Multiwalled Carbon Nanotubes-Reprogrammed Macrophages Facilitate Breast Cancer Metastasis via NBR2/TBX1 Axis

In recent years, carbon nanotubes have emerged as a widely used nanomaterial, but their human exposure has become a significant concern. In our former study, we reported that pulmonary exposure of multiwalled carbon nanotubes (MWCNTs) promoted tumor metastasis of breast cancer; macrophages were key effectors of MWCNTs and contributed to the metastasis-promoting procedure in breast cancer, but the underlying molecular mechanisms remain to be explored. As a follow-up study, we herein demonstrated that MWCNT exposure in breast cancer cells and macrophage coculture systems promoted metastasis of breast cancer cells both in vitro and in vivo; macrophages were skewed into M2 polarization by MWCNT exposure. LncRNA NBR2 was screened out to be significantly decreased in MWCNTs-stimulated macrophages through RNA-seq; depletion of NBR2 led to the acquisition of M2 phenotypes in macrophages by activating multiple M2-related pathways. Specifically, NBR2 was found to positively regulate the downstream gene TBX1 through H3k27ac activation. TBX1 silence rescued NBR2-induced impairment of M2 polarization in IL-4 & IL-13-stimulated macrophages. Moreover, NBR2 overexpression mitigated the enhancing effects of MWCNT-exposed macrophages on breast cancer metastasis. This study uncovered the molecular mechanisms underlying breast cancer metastasis induced by MWCNT exposure.

Pyrolysis-catalysis upcycling of waste plastic using a multilayer stainless-steel catalyst toward a circular economy

Current un-sustainable plastic management is exacerbating plastic pollution, an urgent shift is thus needed to create a recycling society. Such recovering carbon (C) and hydrogen (H) from waste plastic has been considered as one practical route to achieve a circular economy. Here, we performed a simple pyrolysis-catalysis deconstruction of waste plastic via a monolithic multilayer stainless-steel mesh catalyst to produce multiwalled carbon nanotubes (MWCNTs) and H2, which are important carbon material and energy carrier to achieve sustainable development. Results revealed that the C and H recovery efficiencies were as high as 86% and 70%, respectively. The unique oxidation-reduction process and improvement of surface roughness led to efficient exposure of active sites, which increased MWCNTs by suppressing macromolecule hydrocarbons. The C recovery efficiency declined by only 5% after 10 cycles, proving the long-term employment of the catalyst. This catalyst can efficiently convert aromatics to MWCNTs by the vapor-solid-solid mechanism and demonstrate good universality in processing different kinds of waste plastics. The produced MWCNTs showed potential in applications of lithium-ion batteries and telecommunication. Owing to the economic profits and environmental benefits of the developed route, we highlighted its potential as a promising alternative to conventional incineration, simultaneously achieving the waste-to-resource strategy and circular economy.

Interlaminar Properties of Prepregs Reinforced with Multiwalled Carbon Nanotubes/Graphene Oxide

Carbon-fiber-reinforced polymer (CFRP) composites are widely used in industries such as aerospace due to their lightweight nature and high strength. However, weak interfacial bonding strength is one of the main problems of resin-based composites. In this study, a prepreg was prepared by melt mixing. By dispersing nanoreinforcement particles in the resin, the interlaminar shear strength of the CFRP was increased by approximately 23.6%. When only 0.5 wt% multiwalled carbon nanotube (MWCNT) was used for reinforcement, scanning electron microscopy (SEM) micrographs showed that cracks were hindered by the MWCNTs during propagation, causing crack deflection. At the same time, the mechanism of MWCNTs pulling out increased the energy required for crack propagation. When only 0.5 wt% graphene oxide (GO) was added, the reinforcement effect was inferior to that of using the same amount of MWCNTs. The laminar structure formed by GO and the resin matrix adhered to the carbon fiber surface, reducing the degree of destruction of the resin matrix, but its hindering effect on crack propagation was weak. When 0.5 wt% of MWCNT and GO mixture was added, the interlayer shear strength increased from 55.6 MPa in the blank group to 68.7 MPa. The laminar structure of GO provided a platform for the MWCNTs to form a mesh structure inside its matrix. At the same time, the tubular structure of the MWCNTs inhibited the stacking of GO, providing better dispersion and forming a synergistic enhancement effect.

