multi-walled carbon nanotubes Dotaz Zobrazit nápovědu
The studies focusing on magnesium oxychloride cement (MOC) composites have recently become fairly widespread because of MOC's excellent mechanical properties and environmental sustainability. Numerous fillers, admixtures and nano-dopants were studied in order to improve the overall performance of MOC-based derivatives. Some of them exhibited specific flaws, such as a tendency to aggregate, increase in porosity, aeration of the composite matrix, depreciation in water resistance and mechanical strength, etc. In this manuscript, MOC-based composites doped by multi-walled carbon nanotubes (MWCNTs) are designed and tested. In order to modify the final properties of composites, diatomite was admixed as partial substitution of MgO, which was used in the composition of the researched material in excess, i.e., the majority of MgO constituted part of MOC and the rest served as fine filler. The composites were subjected to the broad experimental campaign that covered SEM (scanning electron microscopy), EDS (energy dispersive spectroscopy), HR-TEM (high-resolution transmission electron microscopy), XRD (X-ray diffraction), OM (optical microscopy) and STA-MS (simultaneous thermal analysis with mass spectroscopy). For 28 days hardened samples, macrostructural and microstructural parameters, mechanical properties, hygric and thermal characteristics were experimentally assessed. The incorporation of MWCNTs and diatomite resulted in the significant enhancement of composites' compactness, mechanical strength and stiffness and reduction in water absorption and rate of water imbibition. The thermal properties of the enriched MOC composites yielded interesting values and provided information for future modification of thermal performance of MOC composites with respect to their specific use in practice, e.g., in passive moderation of indoor climate. The combination of MWCNTs and diatomite represents a valuable modification of the MOC matrix and can be further exploited in the design and development of advanced building materials and components.
- Klíčová slova
- diatomite, magnesium oxychloride cement, mechanical and thermal performance, multi-walled carbon nanotubes, structure analysis, thermal stability,
- Publikační typ
- časopisecké články MeSH
Reproductive toxicity of carboxyl-functionalised carbon nanotubes (CNT-COOH), as the most commonly used form of water-soluble CNTs, is not clearly studied. The aim of this study was to investigate in vitro toxicity of carboxylated single-walled and multi-walled CNTs (SWCNT-COOH and MWCNT-COOH) against human spermatozoa. Sperm cells from healthy donors were incubated with 0.1-100 μg/ml of SWCNT-COOH or MWCNT-COOH at 37°C for up to 5 hr. Viability of sperm cells was assessed using MTT test, and sperm motility was evaluated following World Health Organization guideline. Production of reactive oxygen species (ROS) and nitric oxide (NO) in sperm was also assessed. We showed that both MWCNT-COOH and SWCNT-COOH following incubation in vitro with human spermatozoa did not exert negative effect on viability while motility was significantly (p < .05) dropped in a dose-dependent manner. Moreover, there was no significant effect of the type, dose and exposure time of the CNT-COOH on NO production. Exposure of sperm cells to both examined types of CNTs at concentrations as low as 0.1 μg/ml caused a significant increase in ROS levels. In conclusion, carboxylated forms of CNTs seem to be harmful for human spermatozoa. Further studies, especially using in vivo models, are needed to decide about reprotoxicity of carboxylated forms of CNTs.
- Klíčová slova
- carboxylated carbon nanotubes, human spermatozoa, motility, oxidative stress, viability,
- MeSH
- lidé MeSH
- nanotrubičky uhlíkové toxicita MeSH
- spermie účinky léků MeSH
- testy toxicity MeSH
- Check Tag
- lidé MeSH
- mužské pohlaví MeSH
- Publikační typ
- časopisecké články MeSH
- Názvy látek
- nanotrubičky uhlíkové MeSH
Molecular magnets attached to carbon nanotubes (CNT) are being studied as potential candidates for developing spintronic and quantum technologies. However, the functionalization routes used to develop these hybrid systems can drastically affect their respective physiochemical properties. Due to the complexity of this systems, little work has been directed at establishing the correlation between the degree of functionalization and the magnetic character. Here, we demonstrate the chemical functionalization degree associated with molecular magnet loading can be utilized for controlled tuning the magnetic properties of a CNT-lanthanide hybrid complex. CNT functionalization degree was evaluated by interpreting minor Raman phonon modes in relation to the controlled reaction conditions. These findings were exploited in attaching a rare-earth-based molecular magnet (Gd-DTPA) to the CNTs. Inductively coupled plasma mass spectrometry, time-of-flight secondary ion mass spectrometry and super conducting quantum interference device (SQUID) measurements were used to elucidate the variation of magnetic character across the samples. This controlled Gd-DTPA loading on the CNT surface has led to a significant change in the nanotube intrinsic diamagnetism, showing antiferromagnetic coupling with increase in the Weiss temperature with respect to increased loading. This indicates that synthesis of a highly correlated spin system for developing novel spintronic technologies can be realized through a carbon-based hybrid material.
