共查询到19条相似文献,搜索用时 62 毫秒
1.
2.
3.
4.
利用多壁碳纳米管( MWNT)—Nafion和纳米金( GNPs)修饰金电极构建了一种简单、灵敏检测人端粒DNA的电化学阻抗传感器。首先将Nafion分散的MWNT滴涂于Au电极表面,再利用电化学沉积法将GNPs沉积到MWNT—Nafion修饰Au电极表面,以GNPs为载体固定人端粒探针DNA制备DNA传感器。在最优实验条件下,将传感器用于人端粒DNA的检测中,结果表明:目标人端粒DNA的线性范围为1.0×10-13~5.0×10-11mol/L,检出限(S/N=3)为2.5×10-14mol/L。采用MWNT为基底沉积GNPs修饰电极检测的灵敏度显著提高。 相似文献
5.
6.
7.
8.
采用酸氧化法对多壁碳纳米管(MWCNTs)进行表面修饰,并研究了基于MWCNTs/羟乙基纤维素(HEC)复合体系的结露传感特性。通过红外光谱和热失重分析对MWCNTs进行了结构表征。氧化处理有效提高了MWCNTs的分散性。基于改性MWCNTs的结露元件与本征MWCNTs的器件相比表现出更好的开关特性。结露元件在相对湿度(RH)为75 %RH以前伴随湿度变化,电阻变化非常小,而在85 %RH以后呈现电阻的非线性增大。MWCNTs在复合膜中的最佳质量分数约为22 wt%,在100 %RH下灵敏度达到31。 相似文献
9.
以聚二烯丙基二甲基氯化铵(PDDA)为阳离子聚电解质,以乙醇氧化酶(AOD)为带负电的生物分子,结合多壁碳纳米管(MWCNTs),层层自组装(layer-by-layer)制备聚烯丙胺/聚磺化乙烯硫酸盐乙醇(PAA/PVS)3抗干扰膜修饰Pt电极,在此基础上将PDDA与AOD交替组装在修饰好的电极上,构建了电流型乙醇生物传感器.实验结果表明:MWCNTs的引入使电极对H2O2的催化电流明显增大,制成的酶电极可以有效控制酶量的使用,酶膜组装层数为6时最优,对乙醇的灵敏度为2.913 μA/mol/L,在2×10-4~8×10-3mol/L浓度范围内呈良好线性关系,检出限为1.52×10-5mol/L(S/N=3),并且传感器具有良好的抗干扰能力和稳定性. 相似文献
10.
11.
In the present study, a new soft computing framework is developed for solving nanofluidic problems based on fluid flow and heat transfer of multi-walled carbon nanotube (MWCNT) along a flat plate with Navier slip boundary with the help of artificial neural networks (ANNs), Genetic Algorithms (GAs), Interior-Point Algorithm (IPA), and hybridized approach GA-IPA. Original PDEs associated with the problem are transformed into system of nonlinear ODEs using similarity transformation. Mathematical model of transformed system is constructed by exploiting the strength of universal function approximation ability of ANNs and an unsupervised error function is formulated for the system in a least mean square sense. Learning of the design variable of the networks is carried out with GAs supported with IPA for rapid local convergence. The design scheme is applied to solve number of variants by taking water, engine oil, and kerosene oil as a base fluids mixed with different concentrations of MWCNTs. The reliability and effectiveness of the design scheme is measured with the help of results of statistical analysis based on sufficient large number of independent runs of the algorithms rather than single successful run. The comparative studies of the proposed solution are made with standard numerical results in order to establish the correctness of the given scheme. 相似文献
12.
D. ZilliAuthor VitaeP.R. BonelliAuthor Vitae A.L. CukiermanAuthor Vitae 《Sensors and actuators. B, Chemical》2011,157(1):169-176
Multi-walled carbon nanotubes (MWCNTs) are successfully processed in the form of thin films (buckypapers), and their morphology and electrical behaviour are characterized. The MWCNTs are synthesized by the floating catalyst chemical vapour deposition process. The effects of a sequence of treatments applied for MWCNTs purification on the buckypapers electrical behaviour are also examined. Nanocomposite thin films constituted of pristine and purified MWCNTs and Pd nanoparticles are prepared in order to evaluate their viability as H2 sensors at room temperature. For this purpose, the electrical resistance of the nanocomposite films in atmospheres with different H2 concentrations, is determined. Scanning electron microscopy (SEM) images show that the buckypapers and the nanocomposite films are 2D structures constituted by randomly oriented MWCNTs. The buckypapers present a semiconductor-like electrical behaviour as determined by the standard four point method. Room temperature resistivity values of around 10−3 Ω m are assessed. Nanocomposite films show different electrical behaviour depending on the purification treatment applied to the MWCNTs employed. Furthermore, the electrical resistance of the nanocomposite films is found to increase when the measurements are performed in H2 atmosphere. Values of H2 sensitivity at room temperature of the nanocomposite films up to 2.15% are determined for H2 average concentration higher than 350 ppm with short recovery time. 相似文献
13.
