In vivo biological behavior of a water-miscible fullerene: 14C labeling, absorption, distribution, excretion and acute toxicity

Research progress of fullerenes and their derivatives in the field of PDT

In contemporary studies, the predominant utilization of C60 derivatives pertains to their role as photosensitizers or agents that scavenge free radicals. The intriguing coexistence of these divergent functionalities has prompted extensive investigation into water-soluble fullerenes. The photodynamic properties of these compounds find practical applications in DNA cleavage, antitumor interventions, and antibacterial endeavors. Consequently, photodynamic therapy is progressively emerging as a pivotal therapeutic modality within the biomedical domain, owing to its notable levels of safety and efficacy. The essential components of photodynamic therapy encompass light of the suitable wavelength, oxygen, and a photosensitizer, wherein the reactive oxygen species generated by the photosensitizer play a pivotal role in the therapeutic mechanism. The remarkable ability of fullerenes to generate singlet oxygen has garnered significant attention from scholars worldwide. Nevertheless, the limited permeability of fullerenes across cell membranes owing to their low water solubility necessitates their modification to enhance their efficacy and utilization. This paper reviews the applications of fullerene derivatives as photosensitizers in antitumor and antibacterial fields for the recent years.

Multidimensional applications and potential health implications of nanocomposites

This study reviews the concept, classifications, and techniques involved in the synthesis of nanocomposites. The environmental and health implications of nanoparticles and composite materials were detailed, as well as the applications of nanocomposites in water remediation, antibacterial application, and printed circuit boards. The study gave insights into the challenges of water pollution treatment and provided a broad list of nanocomposites that have been explored for water remediation. Moreover, the emergence of multi-drug resistance to many antibiotics has made current antibiotics inadequate in the treatment of disease. This has engineered the development of alternative strategies in the drug industries for the production of effective therapeutic agents, comprising nanocomposites with antibacterial agents. The new therapeutic agents known as nanoantibiotics are more efficient and have paved the way to handle the challenges of antibiotic resistance. In printed circuit boards, nanocomposites have shown promising applications because of their distinct mechanical, thermal, and electrical characteristics. The uniqueness of the write-up is that it provides a broad explanation of the concept, synthesis, application, toxicity, and harmful effects of nanocomposites. Thus, it will provide all-inclusive awareness to readers to identify research gaps and motivate researchers to synthesize novel nanocomposites for use in various fields.

Functionalized Carbon Nanoparticles as Theranostic Agents and Their Future Clinical Utility in Oncology

Over the years, research of nanoparticle applications in pre-clinical and clinical applications has greatly advanced our therapeutic and imaging approaches to many diseases, most notably neoplastic disorders. In particular, the innate properties of inorganic nanomaterials, such as gold and iron oxide, as well as carbon-based nanoparticles, have provided the greatest opportunities in cancer theranostics. Carbon nanoparticles can be used as carriers of biological agents to enhance the therapeutic index at a tumor site. Alternatively, they can also be combined with external stimuli, such as light, to induce irreversible physical damaging effects on cells. In this review, the recent advances in carbon nanoparticles and their use in cancer theranostics will be discussed. In addition, the set of evaluations that will be required during their transition from laboratory investigations toward clinical trials will be addressed.

Fullerenols Prevent Neuron Death and Reduce Oxidative Stress in Drosophila Huntington's Disease Model

Huntington's disease (HD) is one of the human neurodegenerative diseases for which there is no effective treatment. Therefore, there is a strong demand for a novel neuroprotective agent that can alleviate its course. Fullerene derivatives are considered to be such agents; however, they need to be comprehensively investigated in model organisms. In this work, neuroprotective activity of C₆₀(OH)₃₀ and C₁₂₀O(OH)₄₄ fullerenols was analyzed for the first time in a Drosophila transgenic model of HD. Lifespan, behavior, oxidative stress level and age-related neurodegeneration were assessed in flies with the pathogenic Huntingtin protein expression in nerve cells. Feed supplementation with hydroxylated C₆₀ fullerene and C₁₂₀O dimer oxide molecules was shown to diminish the oxidative stress level and neurodegenerative processes in the flies' brains. Thus, fullerenes displayed neuroprotective activity in this model.

Effect of water-soluble fullerenes on macrophage surface ultrastructure revealed by scanning ion conductance microscopy

C₆₀-fullerenes have unique potential in antiviral, drug delivery, photodynamic therapy and other biomedical applications. However, little is known about their effects on macrophage surface morphology and ultrastructure. Here by using contact-free scanning ion conductance microscopy (SICM), we investigated the effects of two water-soluble fullerenes on the surface ultrastructure and function of macrophages. The results showed that these fullerenes would be a promising phagocytosis inhibitor and SICM would be an excellent tool to study the morphological information of adhesive and fragile samples.

Nanoscale morphological changes of macrophages characterized by contact-free SICM and their relationship with phagocytosis after C₆₀-fullerene treatment demonstrate they are a potential phagocytosis inhibitor.

