Cognitive deficits induced by multi-walled carbon nanotubes via the autophagic pathway

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.

The impact of nanomaterials on autophagy across health and disease conditions

Autophagy, a catabolic process integral to cellular homeostasis, is constitutively active under physiological and stress conditions. The role of autophagy as a cellular defense response becomes particularly evident upon exposure to nanomaterials (NMs), especially environmental nanoparticles (NPs) and nanoplastics (nPs). This has positioned autophagy modulation at the forefront of nanotechnology-based therapeutic interventions. While NMs can exploit autophagy to enhance therapeutic outcomes, they can also trigger it as a pro-survival response against NP-induced toxicity. Conversely, a heightened autophagy response may also lead to regulated cell death (RCD), in particular autophagic cell death, upon NP exposure. Thus, the relationship between NMs and autophagy exhibits a dual nature with therapeutic and environmental interventions. Recognizing and decoding these intricate patterns are essential for pioneering next-generation autophagy-regulating NMs. This review delves into the present-day therapeutic potential of autophagy-modulating NMs, shedding light on their status in clinical trials, intervention of autophagy in the therapeutic applications of NMs, discusses the potency of autophagy for application as early indicator of NM toxicity.

Nanoparticles and neurodegeneration: Insights on multiple pathways of programmed cell death regulated by nanoparticles

Currently, nanoparticles (NPs) are extensively applied in the diagnosis and treatment of neurodegenerative diseases (NDs). With the rapid development and increasing exposure to the public, the potential neurotoxicity associated with NDs caused by NPs has attracted the researchers' attentions but their biosafety assessments are still far behind relevant application studies. Based on recent research, this review aims to conduct a comprehensive and systematic analysis of neurotoxicity induced by NPs. The 191 studies selected according to inclusion and exclusion criteria were imported into the software, and the co-citations and keywords of the included literatures were analyzed to find the breakthrough point of previous studies. According to the available studies, the routes of NPs entering into the normal and injured brain were various, and then to be distributed and accumulated in living bodies. When analyzing the adverse effects induced by NPs, we focused on multiple programmed cell deaths (PCDs), especially ferroptosis triggered by NPs and their tight connection and crosstalk that have been found playing critical roles in the pathogenesis of NDs and their underlying toxic mechanisms. The activation of multiple PCD pathways by NPs provides a scientific basis for the occurrence and development of NDs. Furthermore, the adoption of new methodologies for evaluating the biosafety of NPs would benefit the next generation risk assessment (NGRA) of NPs and their toxic interventions. This would help ensure their safe application and sustainable development in the field of medical neurobiology.

Organoids and organoids-on-a-chip as the new testing strategies for environmental toxicology-applications & advantages

An increasing number of harmful environmental factors are causing serious impacts on human health, and there is an urgent need to accurately identify the toxic effects and mechanisms of these harmful environmental factors. However, traditional toxicity test methods (e.g., animal models and cell lines) often fail to provide accurate results. Fortunately, organoids differentiated from stem cells can more accurately, sensitively and specifically reflect the effects of harmful environmental factors on the human body. They are also suitable for specific studies and are frequently used in environmental toxicology nowadays. As a combination of organoids and organ-on-a-chip technology, organoids-on-a-chip has great potential in environmental toxicology. It is more controllable to the physicochemical microenvironment and is not easy to be contaminated. It has higher homogeneity in the size and shape of organoids. In addition, it can achieve vascularization and exchange the nutrients and metabolic wastes in time. Multi-organoids-chip can also simulate the interactions of different organs. These advantages can facilitate better function and maturity of organoids, which can also make up for the shortcomings of common organoids to a certain extent. This review firstly discussed the limitations of traditional toxicology testing platforms, leading to the introduction of new platforms: organoids and organoids-on-a-chip. Next, the applications of different organoids and organoids-on-a-chip in environmental toxicology were summarized and prospected. Since the advantages of the new platforms have not been sufficiently considered in previous literature, we particularly emphasized them. Finally, this review also summarized the opportunities and challenges faced by organoids and organoids-on-a-chip, with the expectation that readers will gain a deeper understanding of their value in the field of environmental toxicology.

