Fullerol-sensitized production of reactive oxygen species in aqueous solution

Selective penetration of fullerenol through pea seed coats mitigates osmosis-repressed germination via chromatin remodeling and transcriptional reprograming

BACKGROUND

The alteration of chromatin accessibility plays an important role in plant responses to abiotic stress. Carbon-based nanomaterials (CBNMs) have attracted increasing interest in agriculture due to their potential impact on crop productivity, showcasing effects on plant biological processes at transcriptional levels; however, their impact on chromatin accessibility remains unknown.

RESULTS

This study found that fullerenol can penetrate the seed coat of pea to mitigate the reduction of seed germination caused by osmotic stress. RNA sequencing (RNA-seq) revealed that the application of fullerenol caused the high expression of genes related to oxidoreduction to return to a normal level. Assay for transposase accessible chromatin sequencing (ATAC-seq) confirmed that fullerenol application reduced the overall levels of chromatin accessibility of numerous genes, including those related to environmental signaling, transcriptional regulation, and metabolism.

CONCLUSION

This study suggests that fullerenol alleviates osmotic stress on various fronts, encompassing antioxidant, transcriptional, and epigenetic levels. This advances knowledge of the working mechanism of this nanomaterial within plant cells. © 2024 Society of Chemical Industry.

Versatile applications of fullerenol nanoparticles

Nanomaterials have become increasingly important over time as research technology has enabled the progressively precise study of materials at the nanoscale. Developing an understanding of how nanomaterials are produced and tuned allows scientists to utilise their unique properties for a variety of applications, many of which are already incorporated into commercial products. Fullerenol nanoparticles C60(OH)n, 2 ≤ n ≤ 44 are fullerene derivatives and are produced synthetically. They have good biocompatibility, low toxicity and no immunological reactivity. In addition, their nanometre size, large surface area to volume ratio, ability to penetrate cell membranes, adaptable surface that can be easily modified with different functional groups, drug release, high physical stability in biological media, ability to remove free radicals, magnetic and optical properties make them desirable candidates for various applications. This review comprehensively summarises the various applications of fullerenol nanoparticles in different scientific fields such as nanobiomedicine, including antibacterial and antiviral agents, and provides an overview of their use in agriculture and biosensor technology. Recommendations are also made for future research that would further elucidate the mechanisms of fullerenols actions.

Rational design of an acceptor-chromophore-relay-catalyst tetrad assembly for water oxidation

We report the step-by-step synthesis of a precious metal-free acceptor-chromophore-relay-catalyst tetrad assembly that exhibits a turnover frequency (TOF) of 7.5 × 10-3 s-1 under neutral conditions. Transient absorption spectroscopic studies indicate that upon fullerenol incorporation into the investigated complexes, charge separation efficiency increases considerably.

The debatable role of singlet oxygen in persulfate-based advanced oxidation processes

Singlet oxygen (¹O₂) attracts much attention in persulfate-based advanced oxidation processes (PS-AOPs), because of its wide pH tolerance and high selectivity toward electron-rich organics. However, there are conflicts about the ¹O₂ role in PS-AOPs on several aspects, including the formation of different key reactive oxygen species (ROS) at similar active sites, pH dependence, broad-spectrum activity, and selectivity in the elimination of organic pollutants. To a large degree, these conflicts root in the drawbacks of the methods to identify and evaluate the role of ¹O₂. For example, the quenchers of ¹O₂ have high reactivity to other ROS and persulfate as well. In addition, electron transfer process (ETP) also selectively oxidizes organics, having a misleading effect on the identification of ¹O₂. Therefore, in this review, we summarized and discussed some basic properties of ¹O₂, the debatable role of ¹O₂ in PS-AOPs on multiple aspects, and the methods and their drawbacks to identify and evaluate the role of ¹O₂. On the whole, this review aims to better understand the role of ¹O₂ in PS-AOPs and further help with its reasonable utilization.

Melanoma Cell Reprogramming and Awakening of Antitumor Immunity as a Fingerprint of Hyper-Harmonized Hydroxylated Fullerene Water Complex (3HFWC) and Hyperpolarized Light Application In Vivo

In our recent study, we showed that in vitro treatment of melanoma cells with hyperpolarized light (HPL) as well as with the second derivative of fullerene, hyper-harmonized hydroxylated fullerene water complex (3HFWC) reduced viability of cells by decreasing their proliferative capacity and inducing senescence and reprogramming towards a normal, melanocytic phenotype. Therefore, we wanted to determine whether these effects persisted in vivo in the syngeneic mouse melanoma model with a combined treatment of HPL irradiation and 3HFWC per os. Our results demonstrated the potent antitumor effects of 3HFWC nanosubstance assisted by HPL irradiation. These effects were primarily driven by the stimulation of melanoma cell growth arrest, the establishment of a senescent phenotype, and melanocytic differentiation on the one hand, and the awakening of the antitumor immune response on the other. In addition, the combined treatment reduced the protumorigenic activity of immune cells by depleting T regulatory cells, myeloid-derived suppressors, and M2 macrophages. The support of the 3HFWC substance by HPL irradiation may be the axis of the new approach design based on tumor cell reprogramming synchronized with the mobilization of the host's protective immune response.

Self-Assembly in water of C60 fullerene into isotropic nanoparticles or nanoplatelets mediated by a cationic amphiphilic polymer

HYPOTHESIS

To disperse high concentration of C₆₀ fullerene in water, we propose to use an emulsification-evaporation process in the presence of an amphiphilic polymer whose chemical structure has been chosen for inducing specific interaction with fullerene The viscosity enhancement provided by self-assembly of the amphiphilic polymers in water should result in high stability of the suspensions. The organic solvent has also to been chosen so as to maximize the initial fullerene concentration.