Multiadducts of C60 Modulate Amyloid-β Fibrillation with Dual Acetylcholinesterase Inhibition and Antioxidant Properties: In Vitro and In Silico Studies

Background: Amyloid-β (Aβ) fibrils induce cognitive impairment and neuronal loss, leading to onset of Alzheimer’s disease (AD). The inhibition of Aβ aggregation has been proposed as a therapeutic strategy for AD. Pristine C60 has shown the capacity to interact with the Aβ peptide and interfere with fibril formation but induces significant toxic effects in vitro and in vivo. Objective: To evaluate the potential of a series of C60 multiadducts to inhibit the Aβ fibrillization. Methods: A series of C60 multiadducts with four to six diethyl malonyl and their corresponding disodium-malonyl substituents were synthesized as individual isomers. Their potential on Aβ fibrillization inhibition was evaluated in vitro, in cellulo, and silico. Antioxidant activity, acetylcholinesterase inhibition capacity, and toxicity were assessed in vitro. Results: The multiadducts modulate Aβ fibrils formation without inducing cell toxicity, and that the number and polarity of the substituents play a significant role in the adducts efficacy to modulate Aβ aggregation. The molecular mechanism of fullerene-Aβ interaction and modulation was identified. Furthermore, the fullerene derivatives exhibited antioxidant capacity and reduction of acetylcholinesterase activity. Conclusion: Multiadducts of C60 are novel multi-target-directed ligand molecules that could hold considerable promise as the starting point for the development of AD therapies.

[Development of Bio-active Fullerene Derivatives Suitable for Drug]

Fullerene (C₆₀) and fullerene derivatives are attractive novel compounds not only for carbon materials of nanotechnology but also for medical fields because of its unique chemical and physical properties. We intend to develop fullerene derivatives as novel lead compounds for drug discovery. At first, we synthesized many types of water-soluble fullerene derivatives to investigate their biological activities because of their poor solubility in water. We found that anionic fullerene derivatives possess anti-oxidant activities, whereas di-cationic fullerene derivatives exhibited antiproliferative activities against various cancer cell lines including drug-resistant cells. Proline-type fullerene derivatives showed inhibitory activities against human immunodeficiency virus (HIV) reverse transcriptase, HIV protease, hepatitis C virus (HCV) NS5B RNA polymerase, and HCV NS3/4A protease. These activities may strongly inhibit virus replication via a synergistic effect and fullerene derivatives may be used as novel multi-target drugs for the treatment of AIDS and hepatitis C in the future.

Toxicological Aspects of Carbon Nanotubes, Fullerenes and Graphenes

Nanomedicines exhibit unbelievable capability in overcoming the hurdles faced in biological applications. Carbon nanotubes (CNTs), graphene-family nanomaterials and fullerenes are a class of engineered nanoparticles that have emerged as a new option for possible use in drug/gene delivery for life-threatening diseases. Their adaptability to pharmaceutical applications has opened new vistas for biomedical applications. Successful applications of this family of engineered nanoparticles in various fields may not support their use in medicine due to inconsistent data on toxicity as well as the lack of a centralized toxicity database. Inconsistent toxicological studies and lack of mechanistic understanding have been the reasons for limited understanding of their toxicological aspects. These nanoparticles, when underivatized or pristine, are considered as safe, however less reactive. The derivatized forms or functionalization changes their chemistry significantly to modify their biological effects including toxicity. They can cause acute and long term injuries in tissues by penetration through the the blood-air barrier, blood-alveolus barrier, blood-brain barrier, and blood-placenta barrier. and by accumulating in the lung, liver, and spleen . The toxicological effects are manifested through inflammatory response, DNA damage, apoptosis, autophagy and necrosis. Other factors that largely influence the toxicity of carbon nanotubes, graphenes and fullerenes are the concentration, functionalization, dimensional and surface topographical factors. Thus, a better understanding of the toxicity profile of CNTs, graphene-family nanomaterials and fullerenes in humans, animals and the environment is of significant importance, to improve their biological safety, to facilitate their wide biological application and for the successful commercial application. The exploration of appropriate cell lines to investigate specific receptors and intracellular targets as well as chronic toxicity beyond the proof-of-concept is required.

