Poly(vinyl chloride)/Nanocarbon Composites for Advanced Potentiometric Membrane Sensor Design.

Polymer nanocomposites filled with carbon nanoparticles (CNPs) are a hot topic in materials science. This article discusses the current research on the use of these materials as interfacial electron transfer films for solid contact potentiometric membrane sensors (SC-PMSs). The results of a comparative study of plasticized poly (vinyl chloride) (pPVC) matrices modified with single-walled carbon nanotubes (SWCNTs), fullerenes-C60, and their hybrid ensemble (SWCNTs-C60) are reported. The morphological characteristics and electrical conductivity of the prepared nanostructured composite films are reported. It was found that the specific electrical conductivity of the pPVC/SWCNTs-C60 polymer film was higher than that of pPVC filled with individual nanocomponents. The effectiveness of this composite material as an electron transfer film in a new potentiometric membrane sensor for detecting phenylpyruvic acid (in anionic form) was demonstrated. Screening for this metabolic product of phenylalanine in body fluids is of significant diagnostic interest in phenylketonuria (dementia), viral hepatitis, and alcoholism. The developed sensor showed a stable and fast Nernstian response for phenylpyruvate ions in aqueous solutions over the wide linear concentration range of 5 × 10-7-1 × 10-3 M, with a detection limit of 10-7.2 M.

The Triumph of the Spin Chemistry of Fullerene C60 in the Light of Its Free Radical Copolymerization with Vinyl Monomers.

The spin theory of fullerenes is taken as a basis concept to virtually exhibit a peculiar role of C60 fullerene in the free radical polymerization of vinyl monomers. Virtual reaction solutions are filled with the initial ingredients (monomers, free radicals, and C60 fullerene) as well as with the final products of a set of elementary reactions, which occurred in the course of the polymerization. The above objects, converted to the rank of digital twins, are considered simultaneously under the same conditions and at the same level of the theory. In terms of the polymerization passports of the reaction solutions, a complete virtual picture of the processes considered is presented.

Chalcogen-Bond-Assisted Formation of the N→C Dative Bonds in the Complexes between Chalcogenadiazoles/Chalcogenatriazoles and Fullerene C60.

The existence of the N→C dative bonds in the complexes between N-containing molecules and fullerenes have been verified both theoretically and experimentally. However, finding stable N→C dative bonds is still a highly challenging task. In this work, we investigated computationally the N→C dative bonds in the complexes formed by fullerene C60 with 1,2,5-chalcogenadiazoles, 2,1,3-benzochalcogenadiazoles, and 1,2,4,5-chalcogenatriazoles, respectively. It was found that the N→C dative bonds are formed along with the formation of the N-Ch···C (Ch = S, Se, Te) chalcogen bonds. In the gas phase, from S-containing complexes through Se-containing complexes to Te-containing complexes, the intrinsic interaction energies become more and more negative, which indicates that the N-Ch···C chalcogen bonds can facilitate the formation of the N→C dative bonds. The intrinsic interaction energies are compensated by the large deformation energy of fullerene C60. The total interaction energies of Te-containing complexes are negative, while both total interaction energies of the S-containing complexes and Se-containing complexes are positive. This means that the N→C dative bonds in the Te-containing complexes are more easily observed in experiments in comparison with those in the S-containing complexes and Se-containing complexes. This study provides a new theoretical perspective on the experimental observation of the N→C dative bonds in complexes involving fullerenes. Further, the formation of stable N→C dative bonds in the complexes involving fullerenes can significantly change the properties of fullerenes, which will greatly simulate and expand the application range of fullerenes.

Ultrathin Two-Dimensional Porous Fullerene Membranes for Ultimate Organic Solvent Separation.