- Klíčová slova
- Raman spectroscopy, multi-walled carbon nanotubes, spintronics,
- MeSH
- diethylentriaminpentaacetát gadolinia chemie MeSH
- lanthanoidy chemie MeSH
- magnetické jevy MeSH
- magnety chemie MeSH
- nanotrubičky uhlíkové chemie ultrastruktura MeSH
- Ramanova spektroskopie MeSH
- spektrometrie hmotnostní sekundárních iontů MeSH
- transmisní elektronová mikroskopie MeSH
- Publikační typ
- časopisecké články MeSH
- Názvy látek
- diethylentriaminpentaacetát gadolinia MeSH
- lanthanoidy MeSH
- nanotrubičky uhlíkové MeSH
Injectable materials have shown great potential in tissue engineering applications. However, bacterial infection is one of the main challenges in using these materials in the field of regenerative medicine. In this study, biogenically synthesized silver nanoparticle-decorated multi-walled carbon nanotubes (Ag/MWCNTs) were deployed for adorning biogenic-derived AgNPs which were subsequently used in the preparation of thermosensitive hydrogels based on hyaluronic acid encompassing these green-synthesized NPs. The antibacterial capacity of AgNPs decorated on MWCNTs synthesized through Camellia sinensis extract in an organic solvent-free medium displayed a superior activity by inhibiting the growth of Gram-negative (E. coli and Klebsiella) and Gram-positive (S. aureus and E. faecalis). The injectable hydrogel nanocomposites demonstrated good mechanical properties, as well. The thermosensitive hyaluronic acid-based hydrogels also exhibited Tgel below the body temperature, indicating the transition from liquid-like behavior to elastic gel-like behavior. Such a promising injectable nanocomposite could be applied as liquid, pomade, or ointment to enter wound cavities or bone defects and subsequently its transition in situ to gel form at human body temperature bodes well for their immense potential application in the biomedical sector.
- Klíčová slova
- Ag NPs, Antibacterial, Camellia sinensis, Green synthesis, Injectable nanocomposite, Nanomedicine, Thermosensitive hydrogels,
- Publikační typ
- časopisecké články MeSH
The supply of safe drinking and clean water is becoming increasingly challenging proposition throughout the world. The deployment of environmentally sustainable nanomaterials with unique advantages namely high efficiency and selectivity, earth-abundance, recyclability, low-cost of production processes, and stability, has been a priority although several important challenges and constraints still remained unresolved. Carbon nanomaterials namely activated carbon, multi-walled- and single-walled carbon nanotubes, have been developed and applied as adsorbents for wastewater treatment and purification; graphene and graphene oxide-based nanomaterials as well as carbon and graphene quantum dots-derived nanomaterials have shown significant promise for water and wastewater treatment and purification, especially, for industrial- and pharmaceutical-laden wastes. This review encompasses advanced carbonaceous nanomaterials and methodologies that are deployed for the elimination of contaminants and ionic metals in aqueous media, and as novel nanosorbents for wastewater, drinking and ground water treatment. Additionally, recent trends and challenges pertaining to the sustainable carbon and graphene quantum dots-derived nanomaterials and their appliances for treating and purifying wastewater are highlighted.
- Klíčová slova
- Carbon dots, Carbon nanotubes, Graphene, Quantum dots, Sustainable nanomaterials, Wastewater treatment,
- MeSH
- čištění vody * MeSH
- nanostruktury * MeSH
- nanotrubičky uhlíkové * MeSH
- odpadní voda MeSH
- voda MeSH
- Publikační typ
- časopisecké články MeSH
- přehledy MeSH
- Názvy látek
- nanotrubičky uhlíkové * MeSH
- odpadní voda MeSH
- voda MeSH
The design of a unipole and a dual band F-shaped antenna was conducted to find the best parameters of prepared antenna. Antenna radiator part is fully made of polymer and nonmetal base composite. Thermoplastic polyurethane (PU) was chosen as a matrix and multi-wall carbon nanotubes (MWCNT) as an electrical conductive filler, which creates conductive network. The use of the composite for the antenna has the advantage in simple preparation through dip coating technique. Minor disadvantage is the usage of solvent for composite preparation. Composite structure was used for radiator part of antenna. The antenna operates in 2.45 and 5.18 GHz frequency bands. DC conductivity of our PU/MWCNT composite is about 160 S/m. With this material, a unipole and a dual band F antenna were realized on 2 mm thick polypropylene substrate. Both antenna designs were also simulated using finite integration technique in the frequency domain (FI-FD). Measurements and full wave simulations of S11 of the antenna showed good agreement between measurements and simulations. Except for S11, the gain and radiation pattern of the antennas were measured and simulated. Maximum gain of the designed unipole antenna is around -10.0 and -5.5 dBi for 2.45 and 5.18 GHz frequency bands, respectively. The manufactured antennas are intended for application in wearable electronics, which can be used to monitor various activities such as walking, sleeping, heart rate or food consumption.