C60 Fullerene Governs Doxorubicin Effect on Metabolic Profile of Rat Microglial Cells In Vitro

Background: C₆₀ fullerenes and their derivatives are actively investigated for the use in neuroscience. Applications of these nanoscale materials require the examination of their interaction with different neural cells, especially with microglia, because these cells, like other tissue resident phagocytes, are the earliest and most sensitive responders to nanoparticles. The aim of this study was to investigate the effect of C₆₀ fullerene and its nanocomplex with doxorubicin (Dox) on the metabolic profile of brain-resident phagocytes-microglia-in vitro. Methods: Resting microglial cells from adult male Wistar rats were used in experiments. Potential C₆₀ fullerene targets in microglial cells were studied by computer simulation. Microglia oxidative metabolism and phagocytic activity were examined by flow cytometry. Griess reaction and arginase activity colorimetric assay were used to explore arginine metabolism. Results: C₆₀ fullerene when used alone did not influence microglia oxidative metabolism and phagocytic activity but shifted arginine metabolism toward the decrease of NO generation. Complexation of C₆₀ fullerene with Dox (C₆₀-Dox) potentiated the ability of the latter to stimulate NO generation. Conclusion: The capability of C₆₀ fullerenes used alone to cause anti-inflammatory shift of microglia arginine metabolism makes them a promising agent for the correction of neuroinflammatory processes involved in neurodegeneration. The potentiating action of C₆₀ fullerene on the immunomodulatory effect of Dox allows us to consider the C₆₀ molecule as an attractive vehicle for this antitumor agent.

Visualization of the tissue distribution of fullerenols in zebrafish (Danio rerio) using imaging mass spectrometry

With the wide application of fullerenols in biomedicine, their environmental exposure risks and toxicity to organisms have been extensively studied. However, there is still a lack of knowledge about the distribution of fullerenols in organisms as an important aspect of their mechanism of toxicity. High-resolution matrix-assisted laser desorption/ionization imaging mass spectrometry (MALDI-IMS) is an emerging technology for researching the distribution of molecules in biological tissue samples. Using this high-resolution technique, we map the distribution of fullerenols in zebrafish tissues, and the results suggest that fullerenols enter the gill, intestine, and muscle tissues and even permeate the blood-brain barrier, reaching the brain of zebrafish after aquatic exposure. Moreover, from the MS images of fullerenols, the distribution amount of fullerenols is highest in the gill, followed by that in the intestine and the small amount in muscle and brain tissues. As an emerging environmental pollutant, the establishment of this research method will provide a new method for the study of the environmental toxicity of carbon nanomaterials. Our results also indicated that this high-resolution imaging method could be applied to explore the mechanism of interaction between carbon nanomaterials and biological systems at the cellular level in the future.

Bioaccumulation, biodistribution，and depuration of 13C-labelled fullerenols in zebrafish through dietary exposure

In aquatic organisms, dietary exposure to nanomaterials is not only one of the important uptake pathways, but it is also one method to assess the transmission risk of the food chain. To address this concern, we quantitatively investigated the accumulation and depuration of fullerenols in the tissues of zebrafish after exposure to fullerenols-contaminated Daphnia magna. After exposure to ¹³C-labelled fullerenol solution at a concentration of 2.5 mg/L for 72 h, the steady state concentration of fullerenols in D. magna was 31.20 ± 1.59 mg/g dry weight. During the 28 d uptake period for zebrafish, fullerenols in the tissues increased in a tissue- and day-dependent manner, and the major target tissues of fullerenols were the intestines and liver, followed by the gill, muscle, and brain. The kinetic parameters of uptake and depuration were also quantitatively analyzed. After depuration for 15 d, a certain amount of residual fullerenols remained in the tissues, especially the brain, where approximately 64 d may be needed to achieve 90% of the cumulative concentration depuration. The calculated distribution-based trophic transfer factors (TTF_d values) (from 0.26 to 0.49) indicated that the tissue biomagnification of fullerenols by zebrafish through dietary exposure may not occur. Transmission electron microscopy (TEM) confirmed the presence of fullerenols in D. magna and the tissues of zebrafish. Our research data are essential for thoroughly understanding of the fate of nanoparticles through the dietary exposure pathway and directing future tissue bioeffect studies regarding target tissues for further research.

Evaluation of the Biodistribution of Serinolamide-Derivatized C60 Fullerene

Carbon nanoparticles have consistently been of great interest in medicine. However, there are currently no clinical materials based on carbon nanoparticles, due to inconsistent biodistribution and excretion data. In this work, we have synthesized a novel C60 derivative with a metal chelating agent (1,4,7-Triazacyclononane-1,4,7-triacetic acid; NOTA) covalently bound to the C60 cage and radiolabeled with copper-64 (t1/2 = 12.7 h). Biodistribution of the material was assessed in vivo using positron emission tomography (PET). Bingel-Hirsch chemistry was employed to functionalize the fullerene cage with highly water-soluble serinolamide groups allowing this new C60 conjugate to clear quickly from mice almost exclusively through the kidneys. Comparing the present results to the larger context of reports of biocompatible fullerene derivatives, this work offers an important evaluation of the in vivo biodistribution, using experimental evidence to establish functionalization guidelines for future C60-based biomedical platforms.

