Search Results (54)

Background: Hyaluronicacid (HA)-conjugated nanocarriers leverage CD44 receptor overexpression on tumor cells for targeted delivery of platinum chemotherapeutics. Methods: This study compares non-functionalized (DDS1) versus HA-conjugated single-walled carbon nanotubes (DDS2) for encapsulation stability and CD44 binding of Cisplatin, Carboplatin, and Lobaplatin. Density Functional Theory calculations employed PBE-GGA with Tkatchenko–Scheffler dispersion and ZORA relativistic treatment, using a finite (8,8) armchair SWCNT (24.6 Å, H-capped) for DDS1 and an EDC/NHS-coupled HA oligomer for DDS2. We computed binding energies, HOMO–LUMO gaps, Molecular Electrostatic Potentials, and energy decompositions. Molecular docking to CD44 (PDB ID: 4PZ3) used Molegro Virtual Docker, validated by re-docking the native HA fragment (RMSD 1.79 Å). Results: DFT binding energies (eV) for DDS2 versus DDS1 were −7.92/−7.48 (Cisplatin), −8.93/−8.30 (Carboplatin), and −9.72/−9.25 (Lobaplatin), indicating enhanced stabilization by HA functionalization. Energy decomposition showed increases of ∼0.4 eV (vdW) and ∼0.2 eV (electrostatic) in DDS2. MEP maps confirmed additional negative-potential regions on DDS2, complementing drug-positive sites. Molecular docking yielded MolDock scores of −171.26 for DDS2 versus −106.68 for DDS1, reflecting stronger CD44 affinity. Docking scores indicate that HA conjugation notably strengthens the predicted affinity of CNT carriers toward the CD44 receptor ($\Delta$Score ≈ −65 kcal mol⁻¹). Conclusions: These results motivate experimental follow-up to confirm whether DDS2 can translate the in silico affinity gains into improved targeted delivery of platinum chemotherapeutics. Full article

In this study, a Brönsted–Lewis bifunctional acidic catalyst PW/UiO/CNTs-OH was synthesized via the hydrothermal method. The parameters for the esterification reaction of oleic acid with methanol catalyzed by PW/UiO/CNTs-OH were optimized using central composite design-response surface methodology (CCD-RSM). A biodiesel yield of 92.9% was achieved under the optimized conditions, retaining 82.3% biodiesel yield after four catalytic cycles. The enhanced catalytic performance of PW/UiO/CNTs-OH can be attributed as follows: the [Zr₆O₄(OH)₄]¹²⁺ anchored on the surface of multi-walled carbon nanotubes (MWCNTs) can serve as nucleation sites for UiO-66, not only encapsulating H₃[P(W₃O₁₀)₄] (HPW) but also reversing the quadrupole moment of MWCNTs to generate Lewis acid sites. In addition, introduction of HPW during synthesis of UiO-66 decreases the solution pH, inducing the protonation of p-phthalic acid (PTA) to disrupt the coordination with the [Zr₆O₄(OH)₄] cluster, thereby creating an unsaturated Zr⁴⁺ site with electron pair-accepting capability, which generates Lewis acid sites. EIS analysis revealed that PW/UiO/CNTs-OH has higher electron migration efficiency than UiO-66 and PW/UiO. Furthermore, NH₃-TPD and Py-IR analyses showed that PW/UiO/CNTs-OH possessed high densities of Lewis acidic sites of 83.69 μmol/g and Brönsted acidic sites of 9.98 μmol/g. Full article

Two-dimensional carbon materials and their derivatives are widely applied as promising electrocatalysts and supports of single-atom sites. Theoretical investigations of 2D carbon materials are usually based on planar models, yet ignore local curvature brought on by possible surface distortion, which can be significant to the exact catalytic performance as has been realized in latest research. In this work, the curvature-influenced electrocatalytic nitrogen reduction reaction (NRR) reactivity of heme-like FeN₄ single-atom site was predicted by a first-principle study, with FeN₄-CNT(m,m) (m = 5~10) models adopted as local curvature models. The results showed that a larger local curvature is favored for NRR, with a lower limiting potential and higher N₂ adsorption affinity, while a smaller local curvature shows lower NH₃ desorption energy and is beneficial for catalyst recovery. Using electronic structures and logarithm fitting, we also found that FeN₄-CNT(5,5) shows an intermediate-spin state, which is different from the high-spin state exhibited by other FeN₄-CNT(m,m) (m = 6~10) models with a smaller local curvature. Full article