EXPERIMENTS

The concentrations of polymer and fullerene, the solvent type and the volume fraction of the organic phase have been varied. Their influence on the concentration of the fullerene dispersions and on the size and shape of the resulting nanoparticles have been investigated by UV-Visible spectroscopy, light scattering and cryo-transmission electron microscopy experiments.

FINDINGS

The resulting nanoparticles consist of aggregates of C₆₀ fullerene stabilized by the cationic polymer with morphologies/sizes tunable through fullerene and polymer concentration. At high fullerene concentration, nanoplatelets are obtained that consist in thin 2D nanocrystals. Their suspensions are very stable with time due to the viscosity of the dispersing aqueous medium. The concentration of fullerene nanoparticles dispersed in water is as high as 8 g/L which corresponds to an upper limit that has never been reached so far.

Surface Activity and Aggregation Behavior of Polyhydroxylated Fullerenes in Aqueous Solutions

Polyhydroxylated fullerene (PHF) surface activity and aggregation behavior at the air-water interface were examined using surface tension and resonance-enhanced second harmonic generation (SHG). Surface tension data showed that PHFs are surface active with a limiting surface excess corresponding to 130 Ų/molecule in aqueous (Millipore water) solutions. Increasing the solution-phase ionic strength (through the addition of NaCl) reduces the PHF surface excess. Conductivity measurements show that PHFs carry a single charge, presumably negative. Surface-specific SHG experiments show a small but measurable fixed wavelength, nonlinear response from solutions having surface excess coverages as low as ∼400 Ų/molecule. The SHG response of PHF solutions in the low-concentration limit shows unexpected behavior, implying that at bulk concentrations below 0.06 mg/mL, PHF monomers adsorb to the surface and interfere destructively with the intrinsic nonlinear susceptibility of the aqueous/vapor interface, leading to a ∼75% reduction in the SH signal. Above a PHF concentration of 0.0.06 mg/mL, the SH signal begins to rise in the Millipore and 50 mM NaCl solutions but remains very low in the 500 mM NaCl solutions. From this behavior, we infer that an increased nonlinear optical response is due to adsorbed aggregates.

Application of Fullerenes as Photosensitizers for Antimicrobial Photodynamic Inactivation: A Review

Antimicrobial photodynamic inactivation (aPDI) is a newly emerged treatment approach that can effectively address the issue of multidrug resistance resulting from the overuse of antibiotics. Fullerenes can be used as promising photosensitizers (PSs) for aPDI due to the advantages of high triplet state yields, good photostability, wide antibacterial spectrum, and permissibility of versatile functionalization. This review introduces the photodynamic activities of fullerenes and the up-to-date understanding of the antibacterial mechanisms of fullerene-based aPDI. The most recent works on the functionalization of fullerenes and the application of fullerene derivatives as PSs for aPDI are also summarized. Finally, certain remaining challenges are emphasized to provide guidance on future research directions for achieving clinical application of fullerene-based aPDI.

Combined Action of Hyper-Harmonized Hydroxylated Fullerene Water Complex and Hyperpolarized Light Leads to Melanoma Cell Reprogramming In Vitro

(1) Background: Their unique structure and electron deficiency have brought fullerenes into the focus of research in many fields, including medicine. The hyper-harmonized hydroxylated fullerene water complex (3HFWC) formulation has solved the limitations of the poor solubility and bioavailability of fullerenes. To achieve better antitumor activity, 3HFWC was combined with short-term irradiation of cells with hyperpolarized light (HPL) generated by the application of a nanophotonic fullerene filter in a Bioptron^® device. The benefits of HPL were confirmed in the microcirculation, wound healing and immunological function. (2) Methods: B16, B16-F10 and A375 melanoma cells were exposed to a wide spectrum of 3HFWC doses and to a single short-term HPL irradiation. (3) Results: Apart from the differences in the redox status and level of invasiveness, the effects of the treatments were quite similar. Decreased viability, morphological alteration, signs of melanocytic differentiation and cellular senescence were observed upon the successful internalization of the nanoquantum substance. (4) Conclusions: Overall, 3HFWC/HPL promoted melanoma cell reprogramming toward a normal phenotype.

Graphene oxide mediated Fe(III) reduction for enhancing Fe(III)/H2O2 Fenton and photo-Fenton oxidation toward chloramphenicol degradation

Slow reduction of Fe(III) in iron-mediated Fenton-like systems strongly limits the decomposition of H₂O₂ to produce hydroxyl radicals (^•OH). Here, we report that graphene oxide (GO) possesses excellent reactivity to enhance the Fe(III)/H₂O₂ Fenton and photo-Fenton oxidation for degrading chloramphenicol (CAP). EPR analysis and quenching tests reveal that ^•OH is the primary oxidant for CAP degradation. The characterization analysis and iron species transformation experiments demonstrate that Fe(III) can combine with the functional groups on the GO surface to form GO-Fe(III) complexes. The chronopotentiometry and cyclic voltammogram suggest that GO can donate electrons to Fe(III) via intramolecular electron transfer and promote H₂O₂ induced Fe(III) reduction by increasing the oxidation capability of Fe(III) due to the formation of GO-Fe(III) complexes, resulting in the strong promotion of the Fe(III)/Fe(II) cycle for producing OH. Moreover, the dark- and vis-GO/Fe(III)/H₂O₂ systems can effectively degrade CAP at initial pH ranging from 2.0 to 4.7. The reusability and stability of GO were evaluated by performing the cyclic degradation experiments of CAP. The OH induced degradation pathway of CAP was proposed involving three stages, based on intermediates analysis of UPLC-QTOF-MS/MS system. Therefore, the GO/Fe(III)/H₂O₂ system with or without visible light shows high potential for application in environmental remediation.

