C60 In Water Research Articles

RETRACTION: Soft Nanotubes with a Hydrophobic Channel Hybridized with Au Nanoparticles: Photothermal Dispersion/Aggregation Control of C60 in Water

AbstractRETRACTION: K. Ishikawa, N. Kameta, M. Aoyagi, M. Asakawa, T. Shimizu, “Soft Nanotubes with a Hydrophobic Channel Hybridized with Au Nanoparticles: Photothermal Dispersion/Aggregation Control of C60 in Water,” Advanced Functional Materials 23 no. 13 (2012): 1677–1683, https://doi.org/10.1002/adfm.201202160.The above article, published online on 22 October 2012 in Wiley Online Library (wileyonlinelibrary.com), has been retracted by agreement between the authors; the journal Editor‐in‐Chief, Jörn Ritterbusch; and Wiley‐VCH GmbH, Weinheim. The retraction has been agreed upon the authors' request following an investigation by the National Institute of Advanced Industrial Science and Technology (AIST), due to image falsification in electron microscopy images. In Figure 1a, the second author used an incorrect scale bar and carelessly placed incorrect scale bars in Figures 1b, 5a, 5b, and 5c. As a result, the research results presented are considered unreliable.

A Flexible Aromatic Amphiphilic Trication for the Solubilization of Hydrophobic Organic Semiconductors in Water

Amphiphiles are widely explored for the solubilization of various hydrophobic molecules especially drugs in water. Recently, aromatic amphiphiles emerged as a new class of molecules for the solubilization of hydrophobic organic semiconductors in water. However, the synthesis of these systems involves several steps and often requires the use of expensive metal catalysts. Here we describe the design and synthesis of a new type of flexible aromatic amphiphilic trication (FAT) and its application for solubilization of hydrophobic organic semiconductors in water. FAT has been synthesized in two steps without the use of any expensive metal catalysts. We observed that FAT self-assembles in water into bilayer two-dimensional (2D) nanosheets composed of hydrophobic naphthalimide units. FAT is found to be effective for the solubilization of various hydrophobic organic semiconductors such as perylene, perylene diimide and C60 in water by encapsulating them into its hydrophobic domains. Moreover, FAT was also explored for the solubilization of a 2D conjugated ladder polymer, TQBQ (triquinoxalinylene and benzoquinone), in water.

An atropisomeric M2L4 cage mixture displaying guest-induced convergence and strong guest emission in water.

Introduction of atropisomeric axes into a bent bispyridine ligand leads to the quantitative formation of a complex mixture of atropisomeric M2L4 cages upon treatment with metal ions. Whereas the isomer ratio of the obtained cage mixture, consisting of up to 42 isomers, is insensitive to temperature and solvent, the quantitative convergence from the mixture to a single isomer is accomplished upon encapsulation of a large spherical guest, namely fullerene C60. The observed isomerization with other guests depends largely on their size and shape (e.g., <10 and 82% convergence with planar triphenylene and bowl-shaped corannulene guests, respectively). Besides the unusual guest-induced convergence, the present cage mixture displays the strongest guest emission (ΦF = 68%) among previously reported MnLm cages and capsules, upon encapsulation of a BODIPY dye in water.

Quantum chemical calculations of the one-electron oxidation potential of nitroxide spin labels in biologically active compounds

Density functional theory and continuum solvent model have been used to determine standard redox potentials of oxidation of cyclic nitroxide radicals and the nitroxide derivatives of chitosan and fullerene C60 in water. Inclusion of structural relaxation of solute in water improves correlation between the measured and calculated oxidation potentials. The underlying limitations of the thermodynamic cycle model have been discussed. The computed oxidation potential of the piperidine–N–oxide derivative of chitosan is several tens mV higher than of the separate radical while the opposite trend was found for the pyrroline–N–oxide derivative of chitosan. The calculations of fullerene C60–TEMPO have shown that the 6,6–methanofullerene is more stable that the 5,6–fulleroid structure. The determined redox potential of oxidation of fullerene C60–TEMPO is significantly higher than of TEMPO in water.

Stable and Biocompatible Monodispersion of C60 in Water by Peptides.

