Search Results (468)

In recent years, harmful algal blooms have led to frequent occurrences of shellfish toxin contamination, posing a significant threat to the safety of aquatic products and public health. As a potent neurotoxin, domoic acid (DA) can accumulate in shellfish, highlighting the urgent need for rapid and highly sensitive detection methods. In this study, we developed a fluorescent aptasensor based on a dual-signal amplification system by combining G-quadruplex (G4) dimers with multi-walled carbon nanotubes (CNTs). The sensor is designed with a hairpin-structured aptamer as the recognition probe, where short multi-walled CNTs serve as both a fluorescence quencher and platform, and G4 dimers are incorporated into the sensing interface to enhance signal output. In the absence of the target, the hairpin-structured aptamer remains closed, keeping the fluorescence signal “off”. Upon binding to DA, the aptamer undergoes a specific conformational change that exposes the G4-dimer sequence. The exposed sequence then binds to thioflavin T (ThT), which in turn generates a greatly enhanced fluorescence signal, leading to a substantial fluorescence enhancement and completing the second stage of the cascade amplification. Under optimal conditions, the constructed sensor achieves rapid detection of DA within 5 min, with a low detection limit of 1.1 ng/mL. This work presents a valuable tool for the rapid and sensitive detection of DA in shellfish, with promising applications in marine environmental monitoring and food safety regulation. Full article

This study introduces a synergistic drop-casting, sonication, and thermal treatment (DSTT) method for fabricating multi-walled carbon nanotube (MWCNT)-coated conductive cotton fabrics. The process produced uniform MWCNT networks with a minimum sheet resistance of 0.072 ± 0.004 kΩ/sq. at ~30 wt.% loading. Scanning electron microscopy confirmed an improved MWCNT network. Reproducibility was demonstrated for different fabric sizes, with resistance values remaining consistent within experimental errors. Stability tests showed only minor changes in sheet resistance after 16 weeks of ambient storage and periodic manual bending. Compared to conventional methods such as room-temperature drying, vacuum drying, and sonication alone, DSTT consistently performed better, yielding fabrics with lower resistance and more reliable conductivity. These results highlight DSTT as a reproducible and scalable method for producing conductive cotton fabrics suitable for smart textiles and wearable electronics. Full article

The main goal of the present article was to develop a methodology for the calculation of the flexural properties of a cement-based matrix with different multi-walled carbon nanotubes’ (CNTs) volume fraction as a reinforcement at early age. The homogenization tool of the ANSA^® software package was exploited for the modelling of the inclusion geometries in a cubic matrix and for mesh generation. A Representative Volume Element (RVE) was constructed with either random orientation tensor algorithm or periodic geometry algorithm tools and for different concentrations of the nano-reinforcement. Finite element modelling (FEM) of the pre-cracked specimens for flexural tests followed, and the numerical results were compared against the experimental ones. Different input parameters were considered, including the reinforcement Poisson’s ratio (ν_CNT) as well as the effective elastic modulus (E_CNT) to predict the flexural behaviour of the nano-reinforced matrices. It was found that both parameters play a pivotal role for the numerical simulation and the best simulation results were obtained for CNTs’ effective elastic modulus E_CNT = 470 GPa and Poisson’s ratio of ν_CNT = 0.10 values for the two (2) different investigated concentrations of carbon nanotubes (0.6 and 1.2%, respectively) in the cementitious matrix. Full article

Although numerous experimental studies have demonstrated the carcinogenic potential of multi-walled carbon nanotubes (MWCNTs) in lungs, the underlying molecular mechanisms—especially gene expression changes associated with different tumor types—remain poorly characterized. To elucidate the molecular signatures associated with MWCNT-induced carcinogenesis, we performed microarray-based gene expression profiling of rat lung tumors induced by MWCNT-7, including both adenocarcinoma (ADC) and malignant mesothelioma (MM), as well as ADCs induced by two types of double-walled CNTs (DWCNTs) differing in fiber length (1.5 µm and 7 µm). Hierarchical clustering revealed that the MWCNT-7-induced MM exhibited a gene expression profile distinct from the ADCs. The ADCs induced by the DWCNTs and the ADC induced by MWCNT-7 shared several pathways that were distinct from those of the MWCNT-7 induced MM. The distinct pathways upregulated in the ADCs versus the MM support the conclusion that MWCNT-induced ADCs arise through distinct biological mechanisms compared to MWCNT-induced MMs and identified tumor-type-specific biomarker candidates: complement factor I (CFI) and secreted phosphoprotein 1 (SPP1) for ADCs, and fibronectin 1 (FN1) for MM. In addition, the gene expression profiles of the ADCs induced by the three fiber types indicate that both types of thin flexible DWCNTs used in the present study promoted a number of carcinogenic pathways in the rat lung that were also promoted by MWCNT-7, which is a class 2B carcinogen. These results support the conclusion that DWCNTs are carcinogenic in the rat lung and highlight the importance of further assessments of the potential lung carcinogenicity of inhaled thin flexible CNTs. Full article

