Sequence-dependent electrical response of ssDNA-decorated carbon nanotube, field-effect transistors to dopamine

• Hari Krishna Salila Vijayalal Mohan,
• Jianing An and
• Lianxi Zheng

Beilstein J. Nanotechnol. 2014, 5, 2113–2121, doi:10.3762/bjnano.5.220

• FETs lack responsivity and selectivity for its detection due to the presence of interfering compounds such as uric acid (UA). Surface modification of CNTs using single-stranded deoxyribonucleic acid (ssDNA) renders the surface responsive to DA and screens the interferent. Due to the presence of

• sequence combinations, which interact differently with CNTs as well as DA, and consequently, this influences the FET response. The transistor electrical parameters such as conductance, transconductance, threshold voltage and hysteresis gap extracted from the current–voltage characteristics are indicators

Effect of channel length on the electrical response of carbon nanotube field-effect transistors to deoxyribonucleic acid hybridization

• Hari Krishna Salila Vijayalal Mohan,
• Jianing An,
• Yani Zhang,
• Chee How Wong and
• Lianxi Zheng

Beilstein J. Nanotechnol. 2014, 5, 2081–2091, doi:10.3762/bjnano.5.217

• of the channel length on hybridization detection. One proposed method to confine hybridization events on the channel surface and to reduce the influence of contacts is the use of long CNTs. Thus the signal response is a consequence of the alteration in the intrinsic electronic property of the SWCNT

• for the detection studies. Specifically, only semiconducting FETs were used for the study. SEM (Jeol, JSM-7600F) was used to verify the existence of the CNTs between the electrodes. AFM (Asylum Research, Cypher AFM) in tapping mode was used to obtain the height profile, which gives the diameter of the

• . on the response of FET when multiple sensing mechanisms contribute to a change in G, gm and Vth. Results and Discussion Figure 1a shows an SEM image of the as-grown, long CNTs. Figure 1b,c shows the AFM image and height profile of an individual SWCNT. The diameter distribution of the SWCNTs is shown

Photodetectors based on carbon nanotubes deposited by using a spray technique on semi-insulating gallium arsenide

• Domenico Melisi,
• Maria Angela Nitti,
• Marco Valentini,
• Antonio Valentini,
• Teresa Ligonzo,
• Giuseppe De Pascali and
• Marianna Ambrico

Beilstein J. Nanotechnol. 2014, 5, 1999–2006, doi:10.3762/bjnano.5.208

• (CNTs) in this field have shown interesting results, in particular in new technologically advanced nanoelectronic devices [4][5]. Photodetectors based on films of CNTs (both bundle and carpet distribution) on silicon, have been previously analyzed in the visible and IR spectral regions [6][7]. Moreover

• the chemical, mechanical and electrical properties make CNTs also suitable to fabricate a wide range of radiation detectors for space applications, high energy physics and medical instrumentation [7][8][9]. The common technique obtain CNT films is chemical vapour deposition (CVD), but some deposition

• deposition technique for depositing CNTs on silicon, starting from a powder, at low temperatures, without catalyst and an intermediate layer [7]. By using this spray technique, CNT films on silicon-based photodetectors were prepared, achieving quantum efficiency (QE) values in the visible light range

Carbon nano-onions (multi-layer fullerenes): chemistry and applications

• Juergen Bartelmess and
• Silvia Giordani

Beilstein J. Nanotechnol. 2014, 5, 1980–1998, doi:10.3762/bjnano.5.207

• ; Review Introduction Since the discovery of the fullerene C60 in 1985 by Curl, Kroto and Smalley [1], carbon nanomaterials have been the focus of interdisciplinary chemical research. In the following years, several other carbon based nanomaterials were discovered, namely carbon nanotubes (CNTs) [2][3][4

• method of choice. The covalent as well as the non-covalent functionalization of CNTs [22][23][24] have been widely studied in the past decades and can serve as inspiration for possible synthetic strategies to decorate CNOs with a variety of functional groups and also to increase the solubility of CNO