Effects of Metallic and Carbon-Based Nanomaterials on Human Pancreatic Cancer Cell Lines AsPC-1 and BxPC-3

Pancreatic cancer, due to its asymptomatic development and drug-resistance, is difficult to cure. As many metallic and carbon-based nanomaterials have shown anticancer properties, we decided to investigate their potential use as anticancer agents against human pancreatic adenocarcinoma. The objective of the study was to evaluate the toxic properties of the following nanomaterials: silver (Ag), gold (Au), platinum (Pt), graphene oxide (GO), diamond (ND), and fullerenol (C₆₀(OH)₄₀) against the cell lines BxPC-3, AsPC-1, HFFF-2, and HS-5. The potential cytotoxic properties were evaluated by the assessment of the cell morphology, cell viability, and cell membrane damage. The cancer cell responses to GO and ND were analysed by determination of changes in the levels of 40 different pro-inflammatory proteins. Our studies revealed that the highest cytotoxicity was obtained after the ND treatment. Moreover, BxPC-3 cells were more sensitive to ND than AsPC-1 cells due to the ND-induced ROS production. Furthermore, in both of the cancer cell lines, ND caused an increased level of IL-8 and a decreased level of TIMP-2, whereas GO caused only decreased levels of TIMP-2 and ICAM-1 proteins. This work provides important data on the toxicity of various nanoparticles against pancreatic adenocarcinoma cell lines.

Anti-inflammatory and antioxidant effects of the nanocomposite Fullerol decrease the severity of intestinal inflammation induced by gut ischemia and reperfusion

Intestinal ischemia is a vascular emergency that arises when blood flow to the intestine is compromised. Reperfusion is necessary to restore intestinal function but might lead to local and systemic inflammatory responses and bacterial translocation, with consequent multiple organ dysfunction syndrome (MODS). During reperfusion occurs production of reactive oxygen species. These species contribute to intestinal injury through direct toxicity or activation of inflammatory pathways. Fullerol is a nanacomposite which has been shown to act as reactive oxygen species and reactive nitrogen species (RNS) scavengers. Thus, our aim was to evaluate whether Fullerol confer anti-inflammatory activity during intestinal ischemia and reperfusion (IIR). Intestinal ischemia was induced by total occlusion of the superior mesenteric artery. Groups were treated with vehicle or Fullerol 10 min before reperfusion. Mice were euthanized after 6 h of reperfusion, and small intestines were collected for evaluation of plasma extravasation, leukocyte influx, cytokine production and histological damage. Bacterial translocation to the peritoneal cavity and reactive oxygen and nitrogen species production by lamina propria cells were also evaluated. Our results showed that treatment with Fullerol inhibited bacterial translocation to the peritoneal cavity, delayed and decreased the lethality rates and diminished neutrophil influx and intestinal injury induced by IIR. Reduced severity of reperfusion injury in Fullerol-treated mice was associated with blunted reactive oxygen and nitrogen species production in leukocytes isolated from gut lamina propria and decreased production of pro-inflammatory mediators. Thus, the present study shows that Fullerol is a potential therapy to treat inflammatory bowel disorders associated with bacterial translocation, such as IIR.

Hand-ground fullerene-nanodiamond composite for photosensitized water treatment and photodynamic cancer therapy

The unique capability of fullerene (C₆₀) to absorb light and generate reactive oxygen species (ROS) has been extensively studied for photosensitized water treatment and cancer therapy. Various material synthesis strategies have been proposed in parallel to overcome its intrinsic hydrophobicity and to enhance availability in water and physiological media. We present here a strikingly simple approach to make C₆₀ available to these applications by hand-grinding dry C₆₀ powder with nanodiamond (ND) using a mortar and pestle. The resulting ND-C₆₀ composite was found to form a stable aqueous colloidal suspension and efficiently drive photosensitized production of ROS under visible light illumination. ND-C₆₀ rapidly adsorbed and oxidized organic contaminants by photogenerated ROS. In the experiments for photodynamic cancer therapy, ND-C₆₀ was internalized by cancer cells and induced cell apoptosis without noticeable toxicity. Treatment of tumor-bearing mice with ND-C₆₀ and light irradiation resulted in tumor shrinkage and prolonged survival time.

Assessment on landfill liners as the barrier against C60 nanoparticles

Owing to the increasing usage of nanomaterials, it is imperative to assess their potential impacts on natural systems, and in particular, investigate if existing barriers can prevent nanomaterial emission in landfills because they will be disposed in landfills at the end of their useful lives. This study inspected the behavior of colloidal fullerene (nC₆₀) in and around landfill liner materials. Sorption isotherm experiments using either natural soil or high density polyethylene geomembrane as sorbents showed that nC₆₀ was readily removed by sorption to soil and precipitation, while there was no sorption to geomembrane. To investigate transport through soil, nC₆₀ was injected into columns of compacted soil layers with a thickness of 3.3-4.2 cm and hydraulic conductivity <1 × 10^-7 cm/s. The nanoparticles rarely passed through the layers owing to self-aggregation and/or screening by the soil layer. When they were detected in the effluent, breakthrough curves of an extraordinary shape were produced, which is presumably attributed to surface modification of collectors by deposited nC₆₀. However, simulation using the obtained mass transport parameters showed that it is unlikely that nC₆₀ from disposed C₆₀-containing products would overcome compacted clay liners; therefore, its migration to the ambient environment would be negligible.

