C | An Open Access Journal from MDPI

3 pages, 198 KiB

Open AccessEditorial

by Carolina Belver and Jorge Bedia

C 2024, 10(4), 102; https://doi.org/10.3390/c10040102 - 4 Dec 2024

Polluted streams, both in their gas and liquid phases, constitute a potential menace to the environment and to living organisms [...] Full article

(This article belongs to the Special Issue Adsorption on Carbon-Based Materials)

5 pages, 227 KiB

Open AccessEditorial

by Olena Okhay and Gil Goncalves

C 2024, 10(4), 101; https://doi.org/10.3390/c10040101 - 3 Dec 2024

Abstract

In recent years, mankind’s energy needs have been increasing; therefore, current research is focused on the collection and storage of energy [...] Full article

(This article belongs to the Special Issue Carbon and Related Composites for Sensors and Energy Storage: Synthesis, Properties, and Application)

20 pages, 5317 KiB

Open AccessArticle

Cocoa Pod Husk Carbon Family for Biogas Upgrading: Preliminary Assessment Using the Approximate Adsorption Performance Indicator

by Khaled Abou Alfa, Diana C. Meza-Sepulveda, Cyril Vaulot, Jean-Marc Le Meins, Camelia Matei Ghimbeu, Louise Tonini, Janneth A. Cubillos, Laurent Moynault, Vincent Platel, Diego Paredes and Cecile Hort

C 2024, 10(4), 100; https://doi.org/10.3390/c10040100 - 29 Nov 2024

Abstract

The preliminary selection of adsorbents for the separation of a gas mixture based on pure gas adsorption remains a critical challenge; thus, an approximate adsorption performance indicator (AAPI) was proposed for the initial evaluation of the adsorbents to separate the biogas main constituents [...] Read more.

The preliminary selection of adsorbents for the separation of a gas mixture based on pure gas adsorption remains a critical challenge; thus, an approximate adsorption performance indicator (AAPI) was proposed for the initial evaluation of the adsorbents to separate the biogas main constituents (carbon dioxide/methane (CO₂/CH₄)) by studying their pure gas adsorption. Three samples derived from cocoa pod husk (CPH), namely Cabosse-500 (pyrolyzed at 500 °C), Cabosse-700 (pyrolyzed at 700 °C), and Cabosse-A-700 (activated with CO₂ at 700 °C), were synthesized, characterized, and evaluated for the pure gases adsorption. This study presents an AAPI evaluation, which takes into account adsorption capacity, approximate selectivity, and heat of adsorption. Adsorption isotherms indicate the ability of the CPH family to selectively capture CO₂ over CH₄, as they have a high approximate selectivity (>1) thanks to their physical properties. Changing the pyrolysis temperature, activation methods, and varying the pressure can significantly change the choice of the most effective adsorbent; Cabosse-A-700 showed better performance than the other two in the low and high pressure range owing to its presence of micropores and mesopores, which enhances the CO₂ adsorption and therefore the AAPI. Full article

(This article belongs to the Special Issue Carbon Functionalization: From Synthesis to Applications)

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11 pages, 2993 KiB

Open AccessArticle

Graphene Xerogel for Drug Release

by Kyriaki Kalyva, Katerina Michalarou, Moch Izzul Haq Al Maruf and Vasilios I. Georgakilas

C 2024, 10(4), 99; https://doi.org/10.3390/c10040099 - 28 Nov 2024

Abstract

By functionalizing reduced graphene oxide with polydopamine, the production of a two-dimensional hydrophilicplatform with hydrophobic areas, suitable for the stabilization and slow and controlled release of hydrophilic and hydrophobic drugs, was realized. The functionalized graphene was first enriched with different organic drug molecules, [...] Read more.

By functionalizing reduced graphene oxide with polydopamine, the production of a two-dimensional hydrophilicplatform with hydrophobic areas, suitable for the stabilization and slow and controlled release of hydrophilic and hydrophobic drugs, was realized. The functionalized graphene was first enriched with different organic drug molecules, either hydrophilic, such as doxorubicin, or hydrophobic, such as curcumin or quercetin, and then incorporated into a xerogel of chitosan and polyvinyl alcohol. The graphene substrate stabilizes the xerogel in water and effectively controls the release of doxorubicin for more than three weeks. The release of curcumin and quercetin in the aqueous environment was equally successful but at different rates. The drug-loaded xerogels also worked effectively after their incorporation into a hemostatic cotton gauze. Full article

