RESUMO
The inherent properties of boron nitride nanotubes (BNNTs) can be further enhanced through the control of their anisotropy. In particular, horizontally aligned BNNTs (HABNNTs) exhibit considerable potential for various applications. However, directly synthesizing HABNNTs is difficult owing to the random floating of BNNTs and the absence of directional forces. Here, we employed a simple, efficient, and universal "surface-like growth" strategy to synthesize high-density and high-quality HABNNTs in the W2B5/Zn precursor system. First, the floating range of BNNTs was restricted to the vicinity of the precursor, and then, directional forces were applied to induce BNNT directional growth along the substrate surface. Experiments and simulations confirmed that the HABNNT orientation could be controlled through manipulation of the directional forces. Furthermore, the strategy was employed for HABNNTs synthesis using the MoB2/Zn, further demonstrating the universality of the approach. Overall, this work offers a fresh perspective on the synthesis of HABNNTs, further expanding their potential applications.
RESUMO
All-solid-state lithium metal batteries (ASSLMBs) have emerged as the most promising next-generation energy storage devices. However, the unsatisfactory ionic conductivity of solid electrolytes at room temperature has impeded the advancement of solid-state batteries. In this work, a multifunctional composite solid electrolyte (CSE) is developed by incorporating boron nitride nanotubes (BNNTs) into polyvinylidene fluoride-hexafluoropropylene (PVDF-HFP). BNNTs, with a high aspect ratio, trigger the dissociation of Li salts, thus generating a greater population of mobile Li+, and establishing long-distance Li+ transport pathways. PVDF-HFP/BNNT exhibits a high ionic conductivity of 8.0 × 10-4 S cm-1 at room temperature and a Li+ transference number of 0.60. Moreover, a Li//Li symmetric cell based on PVDF-HFP/BNNT demonstrates robust cyclic performance for 3400 h at a current density of 0.2 mA cm-2. The ASSLMB formed from the assembly of PVDF-HFP/BNNT with LiFePO4 and Li exhibits a capacity retention of 93.2% after 850 cycles at 0.5C and 25 °C. The high-voltage all-solid-state LiCoO2/Li cell based on PVDF-HFP/BNNT also exhibits excellent cyclic performance, maintaining a capacity retention of 96.4% after 400 cycles at 1C and 25 °C. Furthermore, the introduction of BNNTs is shown to enhance the thermal conductivity and flame retardancy of the CSE.
RESUMO
The growing demand for self-powered systems and the slow progress in energy storage devices have led to the emergence of piezoelectric materials as a promising solution for energy harvesting. This study aims to investigate the effects of chirality, length, and strain rate on the piezoelectric potential of boron nitride nanotubes (BNNTs) through molecular dynamics simulation. Accurate data and guidance are provided to explain the piezoelectricity of chiral nanotubes, as the piezoelectric potentials of these nanotubes have previously remained unclear. The present study focuses on calculating the effect of these parameters based on the atomic model. The observed results stem from the frequencies and internal deformations, as the axial frequencies and deformations exhibit more substantial modifications compared to transverse directions. The piezoelectricity was found to depend on chirality, with the order of BNNT piezoelectricity sufficiency being in the sequence of zigzag > chirality > armchair configurations. The length of the BNNTs was also found to influence piezoelectricity, while the strain rate had no effect. The results also indicate that BNNTs can generate power in the milliwatts range, which is adequate for low-power electronic devices and Internet of Things applications. This research provides valuable insights into the piezoelectricity of chiral nanotubes and offers guidance for designing efficient energy harvesting devices.
RESUMO
The large-scale synthesis of high-quality boron nitride nanotubes (BNNTs) has attracted considerable interests due to their applications in nanocomposites, thermal management, and so on. Despite decades of development, efficient preparation of high-quality BNNTs, which relies on the effective design of precursors and catalysts and deep insights into the catalytic mechanisms, is still urgently needed. Here, a self-catalytic process is designed to grow high-quality BNNTs using ternary W-B-Li compounds. W-B-Li compounds provide boron source and catalyst for BNNTs growth. High-quality BNNTs are successfully obtained via this approach. Density functional theory-based molecular dynamics (DFT-MD) simulations demonstrate that the Li intercalation into the lattice of W2 B5 promotes the formation of W-B-Li liquid and facilitates the compound evaporation for efficient BNNTs growth. This work demonstrates a high-efficient self-catalytic growth of high-quality BNNTs via ternary W-B-Li compounds, providing a new understanding of high-quality BNNTs growth.
