Antiamyloid properties of fullerene C<Subscript>60</Subscript> derivatives

A comparative estimation of the ability of complexes of fullerene C₆₀ with polyvinylpyrrolidone and fullerene C₆₀ derivatives (the sodium salt of the polycarboxylic derivative of fullerene C₆₀, sodium fullerenolate), has been carried out. The fullerenes destroyed amyloid fibrils of the Aβ(1–42) peptide of the brain and the muscle X-protein. A study of the effect of fullerenes on muscle actin showed that complexes of fullerene C₆₀ with polyvinylpyrrolidone and sodium fullerenolate did not prevent the filament formation of actin, nor did they destroy its filaments in vitro. Conversely, sodium salt of the polycarboxylic derivative of fullerene C₆₀ destroyed actin filaments and prevented their formation. It was concluded that sodium fullerenolate and complexes of fullerene C₆₀ with polyvinylpyrrolidone are the most effective antiamyloid compounds among the fullerenes examined.     

Toxic effect of Aβ<Subscript>25–35</Subscript> and fullerene C<Subscript>60</Subscript> on erythrocytes

Using light microscopy and spectrophotometry, it has been shown that amyloid β-peptide Aβ_25–35 and water-soluble fullerene C₆₀ cause lysis of human and rat erythrocytes. Both fullerene C₆₀ and Aβ_25–35 partly inhibited the activities of membrane-associated phosphofructokinase and cytoplasmic lactate dehydrogenase in erythrocytes.     

Effect of fullerenes C<Subscript>60</Subscript> on X-protein amyloids

The inhibitory effect of hydrated fullerene C₆₀ and the sodium salt of the fullerene polycarboxylic derivative C₆₀Cl(C₆H₄CH₂COONa)₅ on the formation of amyloid fibrils by X-protein in vitro has been studied by electron microscopy. It is shown that these compounds not only destroy mature amyloid fibrils but also prevent the formation of new fibrils. This property of fullerenes, which are nanoparticles, can be used to develop a novel medical nanotechnology in the therapy for amyloidoses.     

A DFT study of addition reaction between fragment ion (CH<Subscript>2</Subscript>) units and fullerene (C<Subscript>60</Subscript>) molecule

The theoretical study of the interaction between CH₂ and fullerene (C₆₀) suggests the existence of an addition reaction mechanism; this feature is studied by applying an analysis of electronic properties. Several different effects are evident in this interaction as a consequence of the particular electronic transfer which occurs during the procedure. The addition or insertion of the methylene group results in a process, where the inclusion of CH₂ into a fullerene bond produces the formation of several geometric deformations. A simulation of these procedures was carried out, taking advantage of the dynamic semi-classical Born-Oppenheimer approximation. Dynamic aspects were analyzed at different speeds, for the interaction between the CH₂ group and the two bonds: CC (6, 6) and CC (6, 5) respectively on the fullerene (C₆₀) rings. All calculations which involved electrons employed DFT as well as exchange and functional correlation. The results indicate a tendency for the CH₂ fragment to attack the CC (6, 5) bond.     

Enhanced brain penetration of hexamethonium in complexes with derivatives of fullerene C<Subscript>60</Subscript>

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.     

Computational synthesis of hydrogenated fullerenes from C<Subscript>60</Subscript> to C<Subscript>60</Subscript>H<Subscript>60</Subscript>

Hydrogenation from C₆₀ to C₆₀H₆₀ was studied by an unrestricted broken spin symmetry Hartree–Fock approach implemented in semiempirical codes based on the AM1 technique. The calculations focused on the successive addition of hydrogen molecules to the fullerene cage following the identification of the cage target atoms by calculating the highest atomic chemical susceptibility at each step. The results obtained are analyzed from energy, symmetry, and composition perspectives.     

Reconnoitring the current characteristics of the double C<Subscript>20</Subscript> fullerene molecular device in two probe configuration

It is worth remarking that the C₂₀ cage like isomer has been the topic of concentrated theoretical research. C₂₀ single fullerene molecular devices gained a lot of popularity in the field of nano research due to their superlative doping dependent conductive properties. In this work, the double fullerene device has been considered. Here double fullerene molecular junction is created when two C₂₀ fullerene molecules, one in pristine form and other in doped form, are positioned between gold electrodes. Doping was done firstly by second period elements, boron, nitrogen, oxygen, and fluorine and then by group 14 tetragens, silicon, germanium, tin, and lead. For both the cases current characteristics were investigated. Superior conductivity was observed in the boron doped double C₂₀ molecular device while the fluorine doped device was the least conducting. Further for group 14 doping, the silicon doped double C₂₀ device showed maximum current carrying feature, whereas, least value of current was noted in tin doped C₂₀ device.     