(This article belongs to the Special Issue Carbon Nanohybrids for Biomedical Applications (2nd Edition))

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24 pages, 2843 KiB

Open AccessReview

Graphitic Carbon Nitride: A Novel Two-Dimensional Metal-Free Carbon-Based Polymer Material for Electrochemical Detection of Biomarkers

by Ganesan Kausalya Sasikumar, Pitchai Utchimahali Muthu Raja, Peter Jerome, Rathinasamy Radhamani Shenthilkumar and Putrakumar Balla

C 2024, 10(4), 98; https://doi.org/10.3390/c10040098 - 27 Nov 2024

Abstract

Graphitic carbon nitride (g-C₃N₄) has gained significant attention due to its unique physicochemical properties as a metal-free, two-dimensional, carbon-based polymeric fluorescent substance composed of tris-triazine-based patterns with a slight hydrogen content and a carbon-to-nitrogen ratio of 3:4. It forms [...] Read more.

Graphitic carbon nitride (g-C₃N₄) has gained significant attention due to its unique physicochemical properties as a metal-free, two-dimensional, carbon-based polymeric fluorescent substance composed of tris-triazine-based patterns with a slight hydrogen content and a carbon-to-nitrogen ratio of 3:4. It forms layered structures like graphite and demonstrates exciting and unusual physicochemical properties, making g-C₃N₄ widely used in nanoelectronic devices, spin electronics, energy storage, thermal conductivity materials, and many others. The biomedical industry has greatly benefited from its excellent optical, electrical, and physicochemical characteristics, such as abundance on Earth, affordability, vast surface area, and fast synthesis. Notably, the heptazine phase of g-C₃N₄ displays stable electronic bands. Another significant quality of this semiconductor material is its excellent fluorescence property, which is also helpful in preparing biosensors. Based on g-C₃N₄, electrochemical biosensors have provided better biocompatibility, higher sensitivity, low detection limits, nontoxicity, excellent selectivity, and surface versatility of functionalization for the delicate identification of target analytes. This review covers the latest studies on using efflorescent graphitic carbon nitride to fabricate electrochemical biosensors for various biomarkers. Carbon nitrides have been reported to possess excellent electroactivity properties, a massive surface-to-volume ratio, and hydrogen-bonding functionality, thus allowing electrochemical-based, highly sensitive, and selective detection platforms for an entire array of analytes. Considering the preceding information, this review addresses the fundamentals and background of g-C₃N₄ and its numerous synthesis pathways. Furthermore, the importance of electrochemical sensing of diverse biomarkers is emphasized in this review article. It also discusses the current status of the challenges and future perspectives of graphitic carbon nitride-based electrochemical sensors, which open paths toward their practical application in aspects of clinical diagnostics. Full article

(This article belongs to the Special Issue Carbon-Based Polymer Composites: Synthesis, Processing, Characterization and Applications)

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12 pages, 2385 KiB

Open AccessArticle

Effect of Synthesis Conditions on the Structure and Electrochemical Properties of Vertically Aligned Graphene/Carbon Nanofiber Hybrids

by Mahnoosh Khosravifar, Kinshuk Dasgupta and Vesselin Shanov

C 2024, 10(4), 97; https://doi.org/10.3390/c10040097 - 24 Nov 2024

Abstract

In recent years, significant efforts have been dedicated to understanding the growth mechanisms behind the synthesis of vertically aligned nanocarbon structures using plasma-enhanced chemical vapor deposition (PECVD). This study explores how varying synthesis conditions, specifically hydrocarbon flow rate, hydrocarbon type, and plasma power,—affect [...] Read more.

In recent years, significant efforts have been dedicated to understanding the growth mechanisms behind the synthesis of vertically aligned nanocarbon structures using plasma-enhanced chemical vapor deposition (PECVD). This study explores how varying synthesis conditions, specifically hydrocarbon flow rate, hydrocarbon type, and plasma power,—affect the microstructure, properties, and electrochemical performance of nitrogen-doped vertically aligned graphene (NVG) and nitrogen-doped vertically aligned carbon nanofibers (NVCNFs) hybrids. It was observed that adjustments in these synthesis parameters led to noticeable changes in the microstructure, with particularly significant alterations when changing the hydrocarbon precursor from acetylene to methane. The electrochemical investigation revealed that the sample synthesized at higher plasma power exhibited enhanced electron transfer kinetics, likely due to the higher density of open edges and nitrogen doping level. This study contributes to better understanding the PECVD process for fabricating nanocarbon materials, particularly for sensor applications. Full article