RESUMO
The toxicity of boron nitride nanotubes (BNNTs) has been the subject of conflicting reports, likely due to differences in the residuals and impurities that can make up to 30-60% of the material produced based on the manufacturing processes and purification employed. Four BNNTs manufactured by induction thermal plasma process with a gradient of BNNT purity levels achieved through sequential gas purification, water and solvent washing, allowed assessing the influence of these residuals/impurities on the toxicity profile of BNNTs. Extensive characterization including infrared and X-ray spectroscopy, thermogravimetric analysis, size, charge, surface area, and density captured the alteration in physicochemical properties as the material went through sequential purification. The material from each step is screened using acellular and in vitro assays for evaluating general toxicity, mechanisms of toxicity, and macrophage function. As the material increased in purity, there are more high-aspect-ratio particulates and a corresponding distinct increase in cytotoxicity, nuclear factor-κB transcription, and inflammasome activation. There is no alteration in macrophage function after BNNT exposure with all purity grades. The cytotoxicity and mechanism of screening clustered with the purity grade of BNNTs, illustrating that greater purity of BNNT corresponds to greater toxicity.
Assuntos
Compostos de Boro , Nanotubos , Compostos de Boro/toxicidade , Compostos de Boro/química , Macrófagos , Nanotubos/toxicidade , Nanotubos/químicaRESUMO
Enhancing the thermal conductivity of polymer composites could improve their performance in applications requiring fast heat dissipation. While significant progress has been made, a long-standing issue is the contact thermal resistance between the nanofillers, which could play a critical role in the composite thermal properties. Through systematic studies of contact thermal resistance between individual boron nitride nanotubes (BNNTs) of different diameters, with and without a poly(vinylpyrrolidone) (PVP) interlayer, we show that the contact thermal resistance between bare BNNTs is largely determined by reflection of ballistic phonons. Interestingly, it is found that a PVP interlayer can either enhance or reduce the contact thermal resistance, as a result of converting the ballistic phonon dominated transport into diffusion through the PVP layer. These results disclose a previously unrecognized physical picture of thermal transport at the contact between BNNTs, which provides insights into the design of high thermal conductivity BNNT-polymer composites.
RESUMO
Fullerenes, boron nitride nanotubes (BNNTs), and carbon nanotubes (CNTs) have all been extensively explored for biomedical purposes. This work describes the use of BNNTs and CNTs as mycolactone inhibitors. Density functional theory (DFT) has been used to investigate the chemical properties and interaction mechanisms of mycolactone with armchair BNNTs (5,5) and armchair CNTs (5,5). By examining the optimized structure and interaction energy, the intermolecular interactions between mycolactone and nanotubes were investigated. The findings indicate that mycolactone can be physically adsorbed on armchair CNTs in a stable condition, implying that armchair CNTs can be potential inhibitors of mycolactone. According to DOS plots and HOMO-LUMO orbital studies, the electronic characteristics of pure CNTs are not modified following mycolactone adsorption on the nanotubes. Because of mycolactone's large π-π interactions with CNTs, the estimated interaction energies indicate that mycolactone adsorption on CNTs is preferable to that on BNNTs. CNTs can be explored as potentially excellent inhibitors of mycolactone toxins in biological systems.
Assuntos
Nanotubos de Carbono , Nanotubos , Adsorção , Teoria da Densidade Funcional , Macrolídeos , Nanotubos/química , Nanotubos de Carbono/químicaRESUMO
INTRODUCTION: Chemotherapy with anti-cancer drugs is considered the most common approach for killing cancer cells in the human body. However, some barriers such as toxicity and side effects would limit its usage. In this regard, nano-based drug delivery systems have emerged as cost-effective and efficient for sustained and targeted drug delivery. Nanotubes such as carbon nanotubes (CNT) and boron nitride nanotubes (BNNT) are promising nanocarriers that provide the cargo with a large inner volume for encapsulation. However, understanding the insertion process of the anti-cancer drugs into the nanotubes and demonstrating drug-nanotube interactions starts with theoretical analysis. METHODS: First, interactions parameters of the atoms of 5-FU were quantified from the DREIDING force field. Second, the storage capacity of BNNT (8,8) was simulated to count the number of drugs 5-FU encapsulated inside the cavity of the nanotubes. In terms of the encapsulation process of the one drug 5-FU into nanotubes, it was clarified that the drug 5-FU was more rapidly adsorbed into the cavity of the BNNT compared with the CNT due to the higher van der Waals (vdW) interaction energy between the drug and the BNNT. RESULTS: The obtained values of free energy confirmed that the encapsulation process of the drug inside the CNT and BNNT occurred spontaneously with the free energies of -14 and -25 kcal·mol-1, respectively. DISCUSSION: However, the lower value of the free energy in the system containing the BNNT unraveled more stability of the encapsulated drug inside the cavity of the BNNT comparing the system having CNT. The encapsulation of Fluorouracil (5-FU) anti-cancer chemotherapy drug (commercial name: Adrucil®) into CNT (8,8) and BNNT (8,8) with the length of 20 Å in an aqueous solution was discussed herein applying molecular dynamics (MD) simulation.
