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Burgum MJ, Clift MJD, Evans SJ, Hondow N, Miller M, Lopez SB, Williams A, Tarat A, Jenkins GJ, Doak SH. In Vitro Primary-Indirect Genotoxicity in Bronchial Epithelial Cells Promoted by Industrially Relevant Few-Layer Graphene. Small 2021; 17:e2002551. [PMID: 32734718 DOI: 10.1002/smll.202002551] [Citation(s) in RCA: 19] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/22/2020] [Revised: 06/05/2020] [Indexed: 06/11/2023]
Abstract
Few-layer graphene (FLG) has garnered much interest owing to applications in hydrogen storage and reinforced nanocomposites. Consequently, these engineered nanomaterials (ENMs) are in high demand, increasing occupational exposure. This investigation seeks to assess the inhalation hazard of industrially relevant FLG engineered with: (i) no surface functional groups (neutral), (ii) amine, and (iii) carboxyl group functionalization. A monoculture of human lung epithelial (16HBE14o- ) cells is exposed to each material for 24-h, followed by cytotoxicity and genotoxicity evaluation using relative population doubling (RPD) and the cytokinesis-blocked micronucleus (CBMN) assay, respectively. Neutral-FLG induces the greatest (two-fold) significant increase (p < 0.05) in micronuclei, whereas carboxyl-FLG does not induce significant (p < 0.05) genotoxicity. These findings correlate to significant (p < 0.05) concentration-dependent increases in interleukin (IL)-8, depletion of intracellular glutathione (rGSH) and a depletion in mitochondrial ATP production. Uptake of FLG is evaluated by transmission electron microscopy, whereby FLG particles are observed within membrane-bound vesicles in the form of large agglomerates (>1 µm diameter). The findings of the present study have demonstrated the capability of neutral-FLG and amine-FLG to induce genotoxicity in 16HBE14o- cells through primary indirect mechanisms, suggesting a possible role for carboxyl groups in scavenging radicals produced via oxidative stress.
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Affiliation(s)
- Michael J Burgum
- Institute of Life Science, Swansea University Medical School, Swansea University, Singleton Park, Swansea, Wales, SA2 8PP, UK
| | - Martin J D Clift
- Institute of Life Science, Swansea University Medical School, Swansea University, Singleton Park, Swansea, Wales, SA2 8PP, UK
| | - Stephen J Evans
- Institute of Life Science, Swansea University Medical School, Swansea University, Singleton Park, Swansea, Wales, SA2 8PP, UK
| | - Nicole Hondow
- School of Chemical and Process Engineering, University of Leeds, Leeds, LS2 9JT, UK
| | - Mark Miller
- Centre for Cardiovascular Science, The University of Edinburgh, Queens Medical Research Institute, Edinburgh, EH16 4TJ, UK
| | | | - Adam Williams
- Department of Physics, Swansea University, Singleton Park, Swansea, Wales, SA2 8PP, UK
| | - Afshin Tarat
- Perpetuus Carbon Technologies, Unit B1, Olympus Court, Millstream Way, Swansea Vale, Llansamlet, Swansea, SA70AQ, UK
| | - Gareth J Jenkins
- Institute of Life Science, Swansea University Medical School, Swansea University, Singleton Park, Swansea, Wales, SA2 8PP, UK
| | - Shareen H Doak
- Institute of Life Science, Swansea University Medical School, Swansea University, Singleton Park, Swansea, Wales, SA2 8PP, UK
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Rafique S, Badiei N, Burton MR, Gonzalez-Feijoo JE, Carnie MJ, Tarat A, Li L. Paper Thermoelectrics by a Solvent-Free Drawing Method of All Carbon-Based Materials. ACS Omega 2021; 6:5019-5026. [PMID: 33644610 PMCID: PMC7905928 DOI: 10.1021/acsomega.0c06221] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/22/2020] [Accepted: 01/29/2021] [Indexed: 06/12/2023]
Abstract