(This article belongs to the Special Issue Carbon Functionalization: From Synthesis to Applications)

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11 pages, 4468 KiB

Open AccessArticle

Kinetics of Thermal Decomposition of Carbon Nanotubes Decorated with Magnetite Nanoparticles

by Rubén H. Olcay, Elia G. Palacios, Iván A. Reyes, Laura García-Hernández, Pedro A. Ramírez-Ortega, Sayra Ordoñez, Julio C. Juárez, Martín Reyes, Juan-Carlos González-Islas and Mizraim U. Flores

C 2024, 10(4), 96; https://doi.org/10.3390/c10040096 - 15 Nov 2024

Abstract

Magnetite nanoparticles were synthesized using the green chemistry technique; ferric chloride was used as a precursor agent and Moringa oleifera extract was used as a stabilizer agent. A black powder, characteristic of magnetite, was obtained. X-ray diffraction was performed on the synthesis product [...] Read more.

Magnetite nanoparticles were synthesized using the green chemistry technique; ferric chloride was used as a precursor agent and Moringa oleifera extract was used as a stabilizer agent. A black powder, characteristic of magnetite, was obtained. X-ray diffraction was performed on the synthesis product and identified as magnetite (Fe₃O₄). Scanning electron microscopy characterization shows that nanoparticles have a spherical morphology, with sizes ranging from 15 nm to 35 nm. The synthesis of carbon nanotubes was carried out by the pyrolytic chemical deposition technique, from which multiwalled carbon nanotubes were obtained with diameters of 15–35 nm and of varied length. The decoration was carried out using the wet and sonification technique, where a non-homogeneous coating was obtained around the nanotubes. The thermal decomposition for both decorated and undecorated nanotubes presents two mass losses but with different slopes, where the activation energy for the decorated carbon nanotubes was 79.54 kJ/mol, which shows that the decoration gives more stability to the nanotubes since the activation energy of the undecorated nanotubes is 25.74 kJ/mol. Full article

(This article belongs to the Collection Novel Applications of Carbon Nanotube-Based Materials)

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20 pages, 5602 KiB

Open AccessArticle

Preferential Stripping Analysis of Post-Transition Metals (In and Ga) at Bi/Hg Films Electroplated on Graphene-Functionalized Graphite Rods

by Nastaran Ghaffari, Nazeem Jahed, Zareenah Abader, Priscilla G. L. Baker and Keagan Pokpas

C 2024, 10(4), 95; https://doi.org/10.3390/c10040095 - 12 Nov 2024

Abstract

In this study, we introduce a novel electrochemical sensor combining reduced graphene oxide (rGO) sheets with a bismuth–mercury (Bi/Hg) film, electroplated onto pencil graphite electrodes (PGEs) for the high-sensitivity detection of trace amounts of gallium (Ga³⁺) and indium (In³⁺) [...] Read more.

In this study, we introduce a novel electrochemical sensor combining reduced graphene oxide (rGO) sheets with a bismuth–mercury (Bi/Hg) film, electroplated onto pencil graphite electrodes (PGEs) for the high-sensitivity detection of trace amounts of gallium (Ga³⁺) and indium (In³⁺) in water samples using square wave anodic stripping voltammetry (SWASV). The electrochemical modification of PGEs with rGO and bimetallic Bi/Hg films (ERGO-Bi/HgF-PGE) exhibited synergistic effects, enhancing the oxidation signals of Ga and In. Graphene oxide (GO) was accumulated onto PGEs and reduced through cyclic reduction. Key parameters influencing the electroanalytical performance, such as deposition potential, deposition time, and pH, were systematically optimized. The improved adsorption of Ga³⁺ and In³⁺ ions at the Bi/Hg films on the graphene-functionalized electrodes during the preconcentration step significantly enhanced sensitivity, achieving detection limits of 2.53 nmol L⁻¹ for Ga³⁺ and 7.27 nmol L⁻¹ for In³⁺. The preferential accumulation of each post-transition metal, used in transparent displays, to form fused alloys at Bi and Hg films, respectively, is highlighted. The sensor demonstrated effective quantification of Ga³⁺ and In³⁺ in tap water, with detection capabilities well below the USEPA guidelines. This study pioneers the use of bimetallic films to selectively and simultaneously detect the post-transition metals In³⁺ and Ga³⁺, highlighting the role of graphene functionalization in augmenting metal film accumulation on cost-effective graphite rods. Additionally, the combined synergistic effects of Bi/Hg and graphene functionalization have been explored for the first time, offering promising implications for environmental analysis and water quality monitoring. Full article