Recent Progress on Fullerene-Based Materials: Synthesis, Properties, Modifications, and Photocatalytic Applications

Solar light is an inexpensive energy source making up for energy shortage and solving serious environmental problems. For efficient utilization of solar energy, photocatalytic materials have attracted extensive attention over the last decades. As zero-dimensional carbon nanomaterials, fullerenes (C60, C70, etc.) have been extensively investigated for photocatalytic applications. Due to their unique properties, fullerenes can be used with other semiconductors as photocatalyst enhancers, and also as novel photocatalysts after being dispersed on non-semiconductors. This review summarizes fullerene-based materials (including fullerene/semiconductors and fullerene/non-semiconductors) for photocatalytic applications, such as water splitting, Cr (Ⅵ) reduction, pollutant degradation and bacterial disinfection. Firstly, the optical and electronic properties of fullerene are presented. Then, recent advances in the synthesis and photocatalytic mechanisms of fullerene-based photocatalysts are summarized. Furthermore, the effective performances of fullerene-based photocatalysts are discussed, mainly concerning photocatalytic H2 generation and pollutant removal. Finally, the current challenges and prospects of fullerene-based photocatalysts are proposed. It is expected that this review could bring a better understanding of fullerene-based photocatalysts for water treatment and environmental protection.

Effect of fullerenol nanoparticles on oxidative stress induced by paraquat in honey bees

The enormous progress in nanomaterials development and their use, followed by their inevitable environmental print, has arisen the emerging questions concerning their influence to the living systems. Honey bees are considered to be quite a suitable model system for the risk assessment and prediction of various external influences. To the best of our knowledge, this is the first study dealing with the influence of fullerenol nanoparticles (FNP), a biodegradable carbon nanomaterials' representative, to honey bees. This investigation was conducted with an aim to merge two different open-ended questions: the potential toxic effect of FNP to the bees on the one hand and antioxidative effect of FNP on the other hand. Since FNP antioxidative properties were proved in a number of in vivo models, we hypothesized the similar outcomes, and according to this assumption, we opted for paraquat as a well-known oxidative stress inducer. FNP did not have toxic effect in none of investigated concentrations. The results also confirmed the potential of FNP to reduce oxidative stress through the gene expression of antioxidative enzymes and the change in the redox state of the cells. Additional experiments are needed for a better understanding of the exact mechanism and complex patterns of FNP's activity.

Quantum yields of singlet oxygen of tetrakis (4-carboxyphenyl) porphyrin in different solvents

The singlet oxygen quantum yields of photosensitizers in different solvents are very important for photodynamic therapy (PDT). Here, we investigated the singlet oxygen quantum yields of tetrakis (4-carboxyphenyl) porphyrin (TCPP) in various solvents by the iodide method. Results indicate that TCPP has different singlet oxygen formation efficiency in different solvents. When compared to TCPP dissolved in water, TCPP showed higher singlet oxygen yields in methanol and ethanol, but lower singlet oxygen yields in DMF under identical conditions. In particular, TCPP rapidly precipitated in acetone after potassium iodide added in the solution. The salting out effect of TCPP by potassium iodide in acetone was confirmed by re-dissolving the precipitation in water and the characteristic absorption of TCPP was measured. The phenomenon of salting out for TCPP in acetone suggests that acetone is not a good solvent for singlet oxygen generation when evaluated by the iodide method.

Engineered nanomaterials: From their properties and applications, to their toxicity towards marine bivalves in a changing environment

As a consequence of their unique characteristics, the use of Engineered Nanomaterials (ENMs) is rapidly increasing in industrial, agricultural products, as well as in environmental technology. However, this fast expansion and use make likely their release into the environment with particular concerns for the aquatic ecosystems, which tend to be the ultimate sink for this type of contaminants. Considering the settling behaviour of particulates, benthic organisms are more likely to be exposed to these compounds. In this way, the present review aims to summarise the most recent data available from the literature on ENMs behaviour and fate in aquatic ecosystems, focusing on their ecotoxicological impacts towards marine and estuarine bivalves. The selection of ENMs presented here was based on the OECD's Working Party on Manufactured Nanomaterials (WPMN), which involves the safety testing and risk assessment of ENMs. Physical-chemical characteristics and properties, applications, environmental relevant concentrations and behaviour in aquatic environment, as well as their toxic impacts towards marine bivalves are discussed. Moreover, it is also identified the impacts derived from the simultaneous exposure of marine organisms to ENMs and climate changes as an ecologically relevant scenario.

Molecular Semiconductor Surfactants with Fullerenol Heads and Colored Tails for Carbon Dioxide Photoconversion

The leaf is a prime example of a material converting waste (CO2 ) into value with maximum sustainability. As the most important constituent, it contains the coupled photosystems II and I, which are imbedded in the cellular membrane of the chloroplasts. Can key functions of the leaf be packed into soap? We present next-generation surfactants that self-assemble into bilayer vesicles (similar to the cellular membrane), are able to absorb photons of two different visible wavelengths, and exchange excited charge carriers (similar to the photosystems), followed by conversion of CO2 (in analogy to the leaf). The amphiphiles contain five dye molecules as the hydrophobic entity attached exclusively to one hemisphere of a polyhydroxylated fullerene (Janus-type). We herein report on their surfactant, optical, electronic, and catalytic properties. Photons absorbed by the dyes are transferred to the fullerenol head, where they can react with different species such as CO2 to give formic acid.

