Carbon fullerene and nanotube are probable binders to multiple targets of SARS-CoV-2: Insights from computational modeling and molecular dynamic simulation studies.

The present study aimed to predict the binding potential of carbon nanotube and nano fullerene towards multiple targets of SARS-CoV-2. Based on the virulent functions, the spike glycoprotein, RNA-dependent RNA polymerase, main protease, papain-like protease, and RNA binding domain of the nucleocapsid proteins of SARS-CoV-2 were prioritized as the molecular targets and their three-dimensional (3D) structures were retrieved from the Protein Data Bank. The 3D structures of carbon nanotubes and nano-fullerene were computationally modeled, and the binding potential of these nanoparticles to the selected molecular targets was predicted by molecular docking and molecular dynamic (MD) simulations. The drug-likeness and pharmacokinetic features of the lead molecules were computationally predicted. The current study suggested that carbon fullerene and nanotube demonstrated significant binding towards the prioritized multi-targets of SARS-CoV-2. Interestingly, carbon nanotube showed better interaction with these targets when compared to carbon fullerene. MD simulation studies clearly showed that the interaction of nanoparticles and selected targets possessed stability and conformational changes. This study revealed that carbon nanotubes and fullerene are probably used as effectual binders to multiple targets of SARS-CoV-2, and the study offers insights into the experimental validation and highlights the relevance of utilizing carbon nanomaterials as a therapeutic remedy against COVID-19.

A gadofullerene based liver-specific MRI contrast agent for an early diagnosis of orthotopic hepatocellular carcinoma.

Hepatocellular carcinoma has become one of the most prevalent cancers, with a high mortality rate. Accurate diagnosis at an earlier stage is regarded as an effective measure to reduce the disease-related mortality of liver cancer. Magnetic resonance imaging (MRI) as a non-invasive checking mode has become a powerful tool in medical diagnosis. However, MRI contrast agents for liver-specific imaging either have some side effects or the imaging effect is not ideal. Thus, development of more efficient and security MRI contrast agents for the early diagnosis of hepatocellular carcinoma is urgent. Herein, a kind of water-soluble gadofullerene nanoparticle (GFNP) with high efficiency and security has been successfully used to achieve in situ liver cancer imaging. By comparing GFNPs with different functional groups, Gd@C82 modified by a hydroxyl group (GF-OH) presents the highest contrast efficiency both in vitro and in vivo. Notably, the smallest tumor with a diameter of only 0.5 mm could be clearly observed by GF-OH using MRI. Moreover, the imaging window of GF-OH is more than 3-6 hours. In addition, GF-OH can be mostly excreted from the living body and causes no serious toxicity. These results demonstrate that GF-OH is a safe, efficient MRI contrast agent for the diagnosis of early orthotopic hepatocellular carcinoma.

Characterization and Cytotoxicity of Polyprenol Lipid and Vitamin E-TPGS Hybrid Nanoparticles for Betulinic Acid and Low-Substituted Hydroxyl Fullerenol in MHCC97H and L02 Cells.

BACKGROUND: This study demonstrated an innovative formulation including the polyprenol (GBP) lipid and vitamin E-TPGS hybrid nanoparticles (NPs) which was aimed to control the transfer of betulinic acid (BA) and low-substituted hydroxyl fullerenol (C60(OH)n). Additionally, it developed BA-C60(OH)n-GBP-TPGS-NPs delivery system and researched the anti-hepatocellular carcinoma (HCC) effects. MATERIALS AND METHODS: The NPs were prepared by nanoprecipitation with ultrasonic-assisted emulsification (UAE) method. It was characterized by scanning electronic microscopy (SEM), transmission electron microscopy (TEM), FTIR spectrum, size distribution and zeta potential. Physical and chemical properties were evaluated through measurement of drug release, stability studies, drug loading efficiency (DE) and encapsulation efficiency (EE). Biological activities were evaluated through measurement of MTT assay, lactate dehydrogenase leakage assay (LDH), cell proliferation assays, cell apoptosis analysis, comet assay, wound healing assay, cell invasion and Western blot analysis. RESULTS AND CONCLUSIONS: The NPs exhibited clear distribution characteristics, improved solubility and stability. BA and C60(OH)n for the NPs displayed a biphasic release pattern with sustained drug release properties. The mixture of C60(OH)n with different hydroxyl groups may have a certain effect on the stability of the NPs system itself. The NPs could effectively inhibit MHCC97H cell proliferation, migration and invasion in vitro. Combined use of C60(OH)n and BA in GBP lipids may improve the inhibit effect of C60(OH)n or BA against HCC cells and reduce cytotoxicity and genotoxicity of C60(OH)n for normal cells. We concluded that one of the important mechanisms of BA-C60(OH)n-GBP-TPGS-NPs inhibiting MHCC97H cells is achieved by up-regulating the expression of Caspase-3, Caspase-8 and Caspase-9.

