基于还原氧化石墨烯-碳纳米管复合物的电化学传感器对木犀草素的检测

利用一步电化学原位还原法制备了还原氧化石墨烯/多壁碳纳米管复合物(ErGO/MWCNTs),研究木犀草素在该复合物修饰电极(ErGO-MWCNTs/GCE)上的电化学行为,构筑了一种简易、灵敏的电化学传感器用于木犀草素的检测。结果表明,相较于裸电极和ErGO/GCE,ErGO-MWCNTs/GCE利用两种材料的协同作用有效促进了对木犀草素的电催化性能,表现出更灵敏的电流响应。在优化条件下,峰电流与木犀草素的浓度在2.5×10~(-7)～1.3×10~(-5 )mol·L~(-1)范围内呈良好线性关系,检测限为70 nmol·L~(-1)。     

预阳极化碳糊电极同时测定对乙酰氨基酚和多巴胺

采用循环伏安法制备了预阳极化碳糊电极,研究了对乙酰氨基酚和多巴胺在该修饰电极上的电化学行为。结果表明,预阳极化碳糊电极对对乙酰氨基酚和多巴胺的电化学行为具有良好的电催化作用。对乙酰氨基酚和多巴胺的氧化峰电流与其浓度在2.0×10-6～5.0×10-4mol/L的范围内呈良好的线性关系,检出限分别为6.3×10-7mol/L,2.5×10-7mol/L。方法已用于药物样品中对乙酰氨基酚和多巴胺的测定。     

木犀草素在离子液体修饰电极上的电催化氧化及其测定

用1-丁基-3-甲基咪唑六氟磷酸盐([BMIM]PF₆)疏水性离子液体修饰玻碳电极,在0.2 mol/L磷酸盐缓冲溶液(pH为4.0～8.0)中,运用循环伏安法（CV）和差示脉冲溶出伏安法(DPSV)研究了木犀草素在修饰电极上的电化学行为,建立了测定木犀草素含量的新方法。 实验结果表明,该修饰电极上木犀草素氧化、还原峰电位均负移,峰电流增大。 在-0.2～0.7 V电位区间,pH=7.0的磷酸盐缓冲溶液体系中,木犀草素在修饰电极表面发生的是受吸附控制的准可逆等电子等质子电极反应,电子转移系数α=0.5,吸附量为4.6×10-10 mol/cm²;木犀草素氧化峰电流与其浓度在1.0×10^-10～1.6×10^-8 mol/L范围内呈良好的线性关系,检出限达到3.2×10^-11 mol/L,回收率为98.7%～102.0%;该法操作简单、快速、灵敏、准确;可用于野菊花中类黄酮的测定。     

木犀草素在玻碳电极上的直接电化学行为及其测定

应用循环伏安法研究木犀草素于玻碳电极的电化学行为.在磷酸盐缓冲液中(pH 4.0),-0.2~+0.8V电位区间内,木犀草素于玻碳电极表面发生的电极反应是吸附控制的准可逆2电子转移过程,电子转移系数α=0.66;建立了检测木犀草素含量的差示脉冲伏安法(DPV).在富集电位+0.4 V下,经富集240 s后,测得木犀草素氧化峰电流Ip与其浓度在1.0×10-8~1.0×10-6mol.L-1范围内呈良好的线性关系,最低检出限为5.0×10-9mol.L-1.本法操作简单、快速、灵敏、准确,可为木犀草素药物质量的控制和检测提供一种简便的新方法.     