Investigations on the Thermal Stability of Fullerene-Based (Ag-C<Subscript>70</Subscript>) Nanocomposite Thin Films

Fullerene-based bi-functional nanocomposite thin film (Ag nanoparticles embedded in fullerene C₇₀ matrix) is synthesized by thermal co-deposition method. Thermal stability of Ag-C₇₀ nanocomposite is investigated by annealing the nanocomposite thin film at different temperatures from 80 to 350 °C for 30 min. Optical and structural properties of nanocomposite thin film with respect to high temperature are studied by UV-visible spectroscopy and x-ray diffraction, respectively. Transmission electron microscopy is performed to observe the temperature-dependent size evolution of Ag nanoparticles in fullerene C₇₀ matrix. A large growth of Ag nanoparticles is observed with temperature especially above 200 °C due to enhanced diffusion of Ag in fullerene C₇₀ at higher temperature and Ostwald ripening. The properties of metal-fullerene nanocomposite is not significantly affected up to a temperature of 150 °C. With a further increase in temperature, a major blue shift of ~?33 nm in SPR wavelength is seen at a temperature of 300 °C due to the thermal induced structural transformation of fullerene C₇₀ matrix into amorphous carbon. A very large-sized Ag nanoparticle with a wide size distribution varying from 27.8 ± 0.6 to 330.0 ± 4.5 nm is seen at 350 °C and due to which, a red shift of ~?16 nm is obtained at this temperature. This study throws light on the thermal stability of the devices based on metal-fullerene bi-functional nanocomposite.     

C<Subscript>60</Subscript> fullerene affects elastic properties and osmoregulation reactions of human lymphocytes

The influence of aqueous solution of pristine C₆₀ fullerene (C₆₀FAS) on functional activity of lymphocytes from a healthy person was studied for the first time. By means of atomic force microscopy, it was found that C₆₀FAS in a concentration of 0.1 mg/ml increases the stiffness of the lymphocyte membrane by 41 % (p < 0.05) and lowers the functional activity of the plasmalemma surface, thereby constraining the use of its membrane material in physiological reactions using a hypotonic model in vitro. However, a cell retains the ability to regulate its volume and demonstrates relative resistance to hypo-osmotic stress. The resistance of lymphocytes in hypo-osmotic medium is facilitated by activation of the nucleus by C₆₀ fullerene particles, which regulates the implementation of two consistent phases of an increase and decrease of cell volume, thereby retaining cell viability. All these indicate the impact of C₆₀ fullerene on the cellular nucleus.     

Computational study of enantioselective interaction between C<Subscript>60</Subscript> fullerene and its derivatives with L-histidine

The mechanism of the enantioselective binding of L-histidine with C₆₀ fullerene and its derivatives, (1,2-methanofullerene C₆₀)-61-carboxylic acid, diethyl (1,2-methanofullerene C₆₀)-61-61-dicarboxylate and tert-butyl (1,2-methanofullerene C₆₀)-61-carboxylate based chiral selectors was studied by quantum chemical calculations. All the molecules were fully optimized at RHF/6-31G* basis set. Relative energies between the different complexes were subsequently estimated with single-point electronic energies computed using Møller-Plesset perturbation theory (MP2). Stability and feasibility of all the generated structures were supported by their respective energy minima and fundamental frequencies. It was observed that interaction of fullerene derivatives with L-histidine is due to the existence of hydrogen bonding forces during the complex formation. The intermolecular forces, flow of atomic charges, binding energy, hardness, dipole moment and localization of electrostatic potential are in agreement with enantioselective interaction of L-histidine with C₆₀ fullerene and its derivatives. It is found that theoretical evaluation to be consistent with the experimental data.     

Effect of nitroderivatives of fullerene C<Subscript>60</Subscript> on amyloid fibrils of the brain Aβ(1–42) peptide and muscle X-protein

The antiamyloidogenic capacity of water-soluble nitroderivatives of fullerene C₆₀: methyl ester of L-N-[(2-nitroglyceryl) fullerenyl] proline, methyl ester of L-N-[(2,3-dinitroglyceryl) fullerenyl] proline, and 2-nitroxyethyl ester of L-N-([2-(nitroxy) ethyl] fullerenyl) proline has been studied in vitro by high-resolution electron microscopy. It was shown that these fullerene C₆₀ nitroderivatives are able to prevent the formation of amyloid fibrils by the brain Aβ(1–42)-peptide and muscle X-protein and to destroy mature fibrils. Electron microscopy is a promising method for selecting effective antiamyloidogenic drugs. The antiamyloidogenic activity of nanodimensional fullerene C₆₀ nitroderivatives offers strong possibilities for creating a new nanotechnology for the therapy of amyloidoses.     