The lack of solubility in water and the formation of aggregates hamper many opportunities for technological exploitation of C60. Here, different peptides were designed and synthesized with the aim of monomolecular dispersion of C60 in water. Phenylalanines were used as recognizing moieties, able to interact with C60 through π-π stacking, while a varying number of glycines were used as spacers, to connect the two terminal phenylalanines. The best performance in the dispersion of C60 was obtained with the FGGGF peptidic nanotweezer at a pH of 12. A full characterization of this adduct was carried out. The peptides disperse C60 in water with high efficiency, and the solutions are stable for months both in pure water and in physiological environments. NMR measurements demonstrated the ability of the peptides to interact with C60. AFM measurements showed that C60 is monodispersed. Electrospray ionization mass spectrometry determined a stoichiometry of C60@(FGGGF)4. Molecular dynamics simulations showed that the peptides assemble around the C60 cage, like a candy in its paper wrapper, creating a supramolecular host able to accept C60 in the cavity. The peptide-wrapped C60 is fully biocompatible and the C60 "dark toxicity" is eliminated. C60@(FGGGF)4 shows visible light-induced reactive oxygen species (ROS) generation at physiological saline concentrations and reduction of the HeLa cell viability in response to visible light irradiation.

Photoreaction-driven two-dimensional periodic polyrotaxane-type supramolecular nanoarchitecture.

A 2D polypseudorotaxane-type assembly was constructed using cucurbit[8]uril and styrylpyridinium-bearing triphenylamine. In addition, tunable non-covalent to covalent transition was achieved by [2+2] photodimerization of styrylpyridinium units. Thus, a more stable 2D polyrotaxane-type nanoarchitecture was obtained, which could capture [60]fullerene and further exhibit an excellent photodynamic therapy effect.

Detection of C60 in environmental water using dispersive liquid–liquid micro-extraction followed by high-performance liquid chromatography

ABSTRACTThe wide application of fullerene C60 nanoparticles would inevitably lead to their release into the environment. In order to evaluate the environment risks of C60 and the subsequent effects on ecosystem health, a reliable quantitative methodology of C60 should be established. In this study, a rapid pretreatment method called low-density solvent-based dispersive liquid–liquid micro-extraction (DLLME) combined high-performance liquid chromatography-UV detector (HPLC-UV) was developed to detect C60 in environmental water. In this proposed method, toluene and methanol were chosen as the extraction solvent and the dispersive solvent, respectively. The optimized volume of extraction solvent and dispersive solvent were 100 μL and 10 μL, respectively. And the best shaking time was chosen as 10 min at room temperature for the optimal homogenization procedure for the extraction of C60 in water samples. The enrichment factor of 50 was obtained with 100 μL toluene, and the recoveries of C60 from various environmental samples were in the range of 81.4 ± 5.0–101.4 ± 6.2% at 1.25–5.00 µg/L spiked levels. The detection limits of C60 in tap water, surface water, living sewage and mining waste water were 0.19, 0.29, 0.34 and 0.22 μg/L, respectively. The low detection limit, good linear range and high recoveries of C60 in environmental water indicated that the proposed method could provide an efficient approach for the analysis and tracking of C60 in the environment.

C60 Bioconjugation with Proteins: Towards a Palette of Carriers for All pH Ranges.

The high hydrophobicity of fullerenes and the resulting formation of aggregates in aqueous solutions hamper the possibility of their exploitation in many technological applications. Noncovalent bioconjugation of fullerenes with proteins is an emerging approach for their dispersion in aqueous media. Contrary to covalent functionalization, bioconjugation preserves the physicochemical properties of the carbon nanostructure. The unique photophysical and photochemical properties of fullerenes are then fully accessible for applications in nanomedicine, sensoristic, biocatalysis and materials science fields. However, proteins are not universal carriers. Their stability depends on the biological conditions for which they have evolved. Here we present two model systems based on pepsin and trypsin. These proteins have opposite net charge at physiological pH. They recognize and disperse C60 in water. UV-Vis spectroscopy, zeta-potential and atomic force microscopy analysis demonstrates that the hybrids are well dispersed and stable in a wide range of pH’s and ionic strengths. A previously validated modelling approach identifies the protein-binding pocket involved in the interaction with C60. Computational predictions, combined with experimental investigations, provide powerful tools to design tailor-made C60@proteins bioconjugates for specific applications.