Synthesis and In Vitro Biological Evaluation of Psoralen-Linked Fullerenes

Photodynamic therapy (PDT) is a widely used medicinal treatment for the cancer therapy that utilizes the combination of a photosensitizer (PS) and light irradiation. In this study, we synthesized two novel C₆₀ fullerene derivatives, compounds 1 and 2, with a psoralen moiety that can covalently bind to DNA molecules via cross-linking to pyrimidine under photoirradiation. Along with several fullerene derivatives, the biological properties of several novel compounds have been evaluated. Compounds 1 and 2, which have been shown to induce the production of hydroxyl radicals using several ROS detecting reagents, induced DNA strand breaks with relatively weak activities in the in vitro detection system using a supercoiled plasmid. However, the psoralen-bound fullerene with carboxyl groups (2) only showed genotoxicity in the genotoxicity assay system of the umu test. Compound 2 was also seen to have cytotoxic activities in several cancer cell lines at higher doses compared to water-soluble fullerenes.

Interfacial Chemistry of Conical Fullerene Amphiphiles in Water

Amphiphiles are used for a variety of applications in our daily life and in industrial processes. They typically possess hydrophobic and hydrophilic moieties within the molecule, thereby performing a myriad of functions through the formation of two- and three-dimensional assemblies in water, such as Gibbs monolayers and micelles. However, these functions are often inseparable because they emerge from the same structural feature of the molecule, and are difficult to control because the structural diversity is limited to either long-chain hydrocarbons bearing a polar end group(s) or polymers bearing polar groups exposed to the exterior surface. In this Account, we describe the chemistry of a new class of amphiphiles, conical fullerene amphiphiles (CFAs), utilizing a superhydrophobic [60]fullerene group as a nonpolar apex with added structural features to make it soluble in water. By selective functionalization of only one side of the fullerene molecule, the CFA molecules spontaneously assemble in water through strong hydrophobic interactions among the fullerene apexes and exhibit unusual supramolecular and interfacial behavior. They form unilamellar micelles and vesicles at a critical aggregation concentration as low as micromolar, not showing any air-water and oil-water interfacial activity. The strong preference for self-assembly in water over monolayer formation at an air-water interface makes CFAs unique among conventional nonpolymeric surfactants. The CFA assemblies are often so mechanically robust that they can be transferred to the surface of a solid substrate and analyzed by high-resolution microscopy. Because of this rigid conical structure of a few nanometers in size, CFA molecules aggregate readily in water to form a hierarchical assembly with biomolecules and nanomaterials while maintaining the structural integrity of the CFA aggregate to form multicomponent agglomerates of controllable structural features. For instance, tissue-selective in vivo transport of DNA and siRNA has been achieved. Hybridization of a CFA vesicle with a transition metal catalyst enables the construction of a structurally defined nanospace and an interface for precise control of the nanoscale morphology of polymers. Solubilization of hydrophobic nanocarbons and nanoparticles is also achieved through hemimicelle formation on solid surfaces. The examples reported here illustrate the potential of the conical fullerene motif for the design of amphiphiles as well as supramolecular structures at molecular and tens of nanometers scale.

Food protein amyloid fibrils: Origin, structure, formation, characterization, applications and health implications

Amyloid fibrils have traditionally been considered only as pathological aggregates in human neurodegenerative diseases, but it is increasingly becoming clear that the propensity to form amyloid fibrils is a generic property for all proteins, including food proteins. Differently from the pathological amyloid fibrils, those derived from food proteins can be used as advanced materials in biomedicine, tissue engineering, environmental science, nanotechnology, material science as well as in food science, owing to a combination of highly desirable feature such as extreme aspect ratios, outstanding stiffness and a broad availability of functional groups on their surfaces. In food science, protein fibrillization is progressively recognized as an appealing strategy to broaden and improve food protein functionality. This review article discusses the various classes of reported food protein amyloid fibrils and their formation conditions. It furthermore considers amyloid fibrils in a broad context, from their structural characterization to their forming mechanisms and ensued physical properties, emphasizing their applications in food-related fields. Finally, the biological fate and the potential toxicity mechanisms of food amyloid fibrils are discussed, and an experimental protocol for their health safety validation is proposed in the concluding part of the review.

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.

Disposition of fullerene C60 in rats following intratracheal or intravenous administration

Fullerene C60 is used in a variety of industrial and consumer capacities. As part of a comprehensive evaluation of the toxicity of fullerene C60 by the National Toxicology Program, the disposition following intratracheal (IT) instillation and intravenous (IV) administration of 1 or 5 mg/kg b.wt. fullerene C60 was investigated in male Fischer 344 rats. Following IT instillation, fullerene C60 was detected in the lung as early as 0.5 h post-exposure with minimal clearance over the 168 h period; the concentration increased ≥20-fold with a 5-fold increase in the dose. Fullerene C60 was not detected in extrapulmonary tissues. Following IV administration, fullerene C60 was rapidly eliminated from the blood and was undetectable after 0.5 h post-administration. The highest tissue concentrations of fullerene C60 occurred in the liver, followed by the spleen, lung and kidney. Fullerene C60 was cleared slowly from the kidney and the lung with estimated half-lives of 24 and 139 h, respectively. The liver concentration of fullerene C60 did not change much with time; over 90% of the fullerene C60 remained there over the study duration up to 168 h. Fullerene C60 was also not detected in urine or feces. These data support the hypothesis that fullerene C60 accumulates in the body and therefore has the potential to induce detrimental health effects following exposure.