The catalytic activity of Ni-Fe oxide embedded in CNTs was investigated in terms of valence states and active oxygen species. Ni-Fe oxides were prepared by the sol-gel combustion process, and Ni-Fe oxides embedded in CNT catalysts were synthesized by the catalytic chemical vapor deposition (CCVD) method. The lattice structure of the Ni-Fe oxide catalysts was analyzed, and the lattice distortion was increased with the addition of Fe. The specific surface areas and pore structures of the Ni-Fe oxides embedded in CNTs were determined through the BET method. The nano-sized Ni-Fe oxides embedded in CNTs were observed using morphology analysis. The crystallinity and defects of CNTs were analyzed by Raman spectroscopy, and the I_D/I_G ratio of Ni_1.25Fe_0.75O/CNT was the lowest at 0.36, representing the high graphitization and low structural defects of the CNT surface. The valence states of Fe and Ni were changed by the interaction between catalysts and CNTs. The redox property of the catalysts was evaluated by H₂-TPR analysis, and the H₂ consumption of Ni_1.25Fe_0.75O/CNT was the highest at 2.764 mmol/g. The catalytic activity of Ni-Fe oxide embedded in CNT exhibited much higher activity than Ni-Fe oxide for the selective catalytic reduction of NOx with NH3 in the temperature range of 100 °C to 450 °C. Full article

The photocatalytic decomposition of ammonia to produce N₂ and H₂ was achieved using single-walled carbon nanotube (SWCNT) nanohybrids. The physical modification of ferrocene-dye-encapsulated CNTs by amphiphilic C₆₀-dendron yielded nanohybrids with a dye/CNT/C₆₀ coaxial heterojunction. Upon irradiation with visible light, an aqueous solution of NH₃ and dye@CNT/C₆₀-dendron nanohybrids produced both N₂ and H₂ in a stoichiometric ratio of 1/3. The action spectra of this reaction clearly demonstrated that the encapsulated dye acted as the photosensitizer, exhibiting an apparent quantum yield (AQY) of 0.22% at 510 nm (the λ_max of the dye). This study reports the first example of dye-sensitized ammonia decomposition and provides a new avenue for developing efficient and sustainable photocatalytic hydrogen production systems. Full article

As a novel therapeutic approach, photothermal therapy (PTT) combined with chemotherapy can synergistically produce antitumor effects. Herein, dithiodipropionic acid (DTDP) was used as a donor of disulfide bonds sensitive to the tumor microenvironment for establishing chemical bonding between the photosensitizer indocyanine green amino (ICG-NH₂) and acidified single-walled carbon nanotubes (CNTs). The CNT surface was then coated with conjugates (HD) formed by the targeted modifier hyaluronic acid (HA) and 1,2-tetragacylphosphatidyl ethanolamine (DMPE). After doxorubicin hydrochloride (DOX), used as the model drug, was loaded by CNT carriers, functional nano-delivery systems (HD/CNTs-SS-ICG@DOX) were developed. Nanosystems can effectively induce tumor cell (MCF-7) death in vitro by accelerating cell apoptosis, affecting cell cycle distribution and reactive oxygen species (ROS) production. The in vivo antitumor activity results in tumor-bearing model mice, further verifying that HD/CNTs-SS-ICG@DOX inhibited tumor growth most significantly by mediating a synergistic effect between chemotherapy and PTT, while various functional nanosystems have shown good biological tissue safety. In conclusion, the composite CNT delivery systems developed in this study possess the features of high biocompatibility, targeted delivery, and responsive drug release, and can achieve the efficient coordination of chemotherapy and PTT, with broad application prospects in cancer treatment. Full article