Autophagy regulation by inorganic, organic, and organic/inorganic hybrid nanoparticles: Organelle damage, regulation factors, and potential pathways

The rapid development of nanotechnology requires a more thorough understanding of the potential health effects caused by nanoparticles (NPs). As a programmed cell death, autophagy is one of the biological effects induced by NPs, which maintain intracellular homeostasis by degrading damaged organelles and removing aggregates of defective proteins through lysosomes. Currently, autophagy has been shown to be associated with the development of several diseases. A significant number of research have demonstrated that most NPs can regulate autophagy, and their regulation of autophagy is divided into induction and blockade. Studying the autophagy regulation by NPs will facilitate a more comprehensive understanding of the toxicity of NPs. In this review, we will illustrate the effects of different types of NPs on autophagy, including inorganic NPs, organic NPs, and organic/inorganic hybrid NPs. The potential mechanisms by which NPs regulate autophagy are highlighted, including organelle damage, oxidative stress, inducible factors, and multiple signaling pathways. In addition, we list the factors influencing NPs-regulated autophagy. This review may provide basic information for the safety assessment of NPs.

Autophagy and Biomaterials: A Brief Overview of the Impact of Autophagy in Biomaterial Applications

Macroautophagy (hereafter autophagy), a tightly regulated physiological process that obliterates dysfunctional and damaged organelles and proteins, has a crucial role when biomaterials are applied for various purposes, including diagnosis, treatment, tissue engineering, and targeted drug delivery. The unparalleled physiochemical properties of nanomaterials make them a key component of medical strategies in different areas, such as osteogenesis, angiogenesis, neurodegenerative disease treatment, and cancer therapy. The application of implants and their modulatory effects on autophagy have been known in recent years. However, more studies are necessary to clarify the interactions and all the involved mechanisms. The advantages and disadvantages of nanomaterial-mediated autophagy need serious attention in both the biological and bioengineering fields. In this mini-review, the role of autophagy after biomaterial exploitation and the possible related mechanisms are explored.

Nano-drug delivery system for pancreatic cancer: A visualization and bibliometric analysis

Background: Nano drug delivery system (NDDS) can significantly improve the delivery and efficacy of drugs against pancreatic cancer (PC) in many ways. The purpose of this study is to explore the related research fields of NDDS for PC from the perspective of bibliometrics.

Methods: Articles and reviews on NDDS for PC published between 2003 and 2022 were obtained from the Web of Science Core Collection. CiteSpace, VOSviewer, R-bibliometrix, and Microsoft Excel were comprehensively used for bibliometric and visual analysis.

Results: A total of 1329 papers on NDDS for PC were included. The number of papers showed an upward trend over the past 20 years. The United States contributed the most papers, followed by China, and India. Also, the United States had the highest number of total citations and H-index. The institution with the most papers was Chinese Acad Sci, which was also the most important in international institutional cooperation. Professors Couvreur P and Kazuoka K made great achievements in this field. JOURNAL OF CONTROLLED RELEASE published the most papers and was cited the most. The topics related to the tumor microenvironment such as “tumor microenvironment”, “tumor penetration”, “hypoxia”, “exosome”, and “autophagy”, PC treatment-related topics such as “immunotherapy”, “combination therapy”, “alternating magnetic field/magnetic hyperthermia”, and “ultrasound”, and gene therapy dominated by “siRNA” and “miRNA” were the research hotspots in the field of NDDS for PC.

Conclusion: This study systematically uncovered a holistic picture of the performance of NDDS for PC-related literature over the past 20 years. We provided scholars to understand key information in this field with the perspective of bibliometrics, which we believe may greatly facilitate future research in this field.

Long-Term Social Isolation-Induced Autophagy Inhibition and Cell Senescence Aggravate Cognitive Impairment in D(+)Galactose-Treated Male Mice

Aging is associated with physiological and pathological changes and presents health complications, such as dementia. Isolation has also been associated with the experience of growing old. Both have been linked individually to the incidence of cognitive decline. In this present study, the effects of these two phenomena have been looked at in animal models where aging was induced with D(+)Galactose in mice who underwent long-term post-weaned social isolation (L-PWSI). Assessing cognitive function using Y-maze, Morris water maze (MWM), and passive avoidance tests (PATs) confirmed that cognition is impaired in either of the treatments but worsened when the D(+)Galactose mice were subjected to L-PWSI. Moreover, a synaptic protein, PSD95, and dendritic spines density were significantly reduced in the L-PWSI and D(+)Galactose-treated mice. Our previous study revealed that autophagy deficit is involved in cognitive impairment in the L-PWSI model. Here, we first report the inhibited cell cycle in L-PWSI, combined with the decreased autophagy, aggravates cognitive impairment in D(+)Galactose-treated mice. Beyond these, the autophagy and cell cycle mechanisms that link isolation and aging have been explored. The close association between isolation and aging in humans is very real and needs much research attention going forward for possible therapeutic interventions.