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 (TTFd 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.

Bioconcentration and bioaccumulation of C60 fullerene and C60 epoxide in biofilms and freshwater snails (Radix sp.).

Fullerenes are carbon nanomaterials that have awaken a strong interest due to their adsorption properties and potential applications in many fields. However, there are some gaps of information about their effects and bioconcentration potential in the aquatic biota. In the present work, freshwater biofilms and snails (Radix sp.) were exposed to fullerene C60 aggregates, at concentrations in the low µg/L order, in mesocosms specifically designed to mimic the conditions of a natural stream. The bioconcentration factors of C60 fullerene and its main transformation product, [6,6]C60O epoxide, were studied to the mentioned organisms employing analyses by liquid chromatography coupled to high-resolution mass spectrometry. Our results show that C60 fullerene and its [6,6]C60O present a low bioconcentration factor (BCF) to biofilms: BCFC60 = 1.34 ±â€¯0.95 L/kgdw and BCFC60O = 1.43 ±â€¯0.72 L/kgdw. This suggests that the sorption of these aggregates to biota may be less favoured than it would be suggested by its hydrophobic character. According to our model, the surface of fullerene aggregates is saturated with [6,6]C60O molecules, which exposes the polar epoxide moieties in the surface of the aggregates and decreases their affinity to biofilms. In contrast, freshwater snails showed a moderate capacity to actively retain C60 fullerenes in their organism (BAFC60 = 2670 ±â€¯3070 L/kgdw; BAFC60O = 1330 ±â€¯1680 L/kgdw), probably through ingestion. Our results indicate that the bioaccumulation of these carbon nanomaterials can be hardly estimated using their respective octanol-water partition coefficients, and that their colloidal properties, as well as the feeding strategies of the tested organism, play fundamental roles.

Designing an Amino-Fullerene Derivative C70-(EDA)8 to Fight Superbacteria.

Along with the rapid appearance of superbacteria with multidrug resistance, it is a challenge to develop new antibacterial materials to address this big issue. Herein, we report a novel amine group-modified fullerene derivative (C70-(ethylenediamine)8 abrr. C70-(EDA)8), which reveals a high performance in killing superbacteria, and most importantly, it shows negligible toxicity to the mammalian cells. The strong antibacterial ability of this material was attributed to its unique molecular structure. On one hand, amino groups on the EDA part make it easy to affix onto the outer membrane of multidrug resistance Escherichia coli by electrostatic interactions. On the other hand, the hydrophobic surface on the C70 part makes it easy to form a strong hydrophobic interaction with the inner membrane of bacteria. Finally, C70-(EDA)8 leads to the cytoplast leakage of superbacteria. In contrast, the C70-(EDA)8 is nontoxic for mammalian cells due to different distributions of the negative charges in the cell membrane. In vivo studies indicated that C70-(EDA)8 mitigated bacterial infection and accelerated wound healing by regulating the immune response and secretion of growth factors. Our amine group-based fullerene derivatives are promising for clinical treatment of wound infection and offer a new way to fight against the superbacteria.

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.

The antihyperlipidemic effects of fullerenol nanoparticles via adjusting the gut microbiota in vivo.