木犀草素在多壁碳纳米管修饰碳糊电极上的电化学行为及其与DNA相互作用

采用循环伏安法、差分脉冲法研究了木犀草素在多壁碳纳米管修饰碳糊电极上的电化学行为。在p H 3.29的B-R缓冲体系中,木犀草素在0.502 V和0.452 V处产生一对明显的氧化还原峰,其峰电流与木犀草素浓度在5.0×10~(-8)~1.0×10~(-5)mol/L范围内呈良好的线性关系,木犀草素在电极上是受吸附控制的2质子、2电子电极反应过程;在此基础上研究了木犀草素与DNA的相互作用,随着DNA的浓度增加木犀草素的电化学信号逐渐降低,表明木犀草素能与DNA发生明显的相互作用,进一步研究表明木犀草素与DNA的相互作用是以嵌入方式为主。     

钯掺杂聚精氨酸修饰电极同时测定5-羟基色氨酸和多巴胺

制备了钯掺杂聚L-精氨酸修饰玻碳电极(Pd-PA/GCE),研究了5-羟基色氨酸(5-HTP)和多巴胺(DA)在该修饰电极上的电化学行为,建立了同时测定5-HTP和DA的电化学新方法。在pH=2.0的磷酸缓冲溶液中,扫描速率为160mV/s时,DA在该电极上产生一对氧化还原峰,峰电位分别为0.515V和0.464V;5-HTP在该电极上产生一个氧化峰,峰电位为0.643V,两者的氧化峰电位差达128mV。在最优条件下,同时测定5-HTP和DA的线性范围分别为:9.00×10-7~1.00×10-5 mol/L、1.00×10-5~4.00×10-5 mol/L(5-HTP);7.00×10-7~1.00×10-5 mol/L、1.00×10-5~4.00×10-5 mol/L(DA)。检出限分别为7.0×10-7 mol/L和5.0×10-7 mol/L。方法可用于药剂中5-HTP和DA的测定。     

肾上腺素在对甲苯磺酸修饰电极上的电化学行为

研究了对甲苯磺酸在玻碳电极上电化学聚合的条件及修饰电极的电化学特性, 发现该聚合膜对肾上腺素的电氧化有显著的催化作用, 在pH 7.0的磷酸盐缓冲溶液中, 搅拌富集40 s后, 用循环伏安法对肾上腺素进行了测定, 线性范围: 4.05×10-7～9.45×10-6 mol/L, 检出限为3.2×10-8 mol/L. 对2.0×10-6 mol/L肾上腺素平行测定7次相对标准偏差为2.4%. 该电极有效地排除了抗坏血酸的干扰, 具有良好的稳定性和重现性.     

电化学发光法测定铁

基于Fe(o Phen)33 对鲁米诺电化学发光体系的电还原发光信号的增敏作用,建立了一种测定铁离子的电化学发光新方法。在最佳的实验条件下,该方法测定铁(Ⅲ)的线性范围为4.1×10-7～4.1×10-6mol/L,检出限为1.8×10-7mol/L,相对标准偏差小于5%。     

木犀草素及其苷与牛血清白蛋白的相互作用研究

应用电化学方法和紫外吸收光谱法研究了在生理pH条件下木犀草素(luteolin)和木犀草素苷(luteolin-7-O--βD-glucoside)与牛血清白蛋白(BSA)分子间的相互作用。研究表明:木犀草素和木犀草素苷与BSA形成了一种非电活性的生物超分子化合物;二者的结合常数分别为9.33×106和1.12×106L/mol,结合位点数分别为1.32和1.10。     

聚磺胺嘧啶修饰电极伏安法测定对乙酰氨基酚

利用循环伏安法制备了聚磺胺嘧啶修饰电极, 研究了对乙酰氨基酚在该修饰电极上的电化学行为. 该电极对对乙酰氨基酚有较强的电催化作用. 在pH 9.0的PBS缓冲溶液中, 用循环伏安法和差分脉冲伏安法在该电极上测定了对乙酰氨基酚, 其线性范围分别为4.0×10-6～3.0×10-4 mol/L和2.0×10-7～1.0×10-5 mol/L, 检出限分别为9.0×10-7 mol/L和8.0×10-8 mol/L.     