- Klíčová slova
- carbon nanotubes, composite material, effective conductivity, effective permeability, effective permittivity, polymer antenna, wearable electronics,
- Publikační typ
- časopisecké články MeSH
Poly(ε-caprolactone) (PCL) is a biocompatible resorbable material, but its use is limited due to the fact that it is characterized by the lack of cell adhesion to its surface. Various chemical and physical methods are described in the literature, as well as modifications with various nanoparticles aimed at giving it such surface properties that would positively affect cell adhesion. Nanomaterials, in the form of membranes, were obtained by the introduction of multi-walled carbon nanotubes (MWCNTs and functionalized nanotubes, MWCNTs-f) as well as electro-spun carbon nanofibers (ESCNFs, and functionalized nanofibers, ESCNFs-f) into a PCL matrix. Their properties were compared with that of reference, unmodified PCL membrane. Human osteoblast-like cell line, U-2 OS (expressing green fluorescent protein, GFP) was seeded on the evaluated nanomaterial membranes at relatively low confluency and cultured in the standard cell culture conditions. The attachment and the growth of the cell populations on the polymer and nanocomposite samples were monitored throughout the first week of culture with fluorescence microscopy. Simultaneously, Raman microspectroscopy was also used to track the dependence of U-2 OS cell development on the type of nanomaterial, and it has proven to be the best method for the early detection of nanomaterial/cell interactions. The differentiation of interactions depending on the type of nanoadditive is indicated by the ν(COC) vibration range, which indicates the interaction with PCL membranes with carbon nanotubes, while it is irrelevant for PCL with carbon nanofibers, for which no changes are observed. The vibration range ω(CH2) indicates the interaction for PCL with carbon nanofibers with seeded cells. The crystallinity of the area ν(C=O) increases for PCL/MWCNTs and for PCL/MWCNTs-f, while it decreases for PCL/ESCNFs and for PCL/ESCNFs-f with seeded cells. The crystallinity of the membranes, which is determined by Raman microspectroscopy, allows for the assessment of polymer structure changes and their degradability caused by the secretion of cell products into the ECM and the differentiation of interactions depending on the carbon nanostructure. The obtained nanocomposite membranes are promising bioactive materials.
Graphene oxide (GO) and multi-walled carbon nanotubes (MWCNTs) were added to furcellaran films (FUR). Silver nanoparticles (AgNPs) were prepared by reducing AgNO3 using a FUR matrix as the stabilising agent. The structure and surface morphology of nanocomposite films were obtained using FTIR, SEM and XRD. The molecular weights of furcellaran chains were estimated using HPSEC-MALLS-RI. Characterisation of the films was undertaken to analyse their physical, mechanical and structural properties. SEM analysis revealed that GO, MWCNTs and AgNPs were evenly distributed throughout the FUR surface. FUR + AgNP films showed antimicrobial activity against bacteria and fungi. P. aeruginosa, E. faecalis and S. aureus were the most affected with effective growth inhibition using the disc diffusion method. In the study, the effect of nanofillers on the structural, thermal, mechanical and antimicrobial properties of furcellaran films as potential materials for food packaging is presented.
- Klíčová slova
- Furcellaran, Graphene oxide, Multi-walled carbon nanotubes, Nanocomposite films, Nanofillers, Silver nanoparticles,
- MeSH
- algináty chemie MeSH
- antibakteriální látky chemie farmakologie MeSH
- Bacteria účinky léků MeSH
- biopolymery chemie MeSH
- grafit chemie MeSH
- kovové nanočástice chemie MeSH
- nanokompozity chemie MeSH
- nanotrubičky uhlíkové chemie MeSH
- rostlinné gumy chemie MeSH
- stříbro chemie MeSH
- Publikační typ
- časopisecké články MeSH
- Názvy látek
- algináty MeSH
- antibakteriální látky MeSH
- biopolymery MeSH
- furcellaran MeSH Prohlížeč
- grafit MeSH
- graphene oxide MeSH Prohlížeč
- nanotrubičky uhlíkové MeSH
- rostlinné gumy MeSH
- stříbro MeSH