BACKGROUND: Nanoparticles (NPs) administered orally will meet the gut microbiota, but their impacts on microbiota homeostasis and the consequent physiological relevance remain largely unknown. Here, we describe the modulatory effects and the consequent pharmacological outputs of two orally administered fullerenols NPs (Fol1 C60(OH)7(O)8 and Fol113 C60(OH)11(O)6) on gut microbiota. RESULTS: Administration of Fol1 and Fol113 NPs for 4 weeks largely shifted the overall structure of gut microbiota in mice. The bacteria belonging to putative short-chain fatty acids (SCFAs)-producing genera were markedly increased by both NPs, especially Fol1. Dynamic analysis showed that major SCFAs-producers and key butyrate-producing gene were significantly enriched after treatment for 7-28 days. The fecal contents of SCFAs were consequently increased, which was accompanied by significant decreases of triglycerides and total cholesterol levels in the blood and liver, with Fol1 superior to Fol113. Under cultivation in vitro, fullerenols NPs can be degraded by gut flora and exhibited a similar capacity of inulin to promote SCFA-producing genera. The differential effects of Fol1 and Fol113 NPs on the microbiome may be attributable to their subtly varied surface structures. CONCLUSIONS: The two fullerenol NPs remarkably modulate the gut microbiota and selectively enrich SCFA-producing bacteria, which may be an important reason for their anti-hyperlipidemic effect in mice.

Aspartic acid derivatized hydroxylated fullerenes as drug delivery vehicles for docetaxel: an explorative study.

The objective of the present study was to deliver docetaxel to cancerous cells with enhanced efficacy and safety profile, using aspartic acid linked fullerenols. This aspartic acid derivatized fullerenol conjugate linked with docetaxel was characterized by UV, FT-IR and NMR spectroscopy. Studies for particle size, PDI, zeta potential and FE-SEM were also performed. The conjugate was evaluated for release kinetics, cancer cell cytotoxicity, cellular uptake using confocal laser microscopy and also for pharmacokinetic profile. Cytotoxic studies proved that there was almost 4.3 folds decrease in IC50 with significantly enhanced cellular uptake of the nanometric conjugates. It was observed that the bioavailability was enhanced by 5.8 folds when compared to that of pure DTX. The developed nanoconstructs were erythrocyte compatible and offered decreased protein binding. The findings are encouraging and offer a novel carrier with enhanced efficacy and safety of a drug, belonging to BCS class IV.

Biotransport kinetics and intratumoral biodistribution of malonodiserinolamide-derivatized [60]fullerene in a murine model of breast adenocarcinoma.

[60]Fullerene is a highly versatile nanoparticle (NP) platform for drug delivery to sites of pathology owing to its small size and both ease and versatility of chemical functionalization, facilitating multisite drug conjugation, drug targeting, and modulation of its physicochemical properties. The prominent and well-characterized role of the enhanced permeation and retention (EPR) effect in facilitating NP delivery to tumors motivated us to explore vascular transport kinetics of a water-soluble [60]fullerene derivatives using intravital microscopy in an immune competent murine model of breast adenocarcinoma. Herein, we present a novel local and global image analysis of vascular transport kinetics at the level of individual tumor blood vessels on the micron scale and across whole images, respectively. Similar to larger nanomaterials, [60]fullerenes displayed rapid extravasation from tumor vasculature, distinct from that in normal microvasculature. Temporal heterogeneity in fullerene delivery to tumors was observed, demonstrating the issue of nonuniform delivery beyond spatial dimensions. Trends in local region analysis of fullerene biokinetics by fluorescence quantification were in agreement with global image analysis. Further analysis of intratumoral vascular clearance rates suggested a possible enhanced penetration and retention effect of the fullerene compared to a 70 kDa vascular tracer. Overall, this study demonstrates the feasibility of tracking and quantifying the delivery kinetics and intratumoral biodistribution of fullerene-based drug delivery platforms, consistent with the EPR effect on short timescales and passive transport to tumors.

Positron emission tomography (PET) guided glioblastoma targeting by a fullerene-based nanoplatform with fast renal clearance.