Two-dimensional (2D) materials with high chemical stability have attracted intensive interest in membrane design for the separation of organic solvents. As a novel 2D material, polymeric fullerenes (C60)∞ with distinctive properties are very promising for the development of innovative membranes. In this work, we report the construction of a 2D (C60)∞ nanosheet membrane for organic solvent separation. The pathways of the (C60)∞ nanosheet membrane are constructed by sub-1-nm lateral channels and nanoscale in-plane pores created by the depolymerization of the (C60)∞ nanosheets. Attributing to ordered and shortened transport pathways, the ultrathin porous (C60)∞ membrane is superior in organic solvent separation. The hexane, acetone, and methanol fluxes are up to 1146.3±53, 900.4±41, and 879.5±42 kg ⋅ m-2 ⋅ h-1, respectively, which are up to 130 times higher than those of the state-of-the-art membranes with similar dye rejection. Our findings demonstrate the prospect of 2D (C60)∞ as a promising nanofiltration membrane in the separation of organic solvents from macromolecular compounds such as dyes, drugs, hormones, etc.

Wound healing activity of aqueous dispersion of fullerene C60 produced by "green technology".

In addition to exhibited antioxidant and anti-inflammatory activity, fullerene C60 is a promising wound healing agent. An important stage in the production of fullerene-based ointments is the stability of the aqueous fullerene dispersion (AFD) with minimum size of colloidal fullerene aggregates and sufficiently high concentration. To achieve these parameters tangential flow filtration of fullerene C60 was used ("green technology"). As estimated by small-angle neutron scattering and dynamic light scattering purified AFDs with narrow-size distribution nanoclusters have a size of 6 nm and are assembled into agglomerates which reach a size of 150 nm. The ability of the AFD to exhibit regenerative activity was studied using the animal wound model. This study shows for the first time that the fullerene-based composition stimulates the healing of wounds of various origins. We assume that the mechanism of the AFD wound-healing activity is associated with the aryl hydrocarbon receptor and macrophages activity.

Composition-selective full inclusion host-guest interaction of azobenzene-containing photoresponsive nanoring with fullerene C60.

By means of density functional theory calculations, the encapsulation capabilities of a series of azobenzen-containing photoresponsive nanoring hosts (labeled as host 1, 2, 3, 4, 5 and 6 according to the number of the azo unit, respectively) for fullerene C60 were surveyed. Interestingly and abnormally, it is found that the host 5, of which the diameter is only 1.218 nm, can form stable full inclusion complex with C60 . However, irrespective of their cavity sizes (11.98 ~ 12.94 Å) of the hosts, the structures 1 ~ 4 and 6 were all disable to form inclusion complex with C60 . In this paper, the group-number-composition-selective full inclusion host-guest interaction of the azobenzene-containing nanorings with fullerene C60 is firstly presented. The calculated interaction energies, together with the detection and visualization of the weak interaction regions, provided evidences for the host-guest binding based on relative strong repulsion interaction in the full inclusion complex. Analysis on the frontier orbital feature of the host-guest systems suggests that under the electron excited condition, the chemical activity may be transferred from host 5 to guest C60 by formation of the floating host-guest complex, and the chemical reactivity of the host 5 can be passivated via formation of the full inclusion host-guest complex. Additionally, UV-vis-NIR and 1 H NMR spectra of the hosts before and after the formations of the complexes have been simulated and discussed qualitatively, which may be helpful for further experimental investigations in future.

BOPHY-Fullerene C60 Dyad as a Photosensitizer for Antimicrobial Photodynamic Therapy.

A novel BOPHY-fullerene C60 dyad (BP-C60 ) was designed as a heavy-atom-free photosensitizer (PS) with potential uses in photodynamic treatment and reactive oxygen species (ROS)-mediated applications. BP-C60 consists of a BOPHY fluorophore covalently attached to a C60 moiety through a pyrrolidine ring. The BOPHY core works as a visible-light-harvesting antenna, while the fullerene C60 subunit elicits the photodynamic action. This fluorophore-fullerene cycloadduct, obtained by a straightforward synthetic route, was fully characterized and compared with its individual counterparts. The restricted rotation around the single bond connecting the BOPHY and pyrrolidine moieties led to the formation of two atropisomers. Spectroscopic, electrochemical, and computational studies disclose an efficient photoinduced energy/electron transfer process from BOPHY to fullerene C60 . Photodynamic studies indicate that BP-C60 produces ROS by both photomechanisms (type I and type II). Moreover, the dyad exhibits higher ROS production efficiency than its individual constitutional components. Preliminary screening of photodynamic inactivation on bacteria models (Staphylococcus aureus and Escherichia coli) demonstrated the ability of this dyad to be used as a heavy-atom-free PS. To the best of our knowledge, this is the first time that not only a BOPHY-fullerene C60 dyad is reported, but also that a BOPHY derivative is applied to photoinactivate microorganisms. This study lays the foundations for the development of new BOPHY-based PSs with plausible applications in the medical field.