Computational synthesis of C<Subscript>60</Subscript> cyano- and azopolyderivatives

The cyanation of C₆₀ to C₆₀(CN)₁₈ and the aziridination of C₆₀ to C₆₀(NH)₉ were studied by an unrestricted broken spin symmetry Hartree–Fock approach implemented in semiempirical codes based on the AM1 technique. The calculations focused on the successive addition of CN and NH moieties to the fullerene cage following the identification of the target cage atoms as those with the highest atomic chemical susceptibilities calculated at each step. The results obtained were analyzed from the viewpoint of the parallelism between these derivatives as well as C₆₀ fluorides and hydrides. The difference between the first-stage C₆₀ chlorination and other sterically free processes is discussed.     

Fluorescence analysis of the action of soluble derivatives of fullerene C<Subscript>60</Subscript> on amyloid fibrils of the brain peptide Aβ(1–42)

It has been shown by fluorescence analysis in vitro that the water-soluble sodium salt of the polycarboxylic derivative of fullerene C₆₀, fullerenol, and complexes of fullerene C₆₀ with polyvinylpyrrolidone (mol. wt. 25000 and 10000) destroy amyloid fibrils of the brain peptide Aβ(1–42) and prevent their formation. The results of fluorescence analysis confirmed the data obtained earlier by high-resolution electron microscopy. Fluorescence analysis and electron microscopy are complementary methods for the selection of effective antiamyloid drugs.     

Surface analysis of nitrogen plasma-treated C<Subscript>60</Subscript>/PS nanocomposite films for antibacterial activity

The influence of N₂ plasma on the antibacterial properties of polystyrene/fullerene (C₆₀/PS) nanocomposite films with two concentrations is investigated. A comparison is made between the surface characteristics of the films before and after plasma irradiation for different time intervals. The alterations induced on the surface of the films after treatment are analyzed by contact angle and surface energy measurements, FTIR spectroscopy, and atomic force microscopy. The antibacterial properties, growth, biofilm formation, and adhesion of the nanocomposite films against two multidrug-resistant bacterial strains, Staphylococcus aureus KT337489 and Pseudomonas aeruginosa KT337488, are investigated before and after plasma irradiation. The results indicate that P. aeruginosa is more sensitive to treatment than S. aureus as well as an enhancement of the anti-adhesion of both strains to treated surfaces through exposure.     

Chronic alcoholization-induced damage to astroglia and intensification of lipid peroxidation in the rat brain: Protector effect of hydrated form of fullerene C<Subscript>60</Subscript>

We studied the intensity of lipid peroxidation (LP) and the amount of a marker of astrocytes (glial fibrillary acidic protein, GFAP) in tissues of the rat brain under conditions of long-lasting consumption (12 weeks) of ethyl alcohol, as well as the protective effects of peroral administration of hydrated forms of fullerene ?₆₀ (?₆₀HyFn, FWS, fullerene water solutions). Consumption of ethanol resulted in a rise in the amount of molecular markers of oxidative stress (thiobarbiturate-active compounds) in the cerebral tissues. The level of the filamentous GFAP form in the hippocampus and cerebral cortex of alcoholized animals decreased significantly, which can be a result of death of the population of GFAP-imunnoreactive astrocytes in the brain. In the brain of rats after systematic consumption of both ethanol and an aqueous solution of hydrated fullerenes ?₆₀, the amounts of products of lipid peroxidation and of the astroglial marker did not differ significantly from the respective indices in the control animals. Our data demonstrate the efficiency of hydrated fullerenes as pathogenetic therapeutic remedies for elimination of the negative effects of ethyl alcohol on the CNS.     

Self-stability of C<Subscript>60</Subscript> nanocapsules with radio-iodide content and its interaction with calcium atoms

This paper inquires the C₆₀ capabilities to contain radio-iodide (¹³¹I₂) molecules. The encapsulation conditions are investigated applying first principles method to simulate with geometric optimizations and molecular dynamics at 310 K and atmospheric pressure. We find that the n¹³¹I₂@C₆₀ system, where n?=?1, 2, 3…, is stable if the content does not exceed three molecules of radio-iodide. The application of density functional theory allows us to determine that, the nanocapsules content limit is related with the amount of charge that is transferred from the iodine ¹³¹I₂ molecules to the carbon atoms in the fullerene surface. The Mulliken population analysis reveals that the excess of charge increases the repulsive forces between atoms and the bond length average in the C₆₀ structure. The weakened bonds easily break and will critically damage the encapsulation properties. Additionally, we test the interaction nanocapsules with different amounts of radioactive iodine diatomic molecules content with calcium atoms, and find that only the fullerene containing one radioactive iodine diatomic molecule was able to interact with up to nine atoms of calcium without disrupting or cracking. Other fullerenes with two and three radio iodine diatomic molecules cannot resist the interaction with a single calcium atom without cracking or being broken.

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Graphical Abstract Instability of 3¹³¹I₂@C₆₀ Ca.

