Quantum State-Resolved Structure and Dynamics of C60 Fullerenes.

Local density profiles in adsorption layers of Lennard-Jones fluids on two-dimensional adsorbents with spherical geometry and isotherms of excess (Gibbs) adsorption have been calculated using the classical density functional theory (approximations with weighting coefficients). The local density profiles have been found in hydrogen adsorption layers on C60, C240, and C540 fullerene molecules. The calculations have been performed for both subcritical and supercritical temperature ranges. It has been shown that, at a pressure of 10 MPa and a temperature of 77 K, the gravimetric (mass) hydrogen density on C60 fullerene is 7.6 wt %, which is in good agreement with the results of molecular dynamics simulation and experimental data. It has also been established that the gravimetric hydrogen density on C60 fullerene is higher than that on C240 and C540 fullerenes, being comparable with its value in a slitlike pore of a carbon adsorbent.

Due to the using of removable laminar dentures made of acrylic plastic, the complications in the form of chronic inflammation of the oral mucosa are developed in a certain category of patients, as a result of the complex impact of dentures on the tissues of the prosthetic bed in terms of mechanical, chemical, toxic, microbiological and immunological factors. In conditions of mechanical or chemical damage to the mucous membrane epithelium by the action of the microbial factor the activation of epithelial cells occurs and they acquire the properties of immunocompetent cells. As a result, the epithelial cells begin to produce cytokines. A special place in the implementation of acute inflammatory process is held by proinflammatory cytokines: interleukin (IL-1β) and tumor necrosis factor (TNF-α). They regulate all successive stages in the development of inflammation and an adequate response to the etiological factor. Interleukin 10 (IL-10) is the main anti-inflammatory cytokine, which inhibits the synthesis of proinflammatory cytokines. Determination of the level of pro- and anti-inflammatory cytokines is a diagnostic criterion in the development of prosthetic stomatitis and at the same time it is used to test the effectiveness of the proposed method of prevention or treatment of complications on the part of the tissues of the prosthetic bed.
 The aim of the research is to study the concentration of proinflammatory cytokines (TNFα, IL-1β) and anti-inflammatory cytokines (IL-10) in the oral fluid of patients with complete and partial defects of the dentition after prosthetics with removable laminar dentures made of acrylic plastic and dentures coated with fullerene C60 molecules.
 Material and methods of research. The study included 39 patients who were between 40 to 80 years old, including 19 male (48.7%) and 20 female (51.3%) subjects. The partial and complete defects of the dentition were diagnosed. The control group consisted of apparently healthy individuals, namely 10 people without defects of the dentition and periodontal tissue diseases.
 The patients were divided into 3 groups: the first group comprised apparently healthy people with intact dentition; the second group included patients with complete and partial defects of the dentition after prosthetics with removable laminar dentures made of acrylic plastic (20 patients) 7 days after prosthetics; the third group – patients with complete and partial defects of the dentition with removable laminar dentures made of acrylic plastic (20 patients) 30 days after prosthetics; the fourth group – patients with complete and partial defects of the dentition after prosthetics with removable laminar dentures made of acrylic plastic and coated with fullerene C60 molecules.
 The concentration of cytokines IL-1β and TNFα and IL-10 (pg / ml) was determined in the mouth before treatment at day 7, 2 weeks and 1 month. Statistical processing was conducted using STATISTICA 6.0 (StatSoft, USA).
 Results of the studies and their discussion. The results of the studies show that the level of cytokines in patients before prosthetics is higher than in apparently healthy people. On the 7th and 30th day after prosthetics in the study groups, there was a sharp increase in the concentration of proinflammatory and anti-inflammatory cytokines in the oral fluid as contrasted with the comparison group. These data confirm that activation of local synthesis of proinflammatory cytokines in the oral fluid is an important pathogenetic factor that determines the formation and maintenance of an active inflammatory response in the mucosa of the prosthetic bed. After fullerene C60 coating of the surface of denture, which is in contact with the tissues of the prosthetic bed, there is a significant decrease in the level of proinflammatory (IL-1β and TNFα) and anti-inflammatory (IL-10) cytokines.

The extended Huckel method and the Green’s function method were used to calculate the electronic structure and electrical transport of Au electrode-C60, 2C60 or 4C60 fullerene-Au electrode systems. Furthermore, their electronic structure and electrical transport characteristics were compared and analyzed. The results show that (i) owing to the contact with the Au electrodes, the C60, 2C60 and 4C60 molecules change in their electronic structures significantly, and their energy gaps between LUMO and HOMO are narrow; (ii) the bonding between C60, 2C60 or 4C60 fullerene and Au electrodes is partially covalent and partially electrovalent; and (iii) the conductance of the three fullerenes conforms to the order of C60 > 2C60 > 4C60.