Pharmacokinetics and Toxicology of the Neuroprotective e,e,e-Methanofullerene(60)-63-tris Malonic Acid [C3] in Mice and Primates

BACKGROUND AND OBJECTIVES

Fullerene-based compounds are a novel class of molecules being developed for a variety of biomedical applications, with nearly 1000 publications in this area in the last 4 years alone. One such compound, the e,e,e-methanofullerene(60)-63-tris malonic acid (designated C₃), is a potent catalytic superoxide dismutase mimetic which has shown neuroprotective efficacy in a number of animal models of neurologic disease, including Parkinsonian Macaca fascicularis monkeys. The aim of this study was to characterize its toxicity and pharmacokinetics in mice and monkeys.

METHODS

To assess pharmacokinetics in mice, we synthesized and administered ¹⁴C-C₃ to mice using various routes of delivery, including orally. To assess potential toxicity in primates, serial blood studies and electrocardiograms (ECGs) were obtained from monkeys treated with C₃ (3 or 7 mg/kg/day) for 2  months.

RESULTS AND CONCLUSIONS

The plasma half-life of C₃ was 8.2 ± 0.2 h, and there was wide tissue distribution, including uptake into brain. The compound was cleared by both hepatic and renal excretion. C₃ was quite stable, with minimal metabolism of the compound even after 7 days of treatment. The LD₅₀ in mice was 80 mg/kg for a single intraperitoneal injection, and was > 30 mg/kg/day for sustained administration; therapeutic doses are 1-5 mg/kg/day. For primates, no evidence of renal, hepatic, electrolyte, or hematologic abnormalities were noted, and serial ECGs demonstrated no alteration in cardiac electrical activity. Thus, doses of C₃ that have therapeutic efficacy appear to be well tolerated after 2 years (mice) or 2 months (non-human primates) of treatment.

Nanotechnology, from quantum mechanical calculations up to drug delivery

There are several reasons why nanotechnology is currently considered as the leader among the most intensively developing research trends. Nanomatter often exhibits new properties, other than those of the morphology of a continuous solid. Also, new phenomena appear at the nanoscale, which are unknown in the case of microcrystalline objects. For this reason, nanomaterials have already found numerous applications that are described in this review. However, among intensively developed various branches of nanotechnology, nanomedicine and pharmacology stand out particularly, which opens new possibilities for the development of these disciplines, gives great hope for the creation of new drugs in which toxicological properties are reduced to a minimum, reduces the doses of medicines, offers targeted treatment and increases diagnostic possibilities. Nanotechnology is the source of a great revolution in medicine. It gives great hope for better and faster treatment of many diseases and gives hope for a better tomorrow. However, the creation of new "nanodrugs" requires a special understanding of the properties of nanoparticles. This article is a review work which determines and describes the way of creating new nanodrugs from ab initio calculations by docking and molecular dynamic applications up to a new medicinal product, as a proposal for the personalized medicine, in the early future.

Hierarchical Assembly of siRNA with Tetraamino Fullerene in Physiological Conditions for Efficient Internalization into Cells and Knockdown

Delivery of siRNA is a key technique in alternative gene therapy, where the siRNA cargo must be effectively loaded onto a tailor-designed carrier molecule and smoothly unloaded precisely upon arrival at the target cells or organs. Any toxicity issues also need to be mitigated by suitable choice of the carrier molecule. A water-soluble cationic fullerene, tetra(piperazino)[60]fullerene epoxide (TPFE), was previously shown to be nontoxic and effective for lung-targeted in vivo siRNA delivery by way of agglutination-induced accumulation. We found in this in vitro study that hierarchical reversible assembly of micrometer-sized TPFE-siRNA-serum protein ternary complexes is the key element for effective loading and release, and stabilization of otherwise highly unstable siRNA under the physiological conditions. The amphiphilic TPFE molecule forms a sub-10 nm-sized stable micelle because of strong cohesion between fullerene molecules, and this fullerene aggregate protects siRNA and induces the hierarchical assembly. Unlike popularly used polyamine carriers, TPFE is not toxic at the dose used for the siRNA delivery.

Environmental and Safety Issues With Nanoparticles

Because nanoparticles have superior surface activity and can be applied to the production of particles with various functions, they are extremely important for the future development of sophisticated material technologies. On the other hand, this superior activity of nanoparticles is a cause of trouble from the perspective of safety and does not always have a positive influence on the environment. Attention must also be paid to impact on health. Nevertheless, all technologies have negative aspects, and overcoming these kinds of problems, we will be able to utilize the superior characteristics of nanoparticles for practical purposes. To achieve this goal, it is necessary to fully understand the influence of nanoparticles on the environment and the relevant safety issues.

