Surface Of Multi-walled Carbon Nanotubes Research Articles

Monte Carlo Simulation of Aromatic Molecule Adsorption on Multi-Walled Carbon Nanotube Surfaces Using Coefficient of Conformism of a Correlative Prediction (CCCP)

Using the Monte Carlo technique via CORAL-2024 software, models of aromatic substance adsorption on multi-walled nanotubes were constructed. Possible mechanistic interpretations of such models and the corresponding applicability domains were investigated. In constructing the models, criteria of the predictive potential such as the iIndex of Ideality of Correlation (IIC), the Correlation Intensity Index (CII), and the Coefficient of Conformism of a Correlative Prediction (CCCP) were used. It was assumed that the CCCP could serve as a tool for increasing the predictive potential of adsorption models of organic substances on the surface of nanotubes. The developed models provided good predictive potential. The perspectives on the improvement of the nano-QSPR/QSAR were discussed.

The dispersion method does not affect the in vitro genotoxicity of multi-walled carbon nanotubes despite inducing surface alterations.

Multi-walled carbon nanotubes (MWCNTs) are a desirable class of high aspect ratio nanomaterials (HARNs) owing to their extensive applications. Given their demand, the growing occupational and consumer exposure to these materials has warranted an extensive investigation into potential hazards they may pose towards human health. This study utilised both the in vitro mammalian cell gene mutation and the cytokinesis-blocked micronucleus (CBMN) assays to investigate genotoxicity in human lymphoblastoid (TK6) and 16HBE14o- human lung epithelial cells, following exposure to NM-400 and NM-401 MWCNTs for 24h. To evaluate the potential for secondary genotoxicity, the CBMN assay was applied on a co-culture of 16HBE14o- with differentiated human monocytic (dTHP-1) cells. In addition, two dispersion methods (NanoGenoTox vs. high shear mixing) were utilised prior to exposures and in acellular experiments to assess the effects on MWCNT oxidative potential, aspect ratio and surface properties. These were characterized in chemico as well as by electron microscopy and Raman spectroscopy. Structural damage of NM-400 was observed following both dispersion approaches; Raman spectra highlighted greater oxidative transformation under probe sonication as opposed to high shear mixing. Despite the changes to the oxidative potential of the MWCNTs, no statistically significant genotoxicity was observed under the conditions applied. There was also no visible signs of cellular internaliation of NM-400 or NM-401 into either cell type under the test conditions, which may support the negative genotoxic response. Whilst these HARNs may have oxidative potential, cells have natural protective mechanisms for repairing transient DNA damage. Therefore, it is crucial to evaluate biological endpoints which measure fixed DNA damage to account for the impact of DNA repair mechanisms.

Enhanced Conductivity in Conjugated Microporous Polymers via Integrating of Carbon Nanotubes for Ultrasensitive NO2 Chemiresistive Sensor.

Conjugated microporous polymers (CMPs) present high promise for chemiresistive gas sensing owing to their inherent porosities, high surface areas, and tunable semiconducting properties. However, the poor conductivity hinders their widespread application in chemiresistive sensing. In this work, three typical CMPs (PSATA, PSATB, and PSATT) are synthesized and their chemiresistive gas sensing performance is investigated for the first time. To further improve performance, PSATT are modified on the surface of amino-functionalized multi-walled carbon nanotubes (NH2-MWCNTs) to improve the conductivity. As a result, the obtained material, PSATT-7NC exhibited a high sensitivity of 9766% toward 4 ppm NO2, which is 2.5 times higher than that of pristine PSATT. It also demonstrated remarkable selectivity and excellent long-term stability. Furthermore, the lowest limit of detection (0.79 ppb) among all polymers-based sensors is achieved at a low operating temperature of 100°C. This work provides a valuable strategy into the development of a new material platform for advancing high-performance gas sensing applications.