As practical interest in the flexible or wearable thermoelectric generators (TEGs) has increased, the demand for the high-performance TEGs based on ecofriendly, mechanically resilient, and economically viable TEGs as alternatives to the brittle inorganic materials is growing. Organic or hybrid thermoelectric (TE) materials have been employed in flexible TEGs; however, their fabrication is normally carried out using wet processing such as spin-coating or screen printing. These techniques require materials dissolved or dispersed in solvents; thus, they limit the substrate choice. Herein, we have rationally designed solvent-free, all carbon-based TEGs dry-drawn on a regular office paper using few-layered graphene (FLG). This technique showed very good TE parameters, yielding a power factor of 97 μW m-1 K-2 at low temperatures. The p-type only device exhibited an output power of up to ∼19.48 nW. As a proof of concept, all carbon-based p-n TEGs were created on paper with the addition of HB pencil traces. The HB pencil exhibited low Seebeck coefficients (-7 μV K-1), and the traces were highly resistive compared to FLG traces, which resulted in significantly lower output power compared to the p-type only TEG. The demonstration of all carbon-based TEGs drawn on paper highlights the potential for future low-cost, flexible, and almost instantaneously created TEGs for low-power applications.
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Affiliation(s)
- Saqib Rafique
- College
of Engineering, Swansea University, Swansea SA1 8EN, United Kingdom
| | - Nafiseh Badiei
- College
of Engineering, Swansea University, Swansea SA1 8EN, United Kingdom
| | - Matthew R. Burton
- SPECIFIC,
College of Engineering, Swansea University, Swansea SA1 8EN, United Kingdom
| | | | - Matthew J. Carnie
- SPECIFIC,
College of Engineering, Swansea University, Swansea SA1 8EN, United Kingdom
| | - Afshin Tarat
- Perpetuus
Carbon Technologies Ltd., Unit B1, Olympus Ct, Mill Stream Way, Llansamlet Swansea SA7 0AQ, United
Kingdom
| | - Lijie Li
- College
of Engineering, Swansea University, Swansea SA1 8EN, United Kingdom
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Burgum MJ, Clift MJD, Evans SJ, Hondow N, Tarat A, Jenkins GJ, Doak SH. Few-layer graphene induces both primary and secondary genotoxicity in epithelial barrier models in vitro. J Nanobiotechnology 2021; 19:24. [PMID: 33468168 PMCID: PMC7816456 DOI: 10.1186/s12951-021-00769-9] [Citation(s) in RCA: 19] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2020] [Accepted: 01/06/2021] [Indexed: 12/12/2022] Open
Abstract
BACKGROUND Toxicological evaluation of engineered nanomaterials (ENMs) is essential for occupational health and safety, particularly where bulk manufactured ENMs such as few-layer graphene (FLG) are concerned. Additionally, there is a necessity to develop advanced in vitro models when testing ENMs to provide a physiologically relevant alternative to invasive animal experimentation. The aim of this study was to determine the genotoxicity of non-functionalised (neutral), amine- and carboxyl-functionalised FLG upon both human-transformed type-I (TT1) alveolar epithelial cell monocultures, as well as co-cultures of TT1 and differentiated THP-1 monocytes (d.THP-1 (macrophages)). RESULTS In monocultures, TT1 and d.THP-1 macrophages showed a statistically significant (p < 0.05) cytotoxic response with each ENM following 24-h exposures. Monoculture genotoxicity measured by the in vitro cytokinesis blocked micronucleus (CBMN) assay revealed significant (p < 0.05) micronuclei induction at 8 µg/ml for amine- and carboxyl-FLG. Transmission electron microscopy (TEM) revealed ENMs were internalised by TT1 cells within membrane-bound vesicles. In the co-cultures, ENMs induced genotoxicity in the absence of cytotoxic effects. Co-cultures pre-exposed to 1.5 mM N-acetylcysteine (NAC), showed baseline levels of micronuclei induction, indicating that the genotoxicity observed was driven by oxidative stress. CONCLUSIONS Therefore, FLG genotoxicity when examined in monocultures, results in primary-indirect DNA damage; whereas co-cultured cells reveal secondary mechanisms of DNA damage.