Angiotensin II induces cognitive decline and anxiety-like behavior via disturbing pattern of theta-gamma oscillations

Hypertension is the most common chronic disease accompanied by cognitive decline and anxiety-like behavior. Angiotensin II (Ang II) induces hypertension by activating angiotensin II receptor subtype 1 (AT1R). The purpose of the study was to examine the potential underlying mechanism of alterations in cognition and anxiety-like behavior induced by Ang II. Adult C57 mice were intraperitoneal injected with either 1 mg/kg/d Ang II or saline individually for 14 consecutive days. Ang II resulted in cognitive decline and anxious like behavior in C57 mice. Moreover, Ang II disturbed bidirectional synaptic plasticity and neural oscillation coupling between high theta and gamma on PP (perforant pathway)-DG (dentate gyrus) pathway. In addition, Ang II decreased the expression of N-methyl-d-aspartate receptor (NR) 2A and NR 2B and increased the expression of GABA_AR α1. The data suggest that Ang II disturb neural oscillations via altering excitatory and inhibitory (E/I) balance and eventually damage cognition and anxiety-like behavior in mice.

Multi-walled carbon nanotubes decrease neuronal NO synthase in 3D brain organoids

Multi-walled carbon nanotubes (MWCNTs) might induce the dysfunction of neuronal NO synthase (nNOS) and impair the function of brains. But to the best of our knowledge, this conclusion was made by using laboratory animals or conventional nerve cell cultures; however, these models might not reflect the complex conditions of human brains. Recently, the development of 3D brain organoids (also known as organotypic cultures) derived from human induced pluripotent stem cells (iPSCs) provides a platform to investigate the behaviors of human brains in vitro. In this study, we investigated the toxicity of MWCNTs to 3D brain organoids which expressed the cortical layer markers. It was shown that MWCNTs induced cytotoxicity to 3D brain organoids but not in dose-dependent manner. Exposure to high level of MWCNTs (64 μg/mL) reduced the levels of intracellular NO but increased superoxide. As the mechanism, 64 μg/mL MWCNTs significantly reduced the protein level of nNOS. The nNOS regulators nuclear factor kappa-B (NF-κB) proteins were significantly induced by MWCNTs, whereas Kruppel-like factor 4 (KLF4) proteins were reduced particularly after exposure to low level of MWCNTs (16 μg/mL). The results from fluorescence micro-optical sectioning tomography (MOST) confirmed the decrease of nNOS proteins, not only at the out-layers that directly contacted MWCNTs, but also at the inner-layers. Combined, our results suggested that MWCNTs could decrease nNOS activity by inducing oxidative stress and modulating NF-κB-KLF4 pathway. This study also showed the potential of 3D brain organoids in mechanism-based toxicology studies.

Nanomaterial-mediated autophagy: coexisting hazard and health benefits in biomedicine

BACKGROUND

Widespread biomedical applications of nanomaterials (NMs) bring about increased human exposure risk due to their unique physicochemical properties. Autophagy, which is of great importance for regulating the physiological or pathological activities of the body, has been reported to play a key role in NM-driven biological effects both in vivo and in vitro. The coexisting hazard and health benefits of NM-mediated autophagy in biomedicine are nonnegligible and require our particular concerns.

MAIN BODY

We collected research on the toxic effects related to NM-mediated autophagy both in vivo and in vitro. Generally, NMs can be delivered into animal models through different administration routes, or internalized by cells through different uptake pathways, exerting varying degrees of damage in tissues, organs, cells, and organelles, eventually being deposited in or excreted from the body. In addition, other biological effects of NMs, such as oxidative stress, inflammation, necroptosis, pyroptosis, and ferroptosis, have been associated with autophagy and cooperate to regulate body activities. We therefore highlight that NM-mediated autophagy serves as a double-edged sword, which could be utilized in the treatment of certain diseases related to autophagy dysfunction, such as cancer, neurodegenerative disease, and cardiovascular disease. Challenges and suggestions for further investigations of NM-mediated autophagy are proposed with the purpose to improve their biosafety evaluation and facilitate their wide application. Databases such as PubMed and Web of Science were utilized to search for relevant literature, which included all published, Epub ahead of print, in-process, and non-indexed citations.

CONCLUSION

In this review, we focus on the dual effect of NM-mediated autophagy in the biomedical field. It has become a trend to use the benefits of NM-mediated autophagy to treat clinical diseases such as cancer and neurodegenerative diseases. Understanding the regulatory mechanism of NM-mediated autophagy in biomedicine is also helpful for reducing the toxic effects of NMs as much as possible.

