Rapid analysis technique for strontium,thorium, and uranium in urine samples

The electronic properties of the metal atoms encaged in a fullerence cage were investigated using synchrotron X-ray photoelectron spectroscopy. Systematic variations in photoemission of valence band of Gd@C₈₂, Gd@C₈₂(OH)₁₂, and Gd@C₈₂(OH)₂₂ were observed in Gd 5p levels. The results suggest that the electronic properties of the inner metal atom can be efficiently modulated by surface chemistry of the fullerene cage.     

Synthesis and in vivo study of metallofullerene based MRI contrast agent

Gd@C₈₂(OH)₄₀ has been developed as a new generation of MRI contrast agent. But recently, it was found that Gd@C₈₂(OH) _x with a larger number of OH (x>36) would lead to cage break and hence, release of highly toxic Gd ions. We synthesized the more stable Gd@C₈₂(OH) _x with less OH-number, Gd@C₈₂(OH)₁₆, and studied its proton relaxivity and MRI images. The results indicate that Gd@C₈₂(OH)₁₆ also gives high proton relaxivity, even higher than that of (NMG)₂-Gd-DTPA. The bio-distribution indicated that Gd@C₈₂(OH)₁₆ tends to be entrapped in the liver and kidney and remained in tissue for about 2 hours. The results suggest that the more stable metallofullerene derivative Gd@C₈₂(OH)₁₆ can be the potential candidate of the new MRI contrast agent.     

Voltammetric Behavior of Water‐Soluble Endohedral Metallofullerene Derivatives

Voltammetric behavior of water‐soluble endohedral metallofullerene derivatives Gd@C₈₂(OH)₅(NHCH₂COOH)₉ (GN) and Gd@C₈₂(OH)₆(NHCH₂CH₂SO₃H)₈ (GS) was characterized in 0.1 M KCl solution by CV and DPV. They showed similar redox behavior, that is, a reversible electroreduction process on HMDE was found; in the mean time, an irreversible oxidation process and an irreversible reduction process on GC electrodes were also observed. The results reveal that these two water‐soluble endohedral metallofullerene derivatives have good electron donating ability and poor electron accepting ability due to hydroxy groups, aminoacetic acid and aminoethyl sulfonic acid connected to the C₈₂ cage in comparison with Gd@C₈₂.     

Quantitative analysis of Gd@C<Subscript>82</Subscript>(OH)<Subscript>22</Subscript> and cisplatin uptake in single cells by inductively coupled plasma mass spectrometry

Cisplatin is a commonly used chemotherapeutic drug in cancer treatment, whereas Gd@C₈₂(OH)₂₂ is a new nanomaterial anti-tumor agent. In this study, we determined intracellular Gd@C₈₂(OH)₂₂ and cisplatin after treatment of Hela and 16HBE cells by single cell inductively coupled plasma-mass spectrometry (SC-ICP-MS), which could provide quantitative information at a single-cell level. The cell digestion method validated the accuracy of the SC-ICP-MS. The concentrations of Gd@C₈₂(OH)₂₂ and cisplatin in cells at different exposure times and doses were studied. The SC-ICP-MS is a promising complement to available methods for single cell analysis and is anticipated to be applied further to biomedical research.

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Graphical Abstract The quantitative results of Gd@C₈₂(OH)₂₂ in single cells determined by SC-ICP-MS and acid digestion method, respectively

     

Visible and near-IR spectroscopy of endohedral Gd@C82(C 2v ) and Ho@C82(C 2v ) metallofullerenes and their monoanions

Solutions of endohedral Gd@C₈₂(C _2v ) and Ho@C₈₂(C _2v ) metallofullerenes are studied by means of visible and near-IR spectroscopy upon their conversion from neutral to the anionic form via a redox reaction with the electron donor potassium perchlorotriphenylmethide K(18-crown-6)[C(C₆Cl₅)₃]. The concentrations of the studied solutions of endohedral Gd@C₈₂(C _2v ) and Ho@C₈₂(C _2v ) metallofullerenes in o-dichlorobenzene were determined from the spectroscopic data, and their molar extinction coefficients are calculated.

