In situ fabrication of a water-soluble, self-doped polyaniline nanocomposite: the unique role of DNA functionalized single-walled carbon nanotubes

Dispersion of carbon nanotubes into solvents affects their surface chemistries, electronic structures, and subsequent functionalization. In this Communication, a water-soluble self-doped polyaniline nanocomposite was fabricated by in situ polymerization of the 3-aminophenylboronic acid monomers in the presence of single-stranded DNA dispersed- and functionalized-single-walled carbon nanotubes. For the first time, we found that the carbon nanotubes became novel active stabilizers owing to the DNA functionalization. The nanotubes reduced the polyaniline backbone from the unstable, degradable, fully oxidized pernigraniline state to the stable, conducting emeraldine state because of their reductive ability, which could improve the chemical stability of the self-doped polyaniline. Electrical measurements demonstrate that the conductivity of the nanocomposite was much higher than that of the pure self-doped polyaniline in both acidic and neutral solutions.     

The electronic role of DNA-functionalized carbon nanotubes: efficacy for in situ polymerization of conducting polymer nanocomposites

We have found that the polymerization process was 4,500 times faster when a self-doped polyaniline nanocomposite was fabricated using in situ polymerization in the presence of single-stranded DNA-dispersed and -functionalized single-walled carbon nanotubes (ssDNA-SWNTs). More importantly, the quality of the composite was significantly improved: fewer short oligomers were produced, and the self-doped polyaniline backbone had a longer conjugation length and existed in the more stable and conductive emeraldine state. The functionality of the boronic acid group in the composite and the highly improved electronic performance may lead to broad applications of the composite in flexible electronic devices. Blending of preformed polymer with carbon nanotubes is straightforward and widely used to fabricate nanocomposites. We demonstrate that this simple mixing approach might not fully and synergistically combine the merits of each individual component. Surprisingly, these advantages also cannot be obtained using in situ polymerization with preoxidized ssDNA-SWNTs, which is renowned as the "seed" method for production of conducting-polymer nanowires. The electronic structures of the carbon nanotubes and the monomer-nanotube interaction during polymerization greatly impact the kinetics of nanocomposite fabrication and the electronic performance of the resulting composites.     

Noncovalent nanoassembly of porphyrin on single-walled carbon nanotubes for electrocatalytic reduction of nitric oxide and oxygen

Water-soluble iron(III) meso-tetrakis(N-methylpyridinum-4-yl)porphyrin (FeTMPyP) was successfully immobilized on single-walled carbon nanotubes (SWNTs) via 1-pyrenebutyric acid (PBA). The formed SWNTs/PBA/FeTMPyP film showed an enhanced electrocatalytic peak at −0.70 V and −0.17 V towards reduction of nitric oxide and oxygen, respectively. SWNTs accelerated the electron transfer between FeTMPyP and electrode, and increased the amount of FeTMPyP adsorbed. FeTMPyP acted as a catalyst to decrease the reduction potential, exhibiting a synergy in electrocatalysis. The excellent electrocatalytic behaviors made SWNTs/porphyrin nanocomposite have a promising potential in fabricating new type of biosensors.     

Facile deposition of [60]fullerene and carbon nanotubes on ITO electrode by electrochemical oxidative polymerization of ethylenedioxythiophene

It was found that [60]fullerene encapsulated in p-sulfonatocalix[8]arene and single-walled carbon nanotubes (SWNTs) solubilized by sodium dodecylsulfate can be readily deposited on the ITO electrode by electrochemical oxidative polymerization of ethylenedioxythiophene (EDOT) without chemical modification of these carbon clusters. The driving force for the deposition is an electrostatic interaction between the anionic complexes and the cationic charges of poly(EDOT) formed in the oxidative polymerization process. The surface morphology was thoroughly characterized by scanning electron micrograph: the [60]fullerene/poly(EDOT) film is covered by nano-particles with 20-100 nm diameters whereas the SWNTs/poly(EDOT) film is covered by nanorods with several microm length and ca. 100 nm diameter. The results indicate that the anionic complexes act as nuclei for the polymer growth in the oxidation polymerization. Interestingly, when these modified ITO electrodes were photoirradiated, the appearance of a photocurrent wave was observed. The action spectra showed that the photoexcited energy of [60]fullerene or SWNTs is efficiently collected by the electroconductive poly(EDOT) film and transferred to the ITO electrode.     