(This article belongs to the Special Issue Carbon and Related Composites for Sensors and Energy Storage: Synthesis, Properties, and Application)

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17 pages, 2264 KiB

Open AccessArticle

Towards Photothermal Acid Catalysts Using Eco-Sustainable Sulfonated Carbon Nanoparticles—Part II: Thermal and Photothermal Catalysis of Biodiesel Synthesis

by María Paula Militello, Luciano Tamborini, Diego F. Acevedo and Cesar A. Barbero

C 2024, 10(4), 94; https://doi.org/10.3390/c10040094 - 4 Nov 2024

Abstract

The main goal of this work is to evaluate the ability of sulfonated carbon nanoparticles (SCNs) to induce photothermal catalysis of the biodiesel synthesis reaction (transesterification of natural triglycerides (TGs) with alcohols). Carbon nanoparticles (CNs) are produced by the carbonization of cross-linked resin [...] Read more.

The main goal of this work is to evaluate the ability of sulfonated carbon nanoparticles (SCNs) to induce photothermal catalysis of the biodiesel synthesis reaction (transesterification of natural triglycerides (TGs) with alcohols). Carbon nanoparticles (CNs) are produced by the carbonization of cross-linked resin nanoparticles (RNs). The RNs are produced by condensation of a phenol (resorcinol or natural tannin) with formaldehyde under ammonia catalysis (Stober method). The method produces nanoparticles, which are carbonized into carbon nanoparticles (CNs). The illumination of CNs increases the temperature proportionally (linear) to the nanoparticle concentration and exposure time (with saturation). Solid acid catalysts are made by heating in concentrated sulfuric acid (SEAr sulfonation). The application of either light or a catalyst (SCNs) (at 25 °C) induced low conversions (<10%) for the esterification reaction of acetic acid with bioethanol. In contrast, the illumination of the reaction medium containing SCNs induced high conversions (>75%). In the case of biodiesel synthesis (transesterification of sunflower oil with bioethanol), conversions greater than 40% were observed only when light and the catalyst (SCNs) were applied simultaneously. Therefore, it is possible to use sulfonated carbon nanoparticles as photothermally activated catalysts for Fischer esterification and triglyceride transesterification (biodiesel synthesis). Full article

(This article belongs to the Special Issue Carbons for Health and Environmental Protection (2nd Edition))

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15 pages, 4495 KiB

Open AccessArticle

Fabrication of Cu-Doped Diamond-like Carbon Film for Improving Sealing Performance of Hydraulic Cylinder of Shearers

by Yanrong Yang, Xiang Yu, Zhiyan Zhao and Lei Zhang

C 2024, 10(4), 93; https://doi.org/10.3390/c10040093 - 30 Oct 2024

Abstract

During shearer operation, the piston rod is susceptible to wear from the invasion of pollutants, thus ruining the sealing ring in the hydraulic cylinder. This work attempts to conduct a systematic investigation of Cu-doped diamond-like carbon (Cu-DLC) film to improve the seal performance. [...] Read more.

During shearer operation, the piston rod is susceptible to wear from the invasion of pollutants, thus ruining the sealing ring in the hydraulic cylinder. This work attempts to conduct a systematic investigation of Cu-doped diamond-like carbon (Cu-DLC) film to improve the seal performance. The failure process of the cylinder was analyzed, and relevant parameters were determined. Several Cu-DLC films were deposited on the substrate of the piston rod in a multi-ion beam-assisted system, and their structures and combined tribological performances were investigated. The hardness of the film ranges from 27.6 GPa to 14.8 GPa, and the internal stress ranges from 3500 MPa to 1750 MPa. The steady-state frictional coefficient of the film ranges from 0.04 to 0.15; the wear rate decreases first and then increases, and it reaches its lowest (5.0 × 10⁻⁹ mm³/N·m) at 9.2 at.% content. a:C-Cu_9.2% film presents optimal combined tribological performances in this experiment. The modification mechanism of Cu-DLC film for the seal performance may come from the synergistic effects of (i) the contact force and friction-heat-induced film graphitization, (ii) Cu doping improves the toughness of the film and acts as a solid lubricant, and (iii) the transfer layer plays a role in self-lubrication. Full article