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.

C60-encapsulated TiO2nanoparticles for selective and ultrahigh sensitive detection of formaldehyde.

The current study concerns development of fullerene-C60-encapsulated TiO2nanoparticles hybrid for an efficient detection of volatile organic compounds (VOCs). The nanocomposite was synthesized via chemical route by using hydrated fullerene-C60and sol-gel derived undopedp-type TiO2nanoparticles. The nanocomposite was characterized morphologically and structurally comparing with pure C60clusters and pure TiO2nanoparticles as the reference materials. The average diameter of the C60-encapsulated TiO2nanoparticles was 150 nm whereas the average diameters of C60clusters and pure TiO2nanoparticles were 161 nm and 18 nm respectively. Therefore, all the materials were implemented in interdigitated electrode based planner structured sensors and tested towards multiple VOCs. However, C60-TiO2composite exhibited its natural selectivity towards formaldehyde with a very high sensitivity for the concentration range of 1-1000 ppm. C60-encapsulated TiO2nanoparticles depicted more than double response magnitude (117%) than the pure TiO2nanoparticle (48%) and pure C60particles (40%) and appreciably fast response/recovery (12 s/331 s) towards 100 ppm of formaldehyde at 150 °C. However, the efficient VOC sensing was achieved in C60-encapsulated TiO2sensors possibly due to the extreme reactive surface provided by the oxygen functionalized C60and easy electronic exchange between ambient and the TiO2nanoparticles through C60layers. The combined properties of both C60and TiO2lead to the formation of a promising nanocomposite which provided better sensing characteristics than that of the pure materials.

Fused-Pentagon Isomers of C60 Fullerene Isolated as Chloro and Trifluoromethyl Derivatives.

The carbon cage of buckminsterfullerene Ih -C60 , which obeys the Isolated-Pentagon Rule (IPR), can be transformed to non-IPR cages in the course of high-temperature chlorination of C60 or C60 Cl30 with SbCl5 . The non-IPR chloro derivatives were isolated chromatographically (HPLC) and characterized crystallographically as 1809 C60 Cl16 , 1810 C60 Cl24 , and 1805 C60 Cl24 , which contain, respectively two, four, and four pairs of fused pentagons in the carbon cage. High-temperature trifluoromethylation of the chlorination products with CF3 I afforded a non-IPR CF3 derivative, 1807 C60 (CF3 )12 , which contains four pairs of fused pentagons in the carbon cage. Addition patterns of non-IPR chloro and CF3 derivatives were compared and discussed in terms of the formation of stabilizing local substructures on fullerene cages. A detailed scheme of the experimentally confirmed non-IPR C60 isomers obtained by Stone-Wales cage transformations is presented.

Microcavity Enhanced Raman Spectroscopy of Fullerene C60 Bucky Balls.

Raman spectroscopy is a widely used characterization technique in material science. It is a non-destructive tool with relatively simple instrumentation, and provides intrinsic qualitative information of analytes by probing their vibrational modes. In many cases, Raman enhancement is essential for detecting low-intensity signals in high-noise environments, spectrally unresolved features, and hidden modes. Here we present optical and Raman spectroscopic characterization of fullerene C 60 in a gold microcavity. The fabrication of single-layered gold mirrors is facile, low cost and direct but was proven to give considerably significant enhancement. The findings of this work demonstrate the cavity resonance as a powerful tool in obtaining tunability over individual peak for selective enhancement in the tuned spectral range. The PL of the material within the cavity has demonstrated a red shift assumed to be caused by the low-energy transitions. These transitions are induced by virtual low-energy states generated by the cavity. We further observe that adopting this principle enables resolution of active Raman modes that until now were unobserved. Finally, we assigned the new experimentally observed modes to the corresponding motions calculated by DFT.