Commercial non-functionalized (CNTs) and functionalized carbon nanotubes (CNT-COOH and CNT-NH₂) were used as supports to synthesize vanadium-supported catalysts to be used in the gas phase partial oxidation of furfural towards maleic anhydride (MA). The CNTs and the VO₂-V₂O₅/CNTs, so-called VO/CNT catalysts, were characterized by AAS, TGA, XRD, N₂ adsorption isotherms at −196 °C, Raman, NH₃-TPD and XPS. The surface area values, TGA and XRD results indicate that the larger thermal stability and larger dispersion of vanadium species is reached for the VO/CNT-NH₂ catalyst. XPS indicates presence of surface VO₂ and V₂O₅ species for the non-functionalized (CNT) and functionalized (CNT-COOH and CNT-NH₂) catalysts, with a large interaction of the functional group with the surface vanadium species only for the VO/CNT-NH₂ catalyst. The catalytic activity, evaluated in the range 305 °C to 350 °C, indicates that CO, CO₂ and MA yield (%) and MA productivity are associated to the redox properties of the vanadium species, the oxygen exchange ability of the support and the vanadium–support interaction. For the reaction temperatures between 320 °C and 335 °C, the maximum MA yield (%) is found in the functionalized VO/CNT-COOH and VO/CNT-NH₂ catalysts. This behavior is attributed to a decreased oxidation capability of the CNT with the functionalization. In addition, VO/CNT-NH₂ is the more active and selective catalyst for MA productivity at 305 °C and 320 °C, which is related to the greater interaction of the surface vanadium species with the -NH₂ group, which enhances the redox properties and stabilization of the VO₂ and V₂O₅ surface active sites. Recycling at 350 °C resulted in 100% furfural conversion for all catalysts and a similar MA yield (%) compared to the fresh catalyst, indicating no loss of surface active sites. Full article

The hydroxylated carbon nanotubes (CNTs-OH), due to their propensity to trap electrons, are considered in many applications. Despite many case studies, the effect of the electronic structure of the CNT-OH electrode on its oxidation properties has not received in-depth analysis. In the present study, we used Fe(CN)₆^3−/4− and Ru(NH₃)₆^3+/2+ as redox probes, which differ in charge. The CNT-OH and CNT electrodes used in the cyclic voltammetry were in the form of freestanding films. The concentration of holes in the CNTs-OH, estimated from the upshift of the Raman G-feature, was $2.9\times {10}^{13} {\mathrm{c}\mathrm{m}}^{-2}$. The standard rate constant of the heterogeneous electron transfer (HET) between Fe(CN)₆^3−/4− and the CNTs-OH electrode was $25.9\times {10}^{-4} \mathrm{c}\mathrm{m}·{\mathrm{s}}^{-1}$. The value was more than four times higher than the HET rate on the CNT electrode ($k_s=6.3\times {10}^{-4} \mathrm{c}\mathrm{m}·{\mathrm{s}}^{-1}$), which proves excellent boosting of the redox reaction by the holes. The opposite effect was observed for the Ru(NH₃)₆^3+/2+ redox couple. While the redox reaction rate constant at the CNT electrode was $1.4\times {10}^{-4} \mathrm{c}\mathrm{m}·{\mathrm{s}}^{-1}$, there was a significant suppression of the redox reaction at the CNT-OH electrode ($k_s<0.1\times {10}^{-4} \mathrm{c}\mathrm{m}·{\mathrm{s}}^{-1}$). Based on the DFT calculations and the Gerischer model, we find that the boosting of the HET from the reduced form of the redox couple to CNT-OH occurs when the reduced forms of the redox couples are negatively charged and the occupied reduced states are aligned with acceptor states of the nanotube electrode. Full article

Gemcitabine (2′,2′-difluoro-2′-deoxycytidine), a widely used anticancer drug, is considered a gold standard in treating aggressive pancreatic cancers. Gamma-proteobacteria that colonize the pancreatic tumors contribute to chemoresistance against gemcitabine by metabolizing the drug to a less active and deaminated form. The gemcitabine transporters of these bacteria are unknown to date. Furthermore, there is no complete knowledge of the gemcitabine transporters in Escherichia coli or any other related proteobacteria. In this study, we investigate the complement of gemcitabine transporters in E. coli K-12 and two common chemoresistance-related bacteria (Klebsiella pneumoniae and Citrobacter freundii). We found that E. coli K-12 has two high-affinity gemcitabine transporters with distinct specificity properties, namely, NupC and NupG, whereas the gemcitabine transporters of C. freundii and K. pneumoniae include the NupC and NupG orthologs, functionally indistinguishable from their counterparts, and, in K. pneumoniae, one additional NupC variant, designated KpNupC2. All these bacterial transporters have a higher affinity for gemcitabine than their human counterparts. The highest affinity (K_M 2.5–3.0 μΜ) is exhibited by NupGs of the bacteria-specific nucleoside-H⁺ symporter (NHS) family followed by NupCs (K_M 10–13 μΜ) of the concentrative nucleoside transporter (CNT) family, 15–100 times higher than the affinities reported for the human gemcitabine transporter hENT1/SLC29A1, which is primarily associated with gemcitabine uptake in the pancreatic adenocarcinoma cells. Our results offer a basis for further insight into the role of specific bacteria in drug availability within tumors and for understanding the structure–function differences of bacterial and human drug transporters. Full article