Kolaviron via anti-inflammatory and redox regulatory mechanisms abates multi-walled carbon nanotubes-induced neurobehavioral deficits in rats

Exposure to multi-walled carbon nanotubes (MWCNTs) reportedly elicits neurotoxic effects. Kolaviron is a phytochemical with several pharmacological effects namely anti-oxidant, anti-inflammatory, and anti-genotoxic activities. The present study evaluated the neuroprotective mechanism of kolaviron in rats intraperitoneally injected with MWCNTs alone at 1 mg/kg body weight or orally co-administered with kolaviron at 50 and 100 mg/kg body weight for 15 consecutive days. Following exposure, neurobehavioral analysis using video-tracking software during trial in a novel environment indicated that co-administration of both doses of kolaviron significantly (p < 0.05) enhanced the locomotor, motor, and exploratory activities namely total distance traveled, maximum speed, total time mobile, mobile episode, path efficiency, body rotation, absolute turn angle, and negative geotaxis when compared with rats exposed to MWCNTs alone. Further, kolaviron markedly abated the decrease in the acetylcholinesterase activity and antioxidant defense system as well as the increase in oxidative stress and inflammatory biomarkers induced by MWCNT exposure in the cerebrum, cerebellum, and mid-brain of rats. The amelioration of MWCNT-induced neuronal degeneration in the brain structures by kolaviron was verified by histological and morphometrical analyses. Taken together, kolaviron abated MWCNT-induced neurotoxicity via anti-inflammatory and redox regulatory mechanisms.

High-Resolution Transcranial Electrical Simulation for Living Mice Based on Magneto-Acoustic Effect

Transcranial electrical stimulation is an important neuromodulation tool, which has been widely applied in the cognitive sciences and in the treatment of neurological and psychiatric diseases. In this work, a novel non-invasive method of transcranial electrical stimulation with high-resolution transcranial magneto-acoustic stimulation (TMAS) method has been tested experimentally in living mice for the first time. It can achieve spatial resolution of 2 mm in the cortex and even in the deep brain regions. The induced electrical field of TMAS was simulated and measured using a test sample. Then, an animal experimental system was built, and the healthy as well as Parkinson’s disease (PD) mice were simulated by TMAS in vivo. To investigate the effect of transcranial ultrasound stimulation (TUS) at the same time as TMAS, a TUS group was added in the experiments and its results compared with those of the TMAS group. The results not only demonstrate the high-resolution ability and safety of TMAS, but also show that both TMAS and TUS improved the synaptic plasticity of the PD mice and might improve the spatial learning and memory ability of the healthy mice and the PD mice, although the improvement performance of the TMAS group was superior to that of the TUS-group. Based on the in vivo TMAS studies, we propose that TMAS functions as a dual-mode stimulation combining the electric field of the magneto-acoustic effect and the mechanical force of TUS. Our results also provide an explanation of the mechanism of TMAS. This research suggests that future use of US stimulation in magnetic resonance imaging (MRI)-guided studies should involve careful consideration of the induced magneto-acoustic electrical field caused by the static magnetic field of MRI.

Transcranial Magneto-Acoustic Stimulation Improves Neuroplasticity in Hippocampus of Parkinson's Disease Model Mice

In this study, we have, for the first time, demonstrated the beneficial effects of transcranial magneto-acoustic stimulation (TMAS), a technique based on focused ultrasound stimulation within static magnetic field, on the learning and memory abilities and neuroplasticity of the 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) mouse model of Parkinson's disease (PD). Our results showed that chronic TMAS treatment (2 weeks) improved the outcome of Morris water maze, long-term potentiation (LTP), and dendritic spine densities in the dentate gyrus (DG) region of the hippocampus of PD model mice. To further investigate into the underlying mechanisms of these beneficial effects by TMAS, we quantified the proteins in the hippocampus that regulated neuroplasticity. Results showed that the level of postsynaptic density protein 95 was elevated in the brain of TMAS-treated PD model mice while the level of synaptophysin (SYP) did not show any change. We further quantified proteins that mediated neuroplasticity mechanisms, such as brain-derived neurotrophic factor (BDNF) and other important proteins that mediated neuroplasticity. Results showed that TMAS treatment elevated the levels of BDNF, cAMP response element-binding protein (CREB), and protein kinase B (p-Akt) in the PD model mouse hippocampus, but not in the non-PD mouse hippocampus. These results suggest that the beneficial effects on the neuroplasticity of PD model mice treated with TMAS could possibly be conducted through postsynaptic regulations and mediated by BDNF.