     

Theoretical study of C60(OH)20 and C60(OH)18 fullerenols and B12(OH) 12 2? , Si20O30(OH)20, and Ti20O30(OH)20 polyhydroxyl clusters and their Li-substituted derivatives

The equilibrium geometric parameters and the energetic characteristics of fullerenol molecules C₆₀(OH)₂₀ and C₆₀(OH)₁₈ and fullerenol-like inorganic clusters B₁₂(OH) ₁₂ ^2? , Si₂₀O₃₀(OH)₂₀, and Ti₂₀O₃₀(OH)₂₀ and their derivatives C₆₀(OH)_{20 ? n} (OLi) _n , C₆₀(OH)_{18 ? n} (OLi) _n , B₁₂(OH)_{12 ? n} (OLi) _n ^2? , Si₂₀O₃₀(OH)_{20 ? n} (OLi) _n , and Ti₂₀O₃₀(OH)_{20 ? n} (OLi) _n , in which the H atoms of all or one-half of hydroxyl groups are replaced by Li atoms, have been calculated by the density functional theory B3LYP/6-31G* method. It has been found that partial energies ??E(H/Li) per single substitution of Li for H in the reactions C₆₀(OH)₂₀ + nLiAc ?? C₆₀(OH)_{20 ? n} (OLi) _n + nHAc and C₆₀(OH)₁₈ + nLiAc ?? C₆₀(OH)_{18 ? n} (OLi) _n + nHAc (Ac is acetate) and the energies averaged over the entire series of changes in n, as well as over its first and second halves, do not exceed a few kilocalories per mole. It has been predicted that at least one-half (or more than one-half) of OH groups can be replaced by OLi without noticeable changes in energy; however, with a further increase in n, substitutions become endothermic and require ever-increasing energy inputs. In the completely hydroxylated closo-dodecaborane dianion with an icosahedral [B₁₂] cage and more polar B-O-H bonds, analogous H/Li substitutions are slightly exothermic so that the reaction can proceed somewhat smoother and further (toward larger n values) than in fullerenols, other conditions being the same. In the inorganic clusters Si₂₀O₃₀(OH)₂₀ and Ti₂₀O₃₀(OH)₂₀ with the [Si₂₀] and [Ti₂₀] cages, respectively, and with even more polar Si-O-H and Ti-O-H moieties, the substitutions are even more exothermic (their partial energies ??E(H/Li) increase to 4?C6 kcal/mol). For sodium and potassium analogues, the qualitative pattern persists, but H/Na and H/K substitutions are somewhat less exothermic than the H/Li substitutions. The results are compared to the data of previous calculations of stepwise H/Li and H/Na substitutions in the reactions C60(OH)24 + nLAc ?? C60(OH)_{24 ? n} (OL) _n + nHAc (L = Li, Na).     

Synthesis of radio-metallofullerenols

We traced the synthesis process of water-soluble metallofullerenols using radioactivity. The synthesized yield of ¹⁵³Sm@C₈₂(OH)_n from ¹⁵³Sm@C₈₂ was determined to be about 60%, but 26% of ¹⁵³Sm were adsorbed in size-exclusion gel chromatography column. The recovery yields of activated Sm@C₈₂(OH)_n in nuclear reactor are 5–15% when using Sm@C₈₂(OH)_n as irradiation materials, and they are up to 65–88% when using Sm@C₈₂(OH)_n mixed with a quantity of C₆₀(OH)_m. It was found that the effective synthesis process for a radio-metallofullerenol is the neutron irradiation of metallofullerenol mixed with C₆₀(OH)_m.     

Mass Spectrometric Investigations of Thermodynamic Properties of the RbCl/GdCl3 System

The vaporization of pure RbCl, GdCl₃, and RbCl‐GdCl₃ samples of different phase compositions was investigated in the temperature range between 666 K and 982 K by use of the Knudsen effusion mass spectrometry. The gaseous species RbCl, Rb₂Cl₂, GdCl₃, and RbGdCl₄ were identified in the equilibrium vapours and their partial pressures were determined. The enthalpy of dissociation of RbGdCl₄(g), Δ_dissH°(859 K) = 263.1 ± 7.7 kJ mol^—1, was evaluated by second law treatment of the equilibrium partial pressures. The thermodynamic activities of RbCl and GdCl₃ were obtained at 800 K in the two‐phase fields {Rb₃GdCl₆(s) + liquid} and {RbGd₂Cl₇(s) + GdCl₃(s)}. The Gibbs free energies of formation of the pseudo‐binary phases Rb₃GdCl₆(s), Δ_fG°(800 K) = —75.1 ± 2.5 kJ mol^—1 and RbGd₂Cl₇(s), Δ_fG°(800 K) = —40.6 ± 1.2 kJ mol^—1, were evaluated from the thermodynamic activities of the components. The results are compared with the available literature data.     