Catalytic polymerization and facile grafting of poly(furfuryl alcohol) to single-wall carbon nanotube: preparation of nanocomposite carbon

A nanocomposite carbon was prepared by grafting a carbonizable polymer, poly(furfuryl alcohol) (PFA), to a single-wall carbon nanotube (SWNT). The SWNT was first functionalized with arylsulfonic acid groups on the sidewall via a method using a diazonium reagent. Both Raman and FTIR spectroscopies were used to identify the functional groups on the nanotube surface. HRTEM imaging shows that the SWNT bundles are exfoliated after functionalization. Once this state of the SWNTs was accomplished, the PFA-functionalized SWNT (PFA-SWNT) was prepared by in situ polymerization of furfuryl alcohol (FA). The sulfonic acid groups on the surface of the SWNT acted as a catalyst for FA polymerization, and the resulting PFA then grafted to the SWNTs. The surfaces of the SWNTs converted from hydrophilic to hydrophobic when they were wrapped with PFA. The formation of the polymer and the attraction between it and the sulfonic acid groups were confirmed by IR spectra. A nanocomposite carbon was generated by heating the PFA-SWNT in argon at 600 degrees C, a process during which the PFA was transformed to nanoporous carbon (NPC) and the sulfonic acid groups were cleaved from the SWNT. Based upon the Raman spectra and HRTEM images of the composite, it is concluded that SWNTs survive this process and a continuous phase is formed between the NPC and the SWNT.     

Synthesis of self-doped conducting polyaniline bearing phosphonic acid

As a self-doped conducting polyaniline bearing phosphonic acid, poly(2-methoxyaniline-5-phosphonic acid) (PMAP) was synthesized via oxidative polymerization of 2-methoxyaniline-5-phosphonic acid. The pyridinium salt of thus-obtained PMAP was water-soluble and its film exhibited conductivity.     

Sensitive detection of trifluoperazine using a poly-ABSA/SWNTs film-modified glassy carbon electrode

A poly-ABSA/SWNTs composite-modified electrode was fabricated by electropolymerizing aminobenzene sulphonic acid (ABSA) on the surface of glassy carbon electrode (GCE) modified with single-wall carbon nanotubes (SWNTs). SWNTs provide a 3D porous and conductive network for the polymer immobilization. The nanocomposite film was characterized by scanning electron microscope (SEM) and electrochemical impedance spectroscopy (EIS). The results indicated that this composite-modified electrode had strong electrocatalytic activity toward the oxidation of trifluoperazine (TFP). TFP could effectively accumulate on the modified electrode and generate a sensitive anodic peak at 0.72V (versus SCE) in pH 6.1 phosphate buffer solution. Under the selected conditions, the anodic peak current of TFP was linear with its concentration within the range from 1.0x10(-7) to 1.0x10(-5)molL(-1) and 1.0x10(-5) to 1.0x10(-4)molL(-1), and the detection limit was 1.0x10(-9)molL(-1) (S/N=3). This method was successfully applied to the detection of trifluoperazine in drug samples and the recovery was satisfactory. In comparison with the SWNTs/GCE or poly-ABSA/GCE prepared in the similar way, this composite-modified electrode exhibited better catalytic activity.     