Effectively enhancing oil recovery can be achieved by reducing the viscosity of crude oil. Therefore, this paper investigated the viscosity reduction behavior of carbon nanotube viscosity reducers with different molecular structures at the oil–water interface, aiming to guide the synthesis of efficient viscosity reducers based on molecular structure. This study selected carbon nanotubes with different functional groups (NH₂-CNT, OH-CNT, and COOH-CNT) for research, and carbon nanotubes with varying carbon chain lengths were synthesized. These were then combined with Tween 80 to form a nanofluid. Scanning electron microscopy analysis revealed an increased dispersibility of carbon nanotubes after introducing carbon chains. Contact angle experiments demonstrated that -COOH exhibited the best hydrophilic effect. The experiments of zeta potential, conductivity, viscosity reduction, and interfacial tension showed that, under the same carbon chain length, the conductivity and viscosity reduction rate sequence for different functional groups was -NH₂ < -OH < -COOH. The dispersing and stabilizing ability and interfacial tension reduction sequence for different functional groups was -COOH < -OH < -NH₂. With increasing carbon chain length, conductivity and interfacial tension decreased, and the viscosity reduction rate and the dispersing and stabilizing ability increased. Molecular dynamics simulations revealed that, under the same carbon chain length, the diffusion coefficient sequence for different functional groups was -NH₂ < -OH < -COOH. The diffusion coefficient gradually decreased as the carbon chain length increased, resulting in better adsorption at the oil–water interface. This study holds significant importance in guiding viscosity reduction in heavy oil to enhance oil recovery. Full article

CNT-NH₂-Cu-BTC was prepared via hydrothermal synthesis for the adsorption and separation of CO₂/CH₄ mixtures with 2, 6, and 10% multiwalled carbon nanotube (MWCNT) additions. NH₂-BTC composites were synthesized by changing the organic ligand and adding NH₂-BDC (15, 25, 35, and 45%) to improve the adsorption capacity. MWCNTS were loaded to enhance the water stability of the material. The structure, surface morphology, and pore size distribution of the composites were characterized using X-ray diffraction, scanning electron microscopy, Fourier transform infrared spectroscopy, thermogravimetric analysis, and specific surface area and pore structure measurements. The CO₂/CH₄ selective adsorption performance was studied via breakthrough experiments using a self-made adsorption device. The CO₂ adsorption capacity of Cu-BTC increased due to the addition of NH₂-BDC, with 35%NH₂-Cu-BTC exhibiting the best CO₂ adsorption property, i.e., a CO₂ adsorption capacity of 1.82 mmol/g and a CO₂/CH₄ separation coefficient of 1.44 at 35 °C and 20 mL/min. After adding MWCNTs, 6%CNT-NH₂-Cu-BTC exhibited the best CO₂ adsorption property and water stability, with the CO₂ adsorption capacity increasing to 2.06 mmol/g. 6%CNT-NH₂-Cu-BTC with wet impregnation retained 79% of the CO₂ adsorption capacity of the sample without wet impregnation, demonstrating its excellent water stability under humid conditions. Cyclic experiments with and without wet impregnation were performed. Full article

A Zn–air battery serves as an energy storage solution to address fossil energy and environmental concerns. However, sluggish kinetics in oxygen reduction reactions (ORRs) and oxygen evolution reactions (OERs) demand innovative, cost-effective, and stable bifunctional catalysts to replace precious metal catalysts. In this study, an FeCo-CNTs/KB catalyst was synthesized by pyrolyzing NH₂-MIL-101(Fe) coated with glu-Co and conductive carbon (KB). This hierarchical structure comprises carbon nanotubes (CNTs) grafted onto a carbon matrix, housing abundant FeCo nanoparticles within the nanotubes or matrix. KB introduction enhances FeCo nanoparticle dispersion and fosters uniform CNT formation with smaller diameters, thus exposing active sites. Consequently, the FeCo-CNTs/KB catalyst exhibits remarkable bifunctional electrocatalytic activity: an ORR half-wave potential of 0.84 V and an OER overpotential of 0.45 V (10 mA cm⁻²). Furthermore, the FeCo-CNTs/KB catalyst in a secondary Zn–air battery showcases enduring charge–discharge performance (≥300 h). Full article

