Water-soluble C60 Derivatives Research Articles

Metabolite responses of cucumber on copper toxicity in presence of fullerene C60 derivatives

Copper (Cu) toxicity in crops is a result of excessive release of Cu into environment. Little is known about mitigation of Cu toxicity through the application of carbon-based nanomaterials including water-soluble fullerene C60 derivatives. Two derivatives of fullerene were examined: polyhydroxylated C60 (fullerenol) and arginine C60 derivative. In order to study the response of Cu-stressed plants (Cucumis sativus L.) to these nanomaterials, metabolomics analysis by gas chromatography-mass spectrometry (GC-MS) was performed. Excess Cu (15 μM) caused substantial increase in xylem sap Cu, retarded dry biomass and leaf chlorosis of hydroponically grown cucumber. In Cu-stressed leaves, metabolomes was disturbed towards suppression metabolism of nitrogen (N) compounds and activation metabolism of hexoses. Also, upregulation of some metabolites involving in antioxidant defense system, such as ascorbic acid, tocopherol and ferulic acid, was occurred in Cu-stressed leaves. Hydroponically added fullerene adducts decreased the xylem sap Cu and alleviated Cu toxicity with effectiveness has been most pronounced for arginine C60 derivative. Metabolic responses of plants subjected to high Cu with fullerene derivatives were opposite to that observed under Cu alone. Fatty acids up-regulation (linolenic acid) and antioxidant molecules (tocopherol) down-regulation might indicate that arginine C60 adduct can alleviate Cu induced oxidative stress. Although fullerenol slightly improved cucumber growth, its effect on metabolic state of Cu-stressed plants was not statistically significant. We suggest that tested fullerene C60 adducts have a potential to prevent Cu toxicity in plants through a mechanism associated with their capability to restrict xylem transport of Cu from roots to shoot, and to maintain antioxidative properties of plants.

Synthesis and characterization of water-soluble C60-peptide conjugates.

With the aim of developing biocompatible and water-soluble C60 derivatives, three types of C60-peptide conjugates consisting of hydrophilic oligopeptide anchors (oligo-Lys, oligo-Glu, and oligo-Arg) were synthesized. A previously reported Prato reaction adduct of a biscarboxylic acid-substituted C60 derivative was subjected to a solid phase synthesis for amide formation with N-terminal amines of peptides on resin to successfully provide C60-peptide conjugates with one C60 and two peptide anchors as water-soluble moieties. Among three C60-peptide conjugates prepared, C60-oligo-Lys was soluble in water at neutral pH, and C60-oligo-Glu was soluble in buffer with a higher pH value, but C60-oligo-Arg was insoluble in water and most other solvents. C60-oligo-Lys and C60-oligo-Glu were characterized by 1H and 13C NMR. Photoinduced 1O2 generation was observed in the most soluble C60-oligo-Lys conjugate under visible light irradiation (527 nm) to show the potential of this highly water-soluble molecule in biological systems, for example, as a photosensitizer in photodynamic therapy.

Protective role of fullerenol and arginine C60 fullerene against copper toxicity in cucumber

Copper (Cu), when in excess, is one of the most toxic and hazardous metals to all living organisms, including plants. Engineered nanomaterials have the potential for increasing crop protection. However, the protective role of fullerenes (carbon-based nanoparticles with wide application in various areas) against Cu toxicity in plants is, so far, understudied. The present study investigated whether fullerenes can potentially alleviate Cu toxicity in plants (Cucumis sativus L.). Two water-soluble fullerene C60 derivatives were examined: fullerenol [C60(OH)22–24] and arginine-functionalized fullerene [C60(C6H13N4O2)8H8], under controlled conditions using hydroponics. Plants treated with 15 μM of Cu exhibited typical symptoms of Cu toxicity: impaired growth, leaf chlorosis, reduced photosynthetic activity, nutritional imbalances, and enhanced lipid peroxidation. These symptoms were alleviated in the presence of fullerene derivatives with arginine C60 having the more pronounced effect. Improved cucumber Cu tolerance was attributable to Cu buffering in the root zone (roots and medium), which caused a dramatic decline in Cu transport towards leaves and the elimination of oxidative damage. The Cu removal efficacy of arginine C60 was much greater than that of fullerenol. These fullerenes acted in a dose-dependent manner and removed Cu selectively without significant modification of the bioavailability of other essential nutrients. Treatment with free arginine did not affect Cu immobilization or Cu toxicity. These results suggest that the surface chemistry of the fullerene core is important for the protection of plants under excessive Cu conditions. The information offered a new approach to preparing promising practical materials for alleviating Cu toxicity in plants with potential application in fields.