碳纳米管/聚对甲基吡啶修饰电极测定硝基苯甲酸

采用滴涂法和循环伏安法在玻碳电极上电沉积一层稳定的单壁碳纳米管/聚对甲基吡啶纳米薄膜(SWNTs/POMP)。研究了邻、对硝基苯甲酸在此修饰电极上的电化学行为,建立了电化学同时测定邻、对硝基苯甲酸的新方法。实验结果表明:在0.1 mol/L HClO4溶液中,邻、对硝基苯甲酸在SWNTs/POMP电极上发生不可逆的还原反应,由于碳纳米管和聚合物薄膜的协同效应,SWNTs/POMP电极对邻、对硝基苯甲酸有很好的的电催化作用,并对其响应进行了定量分析。     

Amperometric thrombin aptasensor using a glassy carbon electrode modified with polyaniline and multiwalled carbon nanotubes tethered with a thiolated aptamer

A nanocomposite consisting of polyaniline and multiwalled carbon nanotubes was tethered with a thiolated thrombin-specific aptamer and placed on a glassy carbon electrode (GCE) to obtain a biosensor for thrombin that has a limit of detection of 80 fM. Tethering was accomplished via a thiol-ene reaction between thiolated thrombin aptamer (TTA) and oxidized polyaniline (PANI) that was chemically synthesized in the presence of solution-dispersed multiwalled carbon nanotubes (MWCNTs). The modified GCE exhibits a pair of well-defined redox peaks (at 50/?25 mV) of self-doped PANI in neutral solution, and the tethered TTA-thrombin interaction gives a decreased electrochemical signal. Cyclic voltammetry, scanning electron microscopy and ultraviolet visible spectroscopy were used to characterize the film properties. This amperometric aptasensor is sensitive, selective and reproducible. It was applied to the determination of thrombin in spiked human serum (0.2 to 4 nM) and gave recoveries that ranged from 95 to 102%.

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Graphical abstract A nanocomposite consisting of polyaniline (PANI) and multiwalled carbon nanotubes (MWCNTs) was tethered with a thiolated thrombin aptamer (TTA) and placed on a glassy carbon electrode (GCE) to obtain a biosensor for thrombin that has a 80 f. detection limit.

     

Non-enzymatic Glucose Biosensor Based on Cu/SWNTs Composite Film Fabricated by One-step Electrodeposition

Based on the adsorption of copper ions on single-walled carbon nanotubes(SWNTs) in electrolyte, Cu/SWNTs nanocomposite film was initially prepared on indium-doped tin oxide(ITO) substrate by one-step electrodeposition. This method may provide a versatile and facile pathway to fabricate other SWNTs-supported metal composite films. Electrochemical experiments revealed that the obtained Cu/SWNTs/ITO electrode offered an excellent electrocatalytic activity towards the oxidation of glucose and could be applied to the construction of non-enzymatic glucose biosensor. The linear range of the sensor was 1.0×10–6 to 6.0×10–4 mol/L and the response time was within 2 s. Particularly, its sensitivity reached as high as 1434.67 μA·L·mmol–1·cm–2, which was superior to any other non-enzymatic glucose biosensor based on copper-carbon nanotubes electrode reported previously.     

基于AuNPs/PANI/TNTs纳米复合材料的电化学检测妥布霉素的适配体传感器

本文提出了一种新型的检测妥布霉素的电化学适配体传感器,以差分脉冲伏安法（DPV）作为检测技术,亚甲基蓝作为电化学响应信号. 构建了以纳米复合材料金纳米粒子/聚苯胺/二氧化钛纳米管(AuNPs/PANI/TNTs)修饰玻碳电极的电极支架. 通过透射电子显微镜和X-射线光电子能谱对纳米复合材料进行详细的表征. 循环伏安图和电化学阻抗谱显示AuNPs/PANI/TNTs可以很好地增加电极的界面传导性能. DPV结果显示电流密度的响应和妥布霉素浓度之间存在一个很好的线性关系,并且得到一个宽广的检测范围为0.5 μmol·L^-1到70 μmol·L^-1. 本文提出的适配体基的传感器有很好的重复性和稳定性,作为一个潜在的手段可以应用在生物分析和医疗诊断中.     

A New Composite of O-aminobenzene Sulfonic Acid Self-Doped Polyaniline and Multi-Walled Carbon Nanotubes as a Fiber Coating for Solid-Phase Microextraction Gas Chromatography

Chromatographia - A new composite of o-aminobenzene sulfonic acid self-doped polyaniline (SPAN) and multi-walled carbon nanotubes was prepared on a stainless steel wire by electrochemical method as...     