Piezoelectric crystal membrane chemical sensors based on fullerene C60

C60 fullerenes, comprised of carbon allotropic family, used widely next to graphenes, contain a fused ring structure with 12 hexagons and 20 pentagons. Since its discovery, the C60 fullerene molecule is attracting scientists owing to its symmetric structure, nanometric size, tensile strength, chemical tailoring and drug-loading nature. Fullerenes are known to possess antimicrobial, antiviral, anti-inflammatory, neuroprotective, antioxidant and MRI contrasting properties. Even after the chemical modifications, fullerenes and their derivatives are extensively employed in the drug and gene delivery, especially to the cancerous cells. In the present review, an attempt is made to highlight the promises and challenges of fullerenes in the drug delivery towards cancerous cells. The potentials such as rate-controlled drug release nature, high drug-loading capacity, biocompatible nature, enhanced permeability and retention time in the biological systems have been elaborated. On the other side, various challenging parameters such as tissue toxicity, elimination from the system, stability issues and commercial viability have also been pondered upon. Meanwhile, the availability of certain products of fullerenes in the market gives a ray of hope in drug delivery and other biomedical applications.

The data of thermodesorption mass spectrometry indicate that fullerene C60 molecules are desorbed from a polyimide (PI) surface at temperatures below the PI decomposition onset temperature, while the desorption of C60 from the bulk begins in the temperature region of the polymer decomposition. It is suggested that strong chemical bonds between C60 and PI macromolecules are formed in the bulk in the stage of the polyamic acid preparation and are broken upon destruction of the polymer macromolecules. The character of C60 thermodesorption from the PI surface depends on thickness of the surface film of fullerene C60.

Fullerene impurities in fluids have a significant influence on their thermophysical properties. Therefore, the use of various substances and materials with fullerene impurities opens up wide opportunities for improving the energy efficiency of equipment in which nanofluids are used: phase transition thermoaccumulative materials, working bodies and heat carriers. However, technological progress associated with the introduction of nanotechnologies in various equipment is largely hindered by the still unsolved problem of sedimentation and aggregation stability of nanofluids. And not only at the stage of nanomaterial production, but also during long-term operation in the equipment. The most reliable information about changes in the composition and structure of nanofluid can be obtained by spectral spectrophotometry. The proposed paper presents the results of the study of spectral absorption coefficients for several nanofluids: tetralin/fullereneC60, n-eicosane/fullerene C60 and Suniso 3GS/C60 compressor oil. Samples of different compositions were obtained within the framework of the proposed nanofluid creation technology. Spectrograms were obtained for the studied samples, from which it follows that with increasing concentration of fullerene C60 the spectral absorption coefficients increase in the interval of light wavelengths from 400 to 700 nm. The presence of extremum points on the dependences of spectral absorption coefficients of nanofluids tetralin/C60 and Suniso 3GS/C60 compressor oil in the wavelength range from 450 to 650 nm indicates that not only fullerene C60 molecules but also aggregates (nanoparticles) of different sizes are present in nanofluids.

Cisplatin (Cis-Pt) is a widely used anticancer drug but its therapeutic efficiency is limited by hemato-, cardio-, hepato-, nephro- and neurotoxicity. Complexation of Cis-Pt with C60 fullerene nanoparticle will allow to enhance the antitumor activity of the drug and to reduce its side toxic effects. To estimate the antitumor effects of С60-Cis-Pt nanocomplex in Lewis lung carcinoma (LLC) and analyze hematological toxicity in tumor-bearing mice. Complexation of C60 fullerene and Cis-Pt molecule was studied by computer simulation. С60-Cis-Pt nanocomplex was i.p. injected to LLC-bearing mice in a total dose of 7.5mg/kg (C60:Cis-Pt as 3.75:3.75mg/kg). The survival of tumor-bearing mice and the relative reduction of tumor weight was recorded. Blood indices were determined using the Particle Counter PCE-210automatic hematology analyzer. Computer simulation demonstrated the formation of С60-Cis-Pt nanocomplex in physiological medium and its stability due to the hydrophobic interactions. Treatment with C60-Cis-Pt nanocomplex increased survival time of LLC-bearing mice by 32%, normalized hemoglobin content (up to 100g/l), erythrocyte and platelet count as compared to the untreated LLC-bearing mice. Tumor weight decreased by 35.5%; the mitotic index of tumor cells decreased by 78%, and apoptotic index increased by 75%. The revealed effects of the C60-Cis-Pt nanocomplex were more pronounced than the effects of Cis-Pt or C60 fullerene alone in equivalent dose. Treatment with C60-Cis-Pt nanocomplex prolonged the survival of LLC-bearing mice and reduced anemia in LLC-bearing mice.

