金纳米粒子修饰丝网印刷电极测定化妆品中的汞含量

采用丝网印刷电极,通过电化学沉积法修饰纳米金颗粒,对化妆品中重金属Hg~(2+)进行快速测定.实验结果表明,Hg~(2+)在金纳米粒子修饰电极上可得到灵敏的溶出峰,在优化的实验条件下Hg~(2+)在5—160μg·L~(-1)范围内呈现良好的线性关系,相关系数为0.992,检测限为0.3μg·L~(-1).该方法简便、快速、灵敏度较高、具有较好的选择性和准确性,能满足化妆品中Hg~(2+)含量的检测分析.     

纳米金-适配体电化学传感器用于环境水样中双酚A检测

制备了一种用于检测双酚A的纳米金-适配体电化学传感器.采用恒电位沉积的方法在玻碳电极表面制备金纳米颗粒提高电极的比表面积及导电性,通过Au—S键作用将末端带有巯基、可特异性识别双酚A的适配体固定在电极表面,以[Fe(CN)₆]^3-/4-作为氧化还原探针,通过循环伏安法和交流阻抗法对纳米金-适配体电化学传感器的检测性能进行研究,优化了检测性能的影响因素.当金纳米颗粒沉积时间为400 s、适配体浓度为1μmol·L^-1、富集时间为50 min、检测溶液pH 7.0时,电极阻抗响应与双酚A浓度在1×10^-9—5×10^-6 mol·L^-1范围内呈良好线性关系.发展的传感器具有良好的重现性、稳定性和抗干扰性,并成功应用于环境水样中双酚A的检测,回收率87.4%—110.0%.     

AgNPs/聚萘二胺/碳纳米管复合电极对亚硝酸盐的电化学检测

本文采用简单、环保的电化学沉积法制备银纳米粒子/聚萘二胺/碳纳米管修饰玻碳电极(AgNPs/Poly(1,5-DAN)/CNTs/GCE),并将其应用于亚硝酸盐的定量检测.通过扫描电子显微镜(SEM)、能量散射光谱(EDX)和电化学技术对AgNPs/Poly(1,5-DAN)CNTs/GCE的形貌和性能进行表征,研究该修饰电极快速检测NO~-_2离子的电化学行为和电催化机理.结果表明,由于银纳米粒子、聚萘二胺和碳纳米管复合物的协同作用,AgNPs/Poly(1,5-DAN)CNTs/GCE复合电极的电活性面积和催化性能明显提高.该修饰电极对NO~-_2的检测具有优异的电化学行为,催化机理是2个电子参与的不可逆反应.采用安培法检测低浓度NO~-_2,NO~-_2氧化电流随其浓度的增加而增加,且在1.5×10~(-7)—6.75×10~(-5) mol·L~(-1)(I(μA)=0.0667 C+0.1049,R~2=0.9918)范围内呈现良好的线性关系,检出限低至5×10~(-8) mol·L~(-1)(S/N=3).该AgNPs/Poly(1,5-DAN)CNTs/GCE还具有良好的选择性、稳定性和再现性,成功应用于实际样品中NO~-_2的定量测定,加标回收率为96.7%—106.7%,结果令人满意.     

溶胶-凝胶法固定乙酰胆碱酯酶生物传感器测定有机磷农药

采用溶胶-凝胶法将乙酰胆碱酯酶固定在醋酸纤维膜上,再将酶膜固定在聚四氨基钴酞菁(p-CoTAPc)修饰的玻碳电极(GCE)上,制备了可应用于有机磷农药测定的生物传感器,采用计时安培法对有机磷农药(对硫磷、辛硫磷、氧化乐果)进行检测,检测限分别可达2.0×10-9mol·l-1,1.4×10-9mol·l-1和1.1×10-8mol·l-1.     

聚拉莫三嗪/铋膜修饰电极的电化学行为及分析应用

研究了拉莫三嗪在玻碳电极上的电化学修饰及其修饰电极的电化学行为.在H2SO4介质中,采用循环伏安法制备了聚拉莫三嗪膜修饰玻碳电极(PLTG/GCE),并对修饰层进行了表征;同时研究了用同位镀铋的方法,制得聚拉莫三嗪/铋膜修饰电极(PLTG/Bi/GCE).实验结果表明,铅在聚拉莫三嗪/铋膜修饰电极上可得到灵敏的阳极溶出峰.在最佳实验条件下,Pb2+浓度与其峰电流在4.8×10-8—1.6×10-6mol.L-1范围内呈良好的线性,线性关系为R=0.9979,检测限为8.1×10-9mol.L-1.应用于实际水样中Pb2+的测定,结果满意.     