Assuntos
Antineoplásicos/farmacologia , Compostos de Boro/química , Composição de Medicamentos , Fluoruracila/farmacologia , Nanotubos de Carbono/química , Estabilidade de Medicamentos , Fluoruracila/química , Conformação Molecular , Simulação de Dinâmica Molecular , TermodinâmicaRESUMO
Boron nitride nanotubes (BNNTs) are promising for mechanical applications owing to the high modulus, high strength, and inert chemical nature. However, up to now, precise evaluation of their elastic properties and their relation to defects have not been experimentally established. Herein, the intrinsic elastic modulus of BNNTs and its dependence on intrinsic and deliberately irradiation-induced extrinsic defects have been studied via an electric-field-induced high-order resonance technique inside a high-resolution transmission electron microscope (HRTEM). Resonances up to fourth order for normal modes and third order for parametric modes have been initiated in the cantilevered tubes, and the recorded frequencies are well consistent with the theoretical calculations with a discrepancy of â¼1%. The elastic moduli of the BNNTs measured from high-order resonance is about 906.2 GPa on average, with a standard deviation of 9.3%, which is found to be closely related to the intrinsic defect as cavities in the nanotube walls. Furthermore, electron irradiation in HRTEM has been used to study the effects of defects to elastic moduli and to evaluate the radiation resistance of the BNNTs. Along with an increase in the irradiation dose, the outer diameter has linearly reduced due to the knock-on effects. A defective shell with nearly constant thickness has been formed on the outer surface, and as a result, the elastic modulus decreases gradually to â¼662.9 GPa, which is still 3 times that of steel. Excellent intrinsic elastic properties and decent radiation-resistance prove that BNNTs could be a material of choice for applications in extreme environments, such as those existing in space.
RESUMO
High-temperature thermal photonics presents unique challenges for engineers as the database of materials that can withstand extreme environments are limited. In particular, ceramics with high temperature stability that can support coupled light-matter excitations, that is, polaritons, open new avenues for engineering radiative heat transfer. Hexagonal boron nitride (hBN) is an emerging ceramic 2D material that possesses low-loss polaritons in two spectrally distinct mid-infrared frequency bands. The hyperbolic nature of these frequency bands leads to a large local density of states (LDOS). In 2D form, these polaritonic states are dark modes, bound to the material. In cylindrical form, boron nitride nanotubes (BNNTs) create subwavelength particles capable of coupling these dark modes to radiative ones. In this study, we leverage the high-frequency optical phonons present in BNNTs to create strong mid-IR thermal antenna emitters at high temperatures (938 K). Through direct measurement of thermal emission of a disordered system of BNNTs, we confirm their radiative polaritonic modes and show that the antenna behavior can be observed even in a disordered system. These are among the highest-frequency optical phonon polaritons that exist and could be used as high-temperature mid-IR thermal nanoantenna sources.
RESUMO
Glioblastoma multiforme (GBM) is one of the most aggressive types of brain cancer, characterized by rapid progression, resistance to treatments, and low survival rates; the development of a targeted treatment for this disease is still today an unattained objective. Among the different strategies developed in the latest few years for the targeted delivery of nanotherapeutics, homotypic membrane-membrane recognition is one of the most promising and efficient. In this work, we present an innovative drug-loaded nanocarrier with improved targeting properties based on the homotypic recognition of GBM cells. The developed nanoplatform consists of boron nitride nanotubes (BNNTs) loaded with doxorubicin (Dox) and coated with cell membranes (CM) extracted from GBM cells (Dox-CM-BNNTs). We demonstrated as Dox-CM-BNNTs are able to specifically target and kill GBM cells in vitro, leaving unaffected healthy brain cells, upon successful crossing an in vitro blood-brain barrier model. The excellent targeting performances of the nanoplatform can be ascribed to the protein component of the membrane coating, and proteomic analysis of differently expressed membrane proteins present on the CM of GBM cells and of healthy astrocytes allowed the identification of potential candidates involved in the process of homotypic cancer cell recognition.