Oral administration of graphene oxide nano-sheets induces oxidative stress, genotoxicity, and behavioral teratogenicity in Drosophila melanogaster

The current study checks the effect of various concentrations of dietary graphene oxide (GO) nano-sheets on the development of Drosophila melanogaster. GO was synthesized and characterized by XRD, FTIR, FESEM, and TEM analytical techniques. Various concentrations of GO were mixed with the fly food and flies were transferred to the vial. Various behavioral and morphological as well as genetic defects were checked on the different developmental stages of the offspring. In the larval stage of development, the crawling speed and trailing path change significantly than the control. GO induces the generation of oxygen radicals within the larval hemolymph as evidenced by nitroblue tetrazolium assay. GO induces DNA damage within the gut cell, which was detected by Hoechst staining and within hemolymph by comet assay. Adult flies hatched after GO treatment show defective phototaxis and geotaxis behavior. Besides behavior, phenotypic defects were observed in the wing, eye, thorax bristles, and mouth parts. At 300 mg/L concentration, wing spots were observed. Altogether, the current study finds oral administration of GO which acts as a mutagen and causes various behavioral and developmental defects in the offspring. Here for the first time, we are reporting GO, which acts as a teratogen in Drosophila, besides its extensive medical applications.

Distinct Impacts of Fullerene on Cognitive Functions of Dementia vs. Non-dementia Mice

Fullerene is a family of carbon materials widely applied in modern medicine and ecosystem de-contamination. Its wide application makes human bodies more and more constantly exposed to fullerene particles. Since fullerene particles are able to cross the blood-brain barrier (BBB) (Yamago et al. 1995), if and how fullerene would affect brain functions need to be investigated for human health consideration. For this purpose, we administered fullerene on subcortical ischemic vascular dementia (SIVD) model mice and sham mice, two types of mice with distinct penetration properties of BBB and hence possibly distinct vulnerabilities to fullerene. We studied the spatial learning and memory abilities of mice with Morris water maze (MWM) and the neuroplasticity properties of the hippocampus. Results showed that fullerene administration suppressed outcomes of MWM in sham mice, along with suppressed long-term potentiation (LTP) and dendritic spine densities. Oppositely, recoveries of MWM outcomes and neuroplasticity properties were observed in fullerene-treated SIVD mice. To further clarify the mechanism of the impact of fullerene on neuroplasticity, we measured the levels of postsynaptic density protein 95 (PSD-95), synaptophysin (SYP), brain-derived neurotrophic factor (BDNF), and tropomyosin receptor kinase B (TrkB) by western blot assay. Results suggest that the distinct impacts of fullerene on behavior test and neuroplasticity may be conducted through postsynaptic regulations that were mediated by BDNF.

U1 snRNA over-expression affects neural oscillations and short-term memory deficits in mice

Small nuclear RNAs (snRNAs) and other RNA spliceosomal components are involved in neurological and psychiatric disorders. U1 snRNA has recently been demonstrated to be altered in pathology in some neurodegenerative diseases, but whether it has a causative role is not clear. Here we have studied this by overexpressing U1 snRNA in mice and measured their hippocampal oscillatory patterns and brain functions. Novel object recognition test showed that the recognition index was significantly decreased in the U1 snRNA over-expression mice compared to that in the C57BL mice. U1 snRNA over-expression regulated not only the pattern of neural oscillations but also the expression of neuron excitatory and inhibitory proteins. Here we show that U1 snRNA over-expression contains the shrinkage distribution of theta-power, theta-phase lock synchronization, and theta and low-gamma cross-frequency coupling in the hippocampus. The alternations of neuron receptors by the U1 snRNA overexpression also modulated the decreasing of recognition index, the energy distribution of theta power spectrum with the reductions of theta phase synchronization and phase-amplitude coupling between theta and low-gamma. Linking these all together, our results suggest that U1 snRNA overexpression particularly causes a deficit in short-term memory. These findings make a bedrock of our research that U1 snRNA bridges the gap about the mechanism behind short-term memory based on the molecular and mesoscopic level.

Carbon nanotubes and central nervous system: Environmental risks, toxicological aspects and future perspectives