Hydroxylated Fullerene: A Stellar Nanomedicine to Treat Lumbar Radiculopathy via Antagonizing TNF-α-Induced Ion Channel Activation, Calcium Signaling, and Neuropeptide Production

Current nonsurgical treatments of discogenic lumbar radiculopathy are neither effective nor safe. Our prior studies have suggested that hydroxylated fullerene (fullerol) nanomaterial could attenuate proinflammatory cytokine tumor necrosis factor alpha (TNF-α)-induced neuroinflammation and oxidative stress in mouse dorsal root ganglia (DRG) and primary neurons. Here, we aim to investigate the analgesic effect of fullerol in a clinically relevant lumbar radiculopathy mouse model and to understand its underlying molecular mechanism in mouse DRGs and neurons. Surprisingly, single and local application of fullerol solution (1 μM, 10 μL) was sufficient to alleviate ipsilateral paw pain sensation in mice up to 2 weeks postsurgery. In addition, microCT data suggested fullerol potentially promoted disc height recovery following injury-induced disc herniation. Alcian blue/picrosirius red staining also suggested that fullerol promoted regeneration of extracellular matrix proteins visualized by the presence of abundant newly formed collagen and proteoglycan in herniated discs. For in vitro DRG culture, fullerol attenuated TNF-α-elicited expression of transient receptor potential cation channel subfamily V member 1 (TRPV-1) and neuropeptides release (substance P and calcitonin gene-related peptide). In addition, fullerol suppressed TNF-α-stimulated increase in intracellular Ca²⁺ concentrations in primary neurons. Moreover, Western blot analysis in DRG revealed that fullerol's beneficial effects against TNF-α might be mediated through protein kinase B (AKT) and extracellular protein-regulated kinase (ERK) pathways. These TNF-α antagonizing and analgesic effects indicated therapeutic potential of fullerol in treating lumbar radiculopathy, providing solid preclinical evidence toward further translational studies.

Air Quality Effects on Human Health and Approaches for Its Assessment through Microfluidic Chips

Air quality depends on the various gases and particles present in it. Both natural phenomena and human activities affect the cleanliness of air. In the last decade, many countries experienced an unprecedented industrial growth, resulting in changing air quality values, and correspondingly, affecting our life quality. Air quality can be accessed by employing microchips that qualitatively and quantitatively determine the present gases and dust particles. The so-called particular matter 2.5 (PM2.5) values are of high importance, as such small particles can penetrate the human lung barrier and enter the blood system. There are cancer cases related to many air pollutants, and especially to PM2.5, contributing to exploding costs within the healthcare system. We focus on various current and potential future air pollutants, and propose solutions on how to protect our health against such dangerous substances. Recent developments in the Organ-on-Chip (OoC) technology can be used to study air pollution as well. OoC allows determination of pollutant toxicity and speeds up the development of novel pharmaceutical drugs.

Competitive Inhibition Mechanism of Acetylcholinesterase without Catalytic Active Site Interaction: Study on Functionalized C60 Nanoparticles via in Vitro and in Silico Assays

Acetylcholinesterase (AChE) activity regulation by chemical agents or, potentially, nanomaterials is important for both toxicology and pharmacology. Competitive inhibition via direct catalytic active sites (CAS) binding or noncompetitive inhibition through interference with substrate and product entering and exiting has been recognized previously as an AChE-inhibition mechanism for bespoke nanomaterials. The competitive inhibition by peripheral anionic site (PAS) interaction without CAS binding remains unexplored. Here, we proposed and verified the occurrence of a presumed competitive inhibition of AChE without CAS binding for hydrophobically functionalized C₆₀ nanoparticles (NPs) by employing both experimental and computational methods. The kinetic inhibition analysis distinguished six competitive inhibitors, probably targeting the PAS, from the pristine and hydrophilically modified C₆₀ NPs. A simple quantitative nanostructure-activity relationship (QNAR) model relating the pocket accessible length of substituent to inhibition capacity was then established to reveal how the geometry of the surface group decides the NP difference in AChE inhibition. Molecular docking identified the PAS as the potential binding site interacting with the NPs via a T-shaped plug-in mode. Specifically, the fullerene core covered the enzyme gorge as a lid through π-π stacking with Tyr72 and Trp286 in the PAS, while the hydrophobic ligands on the fullerene surface inserted into the AChE active site to provide further stability for the complexes. The modeling predicted that inhibition would be severely compromised by Tyr72 and Trp286 deletions, and the subsequent site-directed mutagenesis experiments proved this prediction. Our results demonstrate AChE competitive inhibition of NPs without CAS participation to gain further understanding of both the neurotoxicity and the curative effect of NPs.

