基于热控电极的电致化学发光传感器的研究进展

电致化学发光（ECL）检测技术因其具有无需激发光源、仪器简单、灵敏度高、选择性好等特点,被广泛应用于环境分析、生物分析等领域. 温度是影响ECL的主要因素之一,在传统的ECL传感器中大多是通过溶液整体加热的方法来控制温度,这种方法操作繁琐,且溶液中的热不稳定性物质及易挥发性物质容易受到影响,因此电极很少工作在最适宜的温度下. 热控电极技术可以只提高电极表面温度,而维持溶液的整体温度不变,使用起来具有很好的便利性. 作者课题组首次将热控电极引入到ECL传感器的构建中,由于电极表面和溶液之间存在一定的温度梯度,因此可以引发强制对流,从而加快物质的扩散和对流速率;电极表面温度的升高还可以进一步提高电极表面物质的电化学反应速率,这两方面的共同作用提高了ECL检测的灵敏度. 同时,利用热控电极可以解决整体加热所引起的背景信号升高,挥发性、热不稳定性物质易受温度影响等问题,而且通过电极加热的方法可去除电极表面的污染物,从而提高ECL检测的重现性. 本文综述了近年来基于热控电极技术的ECL传感器的研究进展,主要介绍了热控电极的加热方式、电极种类以及热控电极在ECL中的应用等,并分析了该技术在实际应用中面临的主要问题,对该技术未来的发展趋势进行了展望.     

结合光学成像技术研究单颗粒碰撞电化学

近年来,单颗粒碰撞技术在纳米电化学领域受到广泛关注. 该技术通常控制超微电极处于某一电位,检测单个纳米颗粒随机碰撞到电极表面后产生的瞬时电流. 通过分析电流信号,可以研究单个纳米颗粒的性质. 尽管该技术可以检测单个纳米颗粒的电化学或电催化电流,但是传统的单颗粒碰撞技术缺乏空间分辨率,难以识别和表征特定的纳米颗粒. 因此,结合光学成像技术研究单颗粒碰撞电化学来补充电化学技术缺失的空间信息已成为一种趋势. 本文首先简要综述了单颗粒碰撞技术的三种检测原理,主要介绍了近年来单颗粒碰撞技术与荧光显微镜、表面等离激元共振显微镜、全息显微镜和电致化学发光相结合的研究进展,最后展望了单颗粒碰撞技术未来的发展趋势.     

新型电致化学发光分析仪的研制

新型电致化学发光分析仪可以应用在实验室条件下的药物分析、发光材料等一类电化学发光的检测实验中．系统地介绍了电致化学发光分析仪的设计和研制过程,包括仪器原理、设计框图、具体实现方案、主要技术难点和创新点．仪器具有灵敏度高、双检测位置、四样品通道、三维图形显示等特点。     

黄素腺嘌呤二核苷酸在热石墨柱电极上电化学行为及吸附溶出分析

研究了黄素腺嘌呤二核苷酸(FAD)在热石墨柱电极上的电化学行为.发现对吸附有FAD的电极加热同时进行循环伏安扫描,随电极温度升高,氧化还原峰电位负移,峰电流减小,峰形变差.采用方波伏安进行吸附溶出分析,如果只在吸附步骤对电极加热,室温溶出,则随电极温度升高,溶出峰电流显著增加.这主要归因于直接对电极加热引起的强制热对流,这种对流能提高传质,促进吸附,增强溶出响应.5 min预富集对电极加热到72 ℃,检出限可以达到1×10-8 mol/L(S/N=3),比室温27 ℃时降低了一个多数量级,相应灵敏度也明显提高.     

基于血红蛋白/硒化镉量子点多层膜的H2O2生物传感器

合成了水溶性硒化镉(CdSe)量子点,利用组装技术和静电吸附作用,将带正电荷的血红蛋白(Hb)和带负电荷的CdSe量子点层层组装到壳聚糖(chit)修饰的玻碳电极(GCE)表面,构建基于{Hb/CdSe}n多层膜的无电子媒介体的电流型生物传感器({Hb/CdSe}3/chit/GCE).运用紫外-可见吸收光谱、电致化学发光、交流阻抗和循环伏安技术来表征修饰膜,并研究传感器的作用机理、性能及分析应用.结果表明:与量子点薄膜法及量子点/血红蛋白复合物法等固载血红蛋白的其他方法相比,层层组装法能显著提高血红蛋白的固定量,保持血红蛋白的生物活性,增强传感器的灵敏度和稳定性.传感器检测H2O2的线性范围为4.0×10-8～4.8×10-6 mol·L-1(r=0.999 1),检测限为2.0×10-8mol·L-l.多层膜的电致化学发光研究,表明修饰电极有望用于电致化学发光传感器的制备.     