Various model approaches for describing the equilibrium complexation of aromatic biologically active compounds with fullerene C60 molecules are proposed. Equilibrium constants of complexation for structurally different biologically active compounds in the aquatic environment were obtained based on these approaches. Models of continuous and discrete aggregation of C60 molecules are proposed, taking into account the polydisperse nature of fullerene solutions. The model of continuous aggregation considers the sequential growth of aggregates upon addition of C60 fullerene monomers to the already existing aggregates, with the equilibrium self-association constant of fullerene KF being the same for all stages of aggregation. The discrete model takes into account the presence of separate stable aggregates and fractal type of the higher aggregates formation from C60 fullerene aggregates. It is achieved by using the simplest two-level hierarchy of clusters distribution in the fractal series 1-4-7-13, known from the literature data. The model of continuous aggregation represents the classical approach used throughout to describe the aggregation of small molecules, while the discrete aggregation model can only be applied to fullerenes. The results obtained in this study lead to the conclusion that fullerene C60 can form stable complexes with aromatic antitumor drugs, which open the possibility of using these substrates in the future in cancer therapy.

Since it is difficult to simulate the quantum dynamics of large, complex many-body systems, one is led to construct a statistical mechanical description of matter based on a mixture of quantum and classical dynamics. Many physically interesting systems may be partitioned into subsystems where certain degrees of freedom must necessarily be treated quantum mechanically, while others behave classically to a high degree of accuracy. Examples of systems with these characteristics are familiar and include proton and electron transfer processes and systems with electronic degrees of freedom coupled to heavy nuclei. In these cases it is useful to construct a quantum-classical dynamics that not only accounts for the quantum and classical dynamics of the two isolated subsystems but also describes their interaction. [1,2,3] The most widely used approaches are based on surface-hopping schemes where the coupling between the two subsystems induces quantum transitions. [4,5,6,7]

This work describes equations for the potential and force of interaction between C60 fullerene molecules with an ideal infinite graphene sheet on the basis of the Lennard-Jones pair potential. The fall of a fullerene molecule on graphene has been numerically simulated. It is demonstrated that fullerene molecule near the graphene surface execute oscillating motion, with its pattern depending on the initial conditions and interaction parameters. The obtained results are of interest for investigation of the adsorption of fullerene molecules on graphene.

The work is devoted to the study of the gyroscopic phenomena of a rotating C60 fullerene molecule on interaction with a moving particle. To determine the precession characteristics of the C60 fullerene molecule, the pairwise interaction model of nonpolar Lennard-Jones molecules was used. The rotational motion of fullerene was described by the dynamic Euler equations. The influence of the angular velocity and direction of rotation of the fullerene molecule on the deviation from the initial position is investigated.

The time‐dependent mean‐field theory has a long history in describing many‐nucleon dynamics in nuclear physics, and is now widely applied to many‐electron dynamics in atomic, molecular, and condensed matter physics. We present our recent studies in these fields, applying similar computational methods to both nuclear and electronic systems. In the linear response regime, we show calculations of the optical response of a medium mass nucleus and a fullerene molecule C60. The applications in nonlinear regime are also briefly mentioned.

The fullerene molecule C60 is shown to act as a useful sensitizer of a recently discovered photorefractive polymer. Measurements of the steady-state diffraction efficiency, grating growth rate, and other photorefractive properties are presented as a function of C60 concentration, writing intensity, and applied electric field. The dc photoconductivity, grating growth rate, and steady-state diffraction efficiency all increase by as much as a factor of 20 upon doping with up to 0.2 wt % C60. The sensitization appears to result from a small increase in the carrier generation efficiency and a larger increase in the useful optical absorption at the operating wavelength, 647 nm.

ABSTRACTColloidal Au/Ag nanoparticles can be controllably assembled on anodic aluminum oxide (AAO) surfaces; monolayer coating on the membrane on AAO with smaller pores, or a nano-net arrangement along the edges of AAO with larger pores. The supported Au and Ag nanoparticles on the AAO membranes are closely packed and exhibited localized surface plasmon resonance (LSPR). Thus AAO membrane coated with Au or Ag nanoparticles is a highly surface-enhanced Raman scattering (SERS) active substrate. High quality SERS spectra were obtained using fullerene molecules C60 & C70 as the probe molecules and the filtered Au nanoparticles as the substrate. Furthermore, new SERS systems were obtained from Au nanoparticles assembled into the pores of AAO-supported fullerene nano-tubes, and the C60/C70 nano-tube arrays loaded with Au nanoparticles. The new SERS systems made use of the contributions from AAO, the LSPR of the Au nanoparticles, and a uniform assembly of the probe molecules in the nanostructures. These approaches have also been applied to small organic molecule systems using Ag nanoparticles.