Structural, Dielectric, and Impedance Spectroscopic studies of (Zn0.4Mn0.4Ni0.2Ce0.2Fe1.8O4)1-x/(MWCNTs)x Nanocomposites for Future Energy Storage Applications

The novel Zn0.4Mn0.4Ni0.2Ce0.2Fe1.8O4 (ZMNCF) nanoparticles were first produced using the sol-gel auto-combustion method and then dispersed onto the surface of multi-walled carbon nanotubes (MWCNTs) with the aid of ultra-sonication and a series of different concentration of (ZMNCF)1-x/(MWCNTs)x; x = 0 – 20 wt. % nanocomposites were created. X-ray diffraction (XRD) analysis confirmed the Fd-3m space group and spinel structure of synthesized nanoparticles and revealed that the increasing concentration of MWCNTs has a great influence on the structural properties of the spinel ferrites. Transmission electron microscopy (TEM) was used to study the distribution, size and symmetry of nanoparticles and the accumulation of ZMNCF nanoparticles on the outer surfaces of MWCNTs. The estimation of different vibrational bands was examined using Fourier transform infrared (FTIR) spectroscopy. The dielectric and impedance measurements were studied in the frequency spectrum of 25 Hz to 2 MHz at room temperature. A detailed study of polarization mechanisms, Maxwell-Wagner model, and Koop’s theory and the effect of increasing concentration of MWCNTs on grain and grain boundaries have been discussed. The AC conductivity measurements conducted on the synthesized nanoparticles demonstrated an enhancement in conductivity upon the addition of MWCNTs. The percolation threshold for the nanocomposite was found to be between 10 and 15 wt. %, corresponding to a significant increase in conductivity due to the formation of a continuous conductive network. The valuable responses in dielectric properties showed that the synthesized nanocomposites could be used in future energy storage devices.

Label-free electrochemical assessment of human serum and cancer cells to determine the folate receptor cancer biomarker.

The folate receptor (FR) is a well-known biomarker that is overexpressed in many cancer cells, making it a valuable target for cancer diagnostics and therapeutic strategies. However, identifying cancer biomarkers remains a challenge due to factors such as lengthy procedures, high costs, and low sensitivity. This study presents the development of a novel, cost-effective biosensor designed for the detection of FR. To overcome the limitations of traditional immunological methods, which rely on antigen-antibody interactions, we utilized a charge-based affinity approach. Folic acid (FA) was conjugated with poly (diallyl dimethylammonium chloride) (PDDA) using an EDC-NHS linker on the surface of multi-walled carbon nanotubes. The biosensor enabled electrochemical detection of FR through differential pulse voltammetry (DPV), achieving an impressive detection limit of 1.6pg/mL and a dynamic range of 1-10,000ng/mL. Additionally, the biosensor exhibited excellent stability (30days), high selectivity, and repeatability (RSD=3.14%, n=5). This work presents a promising strategy for developing ligand-receptor-based biosensors. It paves the way for future applications in cancer diagnostics and biosystem interfaces, offering high performance and practical advantages.

Two-Dimensional Redox-Active Cerium-Based Metal–Organic Frameworks Coordinated on Carbon Nanotubes as Materials for Supercapacitors

