervous System Injury: A Literature Review

Although the incidence of central nervous system injuries has continued to rise, no promising treatments have been elucidated. Erythropoietin plays an important role in neuroprotection and neuroregeneration as well as in erythropoiesis. Moreover, the current worldwide use of erythropoietin in the treatment of hematologic diseases allows for its ready application in patients with central nervous system injuries. However, erythropoietin has a very short therapeutic time window (within 6–8 hours) after injury, and it has both hematopoietic and nonhematopoietic receptors, which exhibit heterogenic and phylogenetic differences. These differences lead to limited amounts of erythropoietin binding to in situ erythropoietin receptors. The lack of high-quality evidence for clinical use and the promising results of in vitro/in vivo models necessitate fast targeted delivery agents such as nanocarriers. Among current nanocarriers, noncovalent polymer-entrapping or polymer-adsorbing erythropoietin obtained by nanospray drying may be the most promising. With the incorporation of magnetic nanocarriers into an erythropoietin polymer, spatiotemporal external magnetic navigation is another area of great interest for targeted delivery within the therapeutic time window. Intravenous administration is the most readily used route. Manufactured erythropoietin nanocarriers should be clearly characterized using bioengineering analyses of the in vivo size distribution and the quality of entrapment or adsorption. Further preclinical trials are required to increase the therapeutic bioavailability (in vivo biological identity alteration, passage through the lung capillaries or the blood brain barrier, and timely degradation followed by removal of the nanocarriers from the body) and decrease the adverse effects (hematological complications, neurotoxicity, and cytotoxicity), especially of the nanocarrier.

Application of Carbon Nanoparticles in Tracing Lymph Nodes and Locating Tumors in Colorectal Cancer: A Concise Review

Background

Accurate lymph node (LN) staging has considerably prognostic and therapeutic value in patients with colorectal cancer (CRC). The purpose of this study is to evaluate the feasibility of applying carbon nanoparticles (CNPs) to track LN metastases in CRC.

Methods

Two researchers independently screened publications in PubMed, EMBASE, Cochrane and Ovid MEDLINE databases. The keywords were (carbon nanoparticles OR activated carbon nanoparticles) AND (colon cancer OR rectal cancer OR colorectal cancer). Titles and abstracts of the articles were meticulously read to rule out potential publications. Next, full texts of the ultimately obtained eligible publications were retrieved and analyzed in detail.

Results

The search produced 268 publications, and 140 abstracts were identified after a bibliographic review. Finally, 20 studies relevant to our subject were obtained; however, only 14 papers met our inclusion criteria and were included for final review. All studies included have compared the control group with carbon nanoparticles group (control group, defined as nontattooed group; and carbon nanoparticles group, defined as administering carbon nanoparticles during surgery) for their efficacy in intraoperative detecting and positioning. After analysis, appreciably less amount of bleeding (3/5 trials), shorter operation time (2/4 trials), and shorter time to detect lesions and dissect LNs (2/2 trials) were revealed in CNPs group compared to control group. Thirteen studies have recorded the numbers of the harvested LNs in both groups; meanwhile, CNPs group shows superiority to control group in LN retrieval as well (11/13 trials), which also could effectively aid in locating and harvesting more LNs with diameter below 5 mm.

Conclusion

The tracing technique for CNPs is a safe and useful strategy both in localizing tumor and tracing LNs in CRC surgery. But there is still a need for more randomized controlled trials to further establish its contribution to patient survival.