In-situ construction of water-soluble C60 derivative modified cobalt phosphides for efficient electrocatalytic hydrogen evolution in acidic and alkaline media

A zero-dimensional water-soluble ethylenediamine-functionalized C60 derivative (C60(en)n) was used to be in-situ supported on the surface of cobalt phosphides (CoP-Co2P), forming a highly efficient heterostructured electrocatalytic catalyst for the hydrogen evolution reaction (HER). Benefiting from the strong interfacial electronic interaction between C60(en)n and CoP-Co2P, the composite exhibits an exceptional catalytic performance with overpotentials of 129 and 117 mV to achieve a current density of 10 mA cm−2, and Tafel slopes of 59 and 72 mV dec−1 in acidic and alkaline conditions, respectively.

Water-Soluble, Alanine-Modified Fullerene C60 Promotes the Proliferation and Neuronal Differentiation of Neural Stem Cells.

As carbon-based nanomaterials, water-soluble C60 derivatives have potential applications in various fields of biomedicine. In this study, a water-soluble fullerene C60 derivative bearing alanine residues (Ala-C60) was synthesized. The effects of Ala-C60 on neural stem cells (NSCs) as seed cells were explored. Ala-C60 can promote the proliferation of NSCs, induce NSCs to differentiate into neurons, and inhibit the migration of NSCs. Most importantly, the Ala-C60 can significantly increase the cell viability of NSCs treated with hydrogen peroxide (H2O2). The glutathioneperoxidase (GSH-Px) and superoxide dismutase (SOD) activities and glutathione (GSH) content increased significantly in NSCs treated even by 20 μM Ala-C60. These findings strongly indicate that Ala-C60 has high potential to be applied as a scaffold with NSCs for regeneration in nerve tissue engineering for diseases related to the nervous system.

Nanoparticles of water-soluble dyads based on amino acid fullerene C60 derivatives and pyropheophorbide: Synthesis, photophysical properties, and photodynamic activity

Synthesis, spectral properties, and photodynamic activity of water-soluble amino acid fullerene C60 derivatives (AFD) and four original AFD-PPa dyads, obtained by covalent addition of dye pyropheophorbide (PPa) to AFD, were studied. In aqueous solution, these AFD-PPa dyads form nanoassociates as a result of self-assembly. In this case, a significant change in the absorption spectra and strong quenching of the dye fluorescence in the structure of the dyads were observed. A comparison of superoxide or singlet oxygen generation efficiency of the studied compounds in an aqueous solution showed the photodynamic mechanism switching from type II (singlet oxygen generation of the native dye) to I type (superoxide generation of dyads). All dyads have pronounced phototoxicity on cells Hela with IC50 9.2 µM, 9.2 µM, 12.2 µM for dyads Val-C60-PPa, Ala-C60-PPa and Pro-C60-PPa, respectively. Such facilitation of type I photodynamic mechanism could be perspective against hypoxic tumors.

Fullerene-Directed Synthesis of Flowerlike Cu3(PO4)2 Crystals for Efficient Photocatalytic Degradation of Dyes.

Biomineralization is a typical methodology developed by nature to produce calcium-based materials. A method mimicking this process has nowadays become popular for the preparation of artificial organic-inorganic hybrids. Here, Cu3(PO4)2 crystals with a flowerlike morphology have been prepared using water-soluble derivatives of fullerene C60 as templates. In a typical system, flowerlike crystals of Cu3(PO4)2 (denoted FLCs-Cu) were obtained by simply dropping an aqueous solution of CuSO4 into phosphate-buffered saline (PBS) containing a highly water-soluble multiadduct of C60 (fullerenol). The best condition for the preparation of FLCs-Cu appeared at 0.20 mg·mL-1 fullerenol and 0.10 mol·L-1 PBS. During the formation of FLCs-Cu, fullerenol acts as a template and its content in FLCs-Cu is trace (less than 5% by atom) as confirmed by scanning electron microscopy mapping and thermogravimetric analysis. This feature makes fullerenol reusable, and the FLCs-Cu can be prepared repeatedly using the same fullerenol aqueous solution at least 10 times without a noticeable change in the morphology. The N2 adsorption/desorption isotherm showed that the doping of fullerenol increased the specific surface area of the Cu3(PO4)2 crystal. When fullerenol was replaced by C60 monoadducts that are cofunctionalized with a pyrrolidine cation and oligo(poly(ethylene oxide)) chains, FLCs-Cu can form as well, indicating that the strategy of using water-soluble C60 derivative as a template to get FLCs-Cu is universal. As a typical example of practical applications, the photocatalytic activity of the FLCs-Cu was investigated toward the degradation of dyes including rhodamine B and rhodamine 6G. In both cases, efficient photodegradation has been confirmed.