Cerium oxide has emerged as a promising active material for supercapacitors, owing to its abundance, eco-friendliness, and impressive redox properties. Nonetheless, the low external surface area of bulk cerium oxide strongly limits its specific capacitance, which becomes a hurdle for its broad adoption in energy storage systems. As a result, cerium-based metal–organic frameworks (MOFs) have attracted great attention for the use in supercapacitors due to their ultrahigh specific surface areas and tunable porosity. With the hexa-cerium clusters as the building blocks, Ce(IV)-based MOFs are highly stable in neutral aqueous electrolytes. In addition, the redox activity of a part of cerium atoms present in their hexa-cerium nodes makes Ce-MOFs redox-active with an obvious pseudocapacitive behavior. However, even though charges can be transported through the redox-hopping process between cerium-based nodes in the framework during the electrochemical operation, the low electrical conductivity of the pristine cerium-based MOFs still limits the performance of such MOFs in electrochemical energy storage. In this work, nanosheets of a redox-active, two-dimensional (2D), and highly dispersible MOF constructed from hexa-cerium(IV) clusters, CeBTB (BTB = 1,3,5-benzenetribenzoate), which is the only reported 2D Ce(IV)-based MOF in the literature, were directly coordinated onto the surface of carboxylic acid-functionalized multi-walled carbon nanotubes (CNTs) by utilizing a post-synthetically grafting approach; see Fig. 1. Nanocomposites with various CeBTB-CNT ratios were synthesized. Crystallinity, porosity, and morphology of CeBTB and all nanocomposites were first investigated. Powder X-ray diffraction confirms that the CeBTB present in all nanocomposites are still crystalline. Although the majority of nanocomposites with various MOF-to-CNT ratios possess similar specific surface areas compared to the pristine CeBTB and CNTs, the expansion of space between carbon nanotubes or the slight increase in the microporosity of CeBTB can be observed when a minority of CeBTB or a minority of CNTs was incorporated into the nanocomposite, respectively. Electron microscopic images reveal that carbon nanotubes embedded in aggregates of CeBTB sheets can be observed in nanocomposites. In addition, infrared spectra confirm the formation of coordination bonds between the hexa-cerium clusters of CeBTB and carboxylate groups of CNTs during the grafting process. The bulk electrical conductivity of the CeBTB and its nanocomposite is highly tunable; according to the results of two-probe measurements, it ranges from 10-13 S/cm to 10-3 S/cm depending on the ratio between CeBTB and CNTs in the material. Thin films of materials with the same mass loading were then fabricated to measure their capacitive performances in neutral aqueous solutions of Na2SO4. With the electrical conductivity provided by carbon nanotubes and the redox activity of CeBTB between Ce(IV) and Ce(III), the optimal nanocomposite, CeBTB-CNT-2:1, can show a significant enhancement of capacitive performance compared to the pristine CeBTB, pristine CNTs, and the physical mixture of both of them with the same MOF-to-CNT ratio. With such a simple post-synthetically grafting approach that can precisely control the ratio between the 2D MOF and CNTs, the findings here open opportunities for designing numerous composites composed of redox-active 2D-MOFs and nanocarbons with tunable electrical conductivity, redox activity, and functionality; such chemically robust MOF-based composites are considered as potential candidates for a range of applications. Figure 1

Enhancing Asphaltene Adsorption and Dispersion in Crude Oil With Multiwalled Carbon Nanotubes: Optimization via Response Surface Methodology Approach

Summary Carbon nanostructures like multiwalled carbon nanotubes (MWCNTs) offer promising solutions for addressing asphaltene-related challenges in the crude oil industry. Here, MWCNTs were synthesized via the pyrolysis process, and thoroughly characterized using various analytical techniques including Raman spectroscopy, X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, X-ray fluorescence (XRF), transmission electron microscopy, the Brunauer-Emmett-Teller technique, and thermogravimetric analysis (TGA). Subsequently, these MWCNTs were utilized to adsorb asphaltenes from both toluene solutions and actual crude oil samples. XRD, scanning electron microscopy (SEM), and elemental composition analysis were used to analyze the asphaltenes, alongside examining asphaltene adsorption isotherms and kinetics under optimal conditions obtained from response surface methodology coupled with central composite design (RSM-CCD) approach. The developed model exhibited a high accuracy level in predicting the asphaltene adsorption capacity within the specified experimental parameters with R2 = 0.9938 and an adjusted R2 = 0.9859. The maximum capacity of asphaltene adsorption of 709.82 mg/g was obtained at the initial concentration of the asphaltene solution of 1000 mg/L, a contact time of 77.45 minutes, an MWCNT dosage of 0.287 g, and a stirring speed of 517.29 rev/min at 363°K. The asphaltene adsorption kinetics and isotherms toward MWCNTs were consistent with pseudosecond-order and Freundlich models, respectively, suggesting the predominance of a heterogeneous surface multilayer mechanism. Additionally, asphaltene dispersant tests (ADTs), viscometry, and microscopy analysis indicate that synthesized MWCNTs notably delayed the asphaltene aggregation in actual petroleum at an optimal concentration of 200 ppm, achieving a dispersion effectiveness of 70.97% according to ADT experiments. This is due to the large MWCNT surface and favorable interactions between nanoparticles and asphaltene components, leading to efficient control of deposition/aggregation of asphaltene in petroleum. The obtained results suggest that MWCNTs can serve as economically viable and environmentally sustainable asphaltene inhibitors and dispersants for oilfield operations, and their use can address the limitations associated with other nanoparticle types and mitigate issues caused by asphaltene precipitation and deposition.