Cementitious composites incorporating multi-walled carbon nanotubes (MWCNTs), known for their superior mechanical, electrical, and thermal properties, present significant potential for multifunctional infrastructure applications. This study quantitatively evaluates the heat generation behavior, electrical resistivity, and flexural performance of hybrid cementitious composites reinforced with MWCNTs and steel fibers. A total of 72 specimens were tested following ASTM and KS standards, considering MWCNT concentrations of 0.0, 0.5, and 1.0 wt% and a steel fiber content of 2.0 vol%. The results revealed that increasing MWCNT concentration markedly enhanced heat generation, reaching a maximum temperature rise of 80.1 °C, while electrical resistance decreased by over 99% compared with basic mortar. The inclusion of steel fibers slightly reduced heat generation but improved flexural strength by up to twofold due to fiber bridging and crack control. Microstructural analyses (FE-SEM, XRD, and TGA) confirmed the formation of continuous CNT networks that facilitated electron transport and improved matrix densification. Although the findings are based on laboratory-scale specimens, the combined use of MWCNTs and steel fibers offers a promising pathway for developing self-heating, mechanically enhanced cementitious materials applicable to black-ice prevention and durable pavement systems. Full article

The search for high-capacity, stable anode materials is crucial for advancing lithium-ion battery (LIB) technology. Although carbon nanotubes (CNTs) are known for their excellent electrical conductivity and mechanical strength, their practical capacity is still limited. This study presents an advanced anode design by molecular functionalizing both single-walled and multi-walled carbon nanotubes (SWCNTs and MWCNTs) with tetrabromocobalt phthalocyanine (CoPc), resulting in CoPc/SWCNT and CoPc/MWCNT hybrid materials. Metal phthalocyanines (MPcs) are recognized for their tunable and redox-active properties. In CoPc, the redox-active metal centers and π-conjugated structure are uniformly attached to the CNT surface through strong π-π interactions. This synergistic combination significantly boosts the lithium-ion (Li-ion) storage capacity by offering numerous coordination sites for Li-ions and enhancing charge transfer kinetics. Electrochemical analysis shows that the CoPc-SWCNT active anode electrode material shows an impressive reversible capacity of 1216 mAh g⁻¹ after 100 cycles at a current density of 0.1 A g⁻¹, substantially surpassing the capacities of pristine CoPc (327 mAh g⁻¹) and a CoPc/MWCNT hybrid (488 mAh g⁻¹). Furthermore, the CoPc/SWCNT anode exhibited exceptional rate capability and outstanding long-term cyclability. These results underscore the effectiveness of non-covalent functionalization with SWCNTs in enhancing the electrical conductivity, structural stability, and active site utilization of CoPc, positioning CoPc/SWCNT hybrids as a highly promising anode material for high-performance Li-ion storage. Full article

The present paper focuses on the effect of carbon nanotubes (CNTs) on the rheological behavior of polyethylene/polypropylene (PE/PP) blends to improve PE/PP mixtures for industrial applications. In our research, 40 wt% HDPE-60 wt% PP blends were produced by extrusion, and 0.59%, 1.18%, and 2.35% multiwalled carbon nanotubes (MWCNTs) were added. Oscillation rheometry was used to study the HDPE-PP-MWCNT nanocomposites and the unfilled polymers at temperatures of 210, 220, 230, 240, and 250 °C in the angular frequency range of 0.05–628.32 rad/s, with 5% deformation. It was demonstrated that in the presence of CNTs, both the complex viscosity and modulus values increase above the percolation threshold. Additionally, it was observed that the crossover modulus (Gx) for all mixtures decreases with increasing temperature. In addition, at 1.18% CNT content, a second crossover appears at all temperatures, and its value increases with temperature. Full article