Biocatalytic asymmetric synthesis of secondary allylic alcohols using Burkholderia cepacia lipase immobilized on multiwalled carbon nanotubes

The lipase from Burkholderia cepacia (BCL) was immobilized through physical adsorption on pristine and functionalized multiwalled carbon nanotubes (MWCNTs) with carboxyl or amine groups and used in the stereoselective acylation of (R,S)-1-octen-3-ol (1) and (R,S)-(E)-4-phenyl-3-buten-2-ol (4) with vinyl acetate. All immobilized preparations produced better results than free BCL. For (R,S)-4, 50% conversion and E > 200 were obtained in n-hexane or in solvent-free medium. For (R,S)-1, in solvent-free medium, the conversion was 38% with a slight increase in the E-value (E = 10).

Electrochemical Analysis of Sulfisoxazole Using Glassy Carbon Electrode (GCE) and MWCNTs/Rare Earth Oxide (CeO2 and Yb2O3) Modified-GCE Sensors

In this work, new electrochemical sensors based on the modification of glassy carbon electrode (GCE) with multiwalled carbon nanotubes (MWCNTs)-rare metal oxides (REMO) nanocomposites were fabricated by drop-to-drop method of MWCNTs-REMO dispersion in ethanol. REMO nanoparticles were synthesized by precipitation followed by hydrothermal treatment at 180 °C in absence and presence of Triton^TM X-100 surfactant. Cyclic voltammetry (CV) analysis using MWCNTs-CeO₂@GCE and MWCNTs-Yb₂O₃@GCE sensors were used for the analysis of sulfisoxazole (SFX) drug in water samples. The results of CV analysis showed that MWCNTs-REMO@GCE sensors have up to 40-fold higher sensitivity with CeO₂ compared to the bare GCE sensor. The estimated values of the limit of detection (LoD) of this electrochemical sensing using MWCNTs-CeO₂@GCE and MWCNTs-Yb₂O₃@GCE electrodes reached 0.4 and 0.7 μM SFX in phosphate buffer pH = 7, respectively. These findings indicate that MWCNTs-REMO@GCE electrodes are potential sensors for analysis of sulfonamide drugs in water and biological samples.

Multi-Wall Carbon Nanotubes Promote the Growth of Maize (Zea mays) by Regulating Carbon and Nitrogen Metabolism in Leaves

Previous studies have suggested that multiwalled carbon nanotubes (MWCNTs) promote plant growth; however, the mechanism is yet to be fully understood. In this study, the effects of MWCNTs (20, 100, and 500 mg/L) on the carbon (C) and nitrogen (N) metabolism in maize were studied to explore the molecular mechanism of the action of MWCNTs on plants. The results showed that 100 mg/L MWCNTs increased the shoot fresh and dry weight, root fresh weight, and seedling length while other doses showed no significant effects. Further studies showed that 100 mg/L MWCNTs increased the chlorophyll content, transpiration rate, stomatal conductance, and intercellular CO₂ concentration, by 50.6%, 60.8%, 47.2%, and 32.1%, respectively. Activities of key enzymes including sucrose synthase (SS), sucrose phosphate synthase (SPS) and phosphoenolpyruvate carboxylase (PEPC) that are involved in the carbon metabolism, and nitrate reductase (NR), glutamine synthetase (GS), and glutamate synthetase (GOGAT) that are involved in N metabolism, were all upregulated by 100 mg/L MWCNTs, which contributed to the increase of the accumulation of carbohydrates (sugar and starch), soluble protein, and N in plants. These findings suggest that MWCNTs can improve plant growth by regulating the key enzymes involved in C and N metabolism thereby enhancing the carbohydrate production and the use of N and improving plant growth. This study provides significant insights into the molecular mechanism of the positive effects of MWCNTs on plants and provide a basis for the agricultural application of MWCNTs.