Adipose Tissue-Derived Stem Cells Alleviate Cold Allodynia in a Rat Spinal Nerve Ligation Model of Neuropathic Pain

Neuropathic pain caused by lesions or nervous system dysfunction is a neuroimmune disease with limited therapeutic options. Adipose tissue-derived stem cells (ASCs) are multipotent mesenchymal stem cells with potent immunosuppressive properties, and their use as novel cell-based therapeutics have been proposed in many immune diseases. However, the analgesic effect and efficacy of ASCs to treat neuropathic pain remain unclear. This study, thus, investigated whether ASCs or ASC-derived culture medium can relieve neuropathic pain behaviors (i.e., mechanical and cold allodynia) in a rat model with L5 spinal nerve ligation. Intrathecal injection of ASCs significantly reduced cold allodynia, but not mechanical allodynia. Importantly, cold allodynia was completely reversed in rats with repeated injections of ASCs. In contrast, intrathecal injection of ASC-derived culture medium or retro-orbital injection of ASCs had no effect on neuropathic pain behaviors. These results suggest a novel and alternative therapeutic application of ASCs to target specific neuropathic pain behaviors.

Graphene-Based Nanoparticles as Potential Treatment Options for Parkinson's Disease: A Molecular Dynamics Study

INTRODUCTION

The study of abnormal aggregation of proteins in different tissues of the body has recently earned great attention from researchers in various fields of science. Concerning neurological diseases, for instance, the accumulation of amyloid fibrils can contribute to Parkinson's disease, a progressively severe neurodegenerative disorder. The most prominent features of this disease are the degeneration of neurons in the substantia nigra and accumulation of α-synuclein aggregates, especially in the brainstem, spinal cord, and cortical areas. Dopamine replacement therapies and other medications have reduced motor impairment and had positive consequences on patients' quality of life. However, if these medications are stopped, symptoms of the disease will recur even more severely. Therefore, the improvement of therapies targeting more basic mechanisms like prevention of amyloid formation seems to be critical. It has been shown that the interactions between monolayers like graphene and amyloids could prevent their fibrillation.

METHODS

For the first time, the impact of four types of last-generation graphene-based nanostructures on the prevention of α-synuclein amyloid fibrillation was investigated in this study by using molecular dynamics simulation tools.

RESULTS

Although all monolayers were shown to prevent amyloid fibrillation, nitrogen-doped graphene (N-Graphene) caused the most instability in the secondary structure of α-synuclein amyloids. Moreover, among the four monolayers, N-Graphene was shown to present the highest absolute value of interaction energy, the lowest contact level of amyloid particles, the highest number of hydrogen bonds between water and amyloid molecules, the highest instability caused in α-synuclein particles, and the most significant decrease in the compactness of α-synuclein protein.

DISCUSSION

Ultimately, it was concluded that N-Graphene could be the most effective monolayer to disrupt amyloid fibrillation, and consequently, prevent the progression of Parkinson's disease.

Nanomaterial integration into the scaffolding materials for nerve tissue engineering: a review

The nervous system, which consists of a complex network of millions of neurons, is one of the most highly intricate systems in the body. This complex network is responsible for the physiological and cognitive functions of the human body. Following injuries or degenerative diseases, damage to the nervous system is overwhelming because of its complexity and its limited regeneration capacity. However, neural tissue engineering currently has some capacities for repairing nerve deficits and promoting neural regeneration, with more developments in the future. Nevertheless, controlling the guidance of stem cell proliferation and differentiation is a challenging step towards this goal. Nanomaterials have the potential for the guidance of the stem cells towards the neural lineage which can overcome the pitfalls of the classical methods since they provide a unique microenvironment that facilitates cell-matrix and cell-cell interaction, and they can manipulate the cell signaling mechanisms to control stem cells' fate. In this article, the suitable cell sources and microenvironment cues for neuronal tissue engineering were examined. Afterward, the nanomaterials that impact stem cell proliferation and differentiation towards neuronal lineage were reviewed.

The plastic brain: neurotoxicity of micro- and nanoplastics

Given the global abundance and environmental persistence, exposure of humans and (aquatic) animals to micro- and nanoplastics is unavoidable. Current evidence indicates that micro- and nanoplastics can be taken up by aquatic organism as well as by mammals. Upon uptake, micro- and nanoplastics can reach the brain, although there is limited information regarding the number of particles that reaches the brain and the potential neurotoxicity of these small plastic particles.