ВПЛИВ ВУГЛЕЦЕВИХ НАНОТРУБОК НА ТЕРМІЧНУ СТІЙКІСТЬ ТА ТЕРМОМЕХАНІЧІ ВЛАСТИВОСТІ ЕПОКСИДНОГО ПОЛІМЕРУ ЕД-20

The thermal stability and thermomechanical properties of an epoxy composite based on ED-20 epoxy oligomer cured with a polyaniline complex doped with tetrafluoroboric acid (PAn-BF3) The thermal stability and thermomechanical properties of an epoxy composite made from the ED-20 epoxy oligomer, cured with a polyaniline complex doped with tetrafluoroboric acid (PAn-BF3), were examined using differential thermogravimetry (DTG) and thermomechanical analysis (TMA).were investigated using differential thermogravimetry (DTG) and thermomechanical analysis (TMA). Multi-walled carbon nanotubes (MWCNTs) with unmodified (MWNT) and phenyl diazonium tetrafluoroborate-modified surfaces (mMWNT) were used as fillers. At the final stages of thermal degradation at T > 600 °C, the nature of the thermogravimetric curves and the conversion characteristics of polymer thermal degradation are virtually independent of the nature and mass of carbon nanotubes in the composite. At the initial stages of the process, including the region of rapid degradation, the conversion and temperature characteristics of thermal degradation indicate the influence of the nature of carbon nanotubes on the process. While in the case of pristine (unmodified) MWCNTs, the temperature of the onset of polymer mass loss Tp is practically independent of the MWCNT content, in the case of modified mMWNTs, mass loss of the composite is observed at significantly lower temperatures. An increase in the mMWNT content to 2.5 wt% causes a further decrease in the temperature Tp. The reduction in the thermal stability of epoxy composites filled with mMWNTs is chemical. It is associated with the thermal desorption of the modifier - phenyl diazonium tetrafluoroborate from the surface of MWCNTs. The results of the thermomechanical analysis of the studied epoxy polymer composites show that the introduction of a nanoscale filler leads to a significant improvement in the thermomechanical stability of the polymer matrix. This is shown by an increase in the glass transition temperature (Tg), the temperature of the polymer transition to a highly elastic state (Thes), and the high elasticity modulus. This effect is most significant for composites containing 2.5 wt.% carbon nanotubes.

Effect of Carbon Nanotubes Functionalization on the Chemical Composition and Electrochemical Characteristics of Composites with Layered Potassium Manganese Oxide

The influence of pretreatment of multiwalled carbon nanotubes (MWCNTs) in oxidizers (solutions of H2O2 and HNO3) on the structure and electrochemical properties of composites with layered potassium-manganese oxide (KxMnO2) was studied. Composites were obtained by soaking carbon nanotubes in an aqueous solution of KMnO4 at 60 °C. The electrochemical performance of the composites was evaluated by cyclic voltammetry and galvanostatic charge‒discharge methods. It has been established that stronger oxidation of the MWCNTs surface at the functionalization stage leads to a noticeable increase in the reaction rate as well as the optimal potassium content in the KxMnO2 composition, which provides higher capacitive characteristics of the composite (a maximum specific capacitance of 150 F g−1 and a rate capability of 43% with increasing density current from 0.1 to 2.0 A g−1). The resulting composites are promising active components for increasing the capacitive characteristics of conductive carbon black (CB). Compared with an electrode based only on CB, electrodes based on a combination of the composite and CB at a mass ratio of 1:1 showed specific capacitance values approximately 1.5 to 3 times greater, as well as a twofold increase in rate capability (from 35 to 70%) in the range of discharge current density 0.1 to 2.0 A g−1.