(This article belongs to the Special Issue Micro/Nanofabrication of Carbon-Based Devices and Their Applications)

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25 pages, 2092 KiB

Open AccessReview

Advanced Graphene-Based Technologies for Antibiotic Removal from Wastewater: A Review (2016–2024)

by Joydip Sengupta and Chaudhery Mustansar Hussain

C 2024, 10(4), 92; https://doi.org/10.3390/c10040092 - 15 Oct 2024

Abstract

The increasing presence of antibiotics in wastewater poses significant environmental risks, including the promotion of antibiotic resistance and harm to aquatic ecosystems. This study reviews advancements in graphene-based technologies for removing antibiotics from wastewater between 2016 and 2024. Graphene-based platforms, such as graphene [...] Read more.

The increasing presence of antibiotics in wastewater poses significant environmental risks, including the promotion of antibiotic resistance and harm to aquatic ecosystems. This study reviews advancements in graphene-based technologies for removing antibiotics from wastewater between 2016 and 2024. Graphene-based platforms, such as graphene oxide (GO), reduced graphene oxide (rGO), and graphene composites, have shown great promise in this field because of their exceptional adsorption capacities and rapid photocatalytic degradation capabilities. Functionalized graphene materials and graphene integrated with other substances, such as metal oxides and polymers, have enhanced performance in terms of antibiotic removal through mechanisms such as adsorption and photocatalysis. These technologies have been evaluated under various conditions, such as pH and temperature, demonstrating their practical applicability. Despite challenges related to scalability, cost-effectiveness, and environmental impact, the advancements in graphene-based technologies during this period highlight their significant potential for effective antibiotic removal, paving the way for safer and more sustainable environmental management practices. Full article

(This article belongs to the Special Issue Carbon-Based Materials Applied in Water and Wastewater Treatment)

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17 pages, 5669 KiB

Open AccessArticle

Stacking Fault Nucleation in Films of Vertically Oriented Multiwall Carbon Nanotubes by Pyrolysis of Ferrocene and Dimethyl Ferrocene at a Low Vapor Flow Rate

by Ayoub Taallah, Shanling Wang, Omololu Odunmbaku, Lin Zhang, Xilong Guo, Yixin Dai, Wenkang Li, Huanqing Ye, Hansong Wu, Jiaxin Song, Jian Guo, Jiqiu Wen, Yi He and Filippo S. Boi

C 2024, 10(4), 91; https://doi.org/10.3390/c10040091 - 12 Oct 2024

Abstract

Recent observations of superconductivity in low-dimensional systems composed of twisted, untwisted, or rhombohedral graphene have attracted significant attention. One-dimensional moiré superlattices and flat bands have interestingly been identified in collapsed chiral carbon nanotubes (CNTs), opening up new avenues for the tunability of the [...] Read more.

Recent observations of superconductivity in low-dimensional systems composed of twisted, untwisted, or rhombohedral graphene have attracted significant attention. One-dimensional moiré superlattices and flat bands have interestingly been identified in collapsed chiral carbon nanotubes (CNTs), opening up new avenues for the tunability of the electronic properties in these systems. The nucleation of hexagonal moiré superlattices and other types of stacking faults has also been demonstrated in partially collapsed and uncollapsed carbon nano-onions (CNOs). Here, we report a novel investigation on the dynamics of stacking fault nucleation within the multilayered lattices of micrometer-scale vertically oriented films of multiwall CNTs (MWCNTs), resulting from the pyrolysis of molecular precursors consisting of ferrocene or dimethyl ferrocene, at low vapor flow rates of ~5–20 mL/min. Interestingly, local nucleation of moiré-like superlattices (as stacking faults) was found when employing dimethyl ferrocene as the pyrolysis precursor. The morphological and structural properties of these systems were investigated with the aid of scanning and transmission electron microscopies, namely SEM, TEM, and HRTEM, as well as X-ray diffraction (XRD) and Raman point/mapping spectroscopy. Deconvolution analyses of the Raman spectra also demonstrated a local surface oxidation, possibly occurring on defect-rich interfaces, frequently identified within or in proximity of bamboo-like graphitic caps. By employing high-temperature Raman spectroscopy, we demonstrate a post-growth re-graphitization, which may also be visualized as an alternative way of depleting the oxygen content within the MWCNTs’ interfaces through recrystallization. Full article