A simple sensing of hazardous photo-induced superoxide anion radicals using a molecular probe in ZnO-Nanoparticles aqueous medium

The generation of reactive oxygen species (ROS) during the photolysis of sunscreens and sun blockers poses consumer safety concerns while necessitating proper identification and quantitation of ROS species. Here, a colorimetric sensing approach has been developed based on a molecular probe (2,3-bis-(2-methoxy-4-nitro-5-sulfophenyl)-2-H-tetrazolium-5-carboxanilide (XTT) tetrazolium salt) to quantitatively measure the photo-induced superoxide anion radicals (O₂^.) generated from the photocatalysis of zinc oxide nanoparticles (ZnO-NPs) in aqueous solutions. Note that superoxide anion radicals are assumed to be the main reactive oxygen species (ROS) generated from such photocatalysis. The characterisation of ZnO-NPs before and after irradiation showed average particle sizes of 616.5 and 295.3 nm and ζ-potential values of 0 and -24.4 mV, respectively. It is hoped that this proposed protocol can be further developed to efficiently detect other ROS present in inorganic sun blockers and to optimize the utility of various sunscreen formulations.

Environmental fate and risk of ultraviolet- and visible-light-transformed graphene oxide: A comparative study

Currently, there is little comparative data on the colloidal stability and the toxicity of ultraviolet (UV)- and visible-light (VL)-transformed graphene oxide (GO). In order to identify this knowledge gap, the physicochemical properties of UV/VL-transformed GO are investigated in detail. Attempts are made to correlate the physicochemical alterations of UV/VL-transformed GO to the observed changes in its colloidal properties and toxicity. The results show that both UV and VL irradiations induce the significant change in the color, UV-vis absorbance, morphology, surface charge, size, oxygen containing functional groups, total of carbon, and photoluminescence properties of GO. The photo-reaction behavior of GO under UV exposure is different from that under VL irradiation in terms of reaction rate, order, and extent. Finally, the UV and VL irradiations show different effects not only on the colloidal stability of GO in the City water and Dongpu Lake water, but also on the toxicity of GO to Gram-negative Escherichia coli and Gram-positive Staphylococcus aureus bacteria. This study clearly shows how the environmental fate and risk of GO are modified by UV and VL irradiations.

Effects of oxidation degree on photo-transformation and the resulting toxicity of graphene oxide in aqueous environment

Graphene oxide (GO) has been demonstrated to be key component for diverse applications. However, their potential environmental reactivity, fate and risk have not been fully evaluated to date. In this study, we investigated the photochemical reactivity of four types of GO with different oxidation degrees in aqueous environment, and their related toxicity to two bacterial models Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus) was further compared. After UV-irradiation, a large amount of oxygen functional groups on GO were reduced and the electronic conjugations within GO were restored as indicated by UV-visible absorption spectra, X-ray photoelectron spectroscopy and Raman spectroscopy analysis. Moreover, the higher the oxidation degree of the pristine GO was, the more obvious of the photo-transformation changes were. In order to further reveal the photochemical reactivity mechanisms, the reactive oxygen species (ROS) generation of GO was monitored. The quantity of ROS including singlet oxygen (¹O₂), superoxide anions (O₂^·-), and hydroxyl radicals (·OH) increased with increasing oxidation degree of GO, which was in accordance with the previous characterization results. Scanning electron microscopy and cell growth analyses of E. coli and S. aureus showed that the photochemical transformation enhanced the toxicity of GO, which might be due to an increase in functional group density. The higher conductivity of the reduced graphene oxide (RGO) was responsible for its stronger toxicity than GO through membrane damage and oxidative stress to bacteria. This study revealed that the oxidation degrees play important roles in photochemical transformation and the resulting toxicity of GO, which is helpful for understanding the environmental behaviors and risks of GO in aquatic environments.

Fullerene C60 nanomaterial induced oxidative imbalance in gonads of the freshwater fish, Anabas testudineus (Bloch, 1792)

The engineered carbon nanomaterial, fullerene C₆₀, with unique physicochemical properties, released into the aquatic environment is known to formulate high risk factor for the aquatic life. The present study was aimed to investigate fullerene C₆₀ induced oxidative imbalance in ovary and testis of the freshwater fish, Anabas testudineus. The median lethal concentration (96 h-LC₅₀) of fullerene C₆₀ in Anabas testudineus was 50 mg/ L, and fish exposed to two sublethal concentrations i.e., 5 mg/ L and 10 mg/ L (one-tenth and one-fifth of LC₅₀) for short-term (24, 48, 72 and 96 h) and long-term (7, 15, 30 and 60 d) durations. The antioxidant parameters such as the activities of superoxide dismutase (SOD), catalase, glutathione reductase, glutathione peroxidase, the levels of hydrogen peroxide generation and lipid peroxidation were analyzed along with histopathological alterations in gonadal tissues. Both sublethal concentrations of fullerene C₆₀ caused significant (P < 0.05) decrease in the activities of antioxidant enzymes, whereas the levels of hydrogen peroxide generation and lipid peroxidation increased significantly (P < 0.05) in gonads. Fullerene exposure significantly (P < 0.05) increased the mucous deposition with significant (P < 0.05) reduction in the weights of gonads and gonado-somatic index. The histopathological analysis showed prominent alterations in testis and ovary of treated fishes when compared to the control groups. After 60 d of sublethal exposure of fullerene C₆₀, fish were left in the toxicant-free water for another 60 d, in which the changes in the activities of the gonadal antioxidant enzymes and histological alterations were not completely recovered. Hence, from the present study, it was illustrated that fullerene C₆₀ caused oxidative imbalance in the gonads, which may possibly affect the reproductive potential of the fish, Anabas testudineus.