Doping polyaniline with pristine carbon nanotubes into electroactive nanocomposite in neutral and alkaline media

This study describes a facile but effective route to synthesis of electroactive polyaniline (PANI) in the neutral and alkaline media simply with pristine single-walled carbon nanotubes (SWNTs) as the dopant. Cyclic voltammetry (CV) studies reveal that the SWNT/PANI nanocomposite processes a good electrochemical activity in the neutral and alkaline media. Control experiments with PANI mixed with heat-treated SWNTs imply that the electrochemical properties of the SWNT/PANI nanocomposite in the neutral and alkaline media do not result from the presence of carboxylic groups at SWNTs themselves, and in turn show that the pristine SWNTs can be potentially used as a new and effective dopant to preserve the electrochemical property of PANI in the neutral and alkaline media. This property of the SWNT/PANI nanocomposite is reasonably envisaged to be promising for electrochemical investigations and electroanalytical applications, especially for the development of electrochemical sensors, biosensors and biofuel cells.     

Simultaneous determination of nitrophenol isomers at the single-wall carbon nanotube compound conducting polymer film modified electrode

One of the challenging areas of electrochemistry and electroanalytical chemistry is the simultaneous determination of isomers at the same electrode. Con- ventional electrode only possesses a single function of electron transfer; therefore, it is difficult…     

铂粒子修饰单壁碳纳米管/聚苯胺复合膜对甲醛的电催化氧化

在溶有单壁碳纳米管(SWNTs)的苯胺溶液中, 通过电化学共聚合法成功制备了单壁碳纳米管(SWNT)/聚苯胺(PANI)复合膜. 用电沉积法将铂沉积到SWNT/PANI复合膜上. 样品的成分和形貌分别用XRD和SEM表征. 四探针和电化学交流阻抗的研究表明被PANI包裹的SWNTs整齐地排列在复合膜中, 从而提高了复合膜的电导率, 促进了电荷转移. 循环伏安(CV)说明Pt修饰的SWNT/PANI复合膜对于甲醛氧化具有良好的电催化活性及稳定性. 研究结果表明SWNT/PANI复合膜是一种非常好的催化剂载体, 有着广泛的应用前景.     

聚甲苯胺蓝-(多壁碳纳米管/PDDA)_n杂化膜修饰印刷电极的制备及其对NADH的测定

利用静电层层组装的方式在印刷电极表面制备了(多壁碳纳米管/邻苯二甲酸二乙二醇二丙烯酸酯(PDDA))n多层膜,采用电位扫描电聚合法在修饰有多层膜的印刷电极表面聚合甲苯胺蓝,制备了聚甲苯胺蓝-(多壁碳纳米管/PDDA)n杂化膜修饰电极。扫描电镜实验表明,多壁碳纳米管均匀分布在杂化膜中,且多壁碳纳米管的掺杂使杂化膜表现出明显的多孔性。电化学实验表明,杂化膜具有良好的导电性且多壁碳纳米管的掺杂显著增加了聚甲苯胺蓝在电极表面的担载量,提高了检测灵敏度。在pH7.4的磷酸盐缓冲液中,杂化膜修饰电极对β-烟酰胺腺嘌呤二核苷酸(NADH)的氧化具有良好的催化作用,与裸电极相比氧化电位降低了560 mV,灵敏度明显提高。在8.7×10-8~1.3×10-4mol/L范围内,NADH的浓度与氧化电流呈线性关系,检出限为2.8×10-8mol/L,该修饰电极可用于NADH的测定。     

Electrochemical sensor for determination of aflatoxin B1 based on multiwalled carbon nanotubes-supported Au/Pt bimetallic nanoparticles