Disposition of fullerene C60 in rats following intratracheal or intravenous administration.

Fullerene C60 is used in a variety of industrial and consumer capacities. As part of a comprehensive evaluation of the toxicity of fullerene C60 by the National Toxicology Program, the disposition following intratracheal (IT) instillation and intravenous (IV) administration of 1 or 5 mg/kg b.wt. fullerene C60 was investigated in male Fischer 344 rats. Following IT instillation, fullerene C60 was detected in the lung as early as 0.5 h post-exposure with minimal clearance over the 168 h period; the concentration increased ≥20-fold with a 5-fold increase in the dose. Fullerene C60 was not detected in extrapulmonary tissues. Following IV administration, fullerene C60 was rapidly eliminated from the blood and was undetectable after 0.5 h post-administration. The highest tissue concentrations of fullerene C60 occurred in the liver, followed by the spleen, lung and kidney. Fullerene C60 was cleared slowly from the kidney and the lung with estimated half-lives of 24 and 139 h, respectively. The liver concentration of fullerene C60 did not change much with time; over 90% of the fullerene C60 remained there over the study duration up to 168 h. Fullerene C60 was also not detected in urine or feces. These data support the hypothesis that fullerene C60 accumulates in the body and therefore has the potential to induce detrimental health effects following exposure.

Unmodified hydrated С60 fullerene molecules exhibit antioxidant properties, prevent damage to DNA and proteins induced by reactive oxygen species and protect mice against injuries caused by radiation-induced oxidative stress.

Unmodified hydrated С60 fullerene molecules (C60UHFM) were shown to reduce the formation ROS in water and 8-oxoguanine in DNA upon ionizing radiation impact. C60UHFM efficiently eliminate long-lived protein radicals arising after irradiation. In irradiated mice C60UHFM reduce the rate of single/double-strand DNA breaks and amount of chromosomal breaks. The radioprotective activity of C60UHFM was estimated by the survival rate of animals; the dose modification factor for animal survival was 1.3. Hematological tests showed that C60UHFM injection in mice prior to irradiation results in a decrement of irradiation-induced leucopenia and thrombocytopenia. Histological analysis testified that C60UHFM provide significant protection of small intestine tissues in mice against irradiation-induced damage. The obtained data assume that the radioprotective properties of C60UHFM are determined by their antioxidant, antiradical and DNA-protective qualities. Thus, it was demonstrated that C60UHFM are a novel antioxidant and radioprotective agent capable of substantial reduction of the harmful effects of ionizing radiation.

Fullerene C60 with cytoprotective and cytotoxic potential: prospects as a novel treatment agent in Dermatology?

It is known that an excess amount of (oxygen) radicals in the skin can lead to (local cellular) oxidative stress. From one side, oxidative stress can contribute to the existence of various (inflammatory) skin diseases such as acne vulgaris and alopecia, as well as to accelerated photo-ageing of the skin. From the other side, oxidative stress could also be a wanted process for curing particular skin diseases, such as skin cancer and microbial skin infections. Therefore, novel treatment agents with the ability to scavenge or generate radicals can potentially be meaningful in the treatment of various skin diseases, especially for those diseases that have limited effective treatment options. This viewpoint essay will discuss the potential of fullerene C60 , i.e. buckminsterfullerene, derivatives as novel treatment agents in dermatology. Fullerene C60 is an all carbon molecule with a unique dual ability; fullerene C60 can act as a radical scavenger or as an oxygen radical generator. Hence, fullerene C60 derivatives offers most interesting prospects as a therapeutic protective or therapeutic toxic agent. Because of their extraordinary physicochemical properties and numerous chemical functionalization possibilities, chemists can design derivatives with a wide scope of unique properties. The experimental data, mostly from in vitro and in vivo animal studies, on the safety and therapeutic potential of fullerene C60 derivatives, in the field of dermatology will be discussed.