• functionalization of CNOs, especially with small molecules or surfactants, which is widely described for CNTs [23], has not been reported so far. Covalent functionalization Synthetic procedures for the covalent functionalization of CNOs are largely based on previously described strategies for the functionalization

Carbon-based smart nanomaterials in biomedicine and neuroengineering

• Antonina M. Monaco and
• Michele Giugliano

Beilstein J. Nanotechnol. 2014, 5, 1849–1863, doi:10.3762/bjnano.5.196

• in brain implants, are within reach thanks to the advancements in nanotechnology. In particular, carbon-based nanostructured materials, such as graphene, carbon nanotubes (CNTs) and nanodiamonds (NDs), have demonstrated to be highly promising materials for designing and fabricating nanoelectrodes and

• allotropes, the most widely known are carbon nanotubes (CNTs) and fullerenes, graphite and graphene (sp2), and diamond (sp3). From these distinct hybridisations, different properties are inherent to these allotropes. Carbon nanotubes (CNTs): CNTs, first reported by Iijima in 1991 [1], are hollow cylinders

• made of one (i.e., single-walled CNTs, SWCNTs) or several (i.e., multi-walled CNTs, MWCNTs) layers of graphene. They are obtained by a variety of methods, including chemical vapour deposition (CVD) and arc-discharge, and their electronic properties depend solely on geometric parameters, such as

Non-covalent and reversible functionalization of carbon nanotubes

• Antonello Di Crescenzo,
• Valeria Ettorre and
• Antonella Fontana

Beilstein J. Nanotechnol. 2014, 5, 1675–1690, doi:10.3762/bjnano.5.178

• Antonello Di Crescenzo Valeria Ettorre Antonella Fontana Dipartimento di Farmacia, Università “G. d’Annunzio”, Via dei Vestini, 66100 Chieti, Italy 10.3762/bjnano.5.178 Abstract Carbon nanotubes (CNTs) have been proposed and actively explored as multipurpose innovative nanoscaffolds for

• applications in fields such as material science, drug delivery and diagnostic applications. Their versatile physicochemical features are nonetheless limited by their scarce solubilization in both aqueous and organic solvents. In order to overcome this drawback CNTs can be easily non-covalently functionalized

• with different dispersants. In the present review we focus on the peculiar hydrophobic character of pristine CNTs that prevent them to easily disperse in organic solvents. We report some interesting examples of CNTs dispersants with the aim to highlight the essential features a molecule should possess

Growth and structural discrimination of cortical neurons on randomly oriented and vertically aligned dense carbon nanotube networks

• Christoph Nick,
• Sandeep Yadav,
• Ravi Joshi,
• Christiane Thielemann and
• Jörg J. Schneider

Beilstein J. Nanotechnol. 2014, 5, 1575–1579, doi:10.3762/bjnano.5.169

• neurons are attracted towards both types of CNT nano-architectures. For both, neurons form clusters in close vicinity to the CNT structures whereupon the randomly oriented CNTs are more closely colonised than the CNT pillars. Neurons develop communication paths via neurites on both nanoarchitectures

• (CNTs) are attractive for various sensing and electronic applications. These include, but are not limited to, gas sensors [1], mechanical sensors [2], biosensors (e.g., for glucose or DNA) [3][4], and vertical interconnect access (vias) applications based on CNT bundles [5]. CNTs have also sparked

• stimulate neural activity. CNTs do have a high capacity and low impedance, e.g., compared to IrO2 which is widely used as electrical interface for cells, as has been manifested by cyclic voltammetry and impedance spectroscopy [9]. Thus CNTs allow to minimise the stimulation voltage as well as the electrode