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Affiliation(s)
- Michael J Burgum
- Institute of Life Science, Swansea University Medical School, Swansea University, Singleton Park, Swansea, SA2 8PP, Wales, UK
| | - Martin J D Clift
- Institute of Life Science, Swansea University Medical School, Swansea University, Singleton Park, Swansea, SA2 8PP, Wales, UK
| | - Stephen J Evans
- Institute of Life Science, Swansea University Medical School, Swansea University, Singleton Park, Swansea, SA2 8PP, Wales, UK
| | - Nicole Hondow
- School of Chemical and Process Engineering, University of Leeds, Leeds, LS2 9JT, UK
| | - Afshin Tarat
- Perpetuus Carbon Technologies, Unit B1, Olympus Court, Millstream Way, Llansamlet, Swansea Vale, SA70AQ, UK
| | - Gareth J Jenkins
- Institute of Life Science, Swansea University Medical School, Swansea University, Singleton Park, Swansea, SA2 8PP, Wales, UK
| | - Shareen H Doak
- Institute of Life Science, Swansea University Medical School, Swansea University, Singleton Park, Swansea, SA2 8PP, Wales, UK.
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Rafique S, Burton MR, Badiei N, Gonzalez-Feijoo J, Mehraban S, Carnie MJ, Tarat A, Li L. Lightweight and Bulk Organic Thermoelectric Generators Employing Novel P-Type Few-Layered Graphene Nanoflakes. ACS Appl Mater Interfaces 2020; 12:30643-30651. [PMID: 32525306 DOI: 10.1021/acsami.0c06050] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
Graphene exhibits both high electrical conductivity and large elastic modulus, which makes it an ideal material candidate for many electronic devices. At present not much work has been conducted on using graphene to construct thermoelectric devices, particularly due to its high thermal conductivity and lack of bulk fabrication. Films of graphene-based materials, however, and their nanocomposites have been shown to be promising candidates for thermoelectric energy generation. Exploring methods to enhance the thermoelectric performance of graphene and produce bulk samples can significantly widen its application in thermoelectrics. Realization of bulk organic materials in the thermoelectric community is highly desired to develop cheap, Earth-abundant, light, and nontoxic thermoelectric generators. In this context, this work reports a new approach using pressed pellets bars of few-layered graphene (FLG) nanoflakes employed in thermoelectric generators (TEGs). First, FLG nanoflakes were produced by a novel dry physical grinding technique followed by graphene nanoflake liberation using plasma treatment. The resultant material is highly pure with very low defects, possessing 3 to 5-layer stacks as proved by Raman spectroscopy, X-ray diffraction measurement, and scanning electron microscopy. The thermal and electronic properties confirm the anisotropy of the material and hence the varied performance characteristics parallel to and perpendicular to the pressing direction of the pellets. The full thermoelectric properties were characterized both parallel and perpendicular to the pressing direction, and the proof-of-concept thermoelectric generators were fabricated with variable amounts of legs.