Predicted phototoxicities of carbon nano-material by quantum mechanical calculations

The purpose of this research was to develop a predictive model for the phototoxicity potential of carbon nanomaterials (fullerenols and single-walled carbon nanotubes). This model is based on the quantum mechanical (ab initio) calculations on these carbon-based materials and comparison of the triplet excited states of these materials to published work relating phototoxicity of polynuclear aromatic hydrocarbons (PAH) to their predictive triplet excited state energy. A successful outcome will add another tool to the arsenal of predictive methods for the U.S. EPA program offices as they assess the toxicity of compounds in use or coming into commerce. The basis of this research was obtaining the best quantum mechanical structure of the carbon nanomaterial and was fundamental in determining the triplet excited state energy. The triplet excited state, in turn, is associated with the phototoxicity of the material. This project relies heavily on the interaction of the predictive results (physical chemistry) and the experimental results obtained by biologists and toxicologists. The results of the experiments (toxicity testing) will help refine the predictive model, while the predictions will alert the scientists to red flag compounds. It is hoped that a guidance document for the U.S. EPA will be forthcoming to help determine the toxicity of compounds. This can be a screening tool that would rely on further testing for those compounds found by these predictions to be a phototoxic danger to health and the environment.

Carbon Nanomaterials Interfacing with Neurons: An In vivo Perspective

Developing new tools that outperform current state of the art technologies for imaging, drug delivery or electrical sensing in neuronal tissues is one of the great challenges in neurosciences. Investigations into the potential use of carbon nanomaterials for such applications started about two decades ago. Since then, numerous in vitro studies have examined interactions between these nanomaterials and neurons, either by evaluating their compatibility, as vectors for drug delivery, or for their potential use in electric activity sensing and manipulation. The results obtained indicate that carbon nanomaterials may be suitable for medical therapies. However, a relatively small number of in vivo studies have been carried out to date. In order to facilitate the transformation of carbon nanomaterial into practical neurobiomedical applications, it is essential to identify and highlight in the existing literature the strengths and weakness that different carbon nanomaterials have displayed when probed in vivo. Unfortunately the current literature is sometimes sparse and confusing. To offer a clearer picture of the in vivo studies on carbon nanomaterials in the central nervous system, we provide a systematic and critical review. Hereby we identify properties and behavior of carbon nanomaterials in vivo inside the neural tissues, and we examine key achievements and potentially problematic toxicological issues.

Ultrapure laser-synthesized Si-based nanomaterials for biomedical applications: in vivo assessment of safety and biodistribution

Si/SiOx nanoparticles (NPs) produced by laser ablation in deionized water or aqueous biocompatible solutions present a novel extremely promising object for biomedical applications, but the interaction of these NPs with biological systems has not yet been systematically examined. Here, we present the first comprehensive study of biodistribution, biodegradability and toxicity of laser-synthesized Si-SiOx nanoparticles using a small animal model. Despite a relatively high dose of Si-NPs (20 mg/kg) administered intravenously in mice, all controlled parameters (serum, enzymatic, histological etc.) were found to be within safe limits 3 h, 24 h, 48 h and 7 days after the administration. We also determined that the nanoparticles are rapidly sequestered by the liver and spleen, then further biodegraded and directly eliminated in urine without any toxicity effects. Finally, we found that intracellular accumulation of Si-NPs does not induce any oxidative stress damage. Our results evidence a huge potential in using these safe and biodegradable NPs in biomedical applications, in particular as vectors, contrast agents and sensitizers in cancer therapy and diagnostics (theranostics).

Surface modification-mediated biodistribution of ¹³C-fullerene C₆₀ in vivo

BACKGROUND

Functionalization is believed to have a considerable impact on the biodistribution of fullerene in vivo. However, a direct comparison of differently functionalized fullerenes is required to prove the hypothesis. The purpose of this study was to investigate the influences of surface modification on the biodistribution of fullerene following its exposure via several routs of administration.

METHODS

(13)C skeleton-labeled fullerene C60 ((13)C-C60) was functionalized with carboxyl groups ((13)C-C60-COOH) or hydroxyl groups ((13)C-C60-OH). Male ICR mice (~25 g) were exposed to a single dose of 400 μg of (13)C-C60-COOH or (13)C-C60-OH in 200 μL of aqueous 0.9% NaCl solution by three different exposure pathways, including tail vein injection, gavage and intraperitoneal exposure. Tissue samples, including blood, heart, liver, spleen, stomach, kidneys, lungs, brain, large intestine, small intestine, muscle, bone and skin were subsequently collected, dissected, homogenized, lyophilized, and analyzed by isotope ratio mass spectrometry.

RESULTS

The liver, bone, muscle and skin were found to be the major target organs for C60-COOH and C60-OH after their intravenous injection, whereas unmodified C60 was mainly found in the liver, spleen and lung. The total uptakes in liver and spleen followed the order: C60 > > C60-COOH > C60-OH. The distribution rate over 24 h followed the order: C60 > C60-OH > C60-COOH. C60-COOH and C60-OH were both cleared from the body at 7 d post exposure. C60-COOH was absorbed in the gastrointestinal tract following gavage exposure and distributed into the heart, liver, spleen, stomach, lungs, intestine and bone tissues. The translocation of C60-OH was more widespread than that of C60-COOH after intraperitoneal injection.