Nano-rings with a handle – Synthesis of substituted cycloparaphenylenes

• Anne-Florence Tran-Van and
• Hermann A. Wegner

Beilstein J. Nanotechnol. 2014, 5, 1320–1333, doi:10.3762/bjnano.5.145

• as fullerene [1], graphene [2] and carbon nanotubes (CNTs) [3]. Research on these materials has been originally conducted by physicists. Also, the preparation methods relied on physical processes [4][5]. In the past decade the field is also more and more a playground for organic chemists as these

• in the target molecule. For CNTs a selective synthesis, which controls all structural parameters, is of special interest as they determine the properties and, finally, the field of application [7][8][9][10]. For armchair carbon nanotubes, cycloparaphenylenes (CPPs) have been designed as potential

• calculated with the same method (62 kcal/mol). Nanorings with inserted acene units One of the benefits of applying CPPs as templates for the preparation of CNTs is the possibility to control the chirality of the CNT by incorporating the desired chirality into the precursor. The Itami group applied their

Growth and characterization of CNT–TiO₂ heterostructures

• Yucheng Zhang,
• Ivo Utke,
• Johann Michler,
• Gabriele Ilari,
• Marta D. Rossell and
• Rolf Erni

Beilstein J. Nanotechnol. 2014, 5, 946–955, doi:10.3762/bjnano.5.108

• , combining TiO2 nanocrystals and carbon nanotubes (CNTs) offers enhanced photosensitivity and improved photocatalytic efficiency, which is key to achieving sustainable energy and preventing environmental pollution. Hence, it has aroused a tremendous research interest. This report surveys recent research on

• the topic of synthesis and characterization of the CNT–TiO2 interface. In particular, atomic layer deposition (ALD) offers a good control of the size, crystallinity and morphology of TiO2 on CNTs. Analytical transmission electron microscopy (TEM) techniques such as electron energy loss spectroscopy

• /metal oxide material systems. Keywords: atomic layer deposition (ALD); carbon nanotubes; electron energy loss spectroscopy (EELS); interface; titanium dioxide (TiO2); transmission electron microscopy (TEM); Introduction Since the discovery by Iijima in 1991, carbon nanotubes (CNTs) have always been on

Gas sensing with gold-decorated vertically aligned carbon nanotubes

• Prasantha R. Mudimela,
• Mattia Scardamaglia,
• Oriol González-León,
• Nicolas Reckinger,
• Rony Snyders,
• Eduard Llobet,
• Carla Bittencourt and
• Jean-François Colomer

Beilstein J. Nanotechnol. 2014, 5, 910–918, doi:10.3762/bjnano.5.104

• based on nanomaterials have been developed to fabricate small and inexpensive gas sensors with high sensitivity and able to work at room temperature [1]. Among the possible active materials in gas sensing devices, good candidates are carbon nanotubes (CNTs), thanks to their intrinsic properties such as

• very large surface area to volume ratio, high electron mobility, physico-chemical stability and high adsorption capability [2][3][4][5]. The use of CNTs as gas sensors was first proposed by Kong et al., who showed that a dramatic change in the electrical resistance of an individual single-walled

• room temperature), prompt response, short recovery time and reasonable reversibility and stability [2][3][4][6]. A further advance in the development of CNT gas sensing devices was the use of vertically aligned CNTs (VA-CNTs). In this case the sensing device benefits from the unidirectional electrical

An analytical approach to evaluate the performance of graphene and carbon nanotubes for NH₃ gas sensor applications

• Elnaz Akbari,
• Vijay K. Arora,
• Aria Enzevaee,
• Mohamad. T. Ahmadi,
• Mehdi Saeidmanesh,
• Mohsen Khaledian,
• Hediyeh Karimi and
• Rubiyah Yusof

Beilstein J. Nanotechnol. 2014, 5, 726–734, doi:10.3762/bjnano.5.85

• Teknologi Malaysia, Johor Bahru, Malaysia Malaysia–Japan International Institute of Technology (MJIIT), Universiti Teknologi Malaysia, Kuala Lumpur, Malaysia 10.3762/bjnano.5.85 Abstract Carbon, in its variety of allotropes, especially graphene and carbon nanotubes (CNTs), holds great potential for

