Size Of Carbon Nanotubes Research Articles

Study on fragmentation characteristics of carbon nanotube-enhanced concrete and a comparative evaluation of the ZWT and ottosen constitutive model

In order to study the difference between the crushing characteristics of carbon nanotubes (CNTs) concrete and ordinary concrete, this paper conducts a test between ordinary concrete and CNTs concrete with a volume content of 0.3 % at different impact speeds through the Hopkinson test, using fragmentation and particle size distribution as evaluation indexes. Crushed fragments are analyzed from the perspective of concrete pores. Finally, the nonlinear viscoelastic constitutive model and the nonlinear elastic constitutive model of CNTs concrete are then developed and compared. Based on the results, the average pores of the CNTs concrete decreased from 42.0 nm to 38.0 nm, but the pore area increased from 5.743 m2/g to 6.305 m2/g, indicating that CNTs can fill the internal pores. Meanwhile, the average particle size of broken CNTs concrete is significantly larger than that of ordinary concrete. However, the relationship between the crushing particle size and impact velocity is approximately y=A-Bln(x+C) for both concretes. According to the study of concrete constitutive models, compared to the Loand damage model, the combination of Loand model and Mazars model is more accurate in describing concrete damage characteristics, and the average correlation coefficient increases from 0.84 to 0.92. Meanwhile, compared to the Zhu-Wang-Tang (ZWT) model, Ottosen model can better capture the dynamic mechanical properties of CNT concrete, with a correlation coefficient over 0.98.

Unveiling mechanisms of blocking polysulfides by carbon nanotubes

Lithium-sulfur (Li-S) batteries have been considered as a candidate to overcome the limits of Li-ion batteries. However, the polysulfide shuttle effect in Li-S batteries must be addressed before their practical application. A feasible solution to this problem is to insert a carbon nanotube (CNT) interlayer between the Li-S battery cathode and separator for encapsulating polysulfides. Although many CNT interlayers have been developed, how the CNT interlayer blocks polysulfides is still, to a large extent, unknown. In this paper, combined MD simulations and DFT calculations were used to elucidate the effects of CNT size, interspacing, and functional groups on polysulfide encapsulation. Our findings provide new design guidelines for Li-S battery CNT interlayers to optimize the battery performance.

Simultaneous production of syngas and carbon nanotubes from CO2/CH4 mixture over high-performance NiMo/MgO catalyst

Direct conversion of biogas via the integrative process of dry reforming of methane (DRM) and catalytic methane decomposition (CDM) has received a great attention as a promising green catalytic process for simultaneous production of syngas and carbon nanotubes (CNTs). In this work, the effects of reaction temperature of 700–1100 °C and CH4/CO2 ratio of biogas were investigated over NiMo/MgO catalyst in a fixed bed reactor under industrial feed condition of pure biogas. The reaction at 700 °C showed a rapid catalyst deactivation within 3 h due to the formation of amorphous carbon on catalyst surface. At higher temperature of 800–900 °C, the catalyst can perform the excellent performance for producing syngas and carbon nanotubes. Interestingly, the smallest diameter and the highest graphitization of CNTs was obtained at high temperature of 1000 °C, while elevating temperature to 1100 °C leads to agglomeration of Ni particles, resulting in a larger size of CNTs. The reaction temperature exhibits optimum at 800 °C, providing the highest CNTs yield with high graphitization, high syngas purity up to 90.04% with H2/CO ratio of 1.1, and high biogas conversion (XCH4 = 86.44%, XCO2 = 95.62%) with stable performance over 3 h. The typical composition biogas (CH4/CO2 = 1.5) is favorable for the integration process, while the CO2 rich biogas caused a larger grain size of catalyst and a formation of molybdenum oxide nanorods (MoO3). The long-term stability of NiMo/MgO catalyst at 800 °C showed a stable trend (> 20 h). The experimental findings confirm that NiMo/MgO can perform the excellent activity and high stability at the optimum condition, allowing the process to be more promising for practical applications.