CONCLUSIONS

The surface modification of fullerene C60 led to a decreased in its accumulation level and distribution rate, as well as altering its target organs. These results therefore demonstrate that the chemical functionalization of fullerene had a significant impact on its translocation and biodistribution properties. Further surface modifications could therefore be used to reduce the toxicity of C60 and improve its biocompatibility, which would be beneficial for biomedical applications.

β-Cyclodextrin functionalized carbon quantum dots as sensors for determination of water-soluble C60 fullerenes in water

A selective photoluminescence method based on Carbon Quantum Dots (CQDs) functionalized with carboxymethyl-β-cyclodextrin for the direct determination of water-soluble C₆₀ fullerene has been developed.

Quantification of sp2 carbon nanomaterials in biological systems: pharmacokinetics, biodistribution and ecological uptake

The sp2 carbon nanomaterials have fantastic properties and hold great potential in diverse areas, including electronics, energy, environment, biomedicine, and so on. The wide applications of sp2 carbon nanomaterials require the thorough investigations on their biosafety. The quantification of sp2 carbon nanomaterials is the first and crucial step in the biosafety evaluations. In this review, we summarized the quantification technologies for sp2 carbon nanomaterials and compared the advantages/disadvantages of these technologies. The pharmacokinetics, the biodistribution, and the ecological uptake of sp2 carbon nanomaterials were achieved by using the quantification technologies. Furthermore, the influence factors such as surface modification, size, shape, and exposure pathway were concerned, and the general rules in the biological behaviors of sp2 carbon nanomaterials were proposed. The implications to the biomedical applications and biosafety evaluations of sp2 carbon nanomaterials are discussed.

The janus facet of nanomaterials

Application of nanoscale materials (NMs) displays a rapidly increasing trend in electronics, optics, chemical catalysis, biotechnology, and medicine due to versatile nature of NMs and easily adjustable physical, physicochemical, and chemical properties. However, the increasing abundance of NMs also poses significant new and emerging health and environmental risks. Despite growing efforts, understanding toxicity of NMs does not seem to cope with the demand, because NMs usually act entirely different from those of conventional small molecule drugs. Currently, large-scale application of available safety assessment protocols, as well as their furthering through case-by-case practice, is advisable. We define a standard work-scheme for nanotoxicity evaluation of NMs, comprising thorough characterization of structural, physical, physicochemical, and chemical traits, followed by measuring biodistribution in live tissue and blood combined with investigation of organ-specific effects especially regarding the function of the brain and the liver. We propose a range of biochemical, cellular, and immunological processes to be explored in order to provide information on the early effects of NMs on some basic physiological functions and chemical defense mechanisms. Together, these contributions give an overview with important implications for the understanding of many aspects of nanotoxicity.

The isotopic effects of 13C-labeled large carbon cage (C70) fullerenes and their formation process

¹³C-enriched large carbon cage-based fullerenes were synthesized on a large scale by an arc discharge method.

A 90-day study of subchronic oral toxicity of 20 nm, negatively charged zinc oxide nanoparticles in Sprague Dawley rats

PURPOSE

The widespread use of nanoparticles (NPs) in industrial and biomedical applications has prompted growing concern regarding their potential toxicity and impact on human health. This study therefore investigated the subchronic, systemic oral toxicity and no-observed-adverse-effect level (NOAEL) of 20 nm, negatively charged zinc oxide (ZnO(SM20(-))) NPs in Sprague Dawley rats for 90 days.

METHODS

The high-dose NP level was set at 500 mg/kg of bodyweight, and the mid- and low-dose levels were set at 250 and 125 mg/kg, respectively. The rats were observed during a 14-day recovery period after the last NP administration for the persistence or reduction of any adverse effects. Toxicokinetic and distribution studies were also conducted to determine the systemic distribution of the NPs.

RESULTS

No rats died during the test period. However, ZnO(SM20(-)) NPs (500 mg/kg) induced changes in the levels of anemia-related factors, prompted acinar cell apoptosis and ductular hyperplasia, stimulated periductular lymphoid cell infiltration and excessive salivation, and increased the numbers of regenerative acinar cells in the pancreas. In addition, stomach lesions were seen at 125, 250, and 500 mg/kg, and retinal atrophy was observed at 250 and 500 mg/kg. The Zn concentration was dose-dependently increased in the liver, kidney, intestines, and plasma, but not in other organs investigated.

CONCLUSION

A ZnO(SM20(-)) NP NOAEL could not be established from the current results, but the lowest-observed-adverse-effect level was 125 mg/kg. Furthermore, the NPs were associated with a number of undesirable systemic actions. Thus, their use in humans must be approached with caution.