A sensitive and selective imprinted electrochemical sensor for the determination of aflatoxin B₁ (AFB₁) was constructed on a glassy carbon electrode by stepwise modification of functional multiwalled carbon nanotubes (MCNTs), Au/Pt bimetallic nanoparticles (Au/PtNPs), and a thin imprinted film. The fabrication of a homogeneous porous poly o-phenylenediamine (POPD)-grafted Au/Pt bimetallic multiwalled carbon nanotubes nanocomposite film was conducted by controllable electrodepositing technology. The sensitivity of the sensor was improved greatly because of the nanocomposite functional layer; the proposed sensor exhibited excellent selectivity toward AFB₁ owing to the porous molecular imprinted polymer (MIP) film. The surface morphologies of the modified electrodes were characterized using a scanning electron microscope. The performance of the imprinted sensor was investigated by cyclic voltammetry, differential pulse voltammetry, and electrochemical impedance spectroscopy in detail. A linear relationship between the sensor response signal and the logarithm of AFB₁ concentrations ranging from 1?×?10^?10 to 1?×?10^?5 mol L^?1 was obtained with a detection limit of 0.03 nmol L^?1. It was applied to detect AFB₁ in hogwash oil successfully.     

Fabrication and characterization of core/shell structured TiO2/polyaniline nanocomposite

A novel core/shell structured TiO(2)/polyaniline nanocomposite was fabricated by grafting aniline on aminobenzoate monolayer that is chemically adsorbed on the TiO(2) nanocrystal surface. The formation and nanostructure of the nanocomposite were investigated by FT-IR and UV-Vis spectra, TEM, FE-SEM, and TG-DTA analysis. Adsorption of aminobenzoate on the TiO(2) surface is an effective method to obtain the uniform nanocomposite. The thickness of polyaniline layer coating on the TiO(2) nanocrystal surface can be controlled in a range of 2-5 nm by this method. A photoelectrochemical study was carried out on the TiO(2)/polyaniline nanocomposite, and found that polyaniline in the nanocomposite acted as a visible-light sensitizer in a photoelectrochemical reaction. The sensitization effect increased with increasing binding strength between polyaniline and TiO(2). A dye-sensitized solar cell with a short circuit current density of 0.19 mA/cm(2) and an open circuit voltage of 0.35 V was fabricated by using the TiO(2)/polyaniline nanocomposite film as a sensitized electrode.     

Electrochemical fabrication of single-walled carbon nanotubes-DNA complexes by poly(ethylenedioxythiophene) and photocurrent generation by excitation of an intercalated chromophore

It was found that single-walled carbon nanotubes (SWNTs) solubilized into water by complexation with DNA (salmon testes) can be readily deposited on the ITO electrode by electrochemical oxidative polymerization of ethylenedioxythiophene (EDOT). The driving force for this novel deposition is an electrostatic interaction between the anionic charges of wrapping DNA and the cationic charges of poly(EDOT) formed in the oxidative polymerization process. The presence of poly(EDOT), SWNTs and DNA in the composite was confirmed by measurements of UV-Vis, IR, resonance Raman spectra, cyclic voltammetry (CV) and confocal laser scanning microscopy (CLSM). The composite adsorbed a DNA intercalator (ethidium bromide: EB) very efficiently, which is regarded to be further evidence for inclusion of DNA. The surface morphology, characterized by CLSM, SEM and AFM, featured the network structure consisting of 0.5-ca. 10 microm nanorods. Very interestingly, we found that photoexcitation of EB bound to the DNA generates the photocurrent, indicating that the excited energy of EB is injected into SWNTs, which is collected by the electroconductive poly(EDOT) film on the ITO electrode. We believe, therefore, that the present system is a very convenient method to explore new materials related to redox and photochemical functions.     

Pyridine-functionalized single-walled carbon nanotubes as gelators for poly(acrylic acid) hydrogels

Pyridine-functionalized single-walled carbon nanotubes (SWNTs) are prepared from the addition of a pyridine diazonium salt to nanotubes. The location and distribution of the functional groups is determined by atomic force microscopy using electrostatic interactions with gold nanoparticles. The pyridine-functionalized SWNTs are able to act as cross-linkers and hydrogen bond to poly(acrylic acid) to form SWNT hydrogels. The pyridine-functionalized SWNTs are further characterized using Raman, FTIR, UV/vis-NIR, and X-ray photoelectron spectroscopy and thermogravimetric analysis-mass spectrometry.