Antioxidant Properties of Fullerene Derivatives Depend on Their Chemical Structure: A Study of Two Fullerene Derivatives on HELFs.

Oxidative stress is a major issue in a wide number of pathologies (neurodegenerative, cardiovascular, immune diseases, and cancer). Because of this, the search for new antioxidants is an important issue. One of the potential antioxidants that has been enthusiastically discussed in the past twenty years is fullerene and its derivatives. Although in aqueous solutions fullerene derivatives have shown to be antioxidants, their properties in this regard within the cells are controversially discussed. We have studied two different water-soluble fullerene C60 and C70 derivatives on human embryonic lung fibroblasts at a wide range of concentrations. Both of them cause a decrease in cellular ROS at short times of incubation (1 hour). Their prolonged action, however, is fundamentally different: derivative GI-761 causes secondary oxidative stress whereas derivative VI-419-P3K keeps ROS levels under control values. To gain a better understanding of this effect, we assessed factors that could play a role in the response of cells to fullerene derivatives. Increased ROS production occurred due to NOX4 upregulation by GI-761. Derivative VI-419-P3K activated the transcription of antioxidant master regulator NRF2 and caused its translocation to the nucleus. This data suggests that the antioxidant effect of fullerene derivatives depends on their chemical structure.

Effects of Fullerene Derivatives on Activity of Ca2+-ATPase of the Sarcoplasmic Reticulum and cGMP Phosphodiesterase.

We studied the effects of new water-soluble polysubstituted fullerene C60 (PFD) derivatives on activity of Ca2+-Mg2+ ATPase of the sarcoplasmic reticulum and cGMP phosphodiesterase. All examined fullerene derivatives inhibited activity of both enzymes. For instance, PFD-I, PFD-II, PFD-III, PFD-V, PFD-IX, PFD-X, and PFD-XI in a concentration of 5×10-5 M completely inhibited hydrolytic and transport functions of Ca2+-ATPase. These compounds in a concentration of 5×10-6 suppressed active transport of calcium ions by 51±5, 77±8, 52±5, 52±5, 100±10, 80±8, and 100±10%, respectively, and inhibited ATP hydrolysis by 31±3, 78±8, 18±2, 29±3, 78±8, 63±7, and 73±9%, respectively, uncoupling the hydrolytic and transport functions of the enzyme. PFD-I noncompetitive and reversibly reduced activity of Ca2+-ATPase (Ki=2.3×10-6 M). All the studied fullerene derivatives (except for PFD-VII) inhibited cGMP phosphodiesterase by more than 80% in concentration of 10-4 M and higher and by more than 50% in concentration of 10-5 M. PFD-I is a non-competitive reversible inhibitor of cGMP phosphodiesterase (Ki=7×10-6 M). These results allow us to expect antimetastatic, antiaggregatory, antihypertensive and vasodilative activity of the studied compounds.

Nafion-based composite solid electrolytes containing water-soluble fullerene C60 derivatives

Nafion-based composite solid polyelectrolytes containing fullerene C60 and its water-soluble derivatives fullerenol-C60 and tris-malonate-C60 were studied by the impedance spectroscopy method. It was found that introduction of these dopants in Nafion leads to a substantial increase in proton conductivity of the composites in the region of low relative humidity. The reasons for the influence of dopants on proton conductivity of composites were discussed.

