Kinds Of Multi-walled Carbon Nanotubes Research Articles

Structure Formation and Characterization of PEMFC Catalyst Layers Blended with Multi-Walled Carbon Nanotubes

Mass transport properties of catalyst layers (CLs) for proton exchange membrane fuel cells (PEMFCs) are strongly depends on its structure. Structure control, therefore, is important to achieve higher cell performance. However, the CLs have fabricated by trial and error approach. Understanding mechanism and key parameters of the structure determination is necessary. In this study, we especially focused on pore structure in the CLs.The pore structure can depend on aggregate structure of carbon black (CB) which is used as a catalyst support. To clarify effects of the material structure on the pore structure of the CLs, different kinds of sub-micron structured carbon, which are carbon black and multi-walled carbon nanotubes (MWCNTs), were blended in catalyst ink. The carbon black is same type as the catalyst support. MWCNTs have completely different structure with the carbon black in sub-micron scale. Therefore, two kinds of MWCNTs were blended with the platinum-supported carbon in the catalyst ink and the effects on the structure and performance were investigated. One of the MWCNTs is 20-50 nm (CNT2050), which is almost the same as the particle diameter of the carbon black (ca. 30 nm), and the other is 40-70 nm in diameter (CNT4070), which is larger than the particle diameter. The CLs were fabricated by doctor blading and a decal transfer method. Both centrifugal dispersion and ultrasonic treatment were performed to prepare homogeneous catalyst ink. Same platinum supported carbon (TEC10E50E, TKK) was used as a catalyst. Non-platinum supported carbon materials were blended in the catalyst ink at 50 wt.% of all carbon materials including platinum-supported carbon. All of fabricated CLs contain the same amount of platinum, 0.08 mg/cm2.Porosities of the fabricated CLs are 59% (CB), 51% (CNT2050) and 42% (CNT4070), respectively. The porosity of the CL blended with CB is almost the same as a previous report[1]. On the other hand, the catalyst layers blended with MWCNTs showed lower porosity. To evaluate micro-scale structure, microscopic observation was performed as shown in Figure 1 and micro-cracks were counted from obtained images. Area ratio of the micro-cracks to all active area is 0.48% (CB), 0.14% (CNT2050) and 0.0037% (CNT4070), respectively. The CLs blended with the MWCNTs showed fewer micro-cracks than the conventional catalyst layer. Figure 2 shows SEM images of the CLs blended with CB and CNT4070. Upper images are in-plane and lower images are through-plane. The cross-sectional structure was obtained by cross-section polishing method which uses broad argon ion beam[2]. Figure 1 (b) is in-plane of the CL blended with CNT4070 and shows large and deep pore which is not shown in the CL blended with CB, Figure 1 (a). On the other hand, such large pores can’t be observed in through-plane direction, Figure 1 (d). It is showed that the CL blended with CNT4070 has heterogeneous pore structure. Porous structure near catalyst can be compact, although the other area contains large pores.Effects of this characteristic pore structure on the cell performance were evaluated. Polarization curves of the CLs supplying air at different relative humidity (RH) are shown in Figure 3. More drastic voltage drop at high current density is indicated in CNT4070 at high RH condition, although both CLs show almost the same performance at low RH condition. These results suggest that structure of pores which are located near catalyst affect property of flooding.AcknowledgmentThis work was supported by JSPS KAKENHI (25889053). The authors are grateful to Nano-Micro Fabrication Consortium in Kawasaki City for performing the cross-sectional analysis of the CLs.Reference[1] T. Suzuki, S. Tsushima and S. Hirai, J. Power Sources, 233, 269 (2013).[2] T. Suzuki, S. Tsushima and S. Hirai, Int. J. Hydrogen Energy, 36, 12361 (2011).

Enhanced ethylene polymerization of Ni(II) complexes supported on carbon nanotubes

A series of nickel complexes Ni1–Ni4 containing N-(5,6,7-trihydroquinolin-8-ylidene)aminoaryl ligands was prepared in good yields. The amino group present allowed covalent anchoring of these complexes through an amido link onto the surface of two kinds of multi-walled carbon nanotubes (MWCNTs). XPS analysis evidenced that the molecular structure of these Ni(II) complexes was maintained after grafting. Activated by MAO, these catalytic systems promoted ethylene polymerization. Our studies evidenced the beneficial influence of the MWCNTs since in most cases, heterogeneized systems are more active than the corresponding unsupported catalysts, producing higher molecular weight polymers in which MWCNTs are homogeneously dispersed.