(This article belongs to the Special Issue Characterization of Disorder in Carbons (2nd Edition))

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10 pages, 1212 KiB

Open AccessArticle

Optimizing Graphene Oxide Film Quality: The Role of Solvent and Deposition Technique

by Grazia Giuseppina Politano

C 2024, 10(4), 90; https://doi.org/10.3390/c10040090 - 10 Oct 2024

Abstract

Graphene oxide (GO) is a promising material due to its high mechanical strength, electrical conductivity, and optical transparency, making it suitable for applications like optoelectronics and energy storage. This study focuses on a simplified method of depositing and characterizing GO films via drop [...] Read more.

Graphene oxide (GO) is a promising material due to its high mechanical strength, electrical conductivity, and optical transparency, making it suitable for applications like optoelectronics and energy storage. This study focuses on a simplified method of depositing and characterizing GO films via drop casting, particularly using isopropanol and water as solvents, and compares the results with reference samples of graphene produced by chemical vapor deposition (CVD) and GO films deposited by electrophoretic deposition (EPD). The optical properties of these films were analyzed using Variable Angle Spectroscopic Ellipsometry (VASE). The study revealed that GO films prepared with isopropanol exhibited a lower refractive index compared to those using water. Therefore, the research highlighted the significance of solvent choice and deposition method on the overall film quality. This work provides insights into optimizing GO film properties through careful solvent selection, contributing to the broader understanding and application of GO in advanced technologies. Full article

(This article belongs to the Topic Application of Graphene-Based Materials, 2nd Edition)

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24 pages, 5981 KiB

Open AccessArticle

Impact of Dispersive Solvent and Temperature on Supercapacitor Performance of N-Doped Reduced Graphene Oxide

by Ankit Yadav, Rajeev Kumar, Deepu Joseph, Nygil Thomas, Fei Yan and Balaram Sahoo

C 2024, 10(4), 89; https://doi.org/10.3390/c10040089 - 10 Oct 2024

Abstract

This study evaluates the critical roles of the dispersion medium and temperature during the solvothermal synthesis of nitrogen-doped reduced graphene oxide (NG) for enhancing its performance as an active material in supercapacitor electrodes. Using a fixed volume of a solvent (THF, ethanol, acetonitrile, [...] Read more.

This study evaluates the critical roles of the dispersion medium and temperature during the solvothermal synthesis of nitrogen-doped reduced graphene oxide (NG) for enhancing its performance as an active material in supercapacitor electrodes. Using a fixed volume of a solvent (THF, ethanol, acetonitrile, water, N,N-Dimethylformamide, ethylene glycol, or N-Methyl-2-pyrrolidone) as the dispersive medium, a series of samples at different temperatures (60, 75, 95, 120, 150, 180, and 195 °C) are synthesized and investigated. A proper removal of the oxygen moieties from their surface and an optimum number of N-based defects are essential for a better reduction of graphene oxide and better stacking of the NG sheets. The origin of the supercapacitance of NG sheets can be correlated to the inherent properties such as the boiling point, viscosity, dipole moment, and dielectric constant of all the studied solvents, along with the synthesis temperature. Due to the achievement of a suitable synthesis environment, NG synthesized using N,N-Dimethylformamide at 150 °C displays an excellent supercapacitance value of 514 F/g at 0.5 A/g, which is the highest among all our samples and also competitive among several state-of-the-art lightweight carbon materials. Our work not only helps in understanding the origin of the supercapacitance exhibited by graphene-based materials but also tuning them through a suitable choice of synthesis conditions. Full article

(This article belongs to the Special Issue Carbon and Related Composites for Sensors and Energy Storage: Synthesis, Properties, and Application)

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17 pages, 3329 KiB

Open AccessArticle

Role of Graphene Oxide in Disentangling Amyloid Beta Fibrils

by Brianna Duswalt, Isabella Wolson and Isaac Macwan

C 2024, 10(4), 88; https://doi.org/10.3390/c10040088 - 3 Oct 2024

Abstract

Recently, the accumulation of Amyloid Beta (Aβ) in the brain has been linked to the development of Alzheimer’s disease (AD) through the formation of aggregated plaques and neurofibrillary tangles (NFTs). Although carbon nanoparticles were previously shown as having a potential to address AD, [...] Read more.