Multi-Wall Carbon Nanotubes (MWCNTs) are under investigation for their use in biomedical applications, especially in neurological diseases, due to their electrochemical properties. Nevertheless, conflicting results have cast doubt on their safety. To advance their translational potential, we evaluated the cytotoxicity of two MWCNT samples in vivo in both vertebrate and invertebrate animal models. Pristine MWCNTs were, in part, used as prepared (MWCNTs), and, in part, annealed at 2400 °C (a-MWCNTs). The two samples differ in their electrochemical properties: MWCNTs are not electro-conductive, while a-MWCNTs are electro-conductive and negatively charged on their surface. We evaluated the effects of both intranasally delivered MWCNTs on several key markers of cell viability in the olfactory bulbs and hippocampus from healthy adult Wistar rats, as well as their impact on lifespan, genotoxicity, oxidative stress, and aging-related functional markers in the nematode Caenorhabditis elegans. Neither of the two MWCNT samples was cytotoxic towards neuronal cells in the hippocampus. In olfactory bulbs, only electro-conductive a-MWCNTs interacted with two positively charged mitochondrial proteins: Translocase of Outer Mitochondrial Membrane 20 (TOM20) and Cytochrome C (CytC). In C. elegans, neither type of MWCNT affected lifespan or brood size, and cytosolic ROS levels remained unchanged. Notably, treated worms exhibited a significantly delayed aging phenotype. Metallic MWCNTs are biocompatible in living organisms and possess the potential to modulate neural cells functioning in vivo. Full article

Tin(IV) oxide (SnO₂) was deposited onto acid-washed multiwalled carbon nanotubes (MWCNTs) to be used as a support for platinum nanoparticles (PtNPs). The effect of the SnO₂–CNT support on the electrocatalytic activity of the PtNPs for the oxygen reduction reaction (ORR) in 0.1 M HClO₄ solution was investigated. The physical characterization of the catalyst confirms the presence of Pt, Sn and C on the catalyst as well as the presence of the PtNPs on SnO₂. The synthesized catalyst possesses a specific activity of 0.15 mA cm⁻² at 0.9 V, while the commercial Pt/C catalyst showed a specific activity of 0.05 mA cm⁻². Accelerated durability testing (ADT) was performed on both catalysts, with the synthesized PtNP/SnO₂–CNT catalyst retaining over 50% of its initial electrochemically active surface area (ECSA). Thus, the results obtained in this study confirm the positive influence of SnO₂-decorated CNTs on the overall electrocatalytic activity of PtNPs and their stability toward the ORR. Full article

Nitric acid-treated multi-walled carbon nanotubes (CNTs) have been extensively utilized for removing dissolved heavy metals from aqueous systems; however, their use as a capping material to immobilize heavy metals in sediments has rarely been investigated. Consequently, the impact of CNTs on millimeter-scale variations in pore-water heavy metal concentrations along sediment profiles remains poorly understood. In this study, CNTs were applied as a capping agent, and microelectrodes combined with high-resolution diffusive equilibrium in thin-film (HR-Peeper) samplers were employed to simultaneously obtain vertical profiles of pH, soluble copper (Cu) and lead (Pb), and dissolved oxygen (DO) in sediments in order to assess the effectiveness of CNTs in controlling the mobility of Cu and Pb. The results revealed that CNTs application markedly reduced the concentrations of soluble Cu and Pb, with maximum reduction rates of 58.69% and 64.97%, respectively. Compared with the control treatment, CNTs capping decreased the maximum release fluxes of soluble Cu and Pb by 3.78 and 1.91 µg·m⁻²·d⁻¹, respectively. Moreover, CNTs treatment enhanced the stable fractions of Cu and Pb within sediments, thereby improving the sediment’s capacity to retain these metals. Overall, this study demonstrates that CNTs can serve as an effective capping material to inhibit the leaching of Cu and Pb from sediments, offering a promising strategy for the in situ remediation of heavy metal-contaminated sediments. Full article

This study examines advanced cementitious composites incorporating Multi-Walled Carbon Nanotubes (MWCNTs), combining experimental investigations and analytical modeling for enhanced Structural Health Monitoring (SHM) applications. The experimental phase assessed the electrical properties of specimens with varying MWCNT contents, identifying a percolation zone between 0.05 wt% and 0.5 wt%. A dispersion protocol using ultrasonic agitation and a surfactant ensured the uniform distribution of CNTs. Furthermore, a novel micromechanical model, based on established polymer matrix approaches, was used to predict electrical conductivity behavior, accounting for nanotube geometry, concentration, waviness, and tunneling effects. Model predictions confirmed its effectiveness in analyzing structure–property relationships in CNT-based cementitious materials. Full article