Influence of nickel on the electrochemical activity of PtRu/multiwalled carbon nanotubes electrocatalysts for direct methanol fuel cells

This paper presents the effect of Ni in PtRu electrocatalysts over multiwalled carbon nanotubes (MWCNT) utilized for the electro-oxidation of methanol with the purpose of increasing reaction activity and tolerance to carbon monoxide. Two kinds of MWCNT were prepared using the same technique but different catalytic agents, ferrocene, and nickelocene. MWCNT obtained from ferrocene were treated after the synthesis to eliminate amorphous carbon and Fe excess, while MWCNT from nickelocene were used as synthesized to leave the nickel nanoparticles formed during the synthesis. PtRu particles were deposited over the surface of both types of MWCNT in order to study the effect of the Ni presence. The structure of the electrocatalysts was analyzed by transmission electron microscopy (TEM) and X-ray diffraction (XRD). Chemical elemental microanalysis was carried out by X-ray energy dispersive spectroscopy (EDS). The synthesized MWCNT had an average diameter in the order of 60 nm and an average length of about 30 microns. Metallic nanoparticles deposited had a particle size in the order of 10 nm each. The electrochemical surface area (ESA) was measured using CO stripping curves and the activity toward the methanol oxidation reaction was evaluated. The ESA was improved with the presence of Ni, achieving an activity and onset potential similar to a commercial electrocatalyst (20 wt% PtRu/C, ETEK) with a lower PtRu loading (10 wt% PtRu).

Effect of Functionalized Multi-Walled Carbon Nanotubes on the Interfacial Properties of Ramie Fiber/Polylactic Acid (PLA) Composites

Effect of functionalized multi-walled carbon nanotubes (MWCNT) on the interfacial properties of ramie fiber/polylactic acid (PLA) matrix was studied. Ramie fibers were respectively covered by the pristine MWCNT, carboxyl functionalized MWCNT and hydroxide functionalized MWCNT through the simple dip coating method. Scanning electron microscopy (SEM) results showed that all kinds of MWCNT were distributed on the fiber surface at random with some aggregations. Compared to the pristine MWCNT coated fibers with a water contact angle of 84.5 degree, the functionalized MWCNT coating made the fiber surface more hydrophobic. Polarization microscopy indicated that the functional MWCNT could provide the nucleation to form the intact crystalline structure of PLA on the fiber surface. Micro-bond tests showed that the coating of MWCNT on the fiber surface had no significant effect on the interfacial shear strength (IFSS).

Influence of surface oxidation on the morphological and crystallographic structure of multi-walled carbon nanotubes via different oxidants

In this paper, three kinds of multi-walled carbon nanotubes (MWCNTs) with different diameters (outer diameters: 10 to 20, 30 to 50, and >50 nm) and special surface areas (200, 60, and 40 m2/g, respectively) were oxidized in commonly used liquid oxidizers: (1) concentrated nitric acid, (2) a mixture of nitric + sulfuric acids (V:V, 1:3), (3) hydrogen peroxide, (4) a mixture of hydrogen peroxide + sulfuric acid (V:V, 1:1), and (5) acidic potassium permanganate. Morphology of the pristine and oxidized MWCNTs was characterized by scanning electron microscopy which provides sufficient resolution for direct visualization of their outer diameter distribution. Full width at half maximum (FWHM) in the X-ray diffraction (XRD) investigation of the MWCNT samples before and after the oxidation process was measured. After treatment with oxidants, a clear decrease in nanotube diameters along the tube walls was observed. Decrease in the degree of crystallites started with the FWHM widening of the XRD diffraction peaks. The particle (crystallite) size (d002) calculated by Bragg's law and Scherrer equation increased depending on the kind of oxidants; the procedure can be performed using a mixture of HNO3 + H2SO4 on the surface of the MWCNTs with an outer diameter of 10 to 20nm. However, similar are the diffraction patterns of pristine and oxidized MWCNTs. Therefore, the MWCNTs that underwent oxidation process were able to preserve the first features of their structures, even though some narrowing of outer diameters and decreases in crystallites appeared. Nevertheless, the structure of MWCNTs still remains intact to be used as oxidized nanotubes in most applications.