Recently, the accumulation of Amyloid Beta (Aβ) in the brain has been linked to the development of Alzheimer’s disease (AD) through the formation of aggregated plaques and neurofibrillary tangles (NFTs). Although carbon nanoparticles were previously shown as having a potential to address AD, the interactions of Aβ with such nanoparticles have not been studied extensively. In this work, molecular dynamic simulations are utilized to simulate the interactions between a single atomic layer of graphene oxide (GO) and a 12-monomer Aβ fibril. These interactions are further compared to those between GO and five individual monomers of Aβ to further understand the conformational changes in Aβ as an individual monomer and as a component of the Aβ fibril. It was found that out of the 42 residues of the Aβ monomers, residues 27–42 are the most affected by the presence of GO. Furthermore, stability analysis through RMSD, conformational energies and salt bridges, along with nonbonding energy, illustrate that Aβ–Aβ interactions were successfully interrupted and dismantled by GO. Overall, the differences in the interactions between monomeric Aβ consisting of five monomers with GO, an Aβ fibril with GO, and control Aβ monomers among themselves, helped elucidate the potential that GO has to disentangle the Aβ tangles, both in case of individual monomers forming a cluster and as part of the Aβ fibril. Full article

(This article belongs to the Special Issue Carbon Nanohybrids for Biomedical Applications)

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13 pages, 5615 KiB

Open AccessArticle

Self-Assembled Synthesis of Graphene Tubes from Melamine Catalyzed by Calcium Carbonate

by Wenping Zeng, Jingxiang Meng, Xinbo Zheng, Tingting Mao, Jintao Huang and Yonggang Min

C 2024, 10(4), 87; https://doi.org/10.3390/c10040087 - 26 Sep 2024

Abstract

This study investigates the carbon products generated by melamine under various heat-treatment temperatures with the catalysis of calcium carbonate. We discovered that the cost-effective precursor melamine readily self-assembles and curls into graphene tubes when catalyzed by the alkaline earth salt CaCO₃ at [...] Read more.

This study investigates the carbon products generated by melamine under various heat-treatment temperatures with the catalysis of calcium carbonate. We discovered that the cost-effective precursor melamine readily self-assembles and curls into graphene tubes when catalyzed by the alkaline earth salt CaCO₃ at elevated temperatures. Under heat-treatment conditions of 1100 °C and 1200 °C, the growth morphology of graphene tubes with open structures and exceptionally large diameters was observed, and the diameters reached the micron level. These products exhibit a high degree of carbonization and an extremely low nitrogen content, as low as 1.7%. Further, the intensity ratio (ID/IG) of the D band and the G band is as low as 0.79 in Raman characterization. The results show that the products have a certain graphite structure, which proves the catalytic activity of CaCO₃. This is attributed to the incorporation of CaCO₃ into the raw material system, which impedes the complete thermal decomposition of melamine. On the other hand, the resulting CaO particles are evenly distributed along the tubular products, providing certain support for their self-assembly and growth, thereby achieving the efficient growth of graphene tubes. Full article

(This article belongs to the Section Carbon Materials and Carbon Allotropes)

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27 pages, 8205 KiB

Open AccessReview

Recent Advances in Carbon-Based Interfacial Photothermal Converters for Seawater Desalination: A Review

by Xiaoyu Jia, Yuke Niu, Shufang Zhu, Hongwei He and Xu Yan

C 2024, 10(3), 86; https://doi.org/10.3390/c10030086 - 22 Sep 2024

Abstract

Along with the rapid development of society, freshwater shortages have become a global concern. Although existing desalination technologies have alleviated this pressure to some extent, their long-term environmental impact and energy consumption are still questionable. Therefore, it is necessary to find a new [...] Read more.

Along with the rapid development of society, freshwater shortages have become a global concern. Although existing desalination technologies have alleviated this pressure to some extent, their long-term environmental impact and energy consumption are still questionable. Therefore, it is necessary to find a new effective way for seawater desalination with cleaner energy. Solar-driven interfacial water evaporation technology has the advantages of environmental protection, energy saving, high evaporation efficiency, low cost, and strong sustainability, and is considered one of the most effective technologies to relieve water resource stress. This review summarized the recent advances in carbon-based interfacial photothermal converters focused on the preparation methods of 2D and 3D photothermal absorbers, the potential ways to enhance the efficiency of photothermal conversion. Finally, this paper proposed the challenges and future trends of interfacial photothermal converters. Full article

(This article belongs to the Section Carbon Materials and Carbon Allotropes)