Manganese Sulfanyl Porphyrazine-MWCNT Nanohybrid Electrode Material as a Catalyst for H2O2 and Glucose Biosensors.

The demetallation reaction of sulfanyl magnesium(II) porphyrazine with N-ethylphthalimide substituents, followed by remetallation with manganese(II) salts, yields the corresponding manganese(III) derivative (Pz3) with high efficiency. This novel manganese(III) sulfanyl porphyrazine was characterized by HPLC and analyzed using UV-Vis, MS, and FT-IR spectroscopy. Electrochemical experiments of Pz3 conducted in dichloromethane revealed electrochemical activity of the new complex due to both manganese and N-ethylphthalimide substituents redox transitions. Subsequently, Pz3 was deposited on multiwalled carbon nanotubes (MWCNTs), and this hybrid material was then applied to glassy carbon electrodes (GC). The resulting hybrid electroactive electrode material, combining manganese(III) porphyrazine with MWCNTs, showed a significant decrease in overpotential of H2O2 oxidation compared to bare GC or GC electrodes modified with only carbon nanotubes (GC/MWCNTs). This improvement, attributed to the electrocatalytic performance of Mn3+, enabled linear response and sensitive detection of H2O2 at neutral pH. Furthermore, a glucose oxidase (GOx)-containing biosensing platform was developed by modifying the prepared GC/MWCNT/Pz3 electrode for the electrochemical detection of glucose. The bioelectrode incorporating the newly designed Pz3 exhibited good activity in the presence of glucose, confirming effective electronic communication between the Pz3, GOx and MWCNT surface. The linear range for glucose detection was 0.2-3.7 mM.

Heterogenization of Ionic Liquid on Multiwalled Carbon Nanotubes for Lead(II) Ion Detection.

The presence of lead(II) ion poses a significant threat to water systems due to their toxicity and potential health hazards. The detection of Pb2+ ions in contaminated water is very crucial. The ionic liquid functionalized multiwalled carbon nanotubes (IL@MWCNT) nanocomposite was fabricated using ionic liquid (IL) 1-methyl-3-(4-sulfobutyl)-imidazolium chloride and multiwalled carbon nanotubes (MWCNTs) for detection of lead(II) ions. It is a novel method to heterogenize the layer of IL on the surface of MWCNTs. The XPS and FTIR analyses confirm that the ionic liquid is not decomposed during annealing process. Moreover, the XRD analysis shows the presence of MWCNTs and carbon quantum dots (CQDs). The HRTEM results exhibit the aggregation of MWCNTs with IL, and formation of small distorted round shaped flakes of CQDs. Further, the successful heterogenization of IL on the surface of MWCNTs is also confirmed by TGA-DSC analysis. The quenching phenomenon of nanocomposite was observed by UV-Visible spectroscopy. The nanocomposite exhibits high performance for the selective detection of lead(II) ions in comparison to other metal ions. The presence of lead(II) ions eventually reduced the intensity of absorption. A limit of detection (LOD) of 9.16 nM was attained for Pb2+ ions in a concentration range of 0-20 nM.

Multimodal generation of luminol electrochemiluminescence through TEMPO functionalized carbon nanotubes

The utilization of an elaborate nanomaterial is still a prevalent method to generate luminol electrochemiluminescence (ECL). Herein, we report on the multimodal generation of anodic and cathodic luminol ECL through a metal-free nanomaterial. This nanomaterial was prepared by covalently grafting 2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPO) on the surface of multi-walled carbon nanotube (MWCNT). TEMPO-MWCNTs modified electrode exhibit high electrocatalytic activities toward H2O, luminol, H2O2 and O2 during the oxidation/reduction processes. Such electrocatalysis has not only resulted in significant enhancement of luminol ECL, but also enabled the generation of three ECL peaks in luminol/O2 system and two ECL peaks in luminol/H2O2 system on the electrode via different pathways. The natures of these ECL peaks are also revealed through the spooling ECL spectra. Furthermore, an ECL sensor has been designed for sensitive detection of an organophosphorus pesticide (OP) based on the enhanced ECL of luminol/H2O2 system. Therefore, this work suggests that nitroxyl radical functionalized carbon nanomaterial can be used as a new electrocatalyst for studying luminol ECL in the presence of either an endogenous or exogenous co-reactant.