Efficient deep-learning model for predicting mechanical strength of carbon nanotube-reinforced cementitious composites: Database acquisition, framework development and implementation

In response to the growing demand for accurate models predicting the mechanical strength of carbon nanotube (CNT) reinforced cementitious composites, this study introduces a precise deep-learning model. The model, built upon a comprehensive dataset of 219 entries, incorporates 14 input variables considering various composites, cement types, and CNT characteristics. Notably, analysis of the data demonstrates a nuanced understanding of material properties, covering cementitious composites with compressive strength (CS) and flexural strength (FS) ranging from 15 to 140 MPa and 3–17 MPa, respectively. Employing a regularized deep learning neural network architecture, the model exhibits promising performance metrics, with the training dataset showcasing the lowest mean absolute error (MAE) of 2.036. The training and validation datasets demonstrate a high correlation coefficient (0.991 and 0.917, respectively). However, higher MAE values are observed for the testing and validation datasets, indicating potential limitations in generalization. Furthermore, the model's robustness is highlighted by its ability to surpass earlier studies in accuracy for validation datasets. The study elucidates a nonlinear trend in FS and the influence of CNT size on CS, with implications for material design and construction practices.

Optimizing heat transfer rate with sensitivity analysis on nonlinear radiative hydromagnetic hybrid nanofluid flow considering catalytic effects and slip condition: Hamilton–Crosser and Yamada–Ota modelling

AbstractIn current investigation the optimization of heat transportation rate in a nonlinear radiative buoyancy‐driven hydromagnetic carbon nanotube (CNT) hybrid nanofluid flow is analysed. The proposed catalytic effects and slip condition is accounted for the real‐world complexities of the system. The Hamilton–Crosser (HC) and Yamada–Ota (YO) models are employed to characterize the behaviour of the nanofluid. The primary objective is to enhance the heat transmission rate, which is crucial for various engineering applications such as thermal management, energy systems and so forth. To achieve this, sensitivity analysis is performed to identify the most influential parameters affecting heat transfer in the system. By understanding the sensitivity of these parameters, the performance of the system can be improvised. The study focuses on the interplay between key factors including radiative heat transfer, buoyancy‐driven flow, magnetic field influence, catalytic effects, and slip condition. The presence of CNTs in the nanofluid adds another dimension to the complexity of the system that explores the effects of varying the concentration and size of CNTs on the heat transfer rate. By utilizing advanced mathematical modelling and numerical simulations, the performance of the system under different scenarios and identify the optimal conditions for maximizing heat transfer rate is evaluated. The findings of this research provide valuable insights into the design and optimization of heat transfer systems involving nanofluids with nonlinear radiative and hydromagnetic effects. The observation shows that, irrespective to single wall and multi wall CNT nanoparticles the fluid velocity attenuates significantly whereas it favours in enhancing the fluid temperature. Further, the comparative analysis reveals that the heat transfer augments in the case of HC model than that of YO model.

Estimating water transport in carbon nanotubes: a critical review and inclusion of scale effects.

The quasi-frictionless water flow across graphitic surfaces offers vast opportunities for a wide range of applications from biomedical science to energy. However, the conflicting experimental results impede a clear understanding of the transport mechanism and desired flow control. Existing literature proposes numerous modifications and updated boundary conditions to extend classical hydrodynamic theories for nanoflows, yet a consensus or definitive conclusion remains elusive. This study presents a critical review of the proposed modifications of the pressure driven flow or the Hagen-Poiseuille (HP) equations to estimate the flow enhancement through carbon nanotubes (CNTs). For such a case, we performed (semi-)classical molecular dynamics simulations of water flow in various sizes of CNTs, applied the different forms of boundary definitions from the literature, and derived HP equation models by implementing these modifications. By aggregating seven distinct experimental datasets, we tested various flow enhancement models against our measurements. Our findings indicate that including the interfacial layering-based dynamic slip-definition in the proposed HP equations yields accurate estimations. While considering interfacial viscosity predicts the individual CNT experiments well, using the experimental viscosity yields better estimations of measurements for the water flow enhancement through membranes of CNTs. This critical review testing existing literature demonstrates how to refine continuum fluid mechanics to predict water flow enhancement at the nanoscale providing holistic multiscale modeling.