Theoretical prediction of the host-guest interactions between novel photoresponsive nanorings and C60: a strategy for facile encapsulation and release of fullerene.

A series of photoresponsive-group-containing nanorings hosts with 12∼14 Šin diameter is designed by introducing different number of azo groups as the structural composition units. And the host-guest interactions between fullerene C60 and those nanoring hosts were investigated theoretically at M06-2X/6-31G(d)//M06-L/MIDI! and wB97X-D/6-31G(d) levels. Analysis on geometrical characteristics and host-guest binding energies revealed that the designed nanoring molecule (labeled as 7) which is composed by seven azo groups and seven phenyls is the most feasible host for encapsulation of C60 guest among all candidates. Moreover, inferring from the simulated UV-vis-NIR spectroscopy, the C60 guest could be facilely released from the cavity of the host 7 via configuration transformation between trans-form and cis-form of the host under the 563 nm photoirradiation. Additionally, the frontier orbital features, weak interaction regions, infrared, and NMR spectra of the C60@7 host-guest complex have also been investigated theoretically.

Clicked BODIPY-Fullerene-Peptide Assemblies: Studies of Electron Transfer Processes in Self-Assembled Monolayers on Gold Surfaces.

Two BODIPY-C60-peptide assemblies were synthesized by CuAAC reactions of BODIPY-C60 dyads and a helical peptide functionalized with a terminal alkyne group and an azide group, respectively. The helical peptide within these assemblies was functionalized at its other end by a disulfide group, allowing formation of self-assembled monolayers (SAMs) on gold surfaces. Characterizations of these SAMs, as well as those of reference molecules (BODIPY-C60-alkyl, C60-peptide and BODIPY-peptide), were carried out by PM-IRRAS and cyclic voltammetry. BODIPY-C60-peptide SAMs are more densely packed than BODIPY-C60-alkyl and BODIPY-peptide based SAMs. These findings were attributed to the rigid peptide helical conformation along with peptide-peptide and C60-C60 interactions within the monolayers. However, less dense monolayers were obtained with the target assemblies compared to the C60-peptide, as the BODIPY entity likely disrupts organization within the monolayers. Finally, electron transfer kinetics measurements by ultra-fast electrochemistry experiments demonstrated that the helical peptide is a better electron mediator in comparison to alkyl chains. This property was exploited along with those of the BODIPY-C60 dyads in a photo-current generation experiment by converting the resulting excited and/or charge separated states from photo-illumination of the dyad into electrical energy.

Simultaneous determination of 4-ethylphenol and 4-ethylguaicol on C60 modified dual screen-printed electrochemical sensors.

4-ethylphenol and 4-ethylguaicol levels in wine are associated to organoleptic defects that cause consumer rejection accompanied by significant economic losses for producers. Thus, electrochemical sensors based on screen-printed carbon electrodes (SPCEs) modified with activated fullerene C60 (AC60) have been developed for the analysis of both phenols by direct headspace amperometric measurements. Upon optimization of the experimental variables affecting the sensors performance, the AC60/SPCE sensors presented linearity ranges from 9.9 to 65.4 µg/L and from 19.6 to 107.1 µg/L for 4-ethylphenol and 4-ethylguaicol, respectively. The achieved detection capacities were 10.3 µg/L (4-ethylphenol) and 19.6 µg/L (4-ethylguaicol), with a reproducibility of 6.3 % and 9.1 % (n = 3), respectively. In addition, dual-working AC60/SPCE devices were developed for the simultaneous analysis of both phenols using different working potentials for each electrode. The dual systems were successfully applied in the analysis of different spiked wine samples, obtaining good recoveries ranging from 94 to 108 %.