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Affiliation(s)
- Saqib Rafique
- Multidisciplinary Nanotechnology Centre, College of Engineering, Swansea University, Swansea SA1 8EN, United Kingdom
| | - Matthew R Burton
- SPECIFIC, College of Engineering, Swansea University, Swansea SA1 8EN, United Kingdom
| | - Nafiseh Badiei
- Multidisciplinary Nanotechnology Centre, College of Engineering, Swansea University, Swansea SA1 8EN, United Kingdom
| | - Jorge Gonzalez-Feijoo
- Multidisciplinary Nanotechnology Centre, College of Engineering, Swansea University, Swansea SA1 8EN, United Kingdom
| | - Shahin Mehraban
- Materials Advanced Characterization Centre, Future Manufacturing Research Institute, College of Engineering Fabian Way, Crymlyn Burrows, Skewen, Swansea SA1 8EN United Kingdom
| | - Matthew J Carnie
- SPECIFIC, College of Engineering, Swansea University, Swansea SA1 8EN, United Kingdom
| | - Afshin Tarat
- Perpetuus Carbon Technologies Ltd., Unit B1, Olympus Ct, Mill Stream Way, Llansamlet, Swansea SA7 0AQ, United Kingdom
| | - Lijie Li
- Multidisciplinary Nanotechnology Centre, College of Engineering, Swansea University, Swansea SA1 8EN, United Kingdom
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Hernandez-Aldave S, Tarat A, McGettrick JD, Bertoncello P. Voltammetric Detection of Caffeine in Beverages at Nafion/Graphite Nanoplatelets Layer-by-Layer Films. Nanomaterials (Basel) 2019; 9:E221. [PMID: 30736450 PMCID: PMC6410159 DOI: 10.3390/nano9020221] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/29/2018] [Revised: 01/31/2019] [Accepted: 02/01/2019] [Indexed: 12/19/2022]
Abstract
We report for the first time a procedure in which Nafion/Graphite nanoplatelets (GNPs) thin films are fabricated using a modified layer-by-layer (LbL) method. The method consists of dipping a substrate (quartz and/or glassy carbon electrodes) into a composite solution made of Nafion and GNPs dissolved together in ethanol, followed by washing steps in water. This procedure allowed the fabrication of multilayer films of (Nafion/GNPs)n by means of hydrogen bonding and hydrophobic‒hydrophobic interactions between Nafion, GNPs, and the corresponding solid substrate. The average thickness of each layer evaluated using profilometer corresponds to ca. 50 nm. The as-prepared Nafion/GNPs LbL films were characterized using various spectroscopic techniques such as X-ray photoelectron spectroscopy (XPS), energy-dispersive X-ray spectroscopy (EDS), FTIR, and optical microscopy. This characterization highlights the presence of oxygen functionalities that support a mechanism of self-assembly via hydrogen bonding interactions, along with hydrophobic interactions between the carbon groups of GNPs and the Teflon-like (carbon‒fluorine backbone) of Nafion. We showed that Nafion/GNPs LbL films can be deposited onto glassy carbon electrodes and utilized for the voltammetric detection of caffeine in beverages. The results showed that Nafion/GNPs LbL films can achieve a limit of detection for caffeine (LoD) of 0.032 μM and linear range between 20‒250 μM using differential pulse voltammetry, whereas, using cyclic voltammetry LoD and linear range were found to be 24 μM and 50‒5000 μM, respectively. Voltammetric detection of caffeine in beverages showed good agreement between the values found experimentally and those reported by the beverage producers. The values found are also in agreement with those obtained using a standard spectrophotometric method. The proposed method is appealing because it allows the fabrication of Nafion/GNPs thin films in a simple fashion using a single-step procedure, rather than using composite solutions with opposite electrostatic charge, and also allows the detection of caffeine in beverages without any pre-treatment or dilution of the real samples. The proposed method is characterized by a fast response time without apparent interference, and the results were competitive with those obtained with other materials reported in the literature.
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Affiliation(s)
- Sandra Hernandez-Aldave
- Systems and Process Engineering Centre, College of Engineering, Swansea University, Bay Campus, Crwmlyn Burrows, Swansea SA1 8EN, UK.
| | - Afshin Tarat
- Perpetuus Advanced Materials, Unit B1, Olympus Court, Millstream Way, Swansea Vale, Llansamlet, SA7 0AQ, UK.
| | - James D McGettrick
- SPECIFIC, College of Engineering, Swansea University, Bay Campus, Swansea SA1 8EN, UK.
| | - Paolo Bertoncello
- Systems and Process Engineering Centre, College of Engineering, Swansea University, Bay Campus, Crwmlyn Burrows, Swansea SA1 8EN, UK.