Various carbonaceous nanomaterials, including fullerene, carbon nanotube, graphene, and carbon dots, have attracted increasing attention during past decades for their potential applications in biological imaging and therapy. In this study, we have developed a fullerene-based tumor-targeted positron emission tomography (PET) imaging probe. Water-soluble functionalized C60 conjugates were radio-labeled with 64Cu and modified with cyclo (Arg-Gly-Asp) peptides (cRGD) for targeting of integrin αvß3 in glioblastoma. The specificity of fluorescein-labeled C60 conjugates against cellular integrin αvß3 was evaluated in U87MG (integrin αvß3 positive) and MCF-7 cells (integrin αvß3 negative) by confocal fluorescence microscopy and flow cytometry. Our results indicated that cRGD-conjugated C60 derivatives showed better cellular internalization compared with C60 derivatives without the cRGD attachment. Moreover, an interesting finding on intra-nuclei transportation of cRGD-conjugated C60 derivatives was observed in U87MG cells. In vivo serial PET studies showed preferential accumulation of cRGD-conjugated C60 derivatives at in U87MG tumors. In addition, the pharmacokinetic profiles of these fullerene-based nanoparticles conjugated with cRGD and 1,4,7-triazacyclononane-1,4,7-triacetic acid (NOTA) fit well with the three compartment model. The renal clearance of C60-based nanoparticles is remarkably fast, which makes this material very promising for safer cancer theranostic applications. STATEMENT OF SIGNIFICANCE: Safety is one of the major concerns for nanomedicine and nanomaterials with fast clearance profile are highly desirable. Fullerene is a distinct type of zero-dimensional carbon nanomaterial with ultrasmall size, uniform dispersity, and versatile reactivity. Here we have developed a fullerene-based tumor-targeted positron emission tomography imaging probe using water-soluble functionalized C60 conjugates radio-labeled with 64Cu and modified with cyclo (Arg-Gly-Asp) peptides (cRGD) for glioblastoma targeting. The improved tumor targeting property along with fast renal clearance behavior of C60-based nanoparticles makes this material very promising for future safer cancer theranostic applications.

Visible light-switched cytosol release of siRNA by amphiphilic fullerene derivative to enhance RNAi efficacy in vitro and in vivo.

Cationic macromolecules are attractive for use as small interfering RNA (siRNA) carriers due to their performance in non-immunological reactions, customization during synthesis, and low costs compared to viral carriers. However, their low transfection efficiency substantially hinders their application in both clinical practices and academic research, which is mostly attributable to the low capacity of siRNA/cationic macromolecule complexes to escape lysosomes. To address this challenge, we designed an amphiphilic fullerene derivative (C60-Dex-NH2) for efficient and controllable siRNA delivery. To synthesize C60-Dex-NH2, terminally aminated dextran was conjugated to C60. The conjugate was further cationized by covalently introducing ethylenediamine to the dextran. The physicochemical characteristics of C60-Dex-NH2 was examined with elemental analyses, gel permeation chromatography, solid-state nuclear magnetic resonance (13C, HPDEC), agarose gel electrophoresis, and dynamic light scattering. The cytotoxicity, cellular uptake, intracellular distribution, and in vitro RNA interference (RNAi) of siRNA/C60-Dex-NH2 complex was evaluated in the human breast cancer cell line MDA-MB-231. The RNAi efficiencies mediated by C60-Dex-NH2in vivo was evaluated in subcutaneous tumor-bearing mice. The results showed that C60-Dex-NH2 has a specific amphiphilic skeleton and could form micelle-like aggregate structures in water, which could prevent siRNA from destroying by reactive oxygen species (ROS). When exposed to visible light, C60-Dex-NH2 could trigger controllable ROS generation which could destroy the lysosome membrane, promote the lysosomal escape, and enhance the gene silencing efficiency of siRNA in vitro and in vivo. The gene silencing efficiency could reach a maximum of 53% in the MDA-MB-231-EGFP cells and 69% in the 4T1-GFP-Luc2 tumor-bearing mice. STATEMENT OF SIGNIFICANCE: We designed a novel photosensitive amphiphilic carrier (C60-Dex-NH2) for efficient and controllable siRNA delivery, which can be used in gene therapy. We showed that C60-Dex-NH2 could destroy lysosome membrane via controllable generation of ROS when exposed to light, which can help siRNA to escape from lysosome before degradation. This can enhance the gene silencing efficiency significantly and provides a useful way to regulate RNAi efficiency by light. One advantage for C60-Dex-NH2 system is C60 has broad absorbance spectrum and can be activated by weak visible light; Furthermore, C60-Dex-NH2 has a specific amphiphilic structure, which may prevent siRNA from degrading and allows C60-Dex-NH2 to embed into the lipid membrane of lysosome to improve the ROS induced lysosomal disturbance after internalization.

The effects of non-invasive radiofrequency electric field hyperthermia on biotransport and biodistribution of fluorescent [60]fullerene derivative in a murine orthotopic model of breast adenocarcinoma.