RESUMO
Due to recent advances in high-throughput synthesis, research on boron nitride nanotubes (BNNTs) is moving toward applications. One future goal is the assembly of macroscopic articles of high-aspect-ratio, pristine BNNTs. However, these articles are presently unattainable because of insufficient purification and fabrication methods. We introduce a solution process for extracting BNNTs from synthesis impurities without sonication or the use of surfactants and proceed to convert the extracted BNNTs into thin films. The solution process can also be used to convert as-synthesized material-which contains significant amounts of hexagonal boron nitride ( h-BN)-into mats and aerogels with controllable structure and dimension. The solution extraction method, combined with further advances in synthesis and purification, contributes to the development of all-BNNT macroscopic articles, such as fibers and 3-D structures.
RESUMO
Piezoelectric films of poly(vinylidenedifluoride-trifluoroethylene) (P(VDF-TrFE)) and of P(VDF-TrFE)/boron nitride nanotubes (BNNTs) were prepared by cast-annealing and used for SaOS-2 osteoblast-like cell culture. Films were characterized in terms of surface and bulk features, and composite films demonstrated enhanced piezoresponse compared to plain polymeric films (d31 increased by ~80%). Osteogenic differentiation was evaluated in terms of calcium deposition, collagen I secretion, and transcriptional levels of marker genes (Alpl, Col1a1, Ibsp, and Sparc) in cells either exposed or not to ultrasounds (US); finally, a numerical model suggested that the induced voltage (~20-60 mV) is suitable for cell stimulation. Although preliminary, our results are extremely promising and encourage the use of piezoelectric P(VDF-TrFE)/BNNT films in bone tissue regeneration.
Assuntos
Compostos de Boro/farmacologia , Diferenciação Celular , Estimulação Elétrica , Nanotubos/química , Osteossarcoma/patologia , Polivinil/química , Ultrassonografia , Neoplasias Ósseas/tratamento farmacológico , Neoplasias Ósseas/metabolismo , Neoplasias Ósseas/patologia , Compostos de Boro/química , Sobrevivência Celular , Humanos , Nanotubos/efeitos da radiação , Osteossarcoma/tratamento farmacológico , Osteossarcoma/metabolismo , Células Tumorais CultivadasRESUMO
BACKGROUND: Boron nitride nanotubes (BNNTs) represent a new opportunity for drug delivery and clinical therapy. The present work has the objective to investigate pectin-coated BNNTs (P-BNNTs) for their biocompatibility on macrophage cultures, since these cells are among the first components of the immune system to interact with administered nanoparticles. METHODS: As first step, the potential toxicity of P-BNNTs is verified in terms of proliferation, oxidative stress induction and apoptosis/necrosis phenomena. Thereafter, the modulation of immune cell response following P-BNNT exposure is evaluated at gene and protein level, in particular focusing on cytokine release. Finally, P-BNNT internalization is assessed through transmission electron microscopy and confocal microscopy. RESULTS: The results proved that P-BNNTs are not toxic for macrophages up to 50 µg/ml after 24 h of incubation. The cytokine expression is not affected by P-BNNT administration both at gene and protein level. Moreover, P-BNNTs are internalized by macrophages without impairments of the cell structures. CONCLUSIONS: Collected data suggest that P-BNNTs cause neither adverse effects nor inflammation processes in macrophages. GENERAL SIGNIFICANCE: These findings represent the first and fundamental step in immune compatibility evaluation of BNNTs, mandatory before any further pre-clinical testing.
Assuntos
Compostos de Boro/química , Materiais Revestidos Biocompatíveis/química , Macrófagos/metabolismo , Teste de Materiais , Nanotubos/química , Pectinas/química , Animais , Linhagem Celular , Citocinas/biossíntese , Citocinas/imunologia , Regulação da Expressão Gênica/imunologia , Macrófagos/citologia , Macrófagos/imunologia , CamundongosRESUMO
BACKGROUND: Non-viral gene delivery is increasingly investigated as an alternative to viral vectors due to low toxicity and immunogenicity, easy preparation, tissue specificity, and ability to transfer larger sizes of genes. METHODS: In this study, boron nitride nanotubes (BNNTs) are functionalized with oligonucleotides (oligo-BNNTs). The morpholinos complementary to the oligonucleotides attached to the BNNTs (morpholino/oligo-BNNTs) are hybridized to silence the luciferase gene. The morpholino/oligo-BNNTs conjugates are administered to luciferase-expressing cells (MDA-MB-231-luc2) and the luciferase activity is monitored. RESULTS: The luciferase activity is decreased when MDA-MB-231-luc2 cells were treated with morpholino/oligo-BNNTs. CONCLUSIONS: The study suggests that BNNTs can be used as a potential vector to transfect cells. GENERAL SIGNIFICANCE: BNNTs are potential new nanocarriers for gene delivery applications.