电化学法同时测定水样中的间硝基酚和对硝基酚

用微分脉冲伏安法同时测定了水样中含间硝基酚和对硝基酚的混合体系 ,在 0 1mol·l- 1 乙二胺 0 5mol·l- 1 氯化铵 (pH =8 5 0 )底液中于 - 0 5 0V和 - 0 69V (vsAg/AgCl)处出现两个灵敏度高且互不干扰的吸附波 .间硝基酚和对硝基酚分别在 4 0× 1 0 - 7— 8 0×1 0 - 5mol·l- 1 和 2 0× 1 0 - 7— 4 0× 1 0 - 5mol·l- 1 范围内与峰电流ip 呈良好的线性关系 .检测限分别为 8 0× 1 0 - 8mol·l- 1 和 6 0× 1 0 - 8mol·l- 1 .本法可用于环境废水中微量间硝基酚和对硝基酚的同时测定 .另外 ,对双组分体系的吸附性质和电极反应机理作了研究 .     

胶束形态对十六烷基三甲基溴化铵(CTAB)增溶典型苯系物行为的影响

研究了30℃条件下,浓度为1.2×10-4mol·l-1—2.88×10-2mol·l-1的阳离子表面活性剂十六烷基三甲基溴化铵(CTAB)溶液的吸光度及相应浓度条件时对典型苯系物(苯、甲苯和乙苯)的增溶作用.利用表面活性剂的紫外吸收随浓度变化这一特性,从其不同的拐点处求得CTAB的第一、第二临界胶束浓度分别为7.2×10-4mol·l-1和9.6×10-3mol·l-1.在实验浓度范围内,CTAB溶液对苯、甲苯和乙苯的表观溶解度增溶曲线上同样得到两个拐点,即苯7.2×10-4mol·l-1和9.6×10-3mol·l-1,甲苯7.2×10-4mol·l-1和7.2×10-3mol·l-1以及乙苯7.2×10-4mol·l-1和9.6×10-3mol·l-1,这与第一、第二临界胶束浓度相等或相近.由于溶液中CTAB胶束形态随浓度增加而变化,表明胶束形态对CTAB增溶苯系物的行为有显著影响。     

硝基苯在碳纳米管修饰电极上的电化学行为及其分析应用

硝基苯在碳纳米管修饰电极上的电化学行为表明,硝基苯在-0.50V有一灵敏的还原峰,为硝基苯得到四个电子还原为苯胲所形成,电位继续负移,苯胲能继续还原为苯胺.在扫描速度为100mV·s-1,pH=5.0和富集时间为2min的条件下,-0.50V处的还原峰电流与硝基苯在1.5—150mg·l-1范围内线性关系良好,线性系数为0.99992,检测限为0.3mg·l-1.应用于实际废水中硝基苯的测定,相对标准偏差小于5%(n=10),相对误差为-5%— 5%.     

自动进样系统结合电化学法检测河水中总铁

基于自动进样技术结合纳米金(AuNPs)-全氟磺酸(Nafion)修饰电极研制了一种新型的检测系统.通过对检测系统不同条件的优化,如修饰电极的材料、富集时间等条件;在最优条件下,该仪器对于Fe(Ⅲ)的检出限为4.5 nmol·L~(-1),线性范围为25 nmol·L~(-1)—1μmol·L~(-1),最终实现了对河水中总铁含量的检测.将此检测系统与ICP-AES相比较,检测结果基本一致.该仪器具有方便快捷、检测成本低等优点,在实时检测中具有广泛的应用前景.     