Earlier studies indicated that metal and metal-oxide nanoparticles, such as gold (Au) and titanium dioxide (TiO₂) nanoparticles, can also reach the brain to exert a range of neurotoxic effects. Given the similarities between these chemically inert metal(oxide) nanoparticles and plastic particles, this review aims to provide an overview of the reported neurotoxic effects of micro- and nanoplastics in different species and in vitro. The combined data, although fragmentary, indicate that exposure to micro- and nanoplastics can induce oxidative stress, potentially resulting in cellular damage and an increased vulnerability to develop neuronal disorders. Additionally, exposure to micro- and nanoplastics can result in inhibition of acetylcholinesterase activity and altered neurotransmitter levels, which both may contribute to the reported behavioral changes.

Currently, a systematic comparison of the neurotoxic effects of different particle types, shapes, sizes at different exposure concentrations and durations is lacking, but urgently needed to further elucidate the neurotoxic hazard and risk of exposure to micro- and nanoplastics.

Magnetically guided targeted delivery of erythropoietin using magnetic nanoparticles: Proof of concept

The objective of this proof-of-concept study was to demonstrate the targeted delivery of erythropoietin (EPO) using magnetically guided magnetic nanoparticles (MNPs).MNPs consisting of a ferric-ferrous mixture (FeCl3·6H2O and FeCl2·4H2O) were prepared using a co-precipitation method. The drug delivery system (DDS) was manufactured via the spray-drying technique using a nanospray-dryer. The DDS comprised 7.5 mg sodium alginate, 150 mg MNPs, and 1000 IU EPO.Scanning electron microscopy revealed DDS particles no more than 500 nm in size. Tiny particles on the rough surfaces of the DDS particles were composed of MNPs and/or EPO, unlike the smooth surfaces of the only alginate particles. Transmission electron microscopy showed the tiny particles from 5 to 20 nm in diameter. Fourier-transform infrared spectroscopy revealed DDS peaks characteristic of MNPs as well as of alginate. Thermal gravimetric analysis presented that 50% of DDS weight was lost in a single step around 500°C. The mode size of the DDS particles was approximately 850 nm under in vivo conditions. Standard soft lithography was applied to DDS particles prepared with fluorescent beads using a microchannel fabricated to have one inlet and two outlets in a Y-shape. The fluorescent DDS particles reached only one outlet reservoir in the presence of a neodymium magnet. The neurotoxicity was evaluated by treating SH-SY5Y cells in 48-well plates (1 × 10 cells/well) with 2 μL of a solution containing sodium alginate (0.075 mg/mL), MNPs (1.5 mg/mL), or sodium alginate + MNPs. A cell viability assay kit was used to identify a 93% cell viability after MNP treatment and a 94% viability after sodium alginate + MNP treatment, compared with the control. As for the DDS particle neurotoxicity, a 95% cell viability was noticed after alginate-encapsulated MNPs treatment and a 93% cell viability after DDS treatment, compared with the control.The DDS-EPO construct developed here can be small under in vivo conditions enough to pass through the lung capillaries with showing the high coating efficiency. It can be guided using magnetic control without displaying significant neurotoxicity in the form of solution or particles.

An Experimental Investigation of Ultraweak Photon Emission from Adult Murine Neural Stem Cells