Proteins as supramolecular hosts for C60: a true solution of C60 in water.

Hybrid systems have great potential for a wide range of applications in chemistry, physics and materials science. Conjugation of a biosystem to a molecular material can tune the properties of the components or give rise to new properties. As a workhorse, here we take a C60@lysozyme hybrid. We show that lysozyme recognizes and disperses fullerene in water. AFM, cryo-TEM and high resolution X-ray powder diffraction show that the C60 dispersion is monomolecular. The adduct is biocompatible, stable in physiological and technologically-relevant environments, and easy to store. Hybridization with lysozyme preserves the electrochemical properties of C60. EPR spin-trapping experiments show that the C60@lysozyme hybrid produces ROS following both type I and type II mechanisms. Due to the shielding effect of proteins, the adduct generates significant amounts of 1O2 also in aqueous solution. In the case of type I mechanism, the protein residues provide electrons and the hybrid does not require addition of external electron donors. The preparation process and the properties of C60@lysozyme are general and can be expected to be similar to other C60@protein systems. It is envisaged that the properties of the C60@protein hybrids will pave the way for a host of applications in nanomedicine, nanotechnology, and photocatalysis.

Experimental and theoretical study on degradation of oxidized C60 in water via photo-Fenton method

With popular application of fullerene (C60) and its derivative in functional materials, they have been discharged into water. Therefore, it is urgent to develop an effective and environmentally friendly method for removing C60 and its derivative from water. However, an efficient method of degradation of C60 and its derivative in water hasn’t been reported. C60 in water can be oxidized by light to give oxidized C60 (OC60), therefore, degradation of OC60 plays a key role in removal of C60 and its derivative in water. In this paper, OC60 was effectively degraded via photo-Fenton method to give carbon dioxide and H2O. The degradation process was monitored by ultraviolet–visible absorption spectroscopy, X-ray diffraction and scanning electron microscopy. Degradation intermediates were determined by Fourier transform infrared spectroscopy, liquid chromatography-tandem mass spectrometry, and elemental analysis. Density functional theory calculations were used to study the mechanism of hydroxyl radical reaction. Based on experimental data and Gaussian calculations, degradation mechanism of OC60 in water was proposed.

A theoretical study on the C30X15Y15 (X = B, and Al; Y = N, and P) heterofullerenes

Using density functional theory calculations, we investigated the stability, solubility, structural, electronic, and optical properties of C30X15Y15 (X=B, and Al; Y=N, and P) heterofullerenes. The C30B15N15 is found to be the most stable heterofullerene with standard formation enthalpy (ΔH°f) of 222.2kcal/mol, followed by C30Al15N15 (ΔH°f=891.6kcal/mol). The relative stability of fullerenes are as follows: BN>C60>AlN∼BP>AlP, indicating that the BN doping makes the C60 more stable. The XY doping process significantly increases and decreases the solubility of C60 fullerene in water and benzene solvents, respectively. The standard Gibbs free energy of solvation (ΔG°solv) of C60 in water is increased from −0.7 to −33.5kcal/mol by AlN doping process. The dopant X atoms are mainly contributed in generation of occupied states but the Y ones largely create the virtual states. Compared to the pristine C60, the electrical conductivity of the XY doped fullerenes are higher, and the order is as follows: AlP>BP>BN∼AlN>>C60. This indicates that the Al atoms destabilize and P ones stabilize the HOMO and LUMO levels, respectively. The optical gap of these fullerenes is smaller than the HOMO-LUMO gap by about 0.44–0.55eV.

Thermodynamics of hydration of fullerols [C60(OH)n] and hydrogen bond dynamics in their hydration shells.