《Sensors and actuators. A, Physical》2007,133(1):117-127
Multi-walled carbon nanotube (M-CNT)/Nafion nanocomposites were prepared by the dispersion of treated M-CNTs in a Nafion solution; this procedure was done in order to evaluate the influence of M-CNT loading of up to 7 wt.% on the M-CNT distribution behavior, mechanical properties, and the related actuation performance of the composites. As the M-CNT loading rose above 1 wt.%, the uniformly distributed M-CNT bundles induced by the Nafion polymer were determined to be perturbed, resulting in an inhomogeneous distribution. The heterogeneously distributed M-CNT bundles may provide an undesired impact on the connectivity within the Nafion membrane, thus giving rise to the poor electrochemically-generated actuation properties. It is important to note that the nanocomposite having only a 1 wt.% of M-CNT loading exhibited the best actuation performance in terms of the blocking forces produced by the M-CNT nanocomposites in a cantilever form. It can be understood that the performance improvement is caused by the uniform distribution of the M-CNT bundles, which was confirmed by TEM, XRD and electromechanical actuation tests. It is concluded that the M-CNT distribution behavior, induced by interactions between the polymer matrix, Nafion and the M-CNTs and the related electromechanical performance of the composites, are mainly governed by the M-CNT content. Also, DMA testing was performed. 相似文献
14.
Hirohisa TamagawaAuthor Vitae Wenyi LinAuthor VitaeKeiko KikuchiAuthor Vitae Minoru SasakiAuthor Vitae 《Sensors and actuators. B, Chemical》2011,156(1):375-382
Electrical bending control of Nafion-based ionic polymer-metal composite (IPMC) is quite difficult. Unlike a conventional fully hydrated noble metal-coated Nafion type IPMC, however, highly dehydrated silver-coated Nafion type IPMC exhibited better electrical bending controllability. Embedding of the multi-walled carbon nanotube (MWCNT) into Nafion surface promoted adsorption of a larger quantity of silver on the Nafion surface, since the MWCNT surface served as adsorption sites for silver. A MWCNT-embedded Nafion coated with such a large quantity of silver (SCNT-Naf) exhibited large bending curvature under an applied voltage when in a highly dehydrated state, because of large scale induction of silver redox reaction. We could even achieve autonomous bending curvature control of the highly dehydrated SCNT-Naf quantitatively by automatically monitoring total charge imposed on it. 相似文献
15.
Control over interactions with biomolecules holds the key of the applications of carbon nanotubes (CNTs) in biotechnology. Here we report a molecule dynamics study on the encapsulation process of different charged CNTs into DNA nanotubes. Our results demonstrated that insertion process of CNTs into DNA nanotubes are charge-tunable. The positive charged CNTs could spontaneously encapsulate and confined in the hollow of DNA nanotubes under the combination of electrostatic and vdW interaction in our ns scale simulation. The conformation of DNA nanotubes is very stable even after the insertion of CNTs. For pristine CNTs, it could not entirely encapsulated by DNA nanotubes in simulation scale in this study. The encapsulation time of pristine CNTs into DNA nanotubes was estimated about 21.9 s based on the potential of mean force along the reaction coordination of encapsulation process of CNTs into DNA nanotubes. In addition, the encapsulation process was also affected by the diameter of CNTs. These findings highlight the charge-tunable self-assembly process of nanomaterials and biomolecules. Our study suggests that the encapsulated CNTs-DNA nanotubes could be used as building blocks for constructing organic–inorganic hybrid materials and has the potential applications in the field of biosensor, drug delivery system and biomaterials etc. 相似文献
16.