Due to their morphological and physicochemical properties, carbon nanotubes (CNTs) enhance the structural properties of several materials and are produced in great volumes. The production and the manufacturing of CNTs-incorporated products can lead to the potential environmental release of CNTs. For these reasons, CNTs can represent a serious concern for human health. Humans are exposed to nanoparticles through inhalation, ingestion and skin uptake. After their entrance, the particles can reach the Central Nervous System (CNS) through three different pathways: the systemic, olfactory and trigeminal pathways. In the first, through systemic blood circulation, nanoparticles cross both the blood-brain and blood-spinal cord barriers, which are highly selective semipermeable barriers that protect the CNS compartments. The second is the step from the nose to brain route and occurs along axons and via nerve bundles that cross the cribriform plate to the olfactory bulb. In the third, the compounds diffuse through the nasal cavity mucosa to reach the branches of the trigeminal nerve in the olfactory and respiratory regions, and they reach brain stem via axonal transport. After their entrance, CNTs reach the CNS where they may cause cytotoxicity of selected neurons in several CNS regions, impairing molecular pathways and contributing to the onset and progression of chronic brain inflammation, microglia activation and white matter abnormalities with an increased risk for autism spectrum disorders, lower IQ in children, neurodegenerative diseases and stroke. The large surface area to mass ratio of CNTs greatly increases surface reactivity. Despite this property considerable contributes to their toxicological profile in biological systems, also makes CNTs very attractive in the medical field, where they can be used as carriers of bioactive molecules, contrast agents, biological platforms and for many other applications in medicine.

Scanning Techniques for Nanobioconjugates of Carbon Nanotubes

Nanobioconjugates using carbon nanotubes (CNTs) are attractive and promising hybrid materials. Various biological applications using the CNT nanobioconjugates, for example, drug delivery systems and nanobiosensors, have been proposed by many authors. Scanning techniques such as scanning electron microscopy (SEM) and scanning probe microscopy (SPM) have advantages to characterize the CNT nanobioconjugates under various conditions, for example, isolated conjugates, conjugates in thin films, and conjugates in living cells. In this review article, almost 300 papers are categorized based on types of CNT applications, and various scanning data are introduced to illuminate merits of scanning techniques.

Notch1 knockdown disturbed neural oscillations in the hippocampus of C57BL mice

Neural oscillations and their interactions are associated with the coordination of neural groups, which provide a mechanism underlying information processing of brain functions. Notch1 receptor is involved in the neurological and psychiatric disorders, such as neurodevelopmental deficits, cerebral ischemia, Alzheimer's disease and depression. Here, we investigated the dynamics of neural oscillations in hippocampus of Notch1^+/- mice in urethane-anesthetized state. Notch1 knockdown altered the distribution of power in the hippocampal DG areas, reduced theta (3-8 Hz) power and enhanced low gamma (LG, 30-50 Hz) and high gamma (HG, 50-100 Hz) power. Moreover, theta-gamma phase-amplitude coupling in the hippocampal DG area was markedly impaired in the Notch1^+/- mice. The data further showed that the expression of NR2B was decreased, and the expressions of GABAAR_α1, GAD67 and parvalbumin were considerably increased after Notch1 knockdown. Taken together, our results suggest that Notch1 genetic deficiency significantly impaired the corss-frequency coupling of neural oscillations, and their interactions in the hippocampal DG region by means of disrupting the balance of excitatory and inhibitory receptors, which could be an underlying mechanism of cognitive impairment in neuropsychiatric disorders.

Insight into the heterogeneous adsorption of humic acid fluorescent components on multi-walled carbon nanotubes by excitation-emission matrix and parallel factor analysis

The heterogeneous adsorption behavior of commercial humic acid (HA) on pristine and functionalized multi-walled carbon nanotubes (MWCNTs) was investigated by fluorescence excitation-emission matrix and parallel factor (EEM- PARAFAC) analysis. The kinetics, isotherms, thermodynamics and mechanisms of adsorption of HA fluorescent components onto MWCNTs were the focus of the present study. Three humic-like fluorescent components were distinguished, including one carboxylic-like fluorophore C1 (λ_ex/λ_em= (250, 310) nm/428nm), and two phenolic-like fluorophores, C2 (λ_ex/λ_em= (300, 460) nm/552nm) and C3 (λ_ex/λ_em= (270, 375) nm/520nm). The Lagergren pseudo-second-order model can be used to describe the adsorption kinetics of the HA fluorescent components. In addition, both the Freundlich and Langmuir models can be suitably employed to describe the adsorption of the HA fluorescent components onto MWCNTs with significantly high correlation coefficients (R²> 0.94, P< 0.05). The dissimilarity in the adsorption affinity (K_d) and nonlinear adsorption degree from the HA fluorescent components to MWCNTs was clearly observed. The adsorption mechanism suggested that the π-π electron donor-acceptor (EDA) interaction played an important role in the interaction between HA fluorescent components and the three MWCNTs. Furthermore, the values of the thermodynamic parameters, including the Gibbs free energy change (ΔG°), enthalpy change (ΔH°) and entropy change (ΔS°), showed that the adsorption of the HA fluorescent components on MWCNTs was spontaneous and exothermic.