Molecular insights into the nanoconfinement effect on the structure and dynamics of ionic liquids in carbon nanotubes.

The properties and applications of ionic liquids (ILs) have been widely investigated when they are confined within nanochannels such as carbon nanotubes (CNTs). The confined ILs exhibit very different properties from their bulk state due to a nanoconfinement effect, which plays an important role in the performances of devices with ILs. In this work, we studied the effect of the charge carried by CNTs on confined ILs inside CNTs using molecular dynamics simulations. In charged CNTs, cations and anions are distributed separately along the radial directions, and the transition of orientations of the cations between parallel and vertical to CNTs occurs by changing the charge state of CNTs. The number of hydrogen bonds (HBs) formed by the confined ILs can be reduced by switching the surface charge of CNTs from positive to negative due to the contact modes between cations and anions as well as the distributions of cations in CNTs. The diffusivities along and vertical to the axial direction of CNTs were found to be non-monotonic owing to the "trade-off" effect from both ion pair interlocking and anchoring ILs on the CNT walls. Additionally, the region-dependent dynamics of ILs were also related to the intermolecular interactions in different regions of CNTs. Furthermore, the vibrational modes of ILs were obviously influenced in highly charged CNTs as determined by calculating the density of vibrational states, which demonstrated the transitions in the structure and interactions. The density distributions changed from single layer to double layers when increasing the pore size of neutral CNTs while the hydrogen bonds exhibited a non-monotonic tendency versus the pore sizes. Our results might help to understand the structure and dynamics of confined ILs as well as aid optimizing the performance of devices with ILs.

Molecular dynamics investigation for mechanical and failure behaviors of carbon nanotube-reinforced functionally graded aluminum–copper nanocomposites

In this study, molecular dynamics simulation is carried out to investigate the mechanical properties and failure behavior of a novel carbon nanotube-reinforced aluminum-copper alloy nanocomposite (Al–Cu/CNT). The study explores the influence of several key parameters, including the volume fraction of the carbon nanotubes (CNT), the diameter of CNT, the structure (zigzag, armchair, and chiral) of CNT, and the applied strain rate on the mechanical behavior of Al–Cu /CNT nanocomposite structure. The MD simulation results reveal that increasing the volume fraction of the CNT evidently increases the modulus of elasticity whereas it has no detrimental effect on the failure strain levels of the nanocomposites. The size of the CNT exhibits an inverse relationship with the elastic modulus. It is noted that increasing the size of the armchair CNTs results in lower elastic modulus levels and higher failure strain levels. The failure behavior of the Al–Cu /CNT nanocomposite is observed to vary according to the structure of the CNT. The nanostructure with zigzag CNTs experiences a gradual failure mode whilst armchair CNTs lead to a sudden failure in the nanostructures. The applied strain rate plays a minor role on the elastic modulus, but a slight increase in failure strain levels is observed at higher strain rates. The mechanical behavior of functionally graded Al–Cu alloy reinforced with CNT is also investigated (Al–Cu FGM/CNT). Minor changes are noticed in the elastic modulus and the failure strain levels of Al–Cu FGM/CNT with different material variations.