Highly sensitive flexible pressure sensor based on laser ablated Ag-MWCNT /MXene for human motion detection

The complex and dynamic human environment, higher requirements are put forward for the high-performance flexible pressure sensors. The materials selection and microstructure design are crucial to achieve high sensitivity and stability. In this work, we fabricated pressure sensitive layer with multiple dimensional materials. Using laser ablation in liquid method, Ag nanoparticles were uniformly distributed in surface of multi-walled carbon nanotubes (MWCNT). Combined with the delaminated MXene, highly pressure sensitive composite could be prepared due to the reduction of contact resistance under pressure. The corresponding piezoresistive sensors showed high sensitivity (12.7 kPa−1), excellent response speed (150 ms), recovery speed (100 ms), and distinguished cycle stability (3000 cycles). Based on the performance of the sensor, it can realize the monitoring of tiny pressure on the human body, and further realize the detection of human activities and health. In addition, the sensor array has spatial recognition capability, providing a way of thinking for the development needs of future intelligent wearable electronic devices. The sensors can measure changes in resistance caused by finger bending, slight breathing, pulse, vocal cord vibration, and other movements to realize human activity and health monitoring. At the same time, the 3×3 sensor array system can recognize the layout of pressure in space. This simple preparation and low cost of the sensor can Facilitate the progress towards sophisticated wearable electronic gadgets.

Interfacial bonding characteristics of multi-walled carbon nanotube/ultralight foamed concrete

Abstract In the development of carbon nanotube (CNT)-reinforced cement-based matrices, one of the fundamental issues that investigators are confronting is CNT/cement-based matrix interfacial bonding, which determines the load transfer capability from the matrix to the CNT. In the present work, the stress transfer properties of multi-walled carbon nanotubes (MWCNTs) and ultralight foamed concrete matrices were studied using microscopic Raman spectrometry analysis. Two types of CNTs, such as MWCNT and MWCNT-COOH, were considered, wherein MWCNT-COOH was covered with fundamental COOH groups. The results show that the compressive and flexural strengths were 75 and 236% better for ultralight foamed concrete with a dry density of 200 kg/m3 with 0.4 wt% MWCNT-COOH addition, respectively. This indicates that the fundamental COOH groups of the MWCNT play an important role in determining the interfacial bonding characteristics between the MWCNT and the ultralight foamed concrete matrix. Therefore, the attachment of COOH groups with a reasonable concentration to the MWCNT surface may be an effective way to significantly improve the load transfer between the MWCNT and the ultralight foamed concrete matrix, leading to increased compressive and flexural strength values of composites.

Synthesis of Nitronyl Nitroxide Radical-Modified Multi-Walled Carbon Nanotubes and Oxidative Desulfurization in Fuel.

Novel and highly stable nitronyl nitroxide radical (NIT) derivatives were synthesized and coated on the surface of multi-walled carbon nanotubes (MWCNTs) to improve their desulfurization performance. They were characterized by FTIR, UV-vis, SEM, XRD, Raman spectroscopy and ESR. Thiophene in fuel was desulfurized by molecular O2, and the oxidation activity of these compounds was evaluated. At a normal temperature and pressure, the degradation rates of thiophene by four compounds in 4 h can reach 92.66%, 96.38%, 93.25% and 89.49%, respectively. The MWCNTs/NIT-F have a high special activity for the degradation of thiophene, and their desulfurization activity can be recycled for five times without a significant reduction. The mechanistic studies of MWCNTs/NIT composites show that the ammonium oxide ion is the key active intermediate in catalytic oxidative desulfurization, which provides a new choice for fuel oxidative desulfurization. The results show that NIT significantly improves the photocatalytic performance of MWCNTs.