Molecular dynamics simulations of fullerene and fullerols [C60(OH)n, where n = 2-30] in aqueous solutions have been performed for the purpose of obtaining a detailed understanding of the structural and dynamic properties of these nanoparticles in water. The structures, dynamics and hydration free energies of the solute molecules in water have been analysed. Radial distribution functions, spatial density distribution functions and hydrogen bond analyses are employed to characterize the solvation shells of water around the central solute molecules. We have found that water molecules form two solvation shells around the central solute molecule. Hydrogen bonding in the bulk solvent is unaffected by increasing n. The large decrease in solvation enthalpies of these solute molecules for n > 14 enhances solubilisation. The diffusion constants of solute molecules decrease with increasing n. The solvation free energy of C60 in water is positive (52.8 kJ/mol), whereas its value for C60(OH)30 is highly negative (-427.1 kJ/mol). The effects of surface hydroxylation become more dominant once the fullerols become soluble.

Aqueous solubilization of C60 fullerene by natural protein surfactants, latherin and ranaspumin-2

C60 fullerene is not soluble in water and dispersion usually requires organic solvents, sonication or vigorous mechanical mixing. However, we show here that mixing of pristine C60 in water with natural surfactant proteins latherin and ranaspumin-2 (Rsn-2) at low concentrations yields stable aqueous dispersions with spectroscopic properties similar to those previously obtained by more vigorous methods. Particle sizes are significantly smaller than those achieved by mechanical dispersion alone, and concentrations are compatible with clusters approximating 1:1 protein:C60 stoichiometry. These proteins can also be adsorbed onto more intractable carbon nanotubes. This promises to be a convenient way to interface a range of hydrophobic nanoparticles and related materials with biological macromolecules, with potential to exploit the versatility of recombinant protein engineering in the development of nano-bio interface devices. It also has potential consequences for toxicological aspects of these and similar nanoparticles.

Photoenhanced Oxidation of C60 in Water: Exploring the Roles of H2O2 and Hydroxyl Radical Based Reactions

Photoenhanced Oxidation of C60 in Water: Exploring the Roles of H2O2 and Hydroxyl Radical Based Reactions

Investigation on the interactions between fullerene and β-CD-g-hyperbranched polyglycerol to produce water-soluble fullerene

Developing a successful way to solubilize C60 in water is a longstanding, critical, and challenging issue in nanotechnology, biological, and medicine applications because of the great potential of fullerene derivatives in anti-viral therapy. In the current study, an efficient strategy for the preparing of water-soluble C60 at room temperature has been developed by complexion of C60 with hyperbranched polyglycerol linked to the β-cyclodextrin core (β-CD-g-HPG). The interactions between C60 and β-CD-g-HPG were investigated using a range of analytical techniques such as FTIR, NMR, UV–vis spectroscopy as well as visual techniques including SEM and AFM images. The particle size for a 1:2 (C60: β-CD-g-HPG) complex was also determined to be monodisperse ∼60nm from DLS, and it was appropriately matched with the size obtained from SEM pictures. The results show our synthesized hybrid nanomaterials will hopefully find interesting applications in biomedicine.

Removal of aqueous nC60 fullerene from water by low pressure membrane filtration

The potential environmental and health risks of engineered nanoparticles such as buckminsterfullerene C60 in water require their removal during the production of drinking water. We present a study focusing on (i) the removal mechanism and (ii) the elucidation of the role of the membrane pore size during removal of nC60 fullerene nanoparticle suspensions in dead-end microfiltration and ultrafiltration mimicking separation in real industrial water treatment plants. Membranes were selected with pore sizes ranging from 18 nm to 500 nm to determine the significance of the nC60 to membrane pore size ratio and the adsorption affinity between nC60 and membrane material during filtration. Experiments were carried out with a dead-end bench-scale system operated at constant flux conditions including a hydraulic backwash cleaning procedure. nC60 nanoparticles can be efficiently removed by low pressure membrane technology with smaller and, unexpectedly, also by mostly similar or larger pores than the particle size, although the nC60 filtration behaviour appeared to be different. The nC60 size to membrane pore size ratio and the ratio of the cake-layer deposition resistance to the clean membrane resistance, both play an important role on the nC60 filtration behaviour and on the efficiency of the backwash procedure recovering the initial membrane filtration conditions. These results become specifically significant in the context of drinking water production, for which they provide relevant information for an accurate selection between membrane processes and operational parameters for the removal of nC60 in the drinking water treatment.