Potential production of carbon nanotubes from liquid aromatic hydrocarbons over Fe and Ni on alumina powder via catalytic chemical vapor deposition

In this study, liquid aromatic hydrocarbons of benzene C6H6, toluene C7H8, and xylene C8H10 (BTX), which can be abundantly found in industrial waste oil and pyrolysis products of waste plastics, were used as carbon sources to produce carbon nanotubes (CNTs). CNTs were firstly synthesized from liquid benzene over powdered alumina (Al2O3) supported Fe and Ni catalysts at 700 to 850 °C via catalytic chemical vapor deposition (CCVD) method. It was found that, CNTs synthesized from Fe/Al2O3 resulted in significantly higher carbon yields at 1.0–5.6 wt% with relatively higher graphitization analyzed by Raman spectroscopy compared to those of Ni/Al2O3 with the yields only at 0.6–2.8 wt%. However, smaller sizes of CNTs at 20–29 nm could be produced from Ni/Al2O3 compared to 30–38 nm obtained from Fe/Al2O3 due to its smaller crystallite size of the initial catalyst confirmed by X-ray diffraction (XRD) analysis. For both catalysts, with increasing CCVD temperature, the yields tended to increase with a slight increase in CNT diameter and graphitization degree. The temperature of 800 °C was then chosen for further preliminary investigation on potential mass production of CNTs from BTX. By doubling the amount of catalysts, the CNT yield could be approximately twice achieved by maintaining its uniformity and quality because of remaining active sites of the catalysts. In addition, increasing the carbon atoms of aromatic hydrocarbons resulted in improved yields without changing the quality of CNTs. Finally, kinetic mechanisms of CNT growth from BTX decomposition using Fe/Al2O3 catalyst were simply investigated by varying reaction time from 10 to 60 min. At feeding flow of 0.5 ml/min, optimum reaction time was achieved at 30 min in order to produce uniform CNTs at high yields without carbon loss, unreacted BTX, and undesired by-products, which possibly occurred by hydrogenation, catalyst deactivation, and/or side reactions of as-produced gaseous hydrocarbons during CCVD reaction.

The nature of interaction between Au and heteroatoms-doped carbon nanotubes: Size and electronic effects on CO2 electroreduction

Nanostructured metal electrocatalysts have recently been extensively researched for CO2 electroreduction reaction (CO2RR) to CO. Nevertheless, their exhibited low reaction activity can be attributed to the weak adsorption of CO2 (or relevant intermediates) on the catalyst surface. Herein, the potent nanometallic catalyst is selectively designed based on Au nanoparticles (NPs) as a module with heteroatom (O-, N-, and S-) doped carbon nanotubes (CNTs) as supports and used as a booster toward enhancing CO2RR. The structural characterization and electrochemical tests were conducted to study the relationship between the support effects (size and electronic effects) of CNTs and the catalytic performance of Au NPs. By comparison, the S-doped CNTs loading with Au NPs achieved a Faraday efficiency of 97% for CO at − 0.8 V vs RHE and a catalyst stability of 30 h at a current density of ∼ 18 mA cm−2. This work may guide a method to optimize nanometallic electrocatalysts for CO2RR in a relatively cost-effective manner.

Dual role of pulmonary surfactant corona in modulating carbon nanotube toxicity and benzo[a]pyrene bioaccessibility

Inhaled carbon nanotubes (CNTs) can deposit in the deep lung, where they interact with pulmonary surfactant (PS) to form coronas, potentially altering the fate and toxicity profile of CNTs. However, the presence of other contaminants in combination with CNTs may affect these interactions. Here, we used passive dosing and fluorescence-based techniques confirm the partial solubilization of BaPs adsorbed on CNTs by PS in simulated alveolar fluid. MD simulations were performed to elucidate the competition of interactions between BaPs, CNTs, and PS. We found that PS play two opposing roles in altering the toxicity profile of the CNTs. First, the formation of PS coronas reduce CNTs’ toxicity by decreasing the hydrophobicity of the CNTs and decreasing their aspect ratio. Second, the interaction with PS increases the bioaccessibility of BaP through interactions with PS, which may exacerbate the inhalation toxicity of CNTs. These findings suggest that the inhalation toxicity of PS-modified CNTs should consider the bioaccessibility of coexisting contaminants, with the CNT size and aggregation state playing an important role.