Novel electrochemiluminescence sensing platform for ultrasensitive detection of malathion residue in tea based on SiO2NSs doped Luminol/AgNPs as a signal amplification strategy

To address the potential hazards of organophosphorus pesticides (OPs) residues in tea, an electrochemiluminescence (ECL) aptasensor based on functionalized nanomaterials was constructed in this work. Firstly, gold nanoparticles (AuNPs) were attached on the surface of multi-walled carbon nanotubes (MWCNTs) by the constant potential electrodeposition to form a compound, and it was utilized to provide excellent immobilization sites for complementary DNA (cDNA). Subsequently, composite nanomaterials were synthesized by a one-pot method with aminated Luminol/silver nanoparticles@silica nanospheres (NH2-Luminol/Ag@SiO2NSs). Finally, NH2-Luminol/Ag@SiO2NSs was combined with a malathion aptamer (Apt) to obtain signal probes (SPs) for the construction of an aptasensor. The aptasensor had a wide linear range (1×10−3-1×103 ng/mL) and a low limit of detection (LOD) (0.3×10−3 ng/mL). It had the virtues of high sensitivity, wonderful stability and excellent specificity, which could be used for the detection of malathion residue in tea. The work provides a proven way for the construction of a rapid and ultrasensitive aptasensor with low-cost.

Nano-Titanium Oxide-Coated Carbon Nanotubes for Photothermal Therapy in the Treatment of Colorectal Cancer.

Carbon nanotubes (CNTs) display good potential in tumor photothermal therapy (PTT). In this study, it is aimed to investigate the therapeutic potential of nano-titanium oxide-coated multi-walled carbon nanotubes (MCNTs) against colorectal cancer (CRC). First, TiO2 nanosheets are modified on the surface of MCNTs to obtain nano-TiO2-coated MCNTs. Next, cell compatibility validation is conducted on nano-TiO2-coated MCNTs, and it is found that nano-TiO2-coated MCNTs are safe within a certain concentration range (0-200 µgmL⁻1). Interestingly, nano-TiO2-coated MCNTs display a good killing effect in CRC cells under near-infrared (NIR) laser irradiation. Subsequently, nano-TiO2-coated MCNTs markedly promote the proapoptotic effects of NIR laser irradiation and significantly inhibit the expression of cell cycle proteins CCNA1 and CCND1 in CRC cells under NIR laser irradiation, which indicates that nano-TiO2-coated MCNTs exert anti-CRC effects under NIR laser irradiation by regulating cell apoptosis and cell cycle. Furthermore, nano-TiO2-coated MCNTs accelerate inhibitory effects on the AKT signaling pathway under NIR laser irradiation. Finally, a cell line-derived xenograft model is established, and the results showed that nano-TiO2-coated MCNTs significantly exhibit superior tumor-killing ability under NIR laser irradiation in vivo. Collectively, these results demonstrate that nano-TiO2-coated MCNTs with NIR laser irradiation may serve as an effective strategy for the treatment of CRC.

Nano-etching of carbon nanofiber surface and subsequent Fe–N–C thin film coating for enhancement of oxygen evolution reaction

The oxygen evolution reaction (OER) is involved in many electrical–chemical energy conversion systems; however, the slow reaction rate of the OER leads to a high overpotential (η) and low energy efficiency. Recently, an extremely low-η OER phenomenon was observed at a carbonaceous Fe–N-doped thin film with enriched step edges on highly oriented pyrolytic graphite and the carbon fiber surface in an alkaline electrolyte, although the activity was limited. In this study, multi-walled carbon nanotubes (MWCNTs) were used as substrates to utilize their high specific surface areas to develop an active OER catalyst. Nanoscale etching of the MWCNT surface was performed by Fe3O4 nanoparticle loading and subsequent heat treatment in an inert atmosphere, followed by acid washing. Afterwards, a carbonaceous thin film containing Fe and N was coated on the surface via sublimation, deposition, and pyrolysis of Fe phthalocyanine (Pc). A roughened surface was observed for the FePc-derived thin film coated on the nano-etched MWCNT, in contrast to the smooth surface observed for the film coated on the MWCNT without nano-etching. The combination of the nano-etching and the thin-film coating enhanced the OER, which was analyzed by parallel Tafel processes.