Mineralization of phenanthrene sorbed on multiwalled carbon nanotubes

Carbon nanotubes have attracted attention around the world because of their high sorption capacity for hydrophobic organic compounds (HOCs); however, the bioavailability of HOCs sorbed on carbon nanotubes to bacteria is not well known. In the present study, (14) C-labeled and unlabeled phenanthrene was spiked onto four kinds of multiwalled carbon nanotubes (MWCNTs) and aged for 60 d, and the mineralization of phenanthrene sorbed on MWCNTs was studied. The mineralization efficiencies of phenanthrene sorbed on the four kinds of MWCNTs were 2.38, 8.84, 23.88, and 31.47%, respectively, after incubation for 35 d, which were positively correlated with the sum of fast and slow desorption fractions of phenanthrene (p < 0.05). The authors found that the mineralization efficiencies agreed well with the MWCNT properties; the increasing specific surface area and mesopore and micropore volume of MWCNTs caused a significant decrease in the mineralization efficiency of phenanthrene (p < 0.05). After incubation for 35 d, the density of bacteria had a significant positive correlation with both the desorption and the mineralization efficiencies. The authors inferred that, although MWCNTs might have toxic effects on the bacteria, the biodegrading ability of bacteria might not decrease significantly under the influence of MWCNTs with low surface area.

The effect of aspect ratio on the piezoresistive behavior of the multiwalled carbon nanotubes/thermoplastic elastomer nanocomposites

To explore the effect of aspect ratio (AR) of carbon nanotubes (CNT) on the piezoresistive behavior of the composites, four kinds of multiwalled carbon nanotubes (MWNT) with different nominal aspect ratios (AR = 62, 133, 433, and 833) were well dispersed in a thermoplastic elastomer (TPE) via melt blending. The piezoresistivity of the MWNT/TPE nanocomposites was found to be dependent on the nominal MWNT aspect ratios. However, their relationship is non-linear and non-monotonic. By introducing the effective MWNT aspect ratios which are length-dependent and diameter-dependent, it has been demonstrated that the piezoresistivity will decrease with the increase of effective aspect ratios. The length-dependent increase of aspect ratio results in one hundred-fold or more decrease of piezoresistivity, but the diameter-dependent increase of aspect ratios only leads to a slight marginal change of the piezoresistivity. The proper selection of MWNT aspect ratios could enable their utilization to tailor as well as finely tune the piezoresistivity of the MWNT/TPE nanocomposites.

Incorporation of Functionalized Multiwall Carbon Nanotubes into a Polyurethane Matrix

Functionalized and raw multiwall carbon nanotubes (MWCNTs) were investigated colloid-chemically in order to study the role of polar versus nonpolar interaction with a polyurethane (PU) matrix. Both kinds of MWCNTs were dispersed by ultrasonication in the presence of a surfactant (sodium dodecyl sulphate) in aqueous solution. Functional groups on the nanotube surface were characterized by infrared spectroscopy and by theζ-potential in aqueous suspension. Such suspensions were added to waterborne PU dispersions, drop-cast on glass substrates and cured. The percolation threshold for electrical conductivity with polar (functionalized) MWCNTs was reached at 0.24 wt.%, whereas at concentrations as high as 2 wt.%, PU films with nonpolar MWCNTs stayed below the percolation threshold. With an addition of 0.4 wt.% polar MWCNTs, the electrical conductivity increased to &gt;10−6 S/cm in the cured coating layer. These results are interpreted with respect to the chemical nature of the PU matrix.

Adsorption of Natural Organic Matter Surrogates from Aqueous Solution by Multiwalled Carbon Nanotubes

Adsorption of two natural organic matter (NOM) surrogates (tannic acid and gallic acid) by powdered activated carbon (PAC) and four kinds of multiwalled carbon nanotubes (MWCNTs) with different diameters was investigated in aqueous solution. The tannic acid (TA) adsorption isotherm fit the Langmuir model best, while adsorption of gallic acid (GA) fit the Freundlich model. PAC has a higher adsorption capacity for GA due to the pore-filling effect, while TA adsorption on PAC was lower than that on MWCNTs because of the molecule sieving effect. Adsorption of GA and TA on MWCNTs decreased with increasing MWCNT diameter, but neither surface area nor total pore volume alone can fully explain adsorption of the two NOM surrogates on MWCNTs. Adsorption mechanisms including electrostatic interaction, hydrophobic interaction, hydrogen bond, and π–π interaction play roles in the adsorption process. This study implies that NOM properties have a great effect on their adsorption on MWCNTs, and these properties should be further considered when evaluating the risks of NOM-coated nanomaterials.