Lithium–sulfur (Li–S) batteries are expected to be one of the next generations of high-energy-density battery systems due to their high theoretical energy density of 2600 Wh kg⁻¹. Embracing the trends toward flexibility, lightweight design, and cost-effectiveness, paper-based electrodes offer a promising alternative to traditional coated cathodes in Li–S batteries. Within paper-based electrodes, conductive fibers such as carbon nanotubes (CNTs) play a crucial role. They help to form a three-dimensional network within the paper matrix to ensure structural integrity over extended cycling while mitigating the shuttle effect by confining sulfur within the cathode. Herein, we explore how variously functionalized CNTs, serving as conductive fibers, impact the physical and electrochemical characteristics of paper-based sulfur cathodes in Li–S batteries. Specifically, graphitized hydroxylated carbon nanotubes (G-CNTs) exhibit remarkable capacity at low currents owing to their excellent conductivity and interaction with lithium polysulfide (LiPS), achieving the highest initial specific capacity of 1033 mAh g⁻¹ at 0.25 C (1.1 mA cm⁻²). Aminated multi-walled carbon nanotubes (NH₂-CNTs) demonstrate an enhanced affinity for LiPS due to the -NH₂ groups. However, the uneven distribution of these fibers may induce electrode surface passivation during charge–discharge cycles. Notably, hydroxylated multi-walled carbon nanotubes (OH-CNTs) can establish a uniform and stable 3D network with plant fibers, showcasing superior mechanical properties and helping to mitigate Li₂S agglomeration while preserving the electrode porosity. The paper-based electrode integrated with OH-CNTs even retains a specific capacity of approximately 800 mAh g⁻¹ at about 1.25 C (5 mA cm⁻²), demonstrating good sulfur utilization and rate capacity compared to other CNT variants. Full article

The present study focuses on the multifunctional capabilities of carbon nanotube (CNT)-reinforced vitrimers. More specifically, the thermomechanical properties, the Joule effect heating capabilities, the electrical conductivity, the shape memory, and the chemical recycling capacity are explored as a function of the CNT content and the NH₂/epoxy ratio. It is observed that the electrical conductivity increases with the CNT content due to a higher number of electrical pathways, while the effect of the NH₂/epoxy ratio is not as prevalent. Moreover, the T_g of the material decreases when increasing the NH₂/epoxy ratio due to the lower cross-link density, whereas the effect of the CNTs is more complex, in some cases promoting a steric hindrance. The results of Joule heating tests prove the suitability of the proposed materials for resistive heating, reaching average temperatures above 200 °C when applying 100 V for the most electrically conductive samples. Shape memory behavior shows an outstanding shape fixity ratio in every case (around 100%) and a higher shape recovery ratio (95% for the best-tested condition) when decreasing the NH₂/epoxy ratio and increasing the CNT content, as both hinder the rearrangement of the dynamic bonds. Finally, the results of the recyclability tests show the ability to regain the nanoreinforcement for their further use. Therefore, from a multifunctional analysis, it can be stated that the proposed materials present promising properties for a wide range of applications, such as Anti-icing and De-icing Systems (ADIS), Joule heating devices for comfort or thermotherapy, or self-deployable structures, among others. Full article

The primary objective of this research was to develop efficient solid catalysts that can directly convert the lactic acid (LA) obtained from lignocellulosic biomass into alanine (AL) through a reductive amination process. To achieve this, various catalysts based on ruthenium were synthesized using different carriers such as multi-walled carbon nanotubes (MWCNTs), beta-zeolite, and magnetic nanoparticles (MNPs). Among these catalysts, Ru/MNP demonstrated a remarkable yield of 74.0% for alanine at a temperature of 200 °C. This yield was found to be superior not only to the Ru/CNT (55.7%) and Ru/BEA (6.6%) catalysts but also to most of the previously reported catalysts. The characterization of the catalysts and their catalytic results revealed that metallic ruthenium nanoparticles, which were highly dispersed on the external surface of the magnetic carrier, significantly enhanced the catalyst’s ability for dehydrogenation. Additionally, the -NH₂ basic sites on the catalyst further facilitated the formation of alanine by promoting the adsorption of acidic reactants. Furthermore, the catalyst could be easily separated using an external magnetic field and exhibited the potential for multiple reuses without any significant loss in its catalytic performance. These practical advantages further enhance its appeal for applications in the reductive amination of lactic acid to alanine. Full article