Functionalized fullerenes in water: a closer look.

The excellent photophysical properties of C60 fullerenes have spurred much research on their application to aqueous systems for biological and environmental applications. Spontaneous aggregation of C60 in water and the consequent diminution of photoactivity present a significant challenge to aqueous applications. The mechanisms driving the reduction of photoactivity in fullerene aggregates and the effects of functionalization on these processes, however, are not well understood. Here, we take a closer look at the molecular phenomena of functionalized fullerene interactions in water utilizing simulation and experimental tools. Molecular dynamic simulations were performed to investigate time-evolved molecular interactions in systems containing fullerenes with water, oxygen, and/or neighboring fullerene molecules, complimented by physical and chemical characterizations of the fullerenes pre- and postaggregation. Aggregates with widely different photoactivities exhibit similar fullerene-water interactions as well as surface and aggregation characteristics. Photoactive fullerene aggregates had weaker fullerene-fullerene and fullerene-O2 interactions, suggesting the importance of molecular interactions in the sensitization route.

Interaction of C60 with Water: First-Principles Modeling and Environmental Implications

The nature of fullerene-water interactions has been the subject of much research and debate. Specifically, the presence of a stabilizing, negative surface potential on colloidal aggregates of C60 in water is unexpected, given the neutral nature of pure carbon, and is not well understood. Previous simulation efforts have focused on the C60-water interaction using molecular dynamics simulations that lacked the ability to account for charge transfer and distribution interactions. In this study, first-principles density functional theory was used to analyze the fundamental electronic interactions to elucidate the polarization and charge transfer between water and C60. Simulations show that charge is inductively transferred to the C60 from water molecules, with subsequent polarization of the C60 molecule. In a case with two neighboring C60 molecules, the charge polarization induces a charge onto the second C60. Simulation suggests that this charge transfer and polarization may contribute at least partly to the observed negative surface potential of fullerene aggregates and, combined with hydrogen bonding network formation around C60, provides a fundamental driving force for aggregate formation in water.

Stimuli‐Responsive Materials: Soft Nanotubes with a Hydrophobic Channel Hybridized with Au Nanoparticles: Photothermal Dispersion/Aggregation Control of C60 in Water (Adv. Funct. Mater. 13/2013)

Glycolipid-based soft nanotubes with a hydrophilic outer surface and hydrophobic nanochannel encapsulating C60 are reported by Naohiro Kameta and co-workers on page 1677. It is found that the photothermal effect of gold nanoparticles hybridized with the nanotube induces an unfolding of the tubular morphology and leads to compulsive release of C60 in bulk water.

Soft Nanotubes with a Hydrophobic Channel Hybridized with Au Nanoparticles: Photothermal Dispersion/Aggregation Control of C60 in Water

AbstractSimple glycolipid N‐alkaroyl‐β‐D‐glucopyranosylamine 1(n) selectively self‐assembles into sheets in water, nanotubes in alcohols, and helical nanocoils in toluene. All self‐assemblies consist of bilayer membranes in which 1(n) packed in an interdigitated fashion. The outer surface of the sheet is covered with the hydrophilic glucose headgroup of 1(n), whereas those of the nanotube and helical nanocoil are covered with the hydrophobic alkyl‐chain tail of 1(n). Heat treatment of the nanotube in the presence of water induces a rearrangement of the molecular packing of the outermost surface that allows the nanotube to become an effective nanocontainer for the dispersion of fullerene (C60) in water, a result of the ability of the hydrophilic outer surface of the nanotube and the hydrophobic nanochannel to encapsulate C60. The nanotube also exhibits photothermal characteristics after being hybridized with Au nanoparticles (AuNPs). The photothermal effect of the AuNPs allows the nanotube to unfold its tubular morphology and leads to compulsive release of the encapsulated C60 to the bulk water. Application of other nanotubes with similar photostimulated transformation ability should facilitate control of the dispersion/aggregation of other carbon nanomaterials, functional aromatic compounds, and drugs with low solubility in water.