Cancer Hyperthermia Studies: On the Aqueous Structure and Radiofrequency-Induced Heating Properties of a Water-Soluble [60]Fullerene

The symmetrical, malonodiserinolamide hexa-substituted [60]fullerene, C60-ser, is a key water-soluble C60 derivative of interest for the treatment of cancer by radiofrequency(RF)-induced hyperthermia due to its biocompatibility, neutral charge, lipophilicity, and ability to cross restrictive biological membranes. In aqueous solution C60-ser, which is surrounded by 24 hydroxyl groups, maintains relatively stable layers of closely-bound water molecules (hydration sphere), forms highly dynamic aggregates, sized between 100-400 nm in diameter, which exist in equilibrium with individual, hydrated C60-ser molecules. Our recent observations indicate that these dynamic C60-ser aggregates are built up of a single layer of C60-ser molecules, with water locked inside a hollow core structure. Using a thermal imaging camera, aqueous C60-ser solutions have been shown to produce heat when irradiated with an 13.56 MHz RF field (900W) in a concentration-dependent manner with a heating rate of up to 1.0 °C/sec at 10 mg/ml. This result establishes that C60-ser is a neutrally-charged, key [60]fullerene-based nanoparticle, that might be used for the treatment of cancer by RFH-induced hyperthermia. We acknowledge Kanzius Foundation and Welch Foundation Grant C-0627 for financial support. Figure 1

Analyses of the Binding between Water Soluble C60 Derivatives and Potential Drug Targets through a Molecular Docking Approach.

Fullerene C60, a unique sphere-shaped molecule consisting of carbon, has been proved to have inhibitory effects on many diseases. However, the applications of C60 in medicine have been severely hindered by its complete insolubility in water and low solubility in almost all organic solvents. In this study, the water-soluble C60 derivatives and the C60 binding protein’s structures were collected from the literature. The selected proteins fall into several groups, including acetylcholinesterase, glutamate racemase, inosine monophosphate dehydrogenase, lumazine synthase, human estrogen receptor alpha, dihydrofolate reductase and N-myristoyltransferase. The C60 derivatives were docked into the binding sites in the proteins. The binding affinities of the C60 derivatives were calculated. The bindings between proteins and their known inhibitors or native ligands were also characterized in the same way. The results show that C60 derivatives form good interactions with the binding sites of different protein targets. In many cases, the binding affinities of C60 derivatives are better than those of known inhibitors and native ligands. This study demonstrates the interaction patterns of C60 derivatives and their binding partners, which will have good impact on the fullerene-based drug discovery.

Multi-additions of azides onto fullerenes: Formation of water-soluble glycin C60 Derivatives as potential reactive oxygen species scavengers

Multi-additions of azides onto fullerenes: Formation of water-soluble glycin C60 Derivatives as potential reactive oxygen species scavengers

Application of SERS spectroscopy for detection of water-soluble fullerene C60 derivatives and their covalent conjugates with dyes

Application of SERS spectroscopy for detection of water-soluble fullerene C60 derivatives and their covalent conjugates with dyes

Fullerene derivatives as a new class of inhibitors of protein tyrosine phosphatases

In this study, we identified water-soluble C60 and C70 fullerene derivatives as a novel class of protein tyrosine phosphatase inhibitors. The evaluated compounds were found to inhibit CD45, PTP1B, TC-PTP, SHP2, and PTPβ with IC50 values in the low micromolar to high nanomolar range. These results demonstrate a new strategy for designing effective nanoscale protein tyrosine phosphatase inhibitors.

Mechanism of Taq DNA Polymerase Inhibition by Fullerene Derivatives: Insight from Computer Simulations

Experiments have shown that two water-soluble fullerene C(60) derivatives, fullerenol and fullerene trimalonic acid, inhibit duplication of DNA via polymerase chain reaction (PCR). It has further been shown that the target of this inhibition is the DNA polymerase protein routinely used in PCR. We have used a combination of molecular docking and molecular dynamics simulations to study the possible DNA polymerase inhibition mechanisms in atomistic detail. The simulations show structural changes in the tip and two alpha helices of a subdomain, crucial for the polymerase activity, upon fullerene derivative binding. Such tertiary structure changes could prevent the binding of DNA to the protein, causing the inhibition of the PCR process. These findings are in agreement with experimental studies, which have shown that the inhibition is not competitive. The proposed mechanism of inhibition would be common for all DNA polymerase proteins, providing new possibilities in antiviral applications of fullerene derivatives.