非晶碳纳米球的低温石墨化(英文)

The investigation by SEM/TEM, porosity, and X-ray diffraction measurements of the graphitization process starting from amorphous carbon nanospheres, prepared by glucose carbonization, is reported. Aspects studied are the annealing temperature in the 750–1000 °C range, the type of inert carrier gas, and time of treatment in the 2–6 h range. It is investigated how these parameters influence the structural and morphological characteristics of the carbon materials obtained as well as their nanostructure. It is shown that it is possible to maintain after graphitization the round-shaped macro morphology, a high surface area and porosity, and especially a large structural disorder in the graphitic layers stacking, with the presence of rather small ordered domains. These are characteristics interesting for various catalytic applications. The key in obtaining these characteristics is the thermal treatment in a flow of N2. It was demonstrated that the use of He rather than N2 does not allow obtaining the same results. The effect is attributed to the presence of traces of oxygen, enough to create the presence of oxygen functional groups on the surface temperatures higher than 750 °C, when graphitization occurs. These oxygen functional groups favor the graphitization process.     

Photocatalytic carbon dioxide reduction by photocatalyst innovation

The photocatalytic conversion of carbon dioxide into sustainable fuel methanol using carbon quantum dots is highlighted in this paper. The multifaceted roles of carbon quantum dots in photocatalytic reactions and future directions of CQD materials are outlined.     

Synthesis of nickel nanoparticles and carbon encapsulated nickel nanoparticles supported on carbon nanotubes

Nickel nanoparticles were prepared and uniformly supported on multi-walled carbon nanotubes (MWCNTs) by reduction route with CNTs as a reducing agent at 600 °C. As-prepared nickel nanoparticles were single crystalline with a face-center-cubic phase and a size distribution ranging from 10 to 50 nm, and they were characterized by transmission electron microscopy (TEM), high-resolution TEM and X-ray diffraction (XRD). These nickel nanoparticles would be coated with graphene layers, when they were exposed to acetylene at 600 °C. The coercivity values of nickel nanoparticles were superior to that of bulk nickel at room temperature.     

First-principles study of a new type nanojunction: Finite length carbon chain inserted into half of a carbon nanotube

Based on first-principles calculations, we investigate the structure and electronic properties of a carbon atomic chain in finite length inserted into half of a single walled carbon nanotube (SWCNT), which we called half chain@SWCNT or more generally HCS. Comparing the optimized structure of HCS with that of the same chiral indices SWCNT and all carbon chain inserted SWCNT, we find that the geometry of the tube in HCS is slightly altered due to the weakly interacting between the inserted chain and the outer tube wall of HCS. Our calculation of band structure indicates that the armchair (5, 5) HCS exhibits metallic character, which is as that of (5, 5) SWCNT and all carbon chain inserted (5, 5) SWCNT. The zigzag (8, 0) and (9, 0) HCSs have small change in the energy gap compared to the corresponding pristine ones. Due to the downshift of conduction bands originating from the carbon chain, the calculation of band structure shows that chiral (6, 4) HCS is a semiconductor system with a small band gap of 0.94 eV, less than 1.125 eV in pristine SWCNT. The studied HCSs with unique structure and electronic property may construct a new generation nanoscale junctions without the usual heptagon–pentagon defect pair considerations.     

Detection of homocysteine at carbon nanotube paste electrodes

The use of a carbon-nanotube paste (CNTP) electrode provides an effective means for the determination of homocysteine. A decrease of ca. 120 mV in the overpotential for the oxidation of homocysteine compared to a traditional carbon paste electrode, is reported along with greatly enhanced signal-to-noise characteristics. The analytical parameters have been assessed with a linear range from 5 to 200 μM and a detection limit of 4.6 μM. Furthermore, the generic nature of this increased reactivity of the CNTP surface towards thiol moieties has been demonstrated with cysteine, glutathione and n-acetylcysteine, providing a greatly enhanced electrochemical response compared to the carbon paste electrode.     