The aim of this study is to understand the combined and differential biokinetic effects of radiofrequency (RF) electric-field hyperthermia as an adjunctive therapy to [60]fullerene nanoparticle-based drug delivery systems in targeting the micro-vasculature and micro-environments of breast cancer tumors. Intravital microscopy (IVM) is an ideal tool to provide the spatial and temporal resolution needed for quantification in this investigation. The water-soluble and fluorescent [60]fullerene derivative (C60-serPF) was designed to be an amphiphilic nanostructure, which is able to cross several biological membranes and accumulate in tumor tissues by passing through abnormally leaky tumor blood vessels. To elucidate the coupled effects of the highly permeable, but heterogeneous tumor vasculature, with the permeabilizing effects of mild (40-42°C) hyperthermia produced by a local RF field, we controlled variables across tumor and non-tumor mammary gland microvasculature with and without application of RF hyperthermia in each condition. We notice that tumor tissue is characterized by more intense drug extravasation than in contralateral mammary fat pad tissue, which is consistent with enhanced permeability and retention (EPR) effects. The analysis of a permeability parameter (Papp), C60-serPF velocity, and the time of compound influx into the intra- and extra-vascular space suggest that mild RF hyperthermia can improve nanoparticle delivery into tumor tissue.

Aminated carbon-based "cargo vehicles" for improved delivery of methotrexate to breast cancer cells.

The purpose of study was to conjugate and evaluate methotrexate with C60-fullerenes and multi-walled carbon nanotubes (MWCNTs) for better drug delivery to cancer cells, and also to compare these two systems. C60-fullerenes and MWCNTs were functionalized by 1,3-dipolar cycloaddition using glycine and paraformaldehyde. Methotrexate (MTX) was esterified and conjugated to the functionalized carbon-based carriers. The conjugates were characterized for micromeritics and drug conjugation. The systems were evaluated for drug release in various pH, MTT cytotoxicity assay, protein binding, cellular uptake, haemolytic profile and pharmacokinetics. Spectroscopic studies confirmed the successful conjugation of drug to the aminated carbon-based carriers. The developed systems released more drug at the pH of cancer cells to that of the pH of plasma. The carriers were compatible with erythrocytes and offered substantial cytotoxicity. Better cellular uptake was confirmed by confocal laser scanning microscopy. C60-fullerenes/MWCNTs modulated the pharmacokinetic profile of drug in desired manner, resulting in better retention and compartment availability. However, the results from C60-fullerenes were observed to be better than that from MWCNTs. The present findings established the potential of carbon-based aminated nanocarriers for delivery of methotrexate in safer and effective manner.

Molecular dynamics simulation study of translocation of fullerene C60 through skin bilayer: effect of concentration on barrier properties.

The molecular level permeation mechanism of fullerenes and its derivatives through human skin could open a vast area for designing novel nanoparticles for cosmetics and drug delivery applications. In this study, we report the permeation mechanism of pristine fullerene C60 for the first time through the skin lipid layer, as determined via prolonged unconstrained and constrained coarse-grained molecular dynamics simulations. The skin layer was modelled as an equimolar ratio of ceramides, cholesterol and free fatty acids. It was observed that at lower concentrations fullerenes formed small clusters (3 or 5 molecules) in the aqueous phase, which further spontaneously permeated inside the bilayer and remained dispersed inside the bilayer interior. On the other hand, at higher concentrations fullerenes aggregated in the aqueous layer, penetrated in that form and remained aggregated in the bilayer interior. Lower concentrations of fullerenes did not induce significant structural changes in the bilayer, whereas at higher concentrations undulations were observed. The permeability of fullerene molecules was found to be concentration-dependent and was explained in terms of their free energy of permeation (thermodynamics) and diffusivity (dynamics). On the basis of the aggregation and dispersion of fullerenes, an optimum fullerene concentration was determined, which could be used for drug delivery and cosmetic applications.

Development of Gd3N@C80 encapsulated redox nanoparticles for high-performance magnetic resonance imaging.