Evaluation of the Effects of Carbon 60 Nanoparticle Exposure to Adult Zebrafish: A Behavioral and Biochemical Approach to Elucidate the Mechanism of Toxicity

There is a growing concern for the potential toxicity of engineered nanomaterials that have made their way into virtually all novel applications in the electronics, healthcare, cosmetics, technology, and engineering industries, and in particular, biomedical products. However, the potential toxicity of carbon 60 (C₆₀) at the behavioral level has not been properly evaluated. In this study, we used idTracker, a multitracking algorithm to quantitatively assess behavioral toxicity induced by C₆₀ nanoparticles (C₆₀ NPs) in adult zebrafish. We demonstrated that locomotion, novel tank exploration, aggression, shoaling, and color preference activities of the C₆₀ NPs-treated fish was significantly reduced. In addition, the C₆₀ NPs-treated fish also displayed dysregulation of the circadian rhythm by showing lower locomotion activities in both day and night cycles. The biochemical results showed that C₆₀ NPs exposure at low concentration induced oxidative stress and DNA damage, reduced anti-oxidative capacity and ATP (adenosine triphosphate) levels, and induced stress-associated hormones, hypoxia, as well as inflammation marker upregulation in muscle and gill tissues. Together, this work, for the first time, provide direct evidence showing that the chronic exposure of C₆₀ NPs induced multiple behavioral abnormalities in adult zebrafish. Our findings suggest that the ecotoxicity of C₆₀ NPs towards aquatic vertebrates should be carefully evaluated.

Fullerene-modified magnetic silver phosphate (Ag3PO4/Fe3O4/C60) nanocomposites: hydrothermal synthesis, characterization and study of photocatalytic, catalytic and antibacterial activities

In this work, fullerene-modified magnetic silver phosphate (Ag₃PO₄/Fe₃O₄/C₆₀) nanocomposites with efficient visible light photocatalytic and catalytic activity were fabricated by a simple hydrothermal approach. The composition and structure of the obtained new magnetically recyclable ternary nanocomposites were completely characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), Raman spectroscopy, Brunauer–Emmett–Teller (BET) specific surface area analysis, vibrating sample magnetometery (VSM), diffuse reflectance spectroscopy (DRS), field emission scanning electron microscopy (FE-SEM), energy dispersive X-ray (EDX) spectroscopy and transmission electron microscopy (TEM). This novel magnetically recyclable heterogeneous fullerene-modified catalyst was tested for the H₂O₂-assisted photocatalytic degradation of MB dye under visible light. The results show that about 95% of the MB (25 mg L⁻¹, 50 ml) was degraded by the Ag₃PO₄/Fe₃O₄/C₆₀ nanocomposite within 5 h under visible light irradiation. The catalytic performance of the Ag₃PO₄/Fe₃O₄/C₆₀ nanocomposite was then examined for 4-nitrophenol (4-NP) reduction using NaBH₄. This new nanocomposite showed that 4-NP was reduced to 4-aminophenol (4-AP) in 98% yield with an aqueous solution of NaBH₄. In both photocatalytic and catalytic reactions, the Ag₃PO₄/Fe₃O₄/C₆₀ nanocomposite exhibited higher catalytic activity than pure Ag₃PO₄. Moreover, the Ag₃PO₄/Fe₃O₄/C₆₀ nanocomposite could be magnetically separated from the reaction mixture and reused without any change in structure. The antibacterial activity of the nanocomposites was also investigated and they showed good antibacterial activity against a few human pathogenic bacteria.

Fullerene-modified magnetic silver phosphate (Ag₃PO₄/Fe₃O₄/C₆₀) nanocomposites prepared by a hydrothermal route were used as photocatalysts/catalysts for the efficient degradation and reduction of MB dye and 4-nitrophenol, respectively.

The protective roles of TiO2 nanoparticles against UV-B toxicity in Daphnia magna

Aquatic environments are increasingly under environmental stress due to ultraviolet (UV) radiation and potential inputs of nanoparticles with intense application of nanotechnology. In this study, we investigated the interaction between UV-B radiation and titanium nanoparticles (TiO₂-NPs) in a model freshwater cladoceran Daphnia magna. UV-B toxicity to Daphnia magna was examined when the daphnids were exposed to a range of TiO₂-NPs concentrations with an initial 5 or 10min of 200μW/cm² UV-B radiation. In addition, UV-B toxicity was also examined in the presence of TiO₂-NPs in the body of daphnids. Our results demonstrated that the daphnid mortality under UV-B radiation decreased significantly in the presence of TiO₂-NPs both in the water and in the body, indicating that TiO₂-NPs had some protective effects on D. magna against UV-B. Such protective effect was mainly caused by the blockage of UV-B by TiO₂-NPs adsorption. UV-B produced reactive oxygen species (ROS) in the water and in the daphnids, which was not sufficient to cause mortality of daphnids over short periods of radiation. Previous studies focused on the effects of TiO₂-NPs on the toxicity of total UV radiation, and did not attempt to differentiate the potential diverse roles of UV-A and UV-B. Our study indicated that TiO₂-NPs may conversely protect the UV-B toxicity to daphnids.