Hydrophilization and Functionalization of Fullerene C60 with Maleic Acid Copolymers by Forming a Non-Covalent Complex.

In this study, we report an easy approach for the production of aqueous dispersions of C60 fullerene with good stability. Maleic acid copolymers, poly(styrene-alt-maleic acid) (SM), poly(N-vinyl-2-pyrrolidone-alt-maleic acid) (VM) and poly(ethylene-alt-maleic acid) (EM) were used to stabilize C60 fullerene molecules in an aqueous environment by forming non-covalent complexes. Polymer conjugates were prepared by mixing a solution of fullerene in N-methylpyrrolidone (NMP) with an aqueous solution of the copolymer, followed by exhaustive dialysis against water. The molar ratios of maleic acid residues in the copolymer and C60 were 5/1 for SM and VM and 10/1 for EM. The volume ratio of NMP and water used was 1:1.2-1.6. Water-soluble complexes (composites) dried lyophilically retained solubility in NMP and water but were practically insoluble in non-polar solvents. The optical and physical properties of the preparations were characterized by UV-Vis spectroscopy, FTIR, DLS, TGA and XPS. The average diameter of the composites in water was 120-200 nm, and the ξ-potential ranged from -16 to -20 mV. The bactericidal properties of the obtained nanostructures were studied. Toxic reagents and time-consuming procedures were not used in the preparation of water-soluble C60 nanocomposites stabilized by the proposed copolymers.

Comparative Studies of the Structural and Physicochemical Properties of the First Fullerene Derivative FD-C60 (Fullerenol) and Second Fullerene Derivate SD-C60 (3HFWC).

In order to maximally reduce the toxicity of fullerenol (the first derivative of C60, FD-C60), and increase its biomedical efficiency, the second derivative SD-C60 (3HFWC, Hyper-Harmonized Hydroxylated Fullerene Water Complex) was created. Several different methods were applied in the comparative characterization of FD-C60 and SD-C60 with the same OH groups in their core. FD-C60 as an individual structure was about 1.3 nm in size, while SD-C60 as an individual structure was 10-30 nm in size. Based on ten physicochemical methods and techniques, FD-C60 and SD-C60 were found to be two different substances in terms of size, structure, and physicochemical properties; FD-C60, at 100 °C, had endothermic characteristics, while SD-C60, at 133 °C, had exothermic characteristics; FD-C60 did not have water layers, while SD-C60 had water layers; the zeta potential of FD-C60 was -25.85 mV, while it was -43.29 mV for SD-C60. SD-C60 is a promising substance for use in cosmetics and pharmaceuticals.

Antibacterial and Antibiofouling Activities of Carbon Polymerized Dots/Polyurethane and C60/Polyurethane Composite Films.

The cost of treatment of antibiotic-resistant pathogens is on the level of tens of billions of dollars at the moment. It is of special interest to reduce or solve this problem using antimicrobial coatings, especially in hospitals or other healthcare facilities. The bacteria can transfer from medical staff or contaminated surfaces to patients. In this paper, we focused our attention on the antibacterial and antibiofouling activities of two types of photodynamic polyurethane composite films doped with carbon polymerized dots (CPDs) and fullerene C60. Detailed atomic force, electrostatic force and viscoelastic microscopy revealed topology, nanoelectrical and nanomechanical properties of used fillers and composites. A relationship between the electronic structure of the nanocarbon fillers and the antibacterial and antibiofouling activities of the composites was established. Thorough spectroscopic analysis of reactive oxygen species (ROS) generation was conducted for both composite films, and it was found that both of them were potent antibacterial agents against nosocomial bacteria (Klebsiela pneumoniae, Proteus mirabilis, Salmonela enterica, Enterococcus faecalis, Enterococcus epidermis and Pseudomonas aeruginosa). Antibiofouling testing of composite films indicated that the CPDs/PU composite films eradicated almost completely the biofilms of Pseudomonas aeruginosa and Staphylococcus aureus and about 50% of Escherichia coli biofilms.