As novel magnetic resonance imaging (MRI) contrast agent, gadofullerene encapsulated redox nanoparticles (Gd3NPs) were prepared by encapsulation of Gd3N@C80 in the core of core-shell-type polymer micelles composed of original polyamine with a reactive oxygen species (ROS)-scavenging ability. Because Gd3NPs possess biocompatible PEG shell with a smaller size (ca. 50 nm), they had high colloidal stability in a physiological environment, and showed low cytotoxicity. Specific accumulation of Gd3NPs in a tumor was confirmed in tumor-bearing mice after systemic administration. The tumor/muscle (T/M) ratio of the Gd ion reached five at 7.5 h after the administration. T1-weighted MRI signal enhancement of the T/M ratio increased by 8% at 6 h postinjection of Gd3NPs (Gd dose:14.35 µmol/kg). Although Gd3NPs showed a tendency for extended blood circulation, they did not have severe adverse effects, probably due to the confinement of Gd in a hydrophobic fullerene in addition to the ROS-scavenging capacity of these nanoparticles. In sharp contrast, systemic administration of Gd-chelate nanoparticles (GdCNPs) to mice disrupts liver function, increases leukocyte counts, and destroys spleen and skin tissues. Leaking of Gd ions from GdCNPs may cause such adverse effects. Based on these results, we expect that Gd3NPs is high-performance MRI contrast agents for tumor diagnosis.

Enhanced brain penetration of hexamethonium in complexes with derivatives of fullerene C60.

The present report describes development of hexamethonium complexes based on fullerene C60. Hexamethonium has a limited penetration into CNS and therefore can antagonize central effects of nicotine only when given at high doses. In the present studies conducted in laboratory rodents, intraperitoneal administration of hexamethonium-fullerene complexes blocked effects of nicotine (convulsions and locomotor stimulation). When compared to equimolar doses of hexamethonium, complexes of hexamethonium with derivatives of fullerene C60 were 40 times more potent indicating an enhanced ability to interact with central nicotine receptors. Thus, fullerene C60 derivatives should be explored further as potential carrier systems for polar drug delivery into CNS.

Fullerene (C60)-based tumor-targeting nanoparticles with "off-on" state for enhanced treatment of cancer.

The traditional drug delivery systems always suffer from the unexpected drug release during circulation and the sluggish release of drug in target site. To address the problem, an "off-on" type drug delivery system with precise control was developed in this study. Doxorubicin (DOX) was covalently conjugated to fullerene (C60) nanoaggregates via a reactive oxygen species (ROS)-sensitive thioketal linker (C60-DOX NPs), and then the hydrophilic shell (Distearoyl-sn-glycero-3-phosphoethanolamine-PEG-CNGRCK2HK3HK11, DSPE-PEG-NGR) was attached to the outer surface of C60-DOX, giving it (C60-DOX-NGR NP) excellent stability in physiological solutions and active tumor-targeting capacity. C60-DOX-NGR NPs were able to entrap DOX efficiently even at acidic environment (pH5.5) when they were "off" state. In sharp contrast, when the NPs were "on" state, a large number of ROS were generated by C60, leading to the breaking of ROS-sensitive linker, thereby enabling the burst release of DOX. The "off" or "on" state of C60-DOX-NGR NPs could be precisely remote-controlled by a 532nm laser (at a low power density) with a high spatial/temporal resolution. In the in vivo and in vitro studies, the C60-based drug delivery system with "off-on" state exhibited a high antitumor efficacy and a low toxicity to normal tissues due to its tumor-targeting ability, remote-controlled drug release property and combined therapeutic effect (photodynamic therapy combined with chemotherapy).

Bioavailability of classical and novel flame retardants: Effect of fullerene presence.

To understand the behavior of some emerging flame retardants (FRs) in the environment, a nonexhaustive extraction using Tenax was applied to study their behavior in aquatic ecosystems. Desorption of 8 polybrominated diphenyl ethers (PBDEs), 8 methoxylated PBDEs, 3 emerging brominated FRs and 6 halogenated norbornenes from sediments spiked in the laboratory was studied. Results showed that emerging FRs have a similar bioavailability than that of legacy FRs, already banned. In addition, some parameters such as sediment total organic carbon (TOC), aging or nanomaterial (NMs) presence in the sediment were modified in order to study their effects on the bioavailability of FRs. Bioavailability increases with a diminution of sediment TOC, while diminishes with an increase of aging. The study of effect of NM presence was performed at three different pH (acidic, neutral and basic), and for the three scenarios, FR bioavailability decreased with NM presence. The retention of pollutants in the sediment seems to be favoured by NM presence, minimizing their impact on living organisms.