石墨烯-单壁碳纳米管修饰分子印迹传感器测定黑茶中槲皮素

本文以石墨烯(GR)和单壁碳纳米管(SWNTs)为修饰剂,研究其对金电极的增敏效果.并以邻氨基酚为功能单体,槲皮素为模板分子,于金电极表面通过电聚合制备对槲皮素具有特定选择性的分子印迹膜(MIP).采用循环伏安法(CV)和差分脉冲伏安法(DPV)研究了分子印迹膜的形成过程、结构、印迹效果和电化学性能.并用与槲皮素结构相似的化合物芦丁进行干扰实验,结果表明,该印迹膜对槲皮素有较好的选择性.优化了测定槲皮素的条件,绘制了槲皮素的工作曲线,该传感器对槲皮素浓度的线性响应范围3.00×10-7—1.92×10-5mol·L~(-1),线性方程为:I(μA)=~(-1)1.8505+2.6893lgc(mol·L~(-1)),(R=0.9935),检出限为1.00×10-7mol·L~(-1).5次重复测定结果的相对标准偏差为6.8%,放置10 d后,响应值为最初的92.5%,该传感器具有良好的重复性和稳定性.对黑茶样品中的槲皮素含量进行了测定,回收率在97.8%—104.0%之间,结果较为满意.     

Rapid method for on-site determination of phenolic contaminants in water using a disposable biosensor

A disposable biosensor was fabricated using single-walled carbon nanotubes, gold nanoparticles and tyrosinase (SWCNTs-AuNPs-Tyr) modified screen-printed electrodes. The prepared biosensor was applied to the rapid determination of phenolic contaminants within 15 minutes. The SWCNTs-AuNPs-Tyr bionanocomposite sensing layer was characterized with scanning electron microscopy, electrochemical impedance spectroscopy and cyclic voltammetry methods. The characterization results revealed that SWCNTs could lead to a high loading of tyrosinase (Tyr) with the large surface area and the porous morphology, while AuNPs could retain the bioactivity of Tyr and enhance the sensitivity. The detection conditions, including working potential, pH of supporting electrolyte and the amount of Tyr were optimumed. As an example, the biosensor for catechol determination displayed a linear range of 8.0 × 10^-8 to 2.0 × 10^-5 mol·L^-1 with a detection limit of 4.5 × 10^-8 mol·L^-1 (S/N = 3). This method has a rapid response time within 10 s, and shows excellent repeatability and stability. Moreover, the resulting biosensor could be disposable, low-cost, reliable and easy to carry. This kind of new Tyr biosensor provides great potential for rapid, on-site and cost-effective analysis of phenolic contaminants in environmental water samples.     

A Pt-Bi bimetallic nanoparticle catalyst for direct electrooxidation of formic acid in fuel cells

Direct formic acid fuel cells are a promising portable power-generating device, and the development of efficient anodic catalysts is essential for such a fuel cell. In this work Pt-Bi nanoparticles supported on micro-fabricated gold wire array substrate were synthesized using an electrochemical deposition method for formic acid oxidation in fuel cells. The surface morphology and element components of the Pt-Bi/Au nanoparticles were characterized, and the catalytic activities of the three Pt-Bi/Au nanoparticle electrodes with different Pt/Bi ratios for formic acid oxidation were evaluated. It was found that Pt₄Bi₉₆/Au had a much higher catalytic activity than Pt₁₁Bi₈₉/Au and Pt₁₃Bi₈₇/Au, and Pt₄Bi₉₆/Au exhibited a current density of 2.7 mA·cm^-2, which was 27-times greater than that of Pt/Au. The electro-catalytic activity of the Pt-Bi/Au electrode for formic acid oxidation increased with the increasing Bi content, suggesting that it would be possible to achieve an efficient formic acid oxidation on the low Pt-loading. Therefore, the Pt-Bi/Au electrode offers a promising catalyst with a high activity for direct oxidation of formic acid in fuel cells.     

Mechanisms behind the accelerated extracellular electron transfer in <Emphasis Type="Italic">Geobacter sulfurreducens</Emphasis> DL-1 by modifying gold electrode with self-assembled monolayers

Modification of electrode surface with carboxylic acid terminated alkanethiol self-assembled monolayers (SAMs) has been found to be an effective approach to improve the extracellular electron transfer (EET) of electrochemically active bacteria (EAB) on electrode surface, but the underlying mechanism behind such enhanced EET remains unclear. In this work, the gold electrodes modified by mercapto-acetic acid and mercaptoethylamine (Au-COOH, Au-NH₂) were used as anodes in microbial electrolysis cells (MECs) inoculated with Geobacter sulfurreducens DL-1, and their electrochemical performance and the bacteria-electrode interactions were investigated. Results showed that the Fe(CN) ₆ ^3–/4– redox reaction occurred on the Au-NH₂ with a higher rate and a lower resistance than that on the Au or the Au-COOH. Both the MECs with the Au-COOH and Au-NH₂ anodes exhibited a higher current density than that with a bare Au anode. The biofilm formed on the Au-COOH was denser than that on bare Au, while the biofilm on the Au-NH₂ had a greater thickness, suggesting a critical role of direct EET in this system. This work suggests that functional groups such as–COOH and-NH₂ could promote electrode performance by accelerating the direct EET of EAB on electrode surface.     