Neurons like other living cells may have ultraweak photon emission (UPE) during neuronal activity. This study is aimed to evaluate UPE from neural stem cells (NSC) during their serial passaging and differentiation. We also investigate whether the addition of silver nanoparticles (AgNPs) or enhancement of UPE (by AgNPs or mirror) affect the differentiation of NSC. In our method, neural stem and progenitor cells of subventricular zone (SVZ) are isolated and expanded using the neurosphere assay. The obtained dissociated cells allocated and cultivated into three groups: groups: I: cell (control), II: cell + mirror, and III: cell + AgNPs. After seven days, the primary neurospheres were counted and their mean number was obtained. Serial passages continuous up to sixth passages in the control group. Differentiation capacity of the resulting neurospheres were evaluated in vitro by immunocytochemistry techniques. Measurement of UPE was carried out by photomultiplier tube (PMT) in the following steps: at the end of primary culture, six serial cell passages of the control group, before and after of the differentiation for 5 minutes. The results show that neither mirror nor AgNPs affect on the neurosphere number. The UPE of the NSC in the sixth subculturing passage was significantly higher than in the primary passage (P < 0.05). AgNPs significantly increased the UPE of the NSC compared to the control group before and after the differentiation (P < 0.05). Also, the treatment with AgNPs increased 44% neuronal differentiation of the harvested NSCs. UPE of NSC after the differentiation was significantly lower than that before the differentiation in each groups, which is in appropriate to the cell numbers (P < 0.0001). The mirror did not significantly increase UPE, neither before nor after the differentiation of NSC. As a conclusion, NSC have UPE-properties and the intensity is increased by serial passaging that are significant in the sixth passage. The AgNPs increases the UPE intensity of NSC that pushes more differentiation of NSC to the neurons. The mirror was not effective in enhancement of UPE. As a result, UPE measurement may be suitable for assessing and studying the effects of nanoparticles in living cells and neurons.

Effect of PEGylated Magnetic PLGA-PEI Nanoparticles on Primary Hippocampal Neurons: Reduced Nanoneurotoxicity and Enhanced Transfection Efficiency with Magnetofection

Despite broad application of nanotechnology in neuroscience, the nanoneurotoxicity of magnetic nanoparticles in primary hippocampal neurons remains poorly characterized. In particular, understanding how magnetic nanoparticles perturb neuronal calcium homeostasis is critical when considering magnetic nanoparticles as a nonviral vector for effective gene therapy in neuronal diseases. Here, we address the pressing need to systematically investigate the neurotoxicity of magnetic nanoparticles with different surface charges in primary hippocampal neurons. We found that unlike negative and neutral nanoparticles, positively charged magnetic nanoparticles (magnetic poly(lactic-co-glycolic acid) (PLGA)-polyethylenimine (PEI) nanoparticles, MNP-PLGA-PEI NPs) rapidly elevated cytoplasmic calcium levels in primary hippocampal neurons, mainly via extracellular calcium influx regulated by voltage-gated calcium channels. We went on to show that this perturbation of intracellular calcium homeostasis elicited serious cytotoxicity in primary hippocampal neurons. However, our next experiment demonstrated that PEGylation on the surface of MNP-PLGA-PEI NPs shielded the surface charge, thereby preventing the perturbation of intracellular calcium homeostasis. That is, PEGylated MNP-PLGA-PEI NPs reduced nanoneurotoxicity. Importantly, biocompatible PEGylated MNP-PLGA-PEI NPs under an external magnetic field enhanced transfection efficiency (>7%) of plasmid DNA encoding GFP in primary hippocampal neurons compared to NPs without external magnetic field mediation. Moreover, under an external magnetic field, this system achieved gene transfection in the hippocampus of the C57 mouse. Overall, this study is the first to successfully employ biocompatible PEGylated MNP-PLGA-PEI NPs for transfection using a magnetofection strategy in primary hippocampal neurons, thereby providing a nanoplatform as a new perspective for treating neuronal diseases or modulating neuron activities.