Fullerol C60(OH)24 nanoparticles and mycotoxigenic fungi: a preliminary investigation into modulation of mycotoxin production

Increased use of fullerols in various fields and expected increase of their environmental spread impose the necessity for testing fullerol nanoparticles (FNP) effects on microbiota. There is little information available on the interaction of mycotoxigenic fungi and FNP, despite FNP having a great potential of modifying mycotoxin production. Namely, FNP exhibit both ROS-quenching and ROS-producing properties, while oxidative stress stimulates mycotoxin synthesis in the fungi. In order to shed some light on the extent of interaction between FNP and mycotoxigenic fungi, the effects of fullerol C₆₀(OH)₂₄ nanoparticles (10, 100, 1000 ng/mL) on mycelial growth, aflatoxin production and oxidative stress modulation in an aflatoxigenic strain of Aspergillus flavus (NRRL 3251) during 168 h of incubation in a liquid culture medium were examined. FNP slightly reduced mycelial biomass weight, but significantly decreased aflatoxin concentration in media. Lipid peroxide content, superoxide dismutase, catalase and glutathione peroxidase activities suggest that FNP treatments hormetically reduced oxidative stress within fungal cells in turn suppressing aflatoxin production. These findings contribute to the assessment of environmental risk and application potential of fullerols.

Influence of Nanotoxicity on Human Health and Environment: The Alternative Strategies

Currently, nanotechnology revolutionizing both scientific and industrial community due to their applications in the fields of medicine, environmental protection, energy, and space exploration. Despite of the evident benefits of nanoparticles, there are still open questions about the influence of these nanoparticles on human health and environment. This is one of the critical issues that have to be addressed in the near future, before massive production of nanomaterials. Manufactured nanoparticles, which are finding ever-increasing applications in industry and consumer products fall into the category of emerging contaminants with ecological and toxicological effects on populations, communities and ecosystems. The existing experimental knowledge gave evidence that inhaled nanoparticles are less efficiently separated than larger particles by the macrophage clearance mechanisms and these nanoparticles are known to translocate through the lymphatic, circulatory and nervous systems to many tissues and organs, including the brain. In this review we highlight adverse impacts of nanoparticles on human and the environment with special emphasis on green nanoscience as a sustainable alternative.

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.

Photochemical reactivity of aqueous fullerene clusters: C60 versus C70

Over the past few years, there has been a strong interest in exploring the potential impact of fullerenes in the environment. Despite that both C₆₀ and C₇₀ have been detected in environmental matrices, the research on the impact of higher fullerenes, such as C_70, has been largely missing. This study evaluated and compared the phototransformation of aqueous C₆₀ and C₇₀ clusters (nC₆₀ and nC₇₀) and their ¹O₂ production under sunlight and lamp light irradiation (315nm, 360nm and 420nm). The nC₆₀ and nC₇₀ samples formed by direct mixing with water adopted a face-centered cubic (FCC) crystal structure. The apparent quantum yields (AQYs) of fullerene phototransformed were relatively constant over the examined wavelengths, while ¹O₂ production AQYs decreased with increased wavelengths. The long-term fate studies with outdoor sunlight indicated that both nC₆₀ and nC₇₀ lost considerable organic carbon contents (>80%) in water after ∼8 months of irradiation and that the intermediate photoproducts of nC₆₀ and nC₇₀ exhibited a progressively increased level of oxygen-containing functionalities. Overall, the study indicates that nC₇₀ can be photochemically removed under sunlight conditions and that the photoreactivity of nC₆₀ based on AQYs is greater than that of nC₇₀.

Diverse gatekeepers for mesoporous silica nanoparticle based drug delivery systems

Progress on the design of diverse gatekeepers for mesoporous silica nanoparticle based drug delivery systems is summarized.

Different effects of sonication pretreatment on carbon nanomaterials under low hydrogen peroxide concentrations

Dispersing carbon nanomaterials with the aid of sonication has become a widely used procedure for generating homogenous solutions. A systematic study was performed to evaluate the effects of a practical sample preparation procedure that involves mild sonication with/without low concentrations of hydrogen peroxide. Hydrogen peroxide is ubiquitously present in surface water and involved in advanced oxidation processes. Significant oxidation was observed for fullerene in the liquid phase, whereas an appreciable amount of hydrogen was covalently attached to the carbon cage of solid fullerene. Under the same conditions, only the removal of oxidized amorphous carbon was detected for carbon nanotubes. The presence of a low concentration of hydrogen peroxide during sonication exacerbated the effects. The changes in physicochemical properties were characterized quantitatively using X-ray photoelectron spectroscopy and elemental chemical analysis and qualitatively using matrix-assisted laser desorption ionization mass spectroscopy, ¹H nuclear magnetic resonance spectroscopy, Fourier transform infrared spectroscopy and Raman spectroscopy. Our results highlight the effects that can occur during sample preparation step and the potential for misinterpreting the toxicity, reactivity and environmental fate of carbon nanomaterials.

Visible Light Sensitized Production of Hydroxyl Radicals Using Fullerol as an Electron-Transfer Mediator

Fullerenes and their derivatives are known to photosensitize the production of singlet oxygen (¹O₂), but their role in generating hydroxyl radical (^•OH) under visible light has not been reported. Here, we demonstrate that fullerol can mediate the electron transfer from Rhodamine B dye to O₂ under visible light irradiation, achieving simultaneous dye decolorization and ^•OH-induced degradation of 4-chlorophenol. The hydroxyl radical is proposed to be produced via a consecutive reduction of molecular oxygen by fullerol anion radical, which is formed through the electron transfer from the dye to the triplet state of fullerol. Mechanistic investigations using various probe reagents such as superoxide dismutase (superoxide quencher), t-butanol (^•OH quencher), and coumarin (^•OH probe) provided indirect evidence for the generation of ^•OH under visible light. Furthermore, spin trapping technique directly detected the oxidizing species such as ^•OH, HO₂^•, and ¹O₂ in the visible light irradiated solution of RhB/fullerol mixture. It was proposed that the photochemical oxidation mechanism depends on pH: ^•OH production is favored at acidic pH through fullerol-mediated sequential electron transfer while ¹O₂ is generated as a main oxidant at neutral and alkaline condition through the energy-transfer process. Therefore, the photochemical oxidation can be switchable between ^•OH-driven and ¹O₂-driven mechanism by a simple pH adjustment.