Arginine vasopressin ameliorates spatial learning impairments in chronic cerebral hypoperfusion via V1a receptor and autophagy signaling partially

Chronic cerebral hypoperfusion (CCH) is a major factor contributing to neurological disorders and cognitive decline. Autophagy activation is believed to provide both beneficial and detrimental roles during hypoxic/ischemic cellular injury. Although arginine vasopressin (AVP) has been strongly involved in many behaviors, especially in learning and memory, the effects of AVP on CCH and their molecular mechanisms remain unclear. Here, to investigate whether there was neuroprotective effects of AVP on CCH through V1a receptor (an AVP receptor) signaling, permanent bilateral carotid arteries occlusion (two vessel occlusion, 2VO) was used to establish a rat model of CCH, and hypertonic saline (5.3%) was injected intraperitoneally to induce the secretion of AVP. Results showed that hypertonic saline effectively alleviated spatial learning and memory deficit, enhanced synaptic plasticity of CA3-CA1 hippocampal synapses, upregulated N-methyl-d-aspartate receptor subunit 2B (NR2B) and postsynaptic density protein 95 (PSD-95) surface expressions, reduced oxidative stress and increased Nissl bodies in 2VO model rats. These phenomena were significantly decreased by V1a receptor antagonist SR49059. Interestingly, hypertonic saline also upregulated autophagy in the hippocampus of 2VO rats partly through V1a receptor. These findings imply that AVP has a beneficial role for the treatment of cognitive impairments partly through V1a receptor signaling in CCH, which is possibly related to improving synaptic plasticity by promoting NR2B and PSD-95 externalization and by enhancing autophagy.

Oral application of carbon nanofibers in rats increases blood concentration of IL6 and IL10 and decreases locomotor activity

Carbon nanofibers (CNF) are versatile nanomaterials that are widely used in various fields of science and technology. As a consequence, animals as well as humans may be exposed to such compounds via different routes. We hypothesized that oral intake of CNF will lead to an inflammatory reaction and consequently induce behavioral impairments. To address this issue, rats were fed with 500mg/kgCNF for 14days and their locomotor activity, emotional status and cognition were quantified by testing the animals in an open field set-up, elevated plus maze and in the universal problem solving box which provides information about motivation and cognition. The behavioral tests were performed 3 times within 10days. At the end of the experiment, blood samples were collected and the plasma concentrations of IL-6, IL-8, IL-1β, IL-10 and IL-18 were measured. Our results demonstrated an inflammatory reaction determined by a significantly elevated IL-6 concentration. This, however, was counteracted by an even more pronounced increase in IL-10. The behavioral effects were restricted mainly to a decrease in locomotor activity which was significant in the open field test, as well as the elevated plus maze. Other parameters indicative of cognitive performance were not influenced and also the emotional status was largely unaffected. In conclusion, our results revealed that oral intake of 500mg/kgCNF induced some adverse effects, which, however, can be still partially compensated by the organism.

Etidronate rescues cognitive deficits through improving synaptic transmission and suppressing apoptosis in 2-vessel occlusion model rats

Vascular dementia is a neurodegenerative disorder caused by the reduction of cerebral blood flow. It shows a progressive cognitive impairment. In our previous study, we found that etidronate (ET) showed neuroprotective effects against glutamate-injured PC12 cells. Thus, in this study, we aimed to observe the effects of ET on learning and memory impairment and the related mechanism in 2-vessel occlusion (2VO) model rats. Rats were administered a permanent bilateral common carotid artery occlusion to induce vascular dementia model. Two weeks later, 2VO model rats were treated with ET (20 mg/kg/day i.p.) for 1 week. Results showed that ET improved the spatial learning and memory function in 2VO rats detected by Morris water maze experiment. A reduced long-term potentiation was also rescued by ET treatment in 2VO rats. Moreover, the long-term potentiation-related proteins, calcium/calmodulin-dependent protein kinase II (CaMKII), NMDAR 2B and PSD95 were up-regulated after treatment with ET. By testing the levels of malondialdehyde and superoxide dismutase in 2VO rats, we discovered that ET lowered oxidative stress. Furthermore, ET displayed a better anti-apoptosis ability through detecting the levels of Bcl-2 and Bax protein and terminal deoxynucleotidyl transferase dUTP nick-end labeling-positive cells. In conclusion, ET shows neuroprotective effects on 2VO rats through rescuing spatial working memory deficits, and a possible mechanism may be related to the increased synaptic transmission and the inhibition of oxidative stress and apoptosis.

Cisplatin combination drugs induce autophagy in HeLa cells and interact with HSA via electrostatic binding affinity

Cisplatin combination drugs induce autophagy in HeLa cells and interact with HSAviaelectrostatic binding affinity.