Voltammetric determination of Celiptium with carbon paste and lipid-modified carbon paste electrodes

The electrooxidation of the antitumour drug 2-methyl-9-hydroxyellipticinium (Celiptium) was investigated by cyclic, differential-pulse and adsorptive voltammetry at carbon paste (CPE) and lipid-modified carbon paste electrodes (LM-CPE). The influence of the paste composition, i.e., the ratio of graphite to binder, was studied in order to elucidate the nature of the accumulation process at the surface of the CPE. The electrode surface coverage at saturation was calculated. A.c. measurements at the CPE and at the LM-CPE during the accumulation of Celiptium demonstrated an increased differential double layer capacity of the LM-CPE. The influence of several parameters that affect the adsorptive step at the CPE was investigated, such as pH, ionic strength and interfering ions. Improved signals were obtained at the CPE and the detection limit in 0.1 M sodium perchlorate (t_acc.=3 min) was found to be 2 × 10^?10 M. Measurements of the drug in dilute standard serum samples were done using the medium-exchange technique.     

Effect of surface structure on the charge storage capacity of carbon black electrodes

In this work we study the effect of surface structure on the charge storage capacity of carbon black electrodes with various changes in surface chemistry, morphology, and doping species. Cyclic voltammetry and chronopotentiometry studies, performed under alkaline conditions with carbon paste electrodes, indicate the importance of surface structure and grain size on the faradic and capacitive charge contributions of these materials. Among the various carbon blacks studied, the lithiated material shows superior charge storage capacity, suggesting the importance of alkaline metals and oxygenated groups on the carbon surface. For the graphitic carbon, the appearance of a reversible redox process with cycling resembles the electrochemical behavior reported for hydrogen storage in carbon nanotubes. Electronic Publication     

Polycarbonate carbon nanofiber composites

Carbon nanofiber (CNF) composites have the potential for creating inexpensive, semiconducting polymers. These composites require a homogeneous dispersion within the polymer. Many groups have focused on high shear methods such as twin screw extrusion. Although high shear methods produce a homogeneous dispersion, the aspect ratio of the nanofibers is reduced by the mechanical force. In this report, we present results for low shear composite formation via in situ polymerization of cyclic oligomeric carbonates. The composites were characterized by thermal gravimetric analysis, electrical conductivity, scanning electron microscopy and transmission electron microscopy. The composites exhibit minimal aggregation of the carbon nanofibers even at high weight percents. The polycarbonate/CNF composites exhibit an electrical conductivity percolation threshold of 6.3 wt% which is higher compared with similar CNF composites. The composites also show an increase in thermal stability of 40 °C as the CNF loading increases from 0 to 9 wt%.     

Electrocatalytic detection of insulin at RuOx/carbon nanotube-modified carbon electrodes

A bilayer surface coating, prepared by electrodepositing ruthenium oxide (RuOx) onto a carbon nanotube (CNT) layer, offers dramatic improvements in the stability and sensitivity of voltammetric and amperometric measurements of insulin compared to the individual (CNT or RuOx) coated electrodes. The enhanced electrocatalytic activity towards insulin is indicated from lowering the potential of the oxidation process (starting around 0.35 versus Ag/AgCl) and the substantially higher sensitivity over the entire potential range. A wide linear dynamic range (10-800 nM) was achieved with a detection limit of 1 nM. The marked electrocatalytic activity of the RuOx/CNT coating towards insulin is coupled with a greatly enhanced stability. For example, the insulin amperometric response of the RuOx/CNT-coated electrodes is highly stable, with 97% of the initial activity remaining after 60 min stirring of 2 × 10⁻⁶ M solution (compared to significantly faster current diminutions at the RuOx- or CNT-coated surfaces). The results suggest great promise for miniaturized sensors and detectors for monitoring insulin.     

Advanced carbon nanomaterials for electrochemiluminescent biosensor applications

Electrochemiluminescent biosensors are nowadays an established technology in the field of immunosensors and diagnostics. Along with the advent of nanotechnology, the marriage between electrochemiluminescence and nanomaterials results in promising enhancing strategies in many biosensor applications. Among nanomaterials, carbon-based ones are the most used, as (i) scaffolds, (ii) luminophores and (iii) electrode materials of the sensor. In this review, we describe the importance of a rational modification and functionalization of carbon nanomaterials to optimize electrochemiluminescence signal, and we also resume the latest and most relevant applications of electrochemiluminescent biosensors based on carbon nanomaterials.