• applications in variety of sensors because of dangling π-bonds that can react with chemical elements. In spite of their excellent features, carbon nanotubes (CNTs) and graphene have not been fully exploited in the development of the nanoelectronic industry mainly because of poor understanding of the band

• wavelength of carriers. Novel applications [7][8][9] are possible by exploiting the quantum waves in operation of these low-dimensional devices. New materials are being discovered in building novel sensors that can operate on the nanometer scale. Examples of these include graphene and carbon nanotubes (CNTs

Chemi- vs physisorption in the radical functionalization of single-walled carbon nanotubes under microwaves

• Victor Mamane,
• Guillaume Mercier,
• Junidah Abdul Shukor,
• Jérôme Gleize,
• Aziz Azizan,
• Yves Fort and
• Brigitte Vigolo

Beilstein J. Nanotechnol. 2014, 5, 537–545, doi:10.3762/bjnano.5.63

• functionalization; grafting; microwaves; physisorption; Introduction Carbon nanotubes (CNTs) are recognized to have a huge potential in a variety of applications such as electronics, composite materials, energy storage and medicine [1][2][3][4]. From bulk synthesis method, CNTs are often entangled contingent upon

• to the CNTs. It is recognized to be an efficient way to confer specific surface properties [5]. However, the methods generally used for the covalent functionalization of CNTs often require long reaction times (from several hours to days) [6]. The reaction times can be considerably reduced to a few

• conjugated π system of CNTs thereby having a negative impact on their intrinsic properties (conductivity, mechanical properties) [23][24][25]. Low functionalization levels are indisputably preferred for CNT based composites [26]. As a consequence of the fast reaction times achieved under microwave heating, a

A catechol biosensor based on electrospun carbon nanofibers

• Dawei Li,
• Zengyuan Pang,
• Xiaodong Chen,
• Lei Luo,
• Yibing Cai and
• Qufu Wei

Beilstein J. Nanotechnol. 2014, 5, 346–354, doi:10.3762/bjnano.5.39

• calibration curve of the current response on the catechol concentration. It can be seen that the response current increased with the increase in catechol concentration. The linear range was 1–1310 µM (R = 0.998, n = 19), which was much wider than for the biosensor based on CNTs and laccase [33]. And the

Tensile properties of a boron/nitrogen-doped carbon nanotube–graphene hybrid structure

• Kang Xia,
• Haifei Zhan,
• Ye Wei and
• Yuantong Gu

Beilstein J. Nanotechnol. 2014, 5, 329–336, doi:10.3762/bjnano.5.37

• GNHS with 0.5%, 1.0%, 1.5%, 2.0%, 2.5% and 3.5% of N- dopants fracture at either the right or the left end of the structure. The atomic configurations of the GNHS with 2% of N-dopants are presented in Figure 4a-d. Before the initiation of failure, a shearing of the CNTs and an elongation of bonds are

• configurations of the case with 0.75%B and 0.75%N at different strains. Surprisingly, the hybrid structure is found to fracture around four CNTs. After failure, the upper layer is found to break at the outermost two CNTs at the right end, while the lower layer fractures at the second outermost two CNTs. Such

• failure of the hybrid structure around the middle region is also witnessed. As shown in Figure 8f, the top and bottom layers of GNHS-1.5%N1.5%B fracture simultaneously around the two connecting CNTs. In all investigated cases, the self-adhesive behavior between the dangling layers and the bulked

Modeling and optimization of atomic layer deposition processes on vertically aligned carbon nanotubes

• Nuri Yazdani,
• Vipin Chawla,
• Eve Edwards,
• Vanessa Wood,
• Hyung Gyu Park and
• Ivo Utke