Inhibitory effects of multiwall carbon nanotubes with high iron impurity on viability and neuronal differentiation in cultured PC12 cells

The increasing use of carbon nanotubes (CNTs) in biomedical applications has garnered a great concern on their potential negative effects to human health. CNTs have been reported to potentially disrupt normal neuronal function and they were speculated to accumulate and cause brain damage, although a lot of distinct and exceptional properties and potential wide applications have been associated with this material in neurobiology. Fe impurities strapped inside the CNTs may be partially responsible for neurotoxicity generation. In the present study, we selected rat pheochromocytoma (PC12) cells to investigate and compare the effects of two kinds of multiwall carbon nanotubes (MWCNTs) with different concentrations of Fe impurities which usually come from the massive production of CNTs by chemical vapor deposition. Exposure to Fe-high MWCNTs can reduce cell viability and increase cytoskeletal disruption of undifferentiated PC12 cells, diminish the ability to form mature neurites, and then adversely influence the neuronal dopaminergic phenotype in NGF-treated PC-12 cells. The present results highlight the critical role of iron residue in the adverse response to MWCNTs exposure in neural cells. These findings provide useful information for understanding the toxicity and safe application of carbon nanotubes.

Water-Soluble Taurine-Functionalized Multi-Walled Carbon Nanotubes Induce Less Damage to Mitochondria of RAW 264.7 Cells

Multi-walled carbon nanotubes (MWCNTs) are increasingly used and many studies have already showed their cytotoxicity in different kinds of cell lines, while their mechanism is not fully understood. Mitochondria are the relatively sensitive organelle in response to the stress challenged by the exogenous chemicals. The study aimed to evaluate mitochondrial injury and cytotoxicity in mouse peritoneal macrophage cell line (RAW 264.7) induced by the water-soluble taurine functionalized MWCNTs (tau-MWCNTs) and pristine raw MWCNTs (raw-MWCNTs). The different concentrations including 0, 5, 20, 40 and 80 microg/ml for both kinds of MWCNTs were adopted. The cytotoxicity and the mitochondrial function were assessed after 12 h and 24 h treatment. The results revealed that both MWCNTs could produce significantly dose-dependent cytotoxicity and mitochondrial injury including the decrease of mitochondrial membrane potential, the release of cytochrome c from mitochondria and the increase of cytoplasm Ca2+ content. The activities of adenosine triphosphatases (ATPase) and succinodehydrogenase (SDH) of mitochondria were all inhibited after MWCNTs treatment. In conclusion, MWCNTs could lead to mitochondrial injury, which might be one possible pathway of apoptotic cell induction. The findings that tau-MWCNTs exhibited less toxicity compared with raw-MWCNTs support a useful approach to reduce the toxicity of MWCNTs by surface-functionization with taurine.

In vitro toxicity of multi-walled carbon nanotubes in C6 rat glioma cells

The present study aimed to evaluate the potential toxicity and the general mechanism involved in multi-walled carbon nanotubes (MWCNT)-induced cytotoxicity in C6 rat glioma cell line. Two kinds of MWCNT, which were coded as MWCNT1 (measured 10–20nm in diameter and 2μm in average length) and MWCNT2 (measured 40–100nm in diameter and 10μm in average length), were used in this study. To elucidate the possible mechanisms of cytotoxicity induced by MWCNT, MTT assay and flow cytometry analysis for apoptosis and cell cycle, MDA and SOD assays for oxidative stress were quantitatively assessed. The exposure of C6 rat glioma cells to different sizes of two kinds of carbon nanotubes at concentrations between 25 and 400μg/ml decreased the cell viability in a concentration- and time-dependent manner. The exposure of C6 rat glioma cells to MWCNT (200–400μg/ml) resulted in a concentration dependent cell apoptosis and G1 cell cycle arrest, and increased the level of oxidative stress. Results demonstrate that smaller size of MWCNT seems to be more toxic than that of larger one. MWCNT-induced cytotoxicity in C6 cells is probably due to the increased oxidative stress.