电致化学发光-分子印迹传感器测定L-苯丙氨酸

在三联吡啶钌固相电极上,采用溶胶-凝胶法电沉积分子印迹聚合物,制得电致化学发光-分子印迹传感器。研究了该传感器的电化学和电致化学发光性能。结果表明,此传感器对L-苯丙氨酸具有很高的检测灵敏度和良好的选择性。在优化的条件下,测定L-苯丙氨酸的线性范围为1.0×10#11~1.0×10#8mol/L,检出限为3.1×10#12mol/L。此传感器可应用于尿样中L-苯丙氨酸的测定,回收率为94.8%~110.6%。     

CdTe量子点修布电极的阳极电致化学发光

制备了CdTe量子点/Nafion修饰玻碳电极(CdTe QDs/Nafion/GCE),并研究了该修饰电极在中性磷酸盐缓冲溶液(PBS)中的电致化学发光(ECL)行为.结果表明,三丙胺(TPA)作为共反应剂存在时,QDs/Nafion/GCE在中性PBS中可以产生强的阳极电化学发光信号.考察了量子点的用量、Nafion的用量、pH、电解质等条件对ECL的影响.抗坏血酸对QDs/Nafion/GCE的ECL具有抑制作用,且抑制程度与抗坏血酸浓度呈线性关系,为利用电致化学发光法检测抗坏血酸提供了新方法.     

CdTe量子点修饰电极的阳极电致化学发光

制备了CdTe量子点/Nafion修饰玻碳电极(CdTe QDs/Nafion/GCE),并研究了该修饰电极在中性磷酸盐缓冲溶液(PBS)中的电致化学发光(ECL)行为。结果表明,三丙胺(TPA)作为共反应剂存在时,QDs/Nafion/GCE在中性PBS中可以产生强的阳极电化学发光信号。考察了量子点的用量、Nafion的用量、pH、电解质等条件对ECL的影响。抗坏血酸对QDs/Nafion/GCE的ECL具有抑制作用,且抑制程度与抗坏血酸浓度呈线性关系,为利用电致化学发光法检测抗坏血酸提供了新方法。     

碳柱热电极的制备及应用

用铅笔芯制作了不同直径的碳柱热电极,表征了碳柱热电极的电化学和温敏等各种性质。结果表明,碳柱热电极在多次加热过程中均表现出对温度变化的快速响应以及良好的热稳定性。将其应用于痕量铅的方波阳极溶出伏安法测定,65℃时灵敏度比常温高,Pb2＋浓度在1~22μg/L呈线性关系,线性回归系数r=0.995 5,检测限0.5μg/L。     

毛细管电泳电致化学发光法测定牛奶样中的土霉素残留量

以铕离子(Ⅲ)掺杂类普鲁士蓝(Eu-PB)化学修饰铂电极为工作电极,基于铜(Ⅱ)-土霉素配合物对三联吡啶钌(Ⅱ)电致化学发光强度的增敏作用,建立了用毛细管电泳电致化学发光法测定土霉素的新方法。实验对毛细管电泳分离条件和电化学发光检测条件进行了优化。在最佳实验条件下,电致化学发光峰面积与铜(Ⅱ)-土霉素配合物的浓度在0.138～46.1μg/mL范围内呈良好的线性关系,检出限为57.0ng/mL(3σ)。本法用于牛奶样中土霉素残留量的测定,加标回收率为95.5%(n=5)。     