Photocatalytic reduction of triclosan on Au-Cu2O nanowire arrays as plasmonic photocatalysts under visible light irradiation

Triclosan (TCS) is a potential threat to the environment and human health. Photocatalysis can be used to degrade TCS, but the photocatalytic efficiency is usually limited by the photoabsorptivity and photostability of the photocatalyst. In addition, some toxic by-products might also be generated during photocatalytic processes. In this study, we prepared Au-coated Cu2O nanowire arrays (Au-Cu2O NWAs) by beam sputtering Au onto Cu2O nanowires grown from a Cu foil. We found that photocatalytic degradation of TCS under visible light (420 nm < λ < 780 nm) irradiation and Au-Cu2O NWAs had several advantages. Au-Cu2O NWAs had good photoabsorptivity, high photostability (negligible activity loss after 16 runs), excellent photocatalytic activity (47.6 times faster than that of Cu2O), and low yield of dichlorodibenzo-dioxins/dichlorohydroxydibenzofurans. The degradation intermediates were identified as chlorophenoxyphenol, phenoxyphenol, chlorophenol, catechol, phenol, benzoquinone, and lower volatile acids. We developed the degradation pathway of TCS which follows electron reduction and then oxidation by reactive oxygen species. The mechanism was developed and strengthened using the radical trapping and other measurements. The unusual mechanism and photostability of Au-Cu2O NWAs were attributed to the Au/Cu2O/Cu "sandwich"-like structure. This structure yields a sustained and steady internal electric field, raises the conduction band of Cu2O, reinforces the reductive activity of the photo-generated electrons, and eliminates the photo-generated holes that are responsible for the photo-etching of Cu2O.

Fullerene modification of Ag3PO4 for the visible-light-driven degradation of acid red 18

Modification of Ag₃PO₄, by incorporation of fullerene, could improve the photocatalytic performance and structural stability of Ag₃PO₄.

Hydroxylated fullerene-capped, vinblastine-loaded folic acid-functionalized mesoporous silica nanoparticles for targeted anticancer therapy

Fullerenol and anticancer drug loaded pores of folic acid-functionalized mesoporous silica nanoparticles are showcased for targeted anticancer treatment.

Probing Photosensitization by Functionalized Carbon Nanotubes

Carbon nanotubes (CNTs) photosensitize the production of reactive oxygen species that may damage organisms by biomembrane oxidation or mediate environmental transformations of CNTs. Photosensitization by derivatized carbon nanotubes from various synthetic methods, and thus with different intrinsic characteristics (e.g., diameter and electronic properties), has been investigated under environmentally relevant aquatic conditions. We used the CNT-sensitized photoisomerization of sorbic acid ((2E,4E)-hexa-2,4-dienoic acid) and singlet oxygen formation to quantify the triplet states ((3)CNT*) formed upon irradiation of selected single-walled carbon nanotubes (SWCNTs) and multiwalled carbon nanotubes (MWCNTs). The CNTs used in our studies were derivatized by carboxyl groups to facilitate their dispersion in water. Results indicate that high-defect-density (thus well-stabilized), small-diameter, and semiconducting-rich CNTs have higher-measured excited triplet state formation and therefore singlet oxygen ((1)O2) yield. Derivatized SWCNTs were significantly more photoreactive than derivatized MWCNTs. Moreover, addition of sodium chloride resulted in increased aggregation and small increases in (1)O2 production of CNTs. The most photoreactive CNTs exhibited comparable photoreactivity (in terms of (3)CNT* formation and (1)O2 yield) to reference natural organic matter (NOM) under sunlight irradiation with the same mass-based concentration. Selected reference NOM could therefore be useful in evaluating environmental photoreactivity or intended antibacterial applications of CNTs.

In vivo 808 nm image-guided photodynamic therapy based on an upconversion theranostic nanoplatform

A new strategy for efficient in vivo image-guided photodynamic therapy (PDT) has been demonstrated utilizing a ligand-exchange constructed upconversion-C60 nanophotosensitizer. This theranostic platform is superior to the currently reported nanophotosensitizers in (i) directly bonding photosensitizer C60 to the surface of upconversion nanoparticles (UCNPs) by a smart ligand-exchange strategy, which greatly shortened the energy transfer distance and enhanced the (1)O2 production, resulting in the improvement of the therapeutic effect; (ii) realizing in vivo NIR 808 nm image-guided PDT with both excitation (980 nm) and emission (808 nm) light falling in the biological window of tissues, which minimized auto-fluorescence, reduced light scatting and improved the imaging contrast and depth, and thus guaranteed noninvasive diagnostic accuracy. In vivo and ex vivo tests demonstrated its favorable bio-distribution, tumor-selectivity and high therapeutic efficacy. Owing to the effective ligand exchange strategy and the excellent intrinsic photophysical properties of C60, (1)O2 production yield was improved, suggesting that a low 980 nm irradiation dosage (351 J cm(-2)) and a short treatment time (15 min) were sufficient to perform NIR (980 nm) to NIR (808 nm) image-guided PDT. Our work enriches the understanding of UCNP-based PDT nanophotosensitizers and highlights their potential use in future NIR image-guided noninvasive deep cancer therapy.