     

GIAO-DFT-NMR characterization of fullerene-cucurbituril complex: the effects of the C<Subscript>60</Subscript>@CB[9] host-guest mutual interactions

Magnetic shielding constants for an isolated fullerene C₆₀, cucurbituril CB[9], and the host-guest complex C₆₀@CB[9] were calculated as a function of separation of the monomers. Our results in the gas phase and water indicate a significant variation of the magnetic properties for all atoms of the monomers in the complex and after liberation of fullerene C₆₀ from the interior of the CB[9] cavity. The interaction between the two monomers results in a charge transfer that collaborates with a redistribution of electron density to deshield the monomers.

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Graphical Abstract NMR spectroscopy alteration on C₆₀@CB[9] host-guest mutual interactions?

     

Interaction of a Ti-doped semi-fullerene (TiC<Subscript>30</Subscript>) with molecules of CO and CO<Subscript>2</Subscript>

Using density functional theory (DFT) and molecular dynamics (MD), we studied the interaction of a titanium atom with a half of a C₆₀ fullerene (i.e., C₃₀), formed from the corannulene structure with a pentagonal base. We considered atmospheric pressure and 300 K. We found that the most stable adsorption of the titanium atom on C₃₀ occurs in the concave surface of the molecule. Afterward, we investigated the interaction of the system C₃₀-titanium with carbon monoxide and carbon dioxide molecules, respectively. We found that each of these molecules is chemisorbed, with no dissociation. The value of the adsorption energy for the carbon monoxide molecule varies from ?0.897 to ?1.673 eV, and for the carbon dioxide molecule, it is between ?1.065 and ?1.274 eV. These values depend on the initial orientation of these molecules with respect to TiC₃₀.

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Graphical Abstract The TiC₃₀ system chemisorbs CO or CO₂?with no dissociation at atmospheric pressure and 300K

     

Calculations of the C<Subscript>2</Subscript> fragmentation energies of higher fullerenes C<Subscript>80</Subscript> and C<Subscript>82</Subscript>

The C₂ fragmentation energies of the most stable isolated-pentagon-rule (IPR) isomers of the C₈₀ and C₈₂ fullerenes were evaluated with second-order Møller-Plesset (MP2) theory, density-functional theory (DFT) and the semiempirical self-consistent charge density-functional tight-binding (SCC-DFTB) method. Zero-point energy, ionization energy and empirical C₂ corrections were included in the calculation of fragmentation energies for comparison with experimental C₂ fragmentation energies of the fullerene cations. In the case of the most probable Stone-Wales pathway of C₂ fragmentation of C₈₀, the calculated \(D_{0} {\left( {{\text{C}}_{{{\text{80}}}} ^{ + } } \right)}\) agree well with experimental data, whereas in the case of C₈₂ fragmentation, the calculated \(D_{0} {\left( {{\text{C}}_{{{\text{82}}}} ^{ + } } \right)}\) exceed by up to 1.2 eV the experimental ones, which suggests that other IPR isomers may be present in sufficient amounts in experimental samples. Computer-intensive MP2 calculations and DFT calculations with larger basis sets do not yield much improved C₂ fragmentation energies, compared to those reported earlier with B3LYP/3-21G. On the other hand, semiempirical approaches such as SCC-DFTB, which are orders of magnitude less intensive, yield satisfactory fragmentation energies for higher fullerenes and may become a method of choice for routine calculations of fullerenes and carbon nanotubes.

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Figure C₂ fragmentation energies of C₈₀ and C₈₂ fullerenes have been calculated with B3LYP/6-31G* model chemistry, with semiempirical self-consistent-charge density-functional tight-binding (SCC-DFTB) method and with the more rigorous MP2 method. The influence of basis set extension and level of theory on the resulting fragmentation energies is discussed

     

The electronic transport properties of B<Subscript>40</Subscript> fullerenes with chalcogens as anchor atoms

Fullerenes are the most popular molecules to use in applications related to molecular electronics because of their superconductive nature. These molecules show a diverse range of properties, including optical, electronic, and structural characteristics. In this work, we focused on the electronic transport properties of molecular devices consisting of the fullerene B₄₀ or B₄₀ with different anchor atoms between two gold electrodes in a two-probe configuration. The elements used as anchor atoms in the B₄₀ molecules were oxygen, selenium, and sulfur, i.e., chalcogens. The current characteristics of these fullerene-based molecular devices were calculated and analyzed. The analysis highlighted the superior electrical conductivity of the pure B₄₀ device compared to the devices based on its chalcogen-anchored variants. The conductivities of the molecular devices were ranked as follows: pure B₄₀?>?selenium-anchored > sulfur-anchored > oxygen-anchored B₄₀. It was also noted that the devices based on B₄₀ and its chalcogen-anchored variants gave nonzero conductance values at zero bias. These results pave the way for the application of these molecules in future nanodevices utilizing extremely small bias voltages.