直流电场对红串红球菌NCC-1脱硫效率的影响及电刺激机理的初探

研究了脱硫菌--红串红球菌NCC-1在直流电场作用下的生长及脱硫状况,以及实际柴油体系中的脱硫效率,并对外加弱电流加速脱硫菌生长的机理进行了初探。 实验表明,水相适宜范围的电流密度可以提高脱硫菌的脱硫效率,脱硫菌脱硫的最佳电流密度为0.72 A/m²,该条件下,铂电极培养体系菌体比不加电培养体系提前48 h完全降解0.2 mmol/L二苯并噻吩（DBT）。 比相同电流密度钛电极培养体系菌体提前24 h。 铂电极最佳电流密度下菌体对实际柴油的脱硫率可以达到67.4％,比钛电极培养体系菌体高11.7%,高于不加电24.6%。 经验证,发现引起这种变化的主要原因是水的阴极电解产物吸附氢和氢气的比例不同,其中氢气对摇瓶培养菌体促进作用显著。     

Low-Temperature Potassium Batteries Enabled by Electric and Thermal Field Regulation

Recharging batteries operate at sub-zero temperature is usually limited by the slow ion diffusion and uneven charge distribution at low temperature. Here, we report a strategy to regulate electric field and thermal field simultaneously, creating a fast and uniform deposition surroundings for potassium ion in potassium metal batteries (PMBs). This regulation is achieved by using a highly ordered 1D nanoarray electrode which provides a dense and flat surface for uniforming the electric field and high thermal conductivity for reducing the temperature fluctuation. Consequently, this electrode could achieve high-areal capacity of 10 mAh cm⁻². Besides, the dependence of potassium nucleation on temperature is unveiled. Furthermore, a full-cell could steady operate with over 80 % of its room-temperature capacity at −20 °C. Those respectable performances demonstrate that this strategy is valid, potentially providing guidelines for the rational design of advanced electrodes toward PMBs.     

线状铜电极在磷酸溶液中电流混沌振荡的同步行为

研究了恒电位下两个铜线电极在磷酸溶液中的电流混沌振荡行为,通过恒定不同的电位数值,改变单个电极的电流振荡混沌行为,研究了不同混沌间的相互作用.调整线电极间的距离,研究了电极间距对电流振荡行为的影响.实验中两电极的振荡间呈现了复杂的耦合作用,耦合后的频率与耦合前电极原有的频率不同.两电极的混沌电流振荡中呈现出同步、准周期同步和反相同步等现象.电极距离一定时,振荡波形差别很大的两电极的电流容易呈现反相同步和准周期同步,波形差别不大时容易产生同步.强的耦合导致电极间电流振荡的同步,电极距离的加大,电极间电流振荡难以产生同步.对耦合作用机制也进行了探讨.     

Temperaturmessungen am Argon-Niederstrombogen zur Bestimmung der Übergangswahrscheinlichkeiten von Si I-, Se I- und S I-Linien im nahen Vakuum-UV

The temperatures of scon-cooled argon-d.c.-arc under variousexperimental conditions have been measured. It is shown that the Ornstein-method can be applied in the vacuum-ultraviolet region because the optimum temperatures of the spectral lines in this region are very high. The temperature of the arc has been determined in respect to the electric current and the electrode distance. The temperature of the arc rises with increasing current, whereas by varying the distance of the electrodes a temperature maximum is observed which can be explained by the amount of power absorbed by the electrodes. The relative transition probabilities of several lines of Si I, Se I and S I in the vacuum-u.v. have been measured. Some of the values which had already been determined theoretically and experimentally by other authors agree very well with our results.     

Hybrid electrochemical capacitors in aqueous electrolytes: Challenges and prospects

In an internal hybrid capacitor, at least one electrode displays battery-like charge/discharge and the other electrode stores charge reversibly at the electric double-layer (EDL). Recently, a plethora of hybrid cells in aqueous electrolytes have been proposed by coupling an EDL electrode with a battery electrode, the latter made from a variety of redox-active/redox-mediator species either dissolved in the electrolyte or adsorbed/immobilized in nanoporous electrodes. This review presents current opinions, discusses challenges, and supplies recommendation about the hybrid cells with aqueous electrolytes and carbon electrodes.     