Novel Tools towards Magnetic Guidance of Neurite Growth: (I) Guidance of Magnetic Nanoparticles into Neurite Extensions of Induced Human Neurons and In Vitro Functionalization with RAS Regulating Proteins

Parkinson’s disease (PD) is a neurodegenerative disease associated with loss or dysfunction of dopaminergic neurons located in the substantia nigra (SN), and there is no cure available. An emerging new approach for treatment is to transplant human induced dopaminergic neurons directly into the denervated striatal brain target region. Unfortunately, neurons grafted into the substantia nigra are unable to grow axons into the striatum and thus do not allow recovery of the original connectivity. Towards overcoming this general limitation in guided neuronal regeneration, we develop here magnetic nanoparticles functionalized with proteins involved in the regulation of axonal growth. We show covalent binding of constitutive active human rat sarcoma (RAS) proteins or RAS guanine nucleotide exchange factor catalytic domain of son of sevenless (SOS) by fluorescence correlation spectroscopy and multiangle light scattering as well as the characterization of exchange factor activity. Human dopaminergic neurons were differentiated from neural precursor cells and characterized by electrophysiological and immune histochemical methods. Furthermore, we demonstrate magnetic translocation of cytoplasmic γ-Fe₂O₃@SiO₂ core-shell nanoparticles into the neurite extensions of induced human neurons. Altogether, we developed tools towards remote control of directed neurite growth in human dopaminergic neurons. These results may have relevance for future therapeutic approaches of cell replacement therapy in Parkinson’s disease.

Retardation of Axonal and Dendritic Outgrowth Is Associated with the MAPK Signaling Pathway in Offspring Mice Following Maternal Exposure to Nanosized Titanium Dioxide

Exposure to nanosized titanium oxide (nano-TiO₂) has been proven to suppress brain growth in mouse offspring; however, whether retardation of axonal or dendritic outgrowth is associated with activation of the mitogen-activated protein kinase (MAPK) pathway remains unclear. In the present study, pregnant mice were exposed to nano-TiO₂ at 1.25, 2.5, and 5 mg/kg body weight, and the molecular mechanism of axonal or dendritic outgrowth retardation was investigated. The results suggested that nano-TiO₂ crossed the blood-fetal barrier and blood-brain barrier and deposited in the brain of offspring, which retarded axonal and dendritic outgrowth, including the absence of axonal outgrowth, and decreased dendritic filament length, dendritic branching number, and dendritic spine density. Importantly, maternal exposure to nano-TiO₂ increased phosphorylated (p)-extracellular signal-regulated kinase1/2 (ERK1/2, +24.35% to +59.4%), p-p38 (+60.82% to 181.85%), and p-c-jun N-terminal kinase (JNK, +28.28% to 97.28%) expression in the hippocampus of the offspring. These findings suggested that retardation of axonal and dendritic outgrowth in mouse offspring caused by maternal exposure to nano-TiO₂ may be related to excessive activation of the ERK1/2/MAPK signaling pathway. Therefore, the potential toxicity of nano-TiO₂ is a concern, especially in pregnant woman or children who are exposed to nano-TiO₂.

Magnetic Iron Oxide Nanoparticles: Synthesis, Characterization and Functionalization for Biomedical Applications in the Central Nervous System

Magnetic Nanoparticles (MNPs) are of great interest in biomedicine, due to their wide range of applications. During recent years, one of the most challenging goals is the development of new strategies to finely tune the unique properties of MNPs, in order to improve their effectiveness in the biomedical field. This review provides an up-to-date overview of the methods of synthesis and functionalization of MNPs focusing on Iron Oxide Nanoparticles (IONPs). Firstly, synthesis strategies for fabricating IONPs of different composition, sizes, shapes, and structures are outlined. We describe the close link between physicochemical properties and magnetic characterization, essential to developing innovative and powerful magnetic-driven nanocarriers. In conclusion, we provide a complete background of IONPs functionalization, safety, and applications for the treatment of Central Nervous System disorders.

Emerging blood–brain-barrier-crossing nanotechnology for brain cancer theranostics

The advancements, perspectives, and challenges in blood–brain-barrier (BBB)-crossing nanotechnology for effective brain tumor delivery and highly efficient brain cancer theranostics.