Cytotoxicity and TNF-α Secretion in RAW264.7 Macrophages Exposed to Different Fullerene Derivatives

Fullerene derivatives have been reported as potential nanomedicines, however the role of surface chemical modification on the biological effects remains unclear. In this study, five kinds of water soluble C60 derivatives with different surface chemical modification, C60-(OH)20 (HFD), C60-(beta-Ala)10.1 (AFD), C60-(Lys)8.7 (KFD), C60-(Arg)8.6 (RFD) and C60-(NH(CH2)2NH2)8.8 (NFD) were synthesized. Their cytotoxicity as well as TNF-alpha secretions were evaluated in RAW264.7 macrophage cell line. The results show that no significant cytotoxicity can be observed upon 24 h exposure to C60 derivatives at less than 50 microg/mL. However, higher concentration (> 100 microg/mL) of these C60 derivatives decreases the proliferation of RAW264.7. The cytotoxicity of these fullerene derivatives is probably through the apoptosis pathway, while the extent of cytotoxicity varies with the different surface charges. Higher celluar uptake of HFD was observed in RAW264.7 cells than AFD, which correlates with the more toxic effect of HFD over AFD. The secretion of cytokine tumor necrosis factor alpha (TNF-alpha) was determined to evaluate the immunostimulating activity of these fullerene derivatives. The data show that the fullerene derivatives with negative surface charges secrete more TNF-alpha, whereas derivatives with positive charges show insignificant effect. The possible influence of various surface charge property on the observed biological effects is discussed.

Photodynamic anticancer activities of water-soluble C60 derivatives and their biological consequences in a HeLa cell line

Photodynamic therapy is an emerging, externally activatable, treatment modality for various diseases, especially for cancer therapy. The photodynamic activities of tumor targeting water-soluble C60 derivatives (WSFD) were evaluated on HeLa cells. To overcome the poor solubility, biocompatibility and selectivity of C60, we modified C60 with l-phenylalanine, folic acid and l-arginine. Consistent with their photodynamic abilities, WSFD generated the reactive oxygen species after irradiation both in water and in vitro. No dark cytotoxicity was observed using 5μg/mL WSFD during long incubation time. Furthermore, the uptake of WSFD into HeLa cells was much more than normal cells, which indicated the WSFD had selectivity to tumor cells. Investigation of the possible photodynamic activities of WSFD demonstrated that they expressed photokilling activities by raising the level of 1O2/O2- under visible light irradiation. In parallel, following exposure of cells to WSFD and irradiation, a marked decrease in mitochondrial membrane potential, cell viability, activities of superoxide dismutase (SOD), catalase (CAT) and glutathione peroxidase (GSH-Px), as well as increased malondialdehyde (MDA) production were observed. Moreover, WSFD caused significant elevation in caspase-3 activity, and induced apoptotic death. Experiments demonstrated that both chemical properties, such as the chemical structure of adduct and addend numbers, and physical properties, such as degree of aggregation, influenced the ROS-generation abilities, cellular uptake and photodynamic activities of WSFD. The results suggest that WSFD have the potential application in cancer cell inactivation by photodynamic therapy.

Polymeric dressing formulations containing water-soluble fullerene derivatives

The effect of small additions of water-soluble fullerene C60 derivatives on the strength properties of polyvinyl alcohol films was examined. Solutions of polyvinyl alcohol and fullerenol were tested as polymeric dressing formulations for glass-reinforced plastics based on a thermoplastic polyethylene or polyamide matrix.

Dispersing Carbon Nanotubes by Star-Like Water Soluble C<SUB>60</SUB> Derivatives

The properties of three water soluble [3:3] hexakisadducts of C60 1-3 are investigated both in bulk aqueous solutions and at air/water interface. 1-3 have a star-like molecular structure with six hydrophilic quarternary ammonium groups located terminally. 2 and 3 also have increasing number of ethylene oxide groups inserted into their peripheral hydrophilic arms. This molecular structure makes 1-3 highly water soluble, thus difficult to form aggregates in bulk aqueous solutions as revealed by transmission electron microscope observations. But surface tension measurements shows 1-3 still own some amphiphilic properties and can lower the surface tension of water. These unique C60 derivatives are also subjected to disperse carbon nanotubes (CNTs) in water for the first time. It was found the ability of each water soluble C60 derivative to disperse CNTs was mainly dominated by their amphiphilic feature as well as molecular weight.