Repetitive transcranial magnetic stimulation effectively facilitates spatial cognition and synaptic plasticity associated with increasing the levels of BDNF and synaptic proteins in Wistar rats

Repetitive transcranial magnetic stimulation (rTMS) is a non-invasive technique, by which cognitive deficits can be alleviated. Furthermore, rTMS may facilitate learning and memory. However, its underlying mechanism is still little known. The aim of this study was to investigate if the facilitation of spatial cognition and synaptic plasticity, induced by rTMS, is regulated by enhancing pre- and postsynaptic proteins in normal rats. Morris water maze (MWM) test was performed to examine the spatial cognition. The synaptic plasticity, including long-term potentiation (LTP) and depotentiation (DEP), presynaptic plasticity paired-pulse facilitation (PPF), from the hippocampal Schaffer collaterals to CA1 region was subsequently measured using in vivo electrophysiological techniques. The expressions of brain-derived neurotrophic factor (BDNF), presynaptic protein synaptophysin (SYP) and postsynaptic protein NR2B were measured by Western blot. Our data show that the spatial learning/memory and reversal learning/memory in rTMS rats were remarkably enhanced compared to that in the Sham group. Furthermore, LTP and DEP as well as PPF were effectively facilitated by 5Hz-rTMS. Additionally, the expressions of BDNF, SYP and NR2B were significantly increased via magnetic stimulation. The results suggest that rTMS considerably increases the expressions of BDNF, postsynaptic protein NR2B and presynaptic protein SYP, and thereby significantly enhances the synaptic plasticity and spatial cognition in normal animals.

Nano-TiO2 induces autophagy to protect against cell death through antioxidative mechanism in podocytes

Autophagy is a cellular pathway involved in degradation of damaged organelles and proteins in order to keep cellular homeostasis. It plays vital role in podocytes. Titanium dioxide nanoparticles (nano-TiO₂) are known to induce autophagy in cells, but little has been reported about the mechanism of this process in podocytes and the role of autophagy in podocyte death. In the present study, we examined how nano-TiO₂ induced authophagy. Besides that, whether autophagy could protect podocytes from the damage induced by nano-TiO₂ and its mechanism was also investigated. Western blot assay and acridine orange staining presented that nano-TiO₂ significantly enhanced autophagy flux in podocytes. In addition, AMP-activated protein kinase (AMPK) and mammalian target of rapamycin (mTOR) were involved in such process. 3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay indicated that upregulated level of autophagy induced by rapamycin in high concentration nano-TiO₂-treated podocytes could significantly reduce the level of oxidative stress and alleviate podocyte death. Downregulating the level of autophagy with 3-methyladenine had the opposite effects. These findings indicate that nano-TiO₂ induces autophagy through activating AMPK to inhibit mTOR in podocytes, and such autophagy plays a protecting role against oxidative stress on the cell proliferation. Changing autophagy level may become a new treatment strategy to relieve the damage induced by nano-TiO₂ in podocytes.

Influence of multi-walled carbon nanotubes on the cognitive abilities of Wistar rats

Studies of the neurobehavioral effects of carbon nanomaterials, particularly those of multi-walled carbon nanotubes (MWCNTs), have concentrated on cognitive effects, but data are scarce. The aim of this study was to assess the influence of MWCNTs on a number of higher nervous system functions of Wistar rats. For a period of 10 days, two experimental groups were fed with MWCNTs of different diameters (MWCNT-1 group, 8-10 nm; MWCNT-2 group, 18-20 nm) once a day at a dosage of 500 mg/kg. In the open-field test, reductions of integral indications of researching activity were observed for the two MWCNT-treated groups, with a parallel significant (P<0.01) increase in stress levels for these groups compared with the untreated control group. In the elevated plus-maze test, integral indices of researching activity in the MWCNT-1 and MWCNT-2 groups reduced by day 10 by 51 and 62%, respectively, while rat stress levels remained relatively unchanged. In the universal problem solving box test, reductions in motivation and energy indices of researching activity were observed in the two experimental groups. Searching activity in the MWCNT-1 group by day 3 was reduced by 50% (P<0.01) and in the MWCNT-2 group the relevant reduction reached 11.2%. By day 10, the reduction compared with controls, was 64% (P<0.01) and 58% (P<0.01) for the MWCNT-1 and MWCNT-2 groups, respectively. In conclusion, a series of specific tests demonstrated that MWCNT-treated rats experienced a significant reduction of some of their cognitive abilities, a disturbing and worrying finding, taking into consideration the continuing and accelerating use of carbon nanotubes in medicine and science.