Jean-Marc TullianiAuthor Vitae Alessio CavalieriAuthor VitaeSimone MussoAuthor Vitae Eloisa SardellaAuthor VitaeFrancesco GeobaldoAuthor Vitae 《Sensors and actuators. B, Chemical》2011,152(2):144-154
In this work, different techniques are proposed to realize ammonia (NH3) sensors working at room temperature and a preliminary electrical characterization under water vapor and in NH3 atmospheres is presented. Three families of ceramic planar sensors based on a zinc oxide (ZnO) layer overlapped by screen-printed Pd-doped carboxyl groups functionalized multi-walled carbon nanotubes (Pd-COOH-MWCNTs) or by blocks of vertically aligned MWCNTs or by graphite as such and functionalized with fluorinated or nitrogenous functional groups were studied.These sensors were almost insensitive to humidity, while all of them gave a good response in NH3 atmosphere, starting from about 45 ppm in the case of zinc oxide with fluorinated or nitrogenous MWCNTs and graphite or 50 ppm for Pd-COOH-MWCNTs sensors. These results are not actually as good as those reported in the literature, but this preliminary work proposes simpler and cheaper processes to realize NH3 sensor for room temperature applications. 相似文献
17.
Placing electrical charges on nanomaterials is a means to extend their functional capabilities in nanoelectronics and sensoring applications. This paper explores the effect of charging nitrogen bases cytosine (Cyt) and adenine (Ade) via protonation on their noncovalent interaction with carbon nanotubes (CNT) using quantum chemical calculations performed at the M05-2X/6-31++G** level of theory alongside with a molecular graphics method. It is shown that the protonation of the bases causes threefold increase of the interaction energy in the CNT·Cyt·H+ and СNT·Ade·H+ complexes as compared to the CNT complexes formed with neutral bases. There is also some shortening of the base-CNT distance by ca 0.13 Ǻ. The visualization of the electrostatic potential distribution with the molecular graphics reveals that the positive potential due to the protonated bases extends to a cylindrical domain of the nanotube segment adjacent to the base binding site. Furthermore, subtraction of the electrostatic potential maps of the protonated bases from the maps of their complexes with CNTs reveals an area of negative potential on the CNT surface, which reflects the location of the adsorbed base. The positive charge transfer of ca 0.3 e from the protonated bases to the CNT strengthens the interaction in the CNT·Cyt·H+ and СNT·Ade·H+ complexes. The analysis of the frontier orbitals shows that the LUMOs of the complexes mainly reside on the CNT, while the HOMOs spread over both components of each complex. The observed effects may facilitate the design of nanomaterials involving nitrogen bases and CNTs. 相似文献
18.
Irene Taurino Sandro Carrara Mauro Giorcelli Alberto Tagliaferro Giovanni De MicheliAuthor vitae 《Sensors and actuators. B, Chemical》2011,160(1):327
In this study, we report on multi-walled carbon nanotubes fabricated on silicon substrate with four different orientations via chemical vapor deposition. It is well-known that chemical treatments improve the nanotube electrochemical reactivity by creating edge-like defects on their exposed sidewalls. Before use, we performed an acid treatment on carbon nanotubes. To prove the effect of the treatment on these nanostructured electrodes, contact angles were measured. Then, sensitivities and detection limits were evaluated performing cyclic voltammetry. Two target molecules were used: potassium ferricyanide, an inorganic electroactive molecule, and hydrogen peroxide that is a product of reactions catalyzed by many enzymes, such as oxidases and peroxidases. Carbon nanotubes with tilted tips become hydrophilic after the treatment showing a contact angle of 22° ± 2°. This kind of electrode has shown also the best electrochemical performance. Sensitivity and detection limit values are 110.0 ± 0.5 μA/(mM cm2) and 8 μM for potassium ferricyanide solutions and 16.4 ± 0.1 μA/(mM cm2) and 24 μM using hydrogen peroxide as target compound. Considering the results of wettability and voltammetric measurements, nanotubes with tilted tips-based electrodes are found to be the most promising for future biosensing applications. 相似文献
19.
Junxiang GuoAuthor VitaeYaqin ChaiAuthor Vitae Ruo YuanAuthor VitaeZhongju SongAuthor Vitae Zhifen ZouAuthor Vitae 《Sensors and actuators. B, Chemical》2011,155(2):639-645
For the first time a novel derivatized multi-walled carbon nanotubes-based Pb2+ carbon paste electrode is reported. The electrode with optimum composition, exhibits an excellent Nernstian response to Pb2+ ion ranging from 5.9 × 10−10 to 1.0 × 10−2 M with a detection limit of 3.2 × 10−10 M and a slope of 29.5 ± 0.3 mV dec−1 over a wide pH range (2.5-6.5) with a fast response time (25 s) at 25 °C. Moreover, it also shows a high selectivity and a long life time (more than 3 months). Importantly, the response mechanism of the proposed electrode was investigated using AC impedance technique. Finally, the electrode was successfully applied for the determination of Pb2+ ion concentration in environmental samples, e.g. soils, waste waters, lead accumulator waste and black tea, and for potentiometric titration of sulfate anion. 相似文献