Selectivity of Multi-wall Carbon Nanotube Network Sensoric Units to Ethanol Vapors Achieved by Carbon Nanotube Oxidation

Two kinds of multiwall carbon nanotubes (MWCNT) networks “Buckypaper” were made by the vacuum filtration method of MWCNT aqueous suspension. The first one was prepared from pure CNT and the second from its oxidized form. The CNT oxidation increase content of oxygen bonded to the surface of CNT. The sensitivity of MWCNT networks to organic solvent vapors (ethanol and heptane) has been investigated by resistance measurements. The solvents had different polarities given by Hansen solubility parameters and nearly the same volume fractions of saturated vapors at the condition of experiment. CNT oxidation significantly increases the sensitivity of CNT resistive sensoric unit to vapors of ethanol and decrease response to heptane vapors.

Influence of geometries of multi-walled carbon nanotubes on the pore structures of Buckypaper

Influence of geometries, i.e. lengths and diameters, of multi-walled carbon nanotubes (MWCNTs) on pore sizes and distributions as well as resin impregnation quality of Buckypaper was studied. Three kinds of MWCNTs with different lengths and diameters were used to fabricate Buckypapers by the process of vacuum assisted filtration. Scanning electron microscopy (SEM) and N2 adsorption results show that the Buckypaper made of MWCNTs with longer lengths and thinner diameters has the smallest mean pore diameters and best pore size distribution. The results also show that MWCNTs with larger diameters are more inclined to form pore structures with larger pore sizes, and MWCNTs with shorter lengths are more inclined to form pore structures with much wider pore size distribution. Microstructure characterization of the Buckypaper/epoxy composites also exhibited phenomenon of the same rules.

Improved Selectivity of Oxidized Multiwall Carbon Nanotube Network for Detection of Ethanol Vapor

Two kinds of Multiwall carbon nanotubes (MWCNT) networks “Buckypaper” were made by the vacuum filtration method of MWCNT aqueous suspension. The first one was prepared from pure CNT and the second from its oxidized form by acidic KMnO4 as oxidizing agent. The CNT oxidation increase content of oxygen bonded to the surface of CNT decreasing their hydrophobic character. The sensitivity of MWCNT networks to two kind of organic solvent vapors (ethanol and hepane) has been investigated by resistance measurements. The solvents had different polarities given by Hansen solubility parameters and nearly the same volume fractions of saturated vapors at the condition of experiment. CNT oxidation significantly increases the sensitivity of CNT resistive sensor to vapors of ethanol and decrease response to heptane vapors. The present paper demonstrates the effective way how to add proper selectivity for organic vapor detection.

Highly electroconductive multiwalled carbon nanotubes as potentially useful tools for modulating calcium balancing in biological environments

Aiming to explore the mechanisms modulating cell-carbon nanotube interactions, we investigated whether Ca2+ ion balancing between intra- and extracellular environments could be affected by multiwalled carbon nanotubes (MWCNTs). We analyzed the effects induced by two different kinds of MWCNTs (as prepared and annealed at 2400°C) on the intracellular Ca2+ ion levels in rat electrically sensitive cells and on the intercellular junction integrity of rat adenocarcinoma colon cells and platelet aggregation ability, which depend on the Ca2+ concentration in the medium. MWCNTs, purified by annealing and more electroconductive as compared to nonannealed MWCNTs, affected Ca2+ ion balancing between extra- and intracellular environments and induced changes on Ca2+ ion-dependent cellular junctions and platelet aggregation, behaving as the calcium chelator ethylene glycol tetraacetic acid. This could be due to the sorption of cationic Ca2+ ions on CNTs surface because of the excess of negatively charged electrons on the aromatic units formed on MWCNTs after annealing. From the Clinical EditorThe authors investigated whether Ca2+ ion balance between intra- and extracellular space can be modulated by multiwalled carbon nanotubes (MWCNTs). Annealed nanotubes induced changes on Ca2+ dependent cellular junctions and platelet aggregation, behaving similary to ethylene glycol tetraacetic acid, an established calcium chelator.

A carbon nanotube/polymer strain sensor with linear and anti-symmetric piezoresistivity

In this article, a strain sensor made from an epoxy-based nanocomposite using a kind of multi-walled carbon nanotubes (MWNTs), i.e., LMWNT-10, was investigated. It was found that the piezoresistivity of this strain sensor is linear and anti-symmetric in tensile and compressive states within a large strain range, which is different from that of the strain sensor using another type of MWNTs, i.e., MWNT-7, in our previous reports. This linear and anti-symmetric piezoresistivity is very suitable for practical sensor applications. In our experiments, both static and dynamic responses of the two sensors were measured. The experimental results indicate that the completely different piezoresistivity characteristics of the two sensors are probably due to the complete different working mechanisms. For the sensor made from LMWNT-10, the present experimental investigations reveal that its working mechanism should be the piezoresistivity of MWNTs due to deformation of MWNTs. On the other hand, for the strain sensor made from MWNT-7, the dominant working mechanism of this sensor is the tunneling effect caused by the distance changes among carbon nanotubes.