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18 pages, 10499 KiB

Open AccessArticle

Numerical Assessment of Effective Elastic Properties of Needled Carbon/Carbon Composites Based on a Multiscale Method

by Jian Ge, Xujiang Chao, Haoteng Hu, Wenlong Tian, Weiqi Li and Lehua Qi

C 2024, 10(3), 85; https://doi.org/10.3390/c10030085 - 16 Sep 2024

Abstract

Needled carbon/carbon composites contain complex microstructures such as irregular pores, anisotropic pyrolytic carbon, and interphases between fibers and pyrolytic carbon matrices. Additionally, these composites have hierarchical structures including weftless plies, short-cut fiber plies, and needled regions. To predict the effective elastic properties of [...] Read more.

Needled carbon/carbon composites contain complex microstructures such as irregular pores, anisotropic pyrolytic carbon, and interphases between fibers and pyrolytic carbon matrices. Additionally, these composites have hierarchical structures including weftless plies, short-cut fiber plies, and needled regions. To predict the effective elastic properties of needled carbon/carbon composites, this paper proposes a novel sequential multiscale method. At the microscale, representative volume element (RVE) models are established based on the microstructures of the weftless ply, short-cut fiber ply, and needled region, respectively. In the microscale RVE model, a modified Voronoi tessellation method is developed to characterize anisotropic pyrolytic carbon matrices. At the macroscale, an RVE model containing hierarchical structures is developed to predict the effective elastic properties of needled carbon/carbon composites. For the data interaction between scales, the homogenization results of microscale models are used as inputs for the macroscale model. By comparing these against the experimental results, the proposed multiscale model is validated. Furthermore, the effect of porosity on the effective elastic properties of needled carbon/carbon composites is investigated based on the multiscale model. The results show that the effective elastic properties of needled carbon/carbon composites decrease with the increase in porosity, but the extent of decrease is different in different directions. Full article

(This article belongs to the Special Issue Micro/Nanofabrication of Carbon-Based Devices and Their Applications)

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16 pages, 5753 KiB

Open AccessArticle

Enhanced Antibacterial Activity of Carbon Dots: A Hybrid Approach with Levofloxacin, Curcumin, and Tea Polyphenols

by Khurram Abbas, Haimei Zhu, Weixia Qin, Meiyan Wang, Zijian Li and Hong Bi

C 2024, 10(3), 84; https://doi.org/10.3390/c10030084 - 15 Sep 2024

Abstract

Bacterial infections and their increasing resistance to antibiotics pose a significant challenge in medical treatment. This study presents the synthesis and characterization of novel carbon dots (CDs) using levofloxacin (Lf), curcumin (Cur), and tea polyphenols (TP) through a facile hydrothermal method. The synthesized [...] Read more.

Bacterial infections and their increasing resistance to antibiotics pose a significant challenge in medical treatment. This study presents the synthesis and characterization of novel carbon dots (CDs) using levofloxacin (Lf), curcumin (Cur), and tea polyphenols (TP) through a facile hydrothermal method. The synthesized curcumin-tea polyphenol@carbon dots (Cur-TP@CDs) and levofloxacin-tea polyphenol@carbon dots (Lf-TP@CDs) were characterized using transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and Raman spectroscopy, confirming their unique structural and chemical properties. Cur-TP@CDs exhibited an average particle size of 1.32 nanometers (nm), while Lf-TP@CDs averaged 1.58 nm. Both types demonstrated significant antibacterial activity, with Lf-TP@CDs showing superior effectiveness against Staphylococcus aureus (S. aureus) and Escherichia coli (E. coli) in broth dilution and disc diffusion assays. Biofilm inhibition assays revealed a significant reduction in biofilm formation at higher concentrations. The ultraviolet-visible (UV-vis) and photoluminescence (PL) spectral analyses indicated efficient photon emission, and electron paramagnetic resonance (EPR) analysis showed increased singlet oxygen generation, enhancing bactericidal effects. Live and dead bacterial staining followed by scanning electron microscopy (SEM) analysis confirmed dose-dependent bacterial cell damage and morphological deformities. These findings suggest that Cur-TP@CDs and Lf-TP@CDs are promising antibacterial agents, potentially offering a novel approach to combat antibiotic-resistant bacterial infections. Full article

(This article belongs to the Special Issue Carbon Nanohybrids for Biomedical Applications)

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Journal Description

C — Journal of Carbon Research

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