Assuntos
Compostos de Boro/química , Inativação Gênica , Técnicas de Transferência de Genes , Nanotubos/química , Sobrevivência Celular , Vetores Genéticos , Luciferases/genética , Luciferases/metabolismo , Oligonucleotídeos/administração & dosagemRESUMO
We present a facile wet-chemistry method for efficient metal filling of the hollow inner cores of boron nitride nanotubes (BNNTs). The fillers conform to the cross-section of the tube cavity and extend in length from a few nm to hundreds of nm. The methodology is robust and is demonstrated for noble metals (Au, Pt, Pd, and Ag), transition metals (Co), and post-transition elements (In). Transmission electron microscopy and related electron spectroscopy confirm the composition and morphology of the filler nanoparticles. Up to 60% of BNNTs of a given preparation batch have some degree of metal encapsulation, and individual tubes can have up to 10% of their core volume filled during initial loading. The growth, movement, and fusing of metal nanoparticles within the BNNTs are also examined.
RESUMO
Irradiation-induced vacancy defects in multiwalled (MW) boron nitride nanotubes (BNNTs) are investigated via in situ high-resolution transmission electron microscope operated at 80 kV, with a homogeneous distribution of electron beam intensity. During the irradiation triangle-shaped vacancy defects are gradually generated in MW BNNTs under a mediate electron current density (30 A cm(-2)), by knocking the B atoms out. The vacancy defects grow along a well-defined direction within a wall at the early stage as a result of the curvature induced lattice strain, and then develop wall by wall. The orientation or the growth direction of the vacancy defects can be used to identify the chirality of an individual wall. With increasing electron current density, the shape of the irradiation-induced vacancy defects changes from regular triangle to irregular polygon.
RESUMO
A comprehensive overview of current research progress on boron nitride nanotubes (BNNTs) is presented in this article. Particularly, recent advancements in controlled synthesis and large-scale production of BNNTs will first be summarized. While recent success in mass production of BNNTs has opened up new opportunities to implement the appealing properties in various applications, concerns about product purity and quality still remain. Secondly, we will summarize the progress in functionalization of BNNTs, which is the necessary step for their applications. Additionally, selected potential applications in structural composites and biomedicine will be highlighted.
Assuntos
Compostos de Boro/química , Nanotubos/química , Materiais Biocompatíveis/química , Compostos de Boro/síntese química , Técnicas de Química Sintética , Nanotubos/ultraestrutura , Polímeros/química , Relação Estrutura-AtividadeRESUMO
The first BNCT antitumor effects of BNNTs toward B16 melanoma cells were demonstrated. The use of DSPE-PEG2000 was effective for preparation of the BNNT-suspended aqueous solution. BNNT-DSPE-PEG2000 accumulated in B16 melanoma cells approximately three times higher than BSH and the higher BNCT antitumor effect was observed in the cells treated with BNNT-DSPE-PEG2000 compared to those treated with BSH, indicating that BNNT-DSPE-PEG2000 would be a possible candidate as a boron delivery vehicle for BNCT.
Assuntos
Antineoplásicos/administração & dosagem , Compostos de Boro/administração & dosagem , Terapia por Captura de Nêutron de Boro/métodos , Melanoma Experimental/tratamento farmacológico , Melanoma Experimental/radioterapia , Nanotubos , Animais , Antineoplásicos/química , Compostos de Boro/química , Sobrevivência Celular/efeitos dos fármacos , Sobrevivência Celular/efeitos da radiação , Nanotubos/química , Nêutrons , Neoplasias Cutâneas/tratamento farmacológico , Neoplasias Cutâneas/radioterapiaRESUMO
In this work, first-principles density functional theory (DFT) is used to predict oxygen adsorption on two types of hybrid carbon and boron-nitride nanotubes (CBNNTs), zigzag (8,0), and armchair (6,6). Although the chemisorption of O2 on CBNNT(6,6) is calculated to be a thermodynamically unfavorable process, the binding of O2 on CBNNT(8,0) is found to be an exothermic process and can form both chemisorbed and physisorbed complexes. The CBNNT(8,0) has very different O2 adsorption properties compared with pristine carbon nanotubes (CNTs) and boron-nitride nanotube (BNNTs). For example, O2 chemisorption is significantly enhanced on CBNNTs, and O2 physisorption complexes also show stronger binding, as compared to pristine CNTs or BNNTs. Furthermore, it is found that the O2 adsorption is able to increase the conductivity of CBNNTs. Overall, these properties suggest that the CBNNT hybrid nanotubes may be useful as a gas sensor or as a catalyst for the oxygen reduction reaction.