Effect of CNT content and size on the high-temperature particle-erosion resistance of ablative materials for thermal protection systems

Advanced spacecraft development requires high-performance thermal protection systems composed of materials with high particle-erosion resistance. In this study, a particle-erosion test motor was designed to produce a high-temperature particle jet. Subsequently, the effects of carbon nanotube (CNT) content and size on the particle-erosion resistance of ethylene propylene diene monomer (EPDM) composites were analyzed. Composites with an optimum CNT content exhibited the lowest ablation rates; extremely high or low CNT contents increased the ablation rate. Furthermore, the charring rate of the composites with long CNTs were 78.0% and 43.6% lower than those with the baseline-formula composition and those containing conventional CNTs, respectively. Here, the influence of CNT content and size on the particle-erosion resistance of EPDM composites was analyzed from the perspective of the thermal stability of the composites, as well as the char-layer characteristics and vapor deposition.

Highly efficient synthesis of benzyl benzoate directly from self-coupling of benzyl alcohol in water

Benzyl benzoate (BB), an important ester, still demands for green synthesis routes. In this work, by size regulation and proper functionalization of carbon nanotubes (CNTs) as the support of gold catalyst, this ester can be synthesized very efficiently directly from benzyl alcohol via oxidative coupling. More attractively, the reaction is performed using water as green solvent and molecular oxygen as green oxidant. Simultaneously, very high selectivity to BB can be obtained near full conversion within very short reaction time (just 0.5 h), while the low-value benzoic acid byproduct is negligible. This is very different from many reported gold catalysts that yield much benzoic acid and/or benzaldehyde in water. The results show that, besides the size of CNTs (length and diameter), the functionalization of CNTs is also critical for improving both conversion and the selectivity to BB. In addition, the reaction mechanism for forming BB ester is put forward as well.

The Origin of Amphipathic Nature of Short and Thin Pristine Carbon Nanotubes—Fully Recyclable 1D Water‐in‐Oil Emulsion Stabilizers

AbstractShort and thin pristine carbon nanotubes (CNTs) emerge as 1D emulsion stabilizers capable of replacing aquatoxic low‐molecular surfactants. However, inconsistencies in understanding of water–solid interfaces for realistic CNTs hamper their individualization‐driven functionalities, processability in benign media, and compatibility with a broad‐scale of matrices. Pristine CNT processing based on water and inexpensive n‐alkanes within a low energy regime would constitute an important step toward greener technologies. Therefore, structural CNT components are quantitatively assessed, placing various CNTs on the scale from hydrophobicity to hydrophilicity. This structural interweave can lead to amphipathicity enabling the formation of water‐in‐oil emulsions. Combining experiments with theoretical studies, CNTs and CNT emulsions are comprehensively characterized establishing descriptors of the emulsifying behavior of pristine and purified CNTs. They emerge as having hydrophilic open‐ends, small number of oxygen–functionalized/vacancy surface areas, and hydrophobic sidewalls and full caps. The interplay of these regions allows short and thin CNTs to be utilized as fully recyclable 1D surfactants stabilizing water/oil emulsions which, as demonstrated, can be applied as paints for flexible conductive coatings. It is also shown how the amphipathic strength depends on CNT size, the pristine‐to‐oxidized/vacancy domains and the oil‐to‐water ratios.

Hydrogen Bond Dynamics and Phase Transitions of Water inside Carbon Nanotubes.