This work presents the development of carbon nanotubes functionalised with carboxylic acid groups (CNT-COOH) as an oxygen-sensitive electrochemical platform for parallel multi-analyte enzymatic biosensing. The platform was constructed by depositing carboxylic-acid-functionalised single-walled carbon nanotubes covalently onto nanostructured gold electrodes modified with a self-assembled monolayer of 4-aminothiophenol. Atomic force microscopy characterization revealed that the nanotubes attached via their ends to the surface and had a predominantly horizontal orientation. Glucose oxidase, lactate oxidase, glutamate oxidase, and tyrosinase were immobilised onto the electrodes to create selective biosensor for lactate, glucose, glutamate, and dopamine, respectively. A key finding is that incorporating catalase significantly extends the linear detection range for analytes by mitigating the accumulation of hydrogen peroxide. The resulting multifunctional biosensor demonstrated its capability for the simultaneous and independent measurement of glucose, lactate as the key bioanalytes under uniform conditions in blood plasma samples, highlighting its potential for applications in health and food technologies. Full article

Monitoring dopamine (DA) has attracted increasing attention due to alterations in DA levels associated with brain disorders. In addition, the urinary DA concentration plays a significant role in the sympathoadrenal system. A decrease in DA can impair reward-seeking behavior and cognitive flexibility. Therefore, accurate and precise DA detection is necessary. In this study, a poly(3-aminobenzylamine)/functionalized multi-walled carbon nanotube (PABA/f-CNT) composite thin film was fabricated by electrochemical synthesis, or electropolymerization, of 3-aminobenzylamine (3-ABA) monomer and f-CNTs through cyclic voltammetry (CV) on a fluorine-doped tin oxide (FTO)-coated glass substrate, which also served as a working electrode for label-free DA detection in artificial urine. The formation of the film was confirmed by the obtained cyclic voltammogram, electrochemical impedance spectroscopy (EIS) plots, and scanning electron microscope (SEM) and transmission electron microscope (TEM) images. The chemical components of the films were analyzed using attenuated total reflection–Fourier transform infrared (ATR–FTIR) spectroscopy and X-ray photoelectron spectroscopy (XPS). For label-free DA detection, various concentrations (50–1000 nM) of DA were determined in buffer solution through differential pulse voltammetry (DPV). The fabricated PABA/f-CNT film presented two linear ranges of 50–400 nM (R² = 0.9915) and 500–1000 nM (R² = 0.9443), with sensitivities of 1.97 and 0.95 µA·cm⁻²·µM⁻¹, respectively. The limit of detection (LOD) and the limit of quantity (LOQ) were 119.54 nM and 398.48 nM, respectively. In addition, the PABA/f-CNT film provided excellent selectivity against common interferents (ascorbic acid, uric acid, and glucose) with high stability, reproducibility, and repeatability. For potential future medical applications, DA detection was further performed in artificial urine, yielding a high percentage of recovery. Full article

Low-dimensional carbon nanostructures such as nanotubes, nanocones, and nanofibers can be grown in chemical vapor deposition (CVD) synthesis using catalyst nanoparticles. It is commonly observed that the morphology of solid catalyst nanoparticles continuously fluctuates during multi-walled carbon nanotube (MWCNT) growth. Interestingly, when the diameter of the inner tube of the growing MWCNT reduces below a threshold value, the catalyst nanoparticle snaps out of the MWCNT and recovers its spherical shape. If the MWCNT is tapered, the catalyst nanoparticle may also break. In this study, large-scale molecular dynamics simulations and nanomechanical modeling are employed to elucidate the complete process of MWCNT growth coupled with morphological change in the catalytic nanoparticles. It is shown that the tendency to decrease the surface energy of the catalyst nanoparticle is the major underlying driving force for the variation in morphology under the mechanical constraint of the growing MWCNT. Importantly, the predicted critical inner CNT radius at the onset of the shape recovery is in excellent agreement with experimental observations. The combination of molecular dynamics simulations and theoretical modeling offer an alternative perspective on co-evolution of catalyst nanoparticles and the growth of low-dimensional carbon nanostructures. Full article

This study examines the toxicological effects of carbon nanotubes (CNTs) of different diameters—single-walled CNTs (SWCNT, 2 nm) and multi-walled CNTs (MWCNT, 74 nm)—on two macrophage cell lines, rat alveolar NR8383 cells and human differentiated THP-1. Using standardized exposure conditions and employing an integrated omics approach (transcriptomic and proteomic analyses), both CNT types were found to induce cellular stress responses and inflammation, especially in NR8383 cells, with notable involvement of the Sirtuin signaling pathway. After 24 h, MWCNTs uniquely disrupted lipid metabolism in NR8383 cells, resulting in foam cell formation and syncytia. While SWCNTs were less disruptive to metabolic pathways, they significantly altered gene regulation, particularly RNA splicing mechanisms. The dispersion medium—fetal bovine serum (FBS) versus human surfactant—also modulated the observed toxicological responses, highlighting the critical role of the protein corona in influencing CNT-cell interactions. These findings demonstrate that CNT diameter significantly affects cytotoxicity and cellular response pathways in a cell-type-specific manner. Full article