All-Solid-State Potentiometric Ion-Sensors Based on Tailored Imprinted Polymers for Pholcodine Determination

In recent times, the application of the use of ion-selective electrodes has expanded in the field of pharmaceutical analyses due to their distinction from other sensors in their high selectivity and low cost of measurement, in addition to their high measurement sensitivity. Cost-effective, reliable, and robust all-solid-state potentiometric selective electrodes were designed, characterized, and successfully used for pholcodine determination. The design of the sensor device was based on the use of a screen-printed electrode modified with multiwalled carbon nanotubes (MWCNTs) as a solid-contact transducer. Tailored pholcodine (PHO) molecularly imprinted polymers (MIPs) were prepared, characterized, and used as sensory receptors in the presented potentiometric sensing devices. The sensors exhibited a sensitivity of 31.6 ± 0.5 mV/decade (n = 5, R² = 0.9980) over the linear range of 5.5 × 10⁻⁶ M with a detection limit of 2.5 × 10⁻⁷ M. Real serum samples in addition to pharmaceutical formulations containing PHO were analyzed, and the results were compared with those obtained by the conventional standard liquid chromatographic approach. The presented analytical device showed an outstanding efficiency for fast, direct, and low-cost assessment of pholcodine levels in different matrices.

Ionic Liquid-Functionalized Multiwalled Carbon Nanotube-Based Hydrophobic Coatings for Robust Antibacterial Applications

In recent years, the biomimetic superhydrophobic coatings have received tremendous attention, owing to their potential in fabricating self-cleaning surfaces, in environmental applications. Consequently, extensive research has been devoted to create a superhydrophobic surface using the oxidized derivatives of CNTs and graphene. Thus, the design and development of a self-cleaning/superhydrophobic surface with good biocompatibility are an effective approach to deal with the bacterial infections related to biomedical devices used in hospitals. In this context, herein, we have developed the material based on ionic liquid (IL)-functionalized multiwalled carbon nanotubes (MWCNTs) for hydrophobic coatings, which was fully characterized with various techniques such as Fourier transform infrared, powder X-ray diffraction, energy-dispersive X-ray spectroscopy, and scanning electron microscopy. We have evaluated the synthesized ILs for their antibacterial potential against the pathogenic bacterial strains such as Gram-positive (Staphylococcus aureus and methicillin-resistant S. aureus) and Gram-negative (Escherichia coli) bacterial strains. Further, atomic force and scanning electron microscopic studies have been performed to investigate the morphological changes to unravel the mechanism of action, whereas DNA binding study indicates the binding of IL-1d@MWCNT with DNA (K_a = 2.390 × 10⁴ M^-1). Furthermore, the developed material (IL-1d@MWCNT) is coated onto the surface of polyvinyl chloride (PVC) and evaluated for hydrophobicity through water contact angle measurements and possesses long-term antibacterial efficiency against both under-investigating pathogenic strains. For the biocompatibility assay, the obtained coated PVC material has also been evaluated for its cytotoxicity, and results reveal no toxicity against viable cells. These all results are taken together, indicating that by coating with the developed material IL-1d@MWCNT, a robust self-sterilizing surface has achieved, which helps in maintaining a bacteria-free surface.

Carbon Nanotube/Conducting Polymer Hybrid Nanofibers as Novel Organic Bioelectronic Interfaces for Efficient Removal of Protein-Bound Uremic Toxins

Protein-bound uremic toxins (PBUTs) can cause noxious effects in patients suffering from renal failure as a result of inhibiting the transport of proteins and inducing their structural modification. They are difficult to remove through standard hemodialysis (HD) treatment. Herein, we report an organic bioelectronic HD device system for the effective removal of PBUTs through electrically triggered dissociation of protein-toxin complexes. To prepare this system, we employed electrospinning to fabricate electrically conductive quaternary composite nanofiber mats-comprising multiwalled carbon nanotubes (MWCNTs), poly(3,4-ethylenedioxythiophene):polystyrenesulfonate (PEDOT:PSS), poly(ethylene oxide) (PEO), and (3-glycidyloxypropyl)trimethoxysilane (GOPS)-on conventional polyethersulfone (PES) dialysis membranes. These composite nanofiber platforms exhibited (i) long-term water resistance (due to cross-linking among PSS, PEO, and GOPS), (ii) high adhesion strength on the PES membrane (due to GOPS functioning as an adhesion promoter), (iii) enhanced electrical properties [due to the MWCNTs and PEDOT:PSS promoting effective electrical stimulation (ES) operation in devices containing bioelectronic interfaces (BEI)], and (iv) good anticoagulant ability and negligible hemolysis of red blood cells. We employed this organic BEI electronic system as a novel single-membrane HD device to study the removal efficiency of four kinds of uremic toxins [p-cresol (PC), indoxyl sulfate, and hippuric acid as PBUTs; creatinine as a non-PBUT] as well as the effects of ES on lowering the protein binding ratio. Our organic BEI devices provided a high rate of removal of PC with low protein loss after 4 h of a simulated dialysis process. It also functioned with low complement activation, low contact activation levels, and lower amounts of platelet adsorption, suggesting great suitability for use in developing next-generation bioelectronic medicines for HD.