Water dynamics in nanochannels are altered by confinement, particularly in small carbon nanotubes (CNTs). However, the mechanisms behind these effects remain unclear. To address these issues, we carried out extensive molecular dynamics (MD) simulations to investigate the structure and dynamics of water inside CNTs of different sizes (length of 20 nm and diameters vary from 0.8 nm to 5.0 nm) at different temperatures (from 200 K to 420 K). The radial density profile of water inside CNTs shows a single peak near the CNT walls for small nanotubes. For CNTs with larger sizes, water molecules are arranged into coaxial tubular sheets, the number of which increases with the CNT size. Subdiffusive behavior is observed for ultranarrow CNTs with diameters of 0.8 nm and 1 nm. As the size of CNTs increases, Fickian diffusion becomes evident. The hydrogen bond correlation function of water inside CNT decays slower than in bulk water, and the decay rate decreases as we increase the diameter of the CNTs. In large CNTs, the hydrogen bond lifetime of the innermost layer is shorter than the other layers and depends on temperature. Additional analysis of our results reveals that water molecules along the CNT axis show a non-Arrhenius to Arrhenius diffusion crossover. In general, the diffusion transition temperature is higher than that of bulk water, but it depends on the size of the CNT.

Ultrafast nano generation of acoustic waves in water via a single carbon nanotube

Generation of ultra high frequency acoustic waves in water is key to nano resolution sensing, acoustic imaging and theranostics. In this context water immersed carbon nanotubes (CNTs) may act as an ideal optoacoustic source, due to their nanometric radial dimensions, peculiar thermal properties and broad band optical absorption. The generation mechanism of acoustic waves in water, upon excitation of both a single-wall (SW) and a multi-wall (MW) CNT with laser pulses of temporal width ranging from 5 ns down to ps, is theoretically investigated via a multiscale approach. We show that, depending on the combination of CNT size and laser pulse duration, the CNT can act as a thermophone or a mechanophone. As a thermophone, the CNT acts as a nanoheater for the surrounding water, which, upon thermal expansion, launches the pressure wave. As a mechanophone, the CNT acts as a nanopiston, its thermal expansion directly triggering the pressure wave in water. Activation of the mechanophone effect is sought to trigger few nanometers wavelength sound waves in water, matching the CNT acoustic frequencies. This is at variance with respect to the commonly addressed case of water-immersed single metallic nano-objects excited with ns laser pulses, where only the thermophone effect significantly contributes. The present findings might be of impact in fields ranging from nanoscale non-destructive testing to water dynamics at the meso to nanoscale.

Influence of CNT Length on Dispersion, Localization, and Electrical Percolation in a Styrene-Butadiene-Based Star Block Copolymer.

This study followed the approach of dispersing and localizing carbon nanotubes (CNTs) in nanostructured domains of block copolymers (BCPs) by shortening the CNTs via ball milling. The aim was to selectively tune the electrical and mechanical properties of the resulting nanocomposites, e.g., for use as sensor materials. Multiwalled carbon nanotubes (MWCNTs) were ground into different size fractions. The MWCNT length distribution was evaluated via transmission electron microscopy and dynamic light scattering. The nanostructure of the BCPs and the glass transition temperatures of the PB-rich and PS phases were not strongly affected by the addition of CNTs up to 2 wt%. However, AFM and TEM investigations indicated a partial localization of the shortened CNTs in the soft PB-rich phase or at the interface of the PB-rich and PS phase, respectively. The stress-strain behavior of the solution-mixed composites differed little from the mechanical property profile of the neat BCP and was largely independent of CNT amount and CNT size fraction. Significant changes could only be observed for Young’s modulus and strain at break and may be attributed to CNT localization and small changes in morphology. For nanocomposites with unmilled CNTs, the electrical percolation threshold was less than 0.1 wt%. As the CNTs were shortened, the resistivity increased and the percolation threshold shifted to higher CNT contents. Composites with CNTs ground for 7.5 h and 13.5 h showed no bulk conductivity but significantly decreased surface resistivity on the bottom side of the films, which could be attributed to a sedimentation process of the grind and thereby highly compressed CNT agglomerates during evaporation.