Penicillin fermentation residue biochar as a high-performance electrode for membrane capacitive deionization

● We have provided an activated method to remove the toxicity of antibiotic residue. ● PFRB can greatly improve the salt adsorption capacity of MCDI. ● The hierarchical porous and abundant O/N-doped played the key role for the high-capacity desalination. ● A new field of reuse of penicillin fermentation residue has been developed. Membrane capacitive deionization (MCDI) is an efficient desalination technology for brine. Penicillin fermentation residue biochar (PFRB) possesses a hierarchical porous and O/N-doped structure which could serve as a high-capacity desalination electrode in the MCDI system. Under optimal conditions (electrode weight, voltage, and concentration) and a carbonization temperature of 700 °C, the maximum salt adsorption capacity of the electrode can reach 26.4 mg/g, which is higher than that of most carbon electrodes. Furthermore, the electrochemical properties of the PFRB electrode were characterized through cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) with a maximum specific capacitance of 212.18 F/g. Finally, biotoxicity tests have showed that PFRB was non-biotoxin against luminescent bacteria and the MCDI system with the PFRB electrode remained stable even after 27 adsorption–desorption cycles. This study provides a novel way to recycle penicillin residue and an electrode that can achieve excellent desalination.     

Manufactured silver and gold nanoparticles-induced apoptosis by caspase-pathway in human cell lines

Abstract

Metallic nanoparticles have emerged as an important class of nanomaterials for a wide range of industrial and medical applications. Because of the intensive commercial applications, risk assessment of these nanoparticles is of great importance. In the present study, the human hepatoma and leukemia cells were used to characterize the apoptotic effects of silver nanoparticles (4.7 and 42?nm) and gold nanoparticles (30?nm). Apoptotic cells were identified by chromatin condensation and flow cytometry analysis, using Annexin V/PI, TUNEL and caspase activation assays. Flow cytometry analysis showed that the three metallic nanoparticles induced apoptotic cell death in a concentration and time dependent-manner. Moreover, the three nanoparticles induced activation of caspase-3 and -7 in hepatoma and leukemia cells. Apoptotic effects were stronger after exposure of both cell lines with 4.7?nm silver nanoparticles than those obtained with 42?nm silver and 30?nm gold nanoparticles. In conclusion, silver (4.7 and 42?nm) and gold (30?nm) nanoparticles induced apoptosis in hepatoma and leukemia cells via the caspase dependent pathway. The smaller silver nanoparticles (4.7?nm) had a greater ability to induce apoptosis in both cell lines.     

Enhancement of the electrocatalytic oxidation of antibiotic wastewater over the conductive black carbon-PbO2 electrode prepared using novel green approach

• A novel conductive carbon black modified lead dioxide electrode is synthesized. • The modified PbO₂ electrode exhibits enhanced electrochemical performances. • BBD method could predict optimal experiment conditions accurately and reliably. • The modified electrode possesses outstanding reusability and safety. The secondary pollution caused by modification of an electrode due to doping of harmful materials has long been a big concern. In this study, an environmentally friendly material, conductive carbon black, was adopted for modification of lead dioxide electrode (PbO₂). It was observed that the as-prepared conductive carbon black modified electrode (C-PbO₂) exhibited an enhanced electrocatalytical performance and more stable structure than a pristine PbO₂ electrode, and the removal efficiency of metronidazole (MNZ) and COD by a 1.0% C-PbO₂ electrode at optimal conditions was increased by 24.66% and 7.01%, respectively. Results revealed that the electrochemical degradation of MNZ wastewater followed pseudo-first-order kinetics. This intimates that the presence of conductive carbon black could improve the current efficiency, promote the generation of hydroxyl radicals, and accelerate the removal of MNZ through oxidation. In addition, MNZ degradation pathways through a C-PbO₂ electrode were proposed based on the identified intermediates. To promote the electrode to treat antibiotic wastewater, optimal experimental conditions were predicted through the Box-Behnken design (BBD) method. The results of this study suggest that a C-PbO₂ electrode may represent a promising functional material to pretreat antibiotic wastewaters.     