Mechanically Robust 3D Nanostructure Chitosan-Based Hydrogels with Autonomic Self-Healing Properties

Fabrication of hydrogels based on chitosan (CS) with superb self-healing behavior and high mechanical and electrical properties has become a challenging and fascinating topic. Most of the conventional hydrogels lack these properties at the same time. Our objectives in this research were to synthesize, characterize, and evaluate the general properties of chitosan covalently cross-linked with zinc phthalocyanine tetra-aldehyde (ZnPcTa) framework. Our hope was to access an unprecedented self-healable three-dimensional (3D) nanostructure that would harvest the superior mechanical and electrical properties associated with chitosan. The properties of cross-linker such as the structure, steric effect, and rigidity of the molecule played important roles in determining the microstructure and properties of the resulting hydrogels. The tetra-functionalized phthalocyanines favor a dynamic Schiff-base linkage with chitosan to form a 3D porous nanostructure. Based on this strategy, the self-healing ability, as demonstrated by rheological recovery and macroscopic and microscopic observations, is introduced through dynamic covalent Schiff-base linkage between NH₂ groups in CS and benzaldehyde groups at cross-linker ends. The hydrogel was characterized using FT-IR, NMR, UV/vis, and rheological measurements. In addition, cryogenic scanning electron microscopy (cryo-SEM) was employed as a technique to visualize the internal morphology of the hydrogels. Study of the surface morphology of the hydrogel showed a 3D porous nanostructure with uniform morphology. Furthermore, incorporating the conductive nanofillers, such as carbon nanotubes (CNTs), into the structure can modulate the mechanical and electrical properties of the obtained hydrogels. Interestingly, these hydrogel nanocomposites proved to have very good film-forming properties, high modulus and strength, acceptable electrical conductivity, and excellent self-healing properties at neutral pH. Such properties can be finely tuned through variation of the cross-linker and CNT concentration, and as a result these structures are promising candidates for potential applications in various fields of research.

Characterization and in vitro studies of the anticancer effect of oxidized carbon nanotubes functionalized with betulinic acid

Among the array of nanomaterials, carbon nanotubes have shown great potential as drug carriers in the field of nanomedicine, owing to their attractive physicochemical structure, which facilitates functionalization of therapeutic molecules onto their external walls or being encapsulated inside the tubes. The aim of this preliminary study was to formulate betulinic acid (BA), a poorly water-soluble drug, in oxidized multiwalled carbon nanotubes (MWCNT-COOH) for enhanced delivery efficiency into cancer cells with reduced cytotoxicity. The synthesized MWCNT-BA nanocomposite was characterized using ultraviolet-visible, Fourier transform infrared, thermogravimetric analysis, powder X-ray diffraction, and field emission scanning electron microscopy techniques. The loading of BA in MWCNT-COOH nanocarrier was estimated to be about 14.5%-14.8% (w/w), as determined by ultraviolet-visible and thermogravimetric analysis. Fourier transform infrared study shows that the peaks of the resulting MWCNT-BA nanocomposite correlate to the characteristic functional groups of BA and MWCNT-COOH. The powder X-ray diffraction results confirmed that the tubular structures of MWCNT-COOH were not affected by the drug loading mechanism of BA. The release profiles demonstrated that approximately 98% of BA could be released within 22 hours by phosphate-buffered saline solution at pH 7.4 compared with about 22% within 24 hours at pH 4.8. The biocompatibility studies revealed that MWCNT-BA at concentrations <50μg/mL expressed no cytotoxicity effects for mouse embryo fibroblast cells after 72 hours of treatment. The anticancer activity of MWCNT-BA was observed to be more sensitive to human lung cancer cell line when compared with human liver cancer cell line, with half maximal inhibitory concentration values of 2.7 and 11.0μg/mL, respectively. Our findings form a fundamental platform for further investigation of the MWCNT-BA formulation against different types of cancer cells.