Beilstein J. Nanotechnol. 2014, 5, 234–244, doi:10.3762/bjnano.5.25

• guidelines; titania, TiO2; Introduction Recent advances in the synthesis and processing of carbon nanotubes (CNTs) have enabled the prospect of their integration into existing technologies that exploit the high surface area of mesoporous ceramic films [1]. Over the last 10 years, ceramic coated CNTs have

• ceramic coating of the CNTs. Atomic layer deposition (ALD) is a highly attractive option for coating CNTs because it enables a wide range of ceramics and metals to be deposited conformally on arbitrary surface topologies with precise control of layer thickness [1][18]. However, vertically aligned CNT

• functionalization [19][20][21][22][23][24]. In practice, however, chemical vapor deposition (CVD) grown CNTs are prone to a sufficient density of surface defect sites to allow for the nucleation of the ceramic at discrete points along the surface of the CNT. The ceramic then grows from these nucleation sites until

En route to controlled catalytic CVD synthesis of densely packed and vertically aligned nitrogen-doped carbon nanotube arrays

• Slawomir Boncel,
• Sebastian W. Pattinson,
• Valérie Geiser,
• Milo S. P. Shaffer and
• Krzysztof K. K. Koziol

Beilstein J. Nanotechnol. 2014, 5, 219–233, doi:10.3762/bjnano.5.24

• nitrogen-doped carbon nanotubes (N-CNTs). A mixture of toluene (main carbon source), pyrazine (1,4-diazine, nitrogen source) and ferrocene (catalyst precursor) was used as the injection feedstock. To optimize conditions for growing the most dense and aligned N-CNT arrays, we investigated the influence of

• key parameters, i.e., growth temperature (660, 760 and 860 °C), composition of the feedstock and time of growth, on morphology and properties of N-CNTs. The presence of nitrogen species in the hot zone of the quartz reactor decreased the growth rate of N-CNTs down to about one twentieth compared to

• the growth rate of multi-wall CNTs (MWCNTs). As revealed by electron microscopy studies (SEM, TEM), the individual N-CNTs (half as thick as MWCNTs) grown under the optimal conditions were characterized by a superior straightness of the outer walls, which translated into a high alignment of dense

Synthesis of boron nitride nanotubes from unprocessed colemanite

• Saban Kalay,
• Zehra Yilmaz and
• Mustafa Çulha

Beilstein J. Nanotechnol. 2013, 4, 843–851, doi:10.3762/bjnano.4.95

• used to synthesize boron nitride nanotubes (BNNT)s [3][4]. BNNTs, structural analogoues of carbon nanotube (CNT)s, have superior properties than CNTs due to their robust structure which resists high temperatures and harsh chemical conditions. They also have a high hydrogen storage capacity due to the

• ionic nature of the B–N bond [5]. In contrast to CNTs, the BNNTs have a constant and wide band-gap of 5.5 eV. Therefore, they are electrical isolators independent from their size or chirality. In recent studies, it has been indicated that the hydrogen storage capacity of BNNTs is two times greater than

• that of CNTs [6]. It has been theoretically demonstrated that BNNTs can capture ions selectively creating superhydrophobic surfaces [7][8]. Since hexagonal boron nitrides (h-BNs) have a sp2 hybridization, the BNNTs can interact with polymers possessing aromatic rings via π-π interaction. Therefore, the

Size-dependent characteristics of electrostatically actuated fluid-conveying carbon nanotubes based on modified couple stress theory

• Mir Masoud Seyyed Fakhrabadi,
• Abbas Rastgoo and
• Mohammad Taghi Ahmadian

Beilstein J. Nanotechnol. 2013, 4, 771–780, doi:10.3762/bjnano.4.88

• and structures made from different metallic and non-metallic materials, carbon nanomaterials play a special role. For instance, carbon nanotubes (CNTs) possess extraordinary chemical, physical, mechanical and electrical properties. Thus, since their discovery in 1991 by Iijima [13], they have