Electrocatalytic debromination of BDE-47 at palladized graphene electrode

Graphene electrodes （Ti/Gr） were prepared by depositing Gr sheets on Ti substrate, followed by an annealing process for enhancing the adhesion strength. Electrochemical impedance spectroscopies and X-ray dif- fraction patterns displayed that the electrochemical behavior of Ti/Gr electrodes can be improved due to the generation of TiO2 layer at Ti-Gr interface during the annealing process. The palladized Gr electrodes （Ti/Gr/Pd） were prepared by electrochemical depositing Pd nanoparticles on Gr sheets. The debromination ability of Ti/Gr/Pd electrodes was investigated using BDE-47 as a target pollutant with various bias potentials. The results indicated that the BDE-47 degradation rates on Ti/Gr/Pd electrodes increased with the negative bias potentials from 0V to -0.5 V （vs. SCE）. Almost all of the BDE-47 was removed in the debromination reaction on the Ti/Gr/Pd electrode at - 0.5 V for 3 h, and the main product was diphenyl ethers, meaning it is promising to debrominate completely using the Ti/Gr/Pd electrode. Although the debromination rate was slightly slower at -0.3 V than that under -0.5 V, the current efficiency at -0.3 V was higher, because the electrical current acted mostly on BDE-47 rather than on water.     

Size-dependent in vitro cytotoxicity assay of gold nanoparticles

Gold nanoparticles (AuNps) may serve as a promising model to address the size-dependent biological response of cell lines. Their size can be controlled with great precision during chemical synthesis. AuNps have potential applications in drug delivery, cancer diagnosis, and therapy, in the food industry, and for environmental remediation. However, some of the recent literature contains conflicting data regarding the cytotoxicity of gold nanoparticles. Against this background, a systematic study of water soluble gold nanoparticles stabilized by citrate ranging in size from 3?nm to 45?nm were synthesized. The cytotoxicity of these particles were tested by employing the (3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyltetrazolium bromide reduction assay), the neutral red cellular uptake assay, and lactate dehydrogenase release assay. Noticeable differences in the cytotoxic effects depending on the assay, and the nanoparticle size have been found. Citrate stabilized gold nanoparticles with sizes of 3?nm, 8?nm, and 30?nm were more sensitive to the cell lines and caused gradual cell death within 24?h at higher concentrations. This results in IC50 values ranging from 57 to 78?μgmL^?1 depending on the particle size, and cell line combinations. In contrast, AuNps with diameters of 5?nm, 6?nm, 10?nm, 17?nm, and 45?nm were nontoxic up to three to four fold higher concentrations, and at long-term exposure.     

Catalytic decomposition of low level ozone with gold nanoparticles supported on activated carbon

Highly dispersed gold nanoparticles were supported on coal-based activated carbon (AC) by a sol immobilization method and were used to investigate their catalytic activity for low-level ozone decomposition at ambient temperature. Nitrogen adsorption-desorption, scanning electron microscope (SEM), and X-ray photoelectron spectroscopy (XPS) were used to characterize the catalysts before and after ozone decomposition. The results showed that the supported gold nanoparticles prepared with microwave heating were much smaller and more uniformly dispersed on the activated carbon than those prepared with traditional conduction heating, exhibiting higher catalytic activity for ozone decomposition. The pH values of gold precursor solution significantly influenced the catalytic activity of supported gold for ozone decomposition, and the best pH value was 8. In the case of space velocity of 120000h⁻¹, inlet ozone concentration of 50mg/m³, and relative humidity of 45%, the Au/AC catalyst maintained the ozone removal ratio at 90.7% after 2500min. After being used for ozone decomposition, the surface carbon of the catalyst was partly oxidized and the oxygen content increased accordingly, while its specific surface area and pore volume only decreased a little. Ozone was mainly catalytically decomposed by the gold nanoparticles supported on the activated carbon.     

卤素阴离子对镉离子电化学检测的影响

以玻碳电极为工作电极、pH 6.0的磷酸缓冲溶液为底液,研究了卤素离子氯离子、溴离子和碘离子对镉离子在此条件下电化学测定的影响.结果表明,3种卤素离子均能有效提高镉离子的响应电流.此外,当多种卤素离子同时存在时,镉离子的响应电流相对于单一卤素离子能进一步提高.进一步研究表明,卤素离子能吸附于电极表面,通过提高镉在电极表面电化学反应速度以及表面吸附量来提高镉离子的响应电流.