- Centre for NanoHealth, Swansea University, Singleton Campus, Swansea SA2 8PP, UK.
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Tarat A, Nettle CJ, Bryant DTJ, Jones DR, Penny MW, Brown RA, Majitha R, Meissner KE, Maffeis TGG. Microwave-assisted synthesis of layered basic zinc acetate nanosheets and their thermal decomposition into nanocrystalline ZnO. Nanoscale Res Lett 2014; 9:11. [PMID: 24397935 PMCID: PMC3895776 DOI: 10.1186/1556-276x-9-11] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 08/14/2013] [Accepted: 12/22/2013] [Indexed: 06/03/2023]
Abstract
We have developed a low-cost technique using a conventional microwave oven to grow layered basic zinc acetate (LBZA) nanosheets (NSs) from a zinc acetate, zinc nitrate and HMTA solution in only 2 min. The as-grown crystals and their pyrolytic decomposition into ZnO nanocrystalline NSs are characterized by scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS), atomic force microscopy (AFM), X-ray diffraction (XRD) and photoluminescence (PL). SEM and AFM measurements show that the LBZA NSs have typical lateral dimensions of 1 to 5 μm and thickness of 20 to 100 nm. Annealing in air from 200°C to 1,000°C results in the formation of ZnO nanocrystalline NSs, with a nanocrystallite size ranging from 16 nm at 200°C to 104 nm at 1,000°C, as determined by SEM. SEM shows evidence of sintering at 600°C. PL shows that the shape of the visible band is greatly affected by the annealing temperature and that the exciton band to defect band intensity ratio is maximum at 400°C and decreases by a factor of 15 after annealing at 600°C. The shape and thickness of the ZnO nanocrystalline NSs are the same as LBZA NSs. This structure provides a high surface-to-volume ratio of interconnected nanoparticles that is favorable for applications requiring high specific area and low resistivity such as gas sensing and dye-sensitized solar cells (DSCs). We show that resistive gas sensors fabricated with the ZnO NSs showed a response of 1.12 and 1.65 to 12.5 ppm and 200 ppm of CO at 350°C in dry air, respectively, and that DSCs also fabricated from the material had an overall efficiency of 1.3%. PACS: 81.07.-b; 62.23.Kn; 61.82.Fk.
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Affiliation(s)
- Afshin Tarat
- Multidisciplinary Nanotechnology Centre, College of Engineering, University of Swansea, Singleton Park, Swansea SA28PP, UK
| | - Chris J Nettle
- Multidisciplinary Nanotechnology Centre, College of Engineering, University of Swansea, Singleton Park, Swansea SA28PP, UK
| | - Daniel T J Bryant
- SPECIFIC, College of Engineering, University of Swansea, Baglan, Swansea SA2 8PP, UK
| | - Daniel R Jones
- Multidisciplinary Nanotechnology Centre, College of Engineering, University of Swansea, Singleton Park, Swansea SA28PP, UK
| | - Mark W Penny
- Multidisciplinary Nanotechnology Centre, College of Engineering, University of Swansea, Singleton Park, Swansea SA28PP, UK
| | - Richard A Brown
- Multidisciplinary Nanotechnology Centre, College of Engineering, University of Swansea, Singleton Park, Swansea SA28PP, UK
| | - Ravish Majitha
- Department of Materials Science and Engineering, Texas A&M University, College Station, TX 77843, USA
| | - Kenith E Meissner
- Department of Biomedical Engineering, Texas A&M University, Emerging Technology Building, College Station, TX 77843-312, USA
| | - Thierry G G Maffeis
- Multidisciplinary Nanotechnology Centre, College of Engineering, University of Swansea, Singleton Park, Swansea SA28PP, UK
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