Electrochemical properties of Gd@C82 and its anions

Cyclic voltammogram (CV) and differential pulse voltammogram (DPV) of Gd@C₈₂ were measured by using mixed solvent system and low temperature. The sixth and seventh electron transfers for Gd@C₈₂ were observed under this condition. Analysis of its electrochemical data and the changes of its UV–VIS–NIR spectrum indicated that Gd@C₈₂(n−) (n=1,3) anions had been generated by chemical method.     

Anion influence on the hydrated oxides formed by Fe3+ and Fe2+ precipitation

The anion influence on the hydrated oxides formed by Fe³⁺ and Fe²⁺ precipitation simulating the aqueous radioactive waste treatment has been investigated by Mössbauer spectroscopy. Fe₃(SO₄)₂, Fe(NO₃)₃, FeCl₃, FeSO₄ and FeCl₂ were used as iron sources and neutralized by NaOH. The obtained products contain several kinds of amorphous and/or poorly crystallized hydrated oxides, depending on the anion type which exists in solution and on the initial iron valence. The pH influence on the final precipitate is taken into account.     

Phase equilibria in a ternary fullerenol-d(C<Subscript>60</Subscript>(OH)<Subscript>22–24</Subscript>)–SmCl<Subscript>3</Subscript>–H<Subscript>2</Subscript>O system at 25°C

The solubility in a ternary fullerenol-d (C₆₀(OH)_22–24)–SmCl₃–H₂O system at 25°C is studied via isothermal saturation in ampules. The solubility diagram is shown to be a simple eutonic one that consists of two branches corresponding to the crystallization of fullerenol-d (C₆₀(OH)_22–24 · 30H₂O) and samarium(III) chloride SmCl₃ · 6H₂O crystallohydrates and contains one nonvariant eutonic point corresponding to saturation with both crystallohydrates. The long branch of C₆₀(OH)_22–24 · 30H₂O crystallization shows the effect of fullerenol-d salting out of saturated solutions; in contrast, the short branch of SmCl₃ · 6H₂O crystallization shows the pronounced salting-in effect of samarium(III) chloride.     

Isobaric thermoanalytical study of the decomposition process of interstitial graphite-Iron(III) chloride compounds

First-step and second-step interstitial graphite-FeCl₃ compounds were studied by isobaric thermal analysis in the temperature interval of 298 ... 750 K and pressure interval of 10 ... 700 Torr. ΔH ⁰ and ΔS ⁰ values were obtained for the processes C₆FeCI₃ → 0.5 C₁₂FeCI₃ + 0.5 FeCl₃(s) C₆FeCl₃ → 6C + FeCl₃(s) and C₁₂FeCl₃ → 12 C + FeCl₃(s) It was demonstrated that the thermal decomposition process of the interstitial graphite compounds investigated proceeds in stages. Temperature dependence of the heat capacity of the studied compounds was determined in the temperature interval of 298 ... 570 K.     

Polymer‐assisted biocatalysis: Unprecedented enzymatic oxidation of fullerene in aqueous medium

Enzymatic complexes, constructed by linear‐dendritic copolymers and laccase, are used for the unprecedented one‐pot biotransformation of fullerene (C₆₀) into epoxide‐ and hydroxyl‐derivatives under mild and environmentally friendly reaction conditions (45 °C and aqueous medium). The reaction is catalyzed by mediator pairs ‐ N‐hydroxy‐5‐norbornene‐2,3‐dicarboxylic acid imide/1‐Hydroxybenzotriazole or 2,2′‐Azino‐bis(3‐ethylbenzothiazoline‐6‐sulfonic acid)/1‐Hydroxybenzotriazole used in equimolar amounts. After 24 and 48 h, the biotransformation products ? C₆₀O_n, C₆₀(OH)_n, C₆₀(H)_n(OH)_n, and/or C₆₀O_n(H)_m(OH)_m range between 50 and 78%, respectively. Their structure is revealed by FTIR, NMR, and mass‐spectrometry. The mechanism of the process is discussed and elucidated. The reaction procedure allows the repeated usage of the enzyme/linear‐dendritic complex, which retains its catalytic activity after several cycles. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012     

Quantum-chemical modeling of endohedral derivatives of buckminsterfullerenes Gd@C<Subscript>60</Subscript>(CHR)<Subscript>2</Subscript> and Gd@C<Subscript>80</Subscript>(CHR)<Subscript>2</Subscript>

The structural energies of the endohedral derivatives of buckminsterfullerenes Gd@C₆₀(CHR)₂ and Gd@C₈₀(CHR)₂ were calculated by quantum-chemical methods – semiempirical PM3 and nonempirical RHF SCF MO LCAO with the S. Huzinaga MINI minimum basis set and GAMESS software.     