• attracted a lot of scientists and researchers all over the world to study their characteristics as well as their actual and potential applications. A mathematical formulation of the applicability of CNTs in NEMS was conducted by Dequesnes et al. [14]. They applied a model with one degree of freedom in order

• to study the manipulation of CNTs by using electrostatic actuation and vdW interactions. The results revealed that the vdW force played an important role in the deflection and pull-in behaviors of the CNTs. In electrostatic actuation, a voltage is applied to two electrodes with a gap in-between. In

AFM as an analysis tool for high-capacity sulfur cathodes for Li–S batteries

• Renate Hiesgen,
• Seniz Sörgel,
• Rémi Costa,
• Linus Carlé,
• Ines Galm,
• Natalia Cañas,
• Brigitta Pascucci and
• K. Andreas Friedrich

Beilstein J. Nanotechnol. 2013, 4, 611–624, doi:10.3762/bjnano.4.68

• capacity of approximately 1000 mA·g(sulfur)−1 [19][20]. Another approach is based on vertically aligned carbon nanotubes (CNTs) grown on a nickel foil without any binder. To date, these binder-free CNT cathodes contain the highest published total ratio of sulfur (90%) in an electrode [21]. The advantage of

Functionalization of vertically aligned carbon nanotubes

• Eloise Van Hooijdonk,
• Carla Bittencourt,
• Rony Snyders and
• Jean-François Colomer

Beilstein J. Nanotechnol. 2013, 4, 129–152, doi:10.3762/bjnano.4.14

• , Materia Nova Research Center, Mons, Belgium 10.3762/bjnano.4.14 Abstract This review focuses and summarizes recent studies on the functionalization of carbon nanotubes oriented perpendicularly to their substrate, so-called vertically aligned carbon nanotubes (VA-CNTs). The intrinsic properties of

• individual nanotubes make the VA-CNTs ideal candidates for integration in a wide range of devices, and many potential applications have been envisaged. These applications can benefit from the unidirectional alignment of the nanotubes, the large surface area, the high carbon purity, the outstanding electrical

• conductivity, and the uniformly long length. However, practical uses of VA-CNTs are limited by their surface characteristics, which must be often modified in order to meet the specificity of each particular application. The proposed approaches are based on the chemical modifications of the surface by

Electronic and transport properties of kinked graphene

• Jesper Toft Rasmussen,
• Tue Gunst,
• Peter Bøggild,
• Antti-Pekka Jauho and
• Mads Brandbyge

Beilstein J. Nanotechnol. 2013, 4, 103–110, doi:10.3762/bjnano.4.12

• nanoribbons (GNR) [2]. The electronic structure of GNRs depends on width, direction and edge structure – all parameters that to some degree can be controlled. GNRs can be formed by etching [2], by unzipping carbon nanotubes (CNTs) [3], or ultimately be grown with atomic-scale precision by using self-assembly

• a (25,25) nanotube. Experiments by Ruffieux et al. [38] compare hydrogen adsorption on C60 molecules, CNTs, and graphite to show that reactivity is increased with curvature. In our case we find that the local electronic density of states changes little for the atoms on the pristine bent graphene

Low-dose patterning of platinum nanoclusters on carbon nanotubes by focused-electron-beam-induced deposition as studied by TEM

• Xiaoxing Ke,
• Carla Bittencourt,
• Sara Bals and
• Gustaaf Van Tendeloo

Beilstein J. Nanotechnol. 2013, 4, 77–86, doi:10.3762/bjnano.4.9

• nanotubes; FEBID; nanocluster; platinum; patterning; radiation-induced nanostructures; TEM; Introduction Hybrid nanostructures consisting of carbon nanotubes (CNTs) decorated with metal nanoclusters enable access to various electrical and catalytic properties. Therefore, they are considered as building