Alternating current-bipolar electrochemistry

Rotation of a bipolar electrode in a constant electric field between feeder electrodes causes an alternating bipolar current at an AC frequency that depends on the rotation rate. The corresponding oscillation of the feeder current is evaluated by means of a lock-in amplifier. This innovative approach allows the current flowing through the non-wired bipolar electrode in an open bipolar system to be extracted without relying on electrochemical reporter reactions.     

Investigations concerning the work function of doped graphite

In order to reduce the burning off of electrodes in electric arc furnaces, it is necesary to decrease the specific thermal load at the tip in the arc attachment area. This can be achieved by minimizing the work function of the electrode materials, whereby the peak temperature is reduced. The work function of doped graphite electrodes was investigated under conditions prevailing during standard industrial practice in order to achieve transferrable results. The measurement equipment developed to meet this requirement is based on a design first proposed by Bade and Yos. By measuring the peak temperature of the electrode and its current density, the value of the work function of the material was calculated with a modified Richardson equation. Starting from materials with well-known values of the work function, to verify, the accuracy of the experimental method and the mathematical model, those of pure and dopedgraphites were determined. The additives, oxides as a rule, result in a significant reduction in electron work function in the case of magnesium, calcium and cerium oxides.     

Manipulating particles in microfluidics by floating electrodes

Various particle manipulations including enrichment, movement, trapping, separation, and focusing by floating electrodes attached to the bottom wall of a straight microchannel under an imposed DC electric field have been experimentally demonstrated. In contrast to a dielectric microchannel possessing a nearly uniform surface charge (or ζ potential), the metal strip (floating electrode) is polarized under the imposed electric field, resulting in a nonuniform distribution of the induced surface charge with a zero net surface charge along the floating electrode's surface, and accordingly induced-charge electroosmotic flow near the metal strip. The induced induced-charge electroosmotic flow can be regulated by controlling the strength of the imposed electric field and affects both the hydrodynamic field and the particle's motion. By using a single floating electrode, charged particles could be locally concentrated in a section of the channel or in an end-reservoir and move toward either the anode or the cathode by controlling the strength of the imposed electric field. By using double floating electrodes, negatively charged particles could be concentrated between the floating electrodes, subsequently squeezed to a stream flowing in the center region of the microchannel toward the cathodic reservoir, which can be used to focus particles.     

电极材料对NPB/Alq3有机电致发光器件性能的影响

采用不同材料作为有机电致发光器件(OELDs)的电极, 制备了基本结构为[阳极/NPB(40 nm)]/Alq3(50 nm)/阴极]的异质结双层器件, 并通过改变OELDs器件的阴极或阳极来研究电极材料对器件光电性能的影响. 研究结果表明, 各器件电流-电压(I-V)关系的基本特征与陷阱电荷限制电流(TCLC)机制的拟合情况相符. 由于有机材料本身能级的无序性以及载流子迁移率对温度和电场的依赖性, 不同电极的载流子注入能力与其功函数并无直接关系. 双层器件中由于空穴传输层的引入, 使得载流子复合区域位于有机层异质结界面处, 降低了金属阴极对激子的猝灭作用, 从而大大提高了器件性能. 此外, 金属电极OLEDs器件结构具有的微腔效应会导致发射光谱的位移和谱峰宽度变窄, 这表明通过对金属电极的表面改性和优化可使器件性能超过常规结构的器件.     

A novel electric ion resonance cell design with high signal-to-noise ratio and low distortion for Fourier transform mass spectrometry

Performing wideband ion image current detection mass spectrometry experiments with an electric ion trap—e. g., the Paul trap—is a difficult task, as there is a strong crosstalk current induced by the high voltages of the radio frequency (rf) storage field. In a classic Paul trap the metallic hyperbolic electrodes (a ring electrode and two end cap electrodes) are shaped following the isopotential lines of the quadrupole potential distribution. In our new design the ring electrode is replaced by a cylindrical series of ring electrodes with a parabolic potential distribution, whereas the end cap electrodes are used without modification. Thus the quadrupole field within the trap remains unchanged but the capacitances between the electrodes and therefore the crosstalk currents are significantly reduced. The remaining crosstalk is balanced out by an electronic compensation technique. As a consequence the weak signals of the ion-induced charge can be detected with a wideband low-noise amplifier to perform Fourier transform mass spectrometry experiments with improved signal-to-noise ratio.