Iron uptake and toxicity in Caco-2 cells

The differences between the in vitro effects of iron attributed to valence, chelation, and complexation are known in terms of markers of oxidative stress. Few studies, however, describe the effects of iron on general markers of toxicity used in the testing of cell cultures. The aim of the present study was to determine the toxicity and uptake of different salts and iron complexes in the human intestinal cell line, Caco-2.Cells were incubated with 1.5 mM of different species of iron [FeCl₃/nitrilotriacetic acid (NTA) (1:2), FeCl₃/citric acid (1:2), FeCl₃ and FeSO₄] for 22–24 h. Thereafter, toxicological and uptake experiments were performed.The iron uptake, viability (via MTT assay), and membrane stability (via LDH release) of Caco-2 cells incubated with various iron forms differed significantly from untreated controls which showed no detrimental effects on cells and less iron uptake. The lowest signal for cell viability (MTT assay) was found after the incubation of the cells with FeCl₃/citric acid, being significantly different to treatment with FeCl₃, where the highest MTT signal was detected (p=0.002). No differences between the tested iron species could be found regarding cell proliferation (via serial cell counting) and viability using the trypan blue exclusion test. The lowest membrane damage (via LDH release) was registered in cells treated with FeCl₃/citric acid (1:2), whereas the highest LDH release could be found in cells incubated with FeCl₃/NTA (1:2). The highest intracellular iron concentration (measured via GFAAS) was detected after the treatment of Caco-2 cells with FeCl₃ and FeCl₃/NTA (1:2).This study substantiates the importance of the choice of complexes, as NTA seemed to enhance the toxicity of iron, while citric acid inhibited iron uptake and toxicity.     

Nonlinear optical properties of solutions of heavy fullerenes in the near-ultraviolet region

Nonlinear optical properties (particularly optical limiting) are determined for solutions of heavy fullerenes C₇₆ + C₇₈ + C₈₄ + C₉₀ + …, in the near-ultraviolet region (λ ≈ 280 ± 7 nm). It is shown that no optical limiting is observed in solutions of light fullerenes (C₆₀ and C₇₀), but found in solutions of water-soluble fullerenol-d (a mixture of oxypolyalcohols of fullerene C₆₀-C₆₀(OH) _n1O _n2, with their sodium salts) based on light fullerenes.     

Studies on thermochemical properties of ionic liquids based on transition metal

A brown and transparent ionic liquid (IL), [C₄mim][FeCl₄], was prepared by mixing anhydrous FeCl₃ with 1-butyl-3-methylimidazolium chloride ([C₄mim][Cl]), with molar ratio 1/1 under stirring in a glove box filled with dry argon. The molar enthalpies of solution, Δ_s H _m, of [C₄mim][FeCl₄], in water with various molalities were determined by a solution-reaction isoperibol calorimeter at 298.15 K. Considering the hydrolyzation of anion [FeCl₄]⁻ in dissolution process of the IL, a new method of determining the standard molar enthalpy of solution, Δ_s H _m⁰, was put forward on the bases of Pitzer solution theory of mixed electrolytes. The values of Δ_s H _m⁰ and the sum of Pitzer parameters: and were obtained, respectively. In terms of thermodynamic cycle and the lattice energy of IL calculated by Glasser’s lattice energy theory of ILs, the dissociation enthalpy of anion [FeCl₄]⁻, ΔH _dis≈5650 kJ mol⁻¹, for the reaction: [FeCl₄]⁻(g)→Fe³⁺(g)+4Cl⁻(g), was estimated. It is shown that large hydration enthalpies of ions have been compensated by large the dissociation enthalpy of [FeCl₄]⁻ anion, Δ_d H _m, in dissolution process of the IL.     