• blocks for nanoscopic electronic devices [1]. In such hybrid nanostructures, metals are often deposited onto the CNTs by thermal evaporation [2][3][4][5][6] or wet chemistry [7], which results in a non-site-specific covering. However, when using such structures for nanodevice fabrication, specific sites

• of the CNTs need to be functionalized in order to create components with specific properties. For instance, in order to fabricate CNT contacts on electrodes, Pd is thermally evaporated onto both ends by using shadowing masks [8]. In earlier reports, it has been shown that Au nanoclusters can be site

Low-temperature synthesis of carbon nanotubes on indium tin oxide electrodes for organic solar cells

• Andrea Capasso,
• Luigi Salamandra,
• Aldo Di Carlo,
• John M. Bell and
• Nunzio Motta

Beilstein J. Nanotechnol. 2012, 3, 524–532, doi:10.3762/bjnano.3.60

• solar cells based on poly(3-hexylthiophene) (P3HT) and phenyl-C61-butyric acid methyl ester (PCBM), the MWCNT-enhanced electrodes are found to improve the charge-carrier extraction from the photoactive blend, thanks to the additional percolation paths provided by the CNTs. The work function of as

• , such as thermal [8] and solvent annealing [9], or the use of additives in the blend preparation [10]. Along with fullerenes, carbon nanotubes (CNTs) have also been suggested as promising materials to boost solar cell PCE, thanks to their excellent electrical properties and to a favorable aspect ratio

• [11]. In fact, CNTs were initially suggested as a replacement for fullerene [12], because of their ability to create percolation paths through the heterostructure, while providing electron–hole dissociation sites. Being that the electron mobility in fullerenes is rather low [13][14][15], the initial

Conducting composite materials from the biopolymer kappa-carrageenan and carbon nanotubes

• Ali Aldalbahi,
• Jin Chu,
• Peter Feng and
• Marc in het Panhuis

Beilstein J. Nanotechnol. 2012, 3, 415–427, doi:10.3762/bjnano.3.48

• Rico, San Juan, Puerto Rico 00931, USA 10.3762/bjnano.3.48 Abstract Conducting composite films containing carbon nanotubes (CNTs) were prepared by using the biopolymer kappa-carrageenan (KC) as a dispersant. Rheological studies indicated that 0.5% w/v was the appropriate KC concentration for

• dispersing CNTs. Our results showed that multiwalled nanotubes (MWNTs) required less sonic energy than single-walled nanotubes (SWNTs) for the dispersion process to be complete. Films prepared by vacuum filtration exhibited higher conductivity and improved mechanical characteristics compared to those

• prepared by evaporative casting. All composite films displayed sensitivity to water vapour, but MWNT films were more sensitive than SWNT films. Keywords: biopolymers; carbon nanotubes; carrageenan; composite materials; conductivity; mechanical; rheology; Introduction Carbon nanotubes (CNTs) have

Glassy carbon electrodes modified with multiwalled carbon nanotubes for the determination of ascorbic acid by square-wave voltammetry

• Sushil Kumar and
• Victoria Vicente-Beckett

Beilstein J. Nanotechnol. 2012, 3, 388–396, doi:10.3762/bjnano.3.45

• , which results in poor selectivity and reproducibility, thus limiting the use of bare GCEs in quantitative measurements. Presently there are increasing reports on the use of carbon nanotubes (CNTs) in electroanalysis [10]. CNTs may be multiwalled or single-walled depending on the number of layers of

• carbon atoms in the nanotubes [11][12]. CNTs have unique geometric, mechanical, electronic and chemical properties. They possess a high aspect ratio (length/diameter) [13] and large surface areas (typically 200–300 m2/g) and, hence, potentially high electroactivity [14]. The defects present at the open

• ends of the CNTs have been observed to produce relatively low peak potentials and high peak currents in the voltammetry of several electroactive molecules at electrodes modified with CNTs [14][15]. Nafion, a perfluorosulfonated polymer with cation-exchange properties, has been used to stably confine