Crystallinity of biodegradable polymers reinforced with functionalized carbon nanotubes

Well-dispersed multiwall carbon nanotubes (MWCNTs) were prepared by grafting poly(L-lactide-co-e-caprolactone) (PLACL) biodegradable copolymer onto the sidewall of hydroxylated MWCNTs using oligomeric L-lactide (LA) and e-caprolactone (CL). After preparation of MWCNT/PLACL composites, the effect of functionalized MWCNTs on crystallinity of PLACL was investigated by scanning electron microscopy (SEM), X-ray diffraction (XRD), differential scanning calorimetry (DSC), dynamic mechanical analysis (DMA), and polarized light optical microscopy (POM). The surface functionalization effectively improved the dispersion and adhesion of MWCNTs which acted as reinforcing filler in the PLACL polymer matrix and hence improved the physical and thermomechanical properties of the nanocomposites. The glass transition temperature (Tg) and the crystallinity of nanocomposites decreased in comparison with those of neat PLACL when the concentration of functionalized MWCNTs in nanocomposites was 0.5 wt%. With further increment in concentration of functionalized MWCNTs, the Tg of composites increased until the Tg of neat PLACL, and also the crystallinity of composites increased. The functionalized MWCNTs have no significant effect on the melting point of nanocomposites. The MWCNTs acted as heterogeneous nucleation points and increased the lamella size and therefore the crystallinity of PLACL. Furthermore, the larger agglomerated clusters of both kinds of MWCNTs (i.e., MWCNT-grafted-PLACL and pristine MWCNTs) are more effective than small clusters as nucleation points for growing the spherulites.

다중벽 탄소나노튜브와 폴리우레탄 복합화 필름의 물성특성

―This study studies on the physical property of MWNT/PU composit e film for electrostatic dissipation (ESD) function by dispersing multi-wall carbon nanotubes (MWNT) in dimethylfor mamide (DMF) and by combining it with polyurethane(PU). For this purpose, four kinds of MWNT were selected and the composit e films were made by dispersion processing, and their physical properties were measured and investigated in terms of electrica l conductivity. For dispersion parameters, four MWNT contents(0 .5, 1, 2, 5wt%) and two dispersion times(30min, 120min) were select ed. The dispersion property and the electrical conductivity of MWNT/PU film was measured using a UV-Vis spectrometer and condu ctivity measuring apparatus. Finally, their physical properties according to the dispersion conditions were analyzed and discus sed with various processing conditions.

Screening Assay of Very Long Chain Fatty Acids in Human Plasma with Multiwalled Carbon Nanotube-Based Surface-Assisted Laser Desorption/Ionization Mass Spectrometry

Peroxisomal disorders are characterized biochemically by elevated levels of very long chain fatty acids (VLCFAs) in serum. Herein, we describe a novel approach for quantification of VLCFAs in serum, namely, eicosanoic acid (C20:0), docosanoic acid (C22:0), tetracosanoic acid (C24:0), and hexacosanoic acid (C26:0). The methodology is based on (i) enrichment of VLCFA derivatives using multiwalled carbon nanotubes (MWCNTs); (ii) quantification using stable isotope-labeled internal standards; and (iii) direct detection using MWCNT-based surface-assisted laser desorption/ionization-time-of-flight mass spectrometry (SALDI-TOFMS). Four kinds of MWCNTs (Aldrich 636843, 636495, 636509, and 636819) of different lengths and diameters were tested using the developed technique. The data show that 636843, the MWCNT with the largest outer diameter (o.d.), the widest wall thickness, and shortest length, had the best limit of detection (0.5-1 microg/mL) We also found that there was no significant difference in enrichment efficiency of VLCFAs between the four MWCNTs, which suggests that the size of the MWCNT may contribute to desorption/ionization efficiency. To our knowledge, this is the first study to test the enrichment of VLCFAs using MWCNTs of different sizes. We have shown that the VLCFAs adsorbed by MWCNTs can be analyzed by SALDI-TOFMS. In addition, this method does not require liquid/gas chromatography separation, thereby allowing for high-throughput screening of VLCFAs in peroxisomal disorders.