The aggregation of carbon nanotubes deteriorates their adverse effects on pulmonary surfactant monolayer

The wide use of carbon nanotubes (CNTs) increases the concern of their potential risks upon human exposure, especially through respiratory tract. The small size of CNTs allows them to deposit into the deep lung where they inevitably interact with pulmonary surfactant (PS) monolayer and thus could profoundly influence the biophysical function of PS monolayer. Using coarse-grained molecular dynamics simulations, we studied how the aggregation state of CNTs regulated the interactions of different sized CNTs with the PS monolayer at the air-water interface. Compared with the dispersed CNTs, the aggregated CNTs induced more severe structure disturbance of the PS monolayer at both compression and expansion stages. The increased diameter, initial attack angle, and configuration irregularity of the aggregated CNTs enhanced the lipid disturbance around the CNTs and promoted the pore formation on the PS monolayer under a high surface tension. As a result, the aggregated CNTs tended to inhibit the biophysical function of the PS monolayer and were more difficult to be cleared from the monolayer than the dispersed CNTs. Our results suggest that the aggregated CNTs, rather than the dispersed ones, should be given more weight in assessing the pneumonic nanotoxicity caused by the inhaled CNTs.

Microstructure-sensitive investigation on the mechanical behavior of CNT-reinforced composites considering debonding damage based on cohesive finite element method

In this paper, an analytical modeling and numerical approach based on the finite element (FE) method are introduced to study the influence of the real morphology (e.g., length and waviness) and distribution of carbon nanotubes (CNTs) on the mechanical behavior of the CNT-reinforced composites. The analytical model has considered the real morphology effect using the equivalent curved CNTs with perfect bonding. The equivalent chord length, diameter, and waviness have been computed using the abundance of different values of measured parameters in an actual microstructure of the CNTs in the matrix. In the FE method, a computational tool is used to map an actual composite microstructure onto a FE representative volume element (RVE) with the exact shape, size, distribution, and waviness of CNTs. FE analysis has been carried out in both well-bonded and interface-debonding conditions. The cohesive zone model (CZM) with bilinear traction-separation law for both opening and sliding modes has been utilized to capture the debonding at the CNT-matrix interface. Results indicate that in the presence of weak bonding, CNT waviness can enhance the composite stiffness rather than reduce it. A quite different conclusion to what can be obtained with the assumption of perfect adhesion. In the presence of poor bonding, the curvature has a positive effect on composite properties and improves the load transferring from the matrix. FE analysis for different RVEs highlights that the curvature and length of the CNTs are essential features of the microstructure, and they can effectively influence the mechanical properties of the material. Results demonstrate that the equivalent curved CNTs cannot appropriately represent the real microstructure.

Mucosal Delivery of HIV-1 Glycoprotein Vaccine Candidate Enabled by Short Carbon Nanotubes.

The HIV-1 envelope glycoprotein spike is the target of antibodies, and therefore represents the main viral antigen for antibody-based vaccine design. One of the challenges in HIV-1 vaccine development is finding efficient ways for the immune system to recognize and respond to HIV-1 without establishing an infection. Since HIV-1 enters the body at mucosal surfaces, induction of immune response at these sites is a preferred preventive approach. Nasal administration is a very effective route for mucosal immunization since it can stimulate mucosal immune responses both locally and distantly. In this paper, Luna develops a safe, short carbon nanotube (CNT)-based, needle-free delivery platform known as "CNTVac". The size of short CNT was controlled to possess HIV-1 particle-like morphology (100-200 nm) capable of efficiently delivering a broad range of antigens intranasally. PEG-Lipid served as the antigen conformation protector and mucosal barrier penetration enhancer (Schematic Figure) was localized between V1V2 antigens, which caused highly enhanced local IgA and systemic antibody IgG responses in mice and rabbits. The short CNT incorporated with PEG-Lipid could not only serve as efficient delivery system but also reduce the amount of lipid usage in order to balance the vaccine dosage in order to eliminate the potential adverse effect. These data suggest a promising platform technology for vaccine delivery.