Crystal structures of two (5,5,7,12,12,14‐hexamethyl‐1,4,8,11‐tetraazacyclotetradecane)iron(III) complexes

Reported in this contribution are the synthesis and crystal structures of two new Fe^III complexes of 5,5,7,12,12,14‐hexamethyl‐1,4,8,11‐tetraazacyclotetradecane (HMC), namely, dichlorido(5,5,7,12,12,14‐hexamethyl‐1,4,8,11‐tetraazacyclotetradecane)iron(III) chloride, [FeCl₂(C₁₆H₃₆N₄)]Cl or cis‐[FeCl₂(rac‐HMC)]Cl ( 1 ), and dichlorido(5,5,7,12,12,14‐hexamethyl‐1,4,8,11‐tetraazacyclotetradecane)iron(III) tetrachloridoferrate, [FeCl₂(C₁₆H₃₆N₄)][FeCl₄] or trans‐[FeCl₂(meso‐HMC)][FeCl₄] ( 2 ). Single‐crystal X‐ray diffraction studies revealed that both 1 and 2 adopt a pseudo‐octahedral geometry, where the macrocycles adopt folded and planar geometries, respectively. The chloride ligands in 1 are cis to each other, while those in 2 have a trans configuration. The relevant bond angles in 1 deviate substantially from an ideal octahedral coordination geometry, with the angles between the cis substituents varying from 81.55 (5) to 107.56 (4)°, and those between the trans‐ligating atoms varying from 157.76 (8) to 170.88 (3)°. In contrast, 2 adopts a less strained configuration, in which the N—Fe—N angles vary from 84.61 (8) to 95.39 (8)° and the N—Fe—Cl angles vary from 86.02 (5) to 93.98 (5)°.     

Enhanced radical scavenging activity of polyhydroxylated C<Subscript>60</Subscript> functionalized cellulose nanocrystals

A first demonstration of conjugated polyhydroxylated fullerene (C₆₀(OH)₃₀) on the surface of cellulose nanocrystals (CNC)s is reported. These nanohybrids display favourable antioxidant performance and are an attractive alternative to derivatized fullerene nanocages reported previously. UV–Vis measurements indicated that the C₆₀(OH)₃₀-CNC system scavenged 2,2-diphenyl-1-picrylhydrazyl (DPPH) free radicals to a greater degree than C₆₀(OH)₃₀ alone, due to the nucleation of C₆₀(OH)₃₀ on the surface of CNC and high colloidal stability of the engineered nanohybrid. A mechanism for the 2-stage process of the radical reaction with C₆₀(OH)₃₀-CNC is proposed, and modelled by pseudo-first order kinetics. Successful grafting of C₆₀(OH)₃₀ on CNC was confirmed by FTIR, while TEM revealed the morphology of the system with a grafting degree of 20.8 % C₆₀(OH)₃₀. Zeta potential measurements of C₆₀(OH)₃₀-CNC in aqueous solution showed a high stability in the pH range 4.0-8.0, indicating functionality of the CNC based antioxidant system as a biocompatible and sustainable protocol with potential for use in personal care applications.     

Bioluminescent Enzymatic Assay as a Tool for Studying Antioxidant Activity and Toxicity of Bioactive Compounds

A bioluminescent assay based on a system of coupled enzymatic reactions catalyzed by bacterial luciferase and NADH:FMN‐oxidoreductase was developed to monitor toxicity and antioxidant activity of bioactive compounds. The assay enables studying toxic effects at the level of biomolecules and physicochemical processes, as well as determining the toxicity of general and oxidative types. Toxic and detoxifying effects of bioactive compounds were studied. Fullerenols, perspective pharmaceutical agents, nanosized particles, water‐soluble polyhydroxylated fullerene‐60 derivatives were chosen as bioactive compounds. Two homologous fullerenols with different number and type of substituents, C₆₀O_2–4(OH)_20–24 and Fe_0.5C₆₀(OH) _xO_y (x + y = 40–42), were used. They suppressed bioluminescent intensity at concentrations >0.01 g L^?1 and >0.001 g L^?1 for C₆₀O_2–4(OH)_20‐24 and Fe_0.5C₆₀(OH)_xO_y, respectively; hence, a lower toxicity of C₆₀O_2–4(OH)_20–24 was demonstrated. Antioxidant activity of fullerenols was studied in model solutions of organic and inorganic oxidizers; changes in toxicities of general and oxidative type were determined; detoxification coefficients were calculated. Fullerenol C₆₀O_2–4(OH)_20–24 revealed higher antioxidant ability at concentrations 10^?17?10^?5 g L^?1. The difference in the toxicity and antioxidant activity of fullerenols was explained through their electron donor/acceptor properties and different catalytic activity. Principles of bioluminescent enzyme assay application for evaluating the toxic effect and antioxidant activity of bioactive compounds were summarized and the procedure steps were described.