Effect of MWCNTs surface functionalization on the characterization of PVA/MWCNTs nanocomposites

The present study aims to put forward the role of surface functionalization of multi-walled carbon nanotubes (MWCNTs) on the enhancement thermal and hydrophilicity properties of new nanocomposite based poly(vinyl alcohol)/surface functionalized MWCNTs (PVA/MWCNTs), prepared by a facile phase inversion process. In this study, the fabrication of PVA/MWCNTs nanocomposites is carried out using functionalized MWCNTs (f-MWCNTs) with different functional groups (–OH, –COOH, –NH2). The structural, morphological, thermal, hydrophilicity and physico-chemical properties of PVA/MWCNTs nanocomposites are characterized by XRD, FE-SEM, FT-IR, TGA and contact angle measurement. The FT-IR results confirm the formation of a hydrogen bond between MWCNTs and PVA chain. XRD analysis indicates an improvement in the crystallinity of the PVA/MWCNTs nanocomposite. TGA results reveal that the PVA/f-MWCNTs nanocomposites show higher thermal stability than pure PVA. It is revealed that PVA/MWCNTs nanocomposites based functionalized MWCNTs remarkably increase the degradation temperature, and thus enhancing the thermal properties. The highest weight loss (30.7 wt%) and degradation temperature (520 °C) values are obtained with PVA/f-MWCNTs(0.5 wt%). The contact angle measurement confirms that the hydrophobic properties of pure PVA became hydrophilic because of the functional groups of MWCNTs. The hydrophilicity of PVA/MWCNTs nanocomposites is increased with the increase in wt% of MWCNTs embedded in the nanocomposite.

Recyclable Ag-Au bimetallic nanoparticles supported on acid functionalized multi walled carbon nanotubes for effective catalytic applications

In the present investigation, in situ green reduction approach is used to uniformly decorate the Ag-Au bimetallic nanoparticles (BNPs) on the surface of acid functionalised multi-walled carbon nanotubes (MWCNTs). The adsorbed Terminalia catappa aqueous leaf extract biopolymers on the surface of MWCNTs can increase the in situ reduction of Ag, Au ions to Ag-Au BNPs and stabilise them which can operate as a capper/stabiliser and reductant agent. X-ray diffraction (XRD), high-resolution transmission electron microscopy (HR-TEM), scanning electron microscopy - energy dispersive x-ray spectroscopy (SEM-EDX), Fourier-transform infrared spectroscopy (FT-IR) and UV–visible spectroscopy techniques were employed to examine the structures, morphologies, composition, chemical bonds and optical properties of the functionalised MWCNTs and the nanohybrid. The results revealed that the spherical T.C-Ag-Au bimetallic nanoparticle with average size 12.4 nm was uniformly distributed on the surface of modified MWCNTs. Finally, evaluation of the catalytic activity of the T.C-Ag-Au BNPs decorated MWCNTs exhibited excellent catalytic performance for completing the reduction of 4-Nitrophenol (4-NP) and degradation of alizarin red (AR) dye at ambient temperature with a great rate constant and the degradation efficiency of 98.7% and 96.4%, respectively. The order of reaction, rate constant, half-life and mechanism of catalytic activity of the T.C-Ag-Au BNPs@COOH-MWCNTs nanohybrid were calculated using the Langmuir–Hinshelwood model. The catalyst can be retained and reapplied eight times without affecting its catalytic performance. The interaction between T.C-Ag-Au BNPs and MWCNTs has a synergistic effect, which is accountable for the enhanced catalytic activity.