An inlaying ultra-thin carbon paste electrode modified with functional single-wall carbon nanotubes for simultaneous determination of three purine derivatives

A functional single-wall carbon nanotube film electrode (SWNTE) was constructed on the surface of inlaying ultra-thin carbon paste electrode (IUTCPE). The precursor film was formed by direct inlaying carbon paste onto nichrome substrate. Scanning electron microscope (SEM) was employed to characterize the electrode surface. The electrochemical behavior of SWNT/IUTCPE for xanthine (Xa), hypoxanthine (Hxa) and uric acid (UA) was investigated by various electrochemical techniques. The SWNT/IUTCPE exhibited an excellent electrocatalysis and enhancement of the current response for the purine derivatives. Three well-defined oxidation peaks of Xa, Hxa and UA were appeared at the electrode. The proposed electrode can be applied to determine Xa, Hxa and uric acid in human urine simultaneously without any pretreatment.     

Selective potentiometric determination of uric acid with uricase immobilized on ZnO nanowires

In this study, a potentiometric uric acid biosensor was fabricated by immobilization of uricase onto zinc oxide (ZnO) nanowires. Zinc oxide nanowires with 80-150 nm in diameter and 900 nm to 1.5 μm in lengths were grown on the surface of a gold coated flexible plastic substrate. Uricase was electrostatically immobilized on the surface of well aligned ZnO nanowires resulting in a sensitive, selective, stable and reproducible uric acid biosensor. The potentiometric response of the ZnO sensor vs Ag/AgCl reference electrode was found to be linear over a relatively wide logarithmic concentration range (1-650 μM) suitable for human blood serum. By applying a Nafion^® membrane on the sensor the linear range could be extended to 1-1000 μM at the expense of an increased response time from 6.25 s to less than 9 s. On the other hand the membrane increased the sensor durability considerably. The sensor response was unaffected by normal concentrations of common interferents such as ascorbic acid, glucose, and urea.     

Optimization of screen-printing parameters of SN9000 ink for pinholes using Taguchi method in chip on film packaging

The influence of pinholes on the chip on film (COF) in screen-printing was studied in this paper. Yield improvement is the most challenging part of COF manufacturing in view of its processing complexity, mainly in the screen-printing process. The process parameters such as ink capacity, origin control distance, angle of the squeezer, method of mixing, freshness of ink, speed of printing, and speed of scraper are considered to improve the pinholes. In Taguchi method, a two level orthogonal array is used to determine the signal-to-noise (S/N) ratio. Analysis of variance and the F-test values are used to determine the most significant process parameters affecting the pinholes. Confirmation analysis tests with the optimal levels of process parameters are carried out. The results of the experiment show that Taguchi method is a very suitable approach with regard to solving quality problems related to such pinholes.     

A disposable amperometric biosensor for determining total cholesterol in whole blood

A disposable amperometric biosensor for detecting the total cholesterol was fabricated which comprises a sensing electrode and a reference electrode in simultaneous contact with an integrated reagent layer. The integrated reagent layer formed by coating a working ink containing cholesterol esterase, cholesterol dehydrogenase, coenzyme, redox mediator, surfactant, stabilizer, filler and at least one aqueous thickening agent. The biosensor showed the linearity for 50-500 mg/dL cholesterol acetate. The minimum detection limit of the cholesterol was 50 mg/dL. The effects of temperature and the stability of immobilized enzymes were also studied. A good correlation was found among cholesterol values obtained by commercial colorimetric test strip and clinical/laboratory methods. The biosensor showed an acceptable reproducibility, good stability and low interferences.     

正弦波伏安法检测尿酸的研究

以玻碳电极为工作电极,利用正弦波伏安法在磷酸缓冲液中选择性检测尿酸.通过傅立叶变换比较了纯的磷酸缓冲液、尿酸和抗坏血酸的正弦波伏安法频域响应,进而发现在第5次谐波处选择性检测尿酸的可能.相比于传统的尿酸检测技术,该技术具有较高的信噪比,操作简单且无需对样品进行预处理.分析了玻碳电极表面抗坏血酸和尿酸的线性扫描响应,在不同扫描速率下两者的伏安图变化趋势相同.在裸玻碳电极表面,利用正弦波伏安法检测尿酸的检测限为1.0μmol/L,在250倍浓度的抗坏血酸共存时仍能利用第5次谐波选择性检测出尿酸.     

不同表面活性剂对尿酸电化学行为的影响

在银掺杂聚L-苯丙胺酸修饰电极上,以人体代谢产物尿酸为探针,研究了不同表面活性剂(十六烷基三甲基溴化铵(CTMAB)、十二烷基硫酸钠(SDS)和聚乙二醇单辛基苯基醚(Triton X-100))存在下对尿酸电化学行为的影响。结果表明,三种不同类型表面活性剂对尿酸的电化学行为均有影响,不同表面活性剂存在下,尿酸在修饰电极上氧化电位变化不大,氧化电流均有所降低,在研究的三种不同类型表面活性剂中,对峰电流的影响最大的是CTMAB、最小的是SDS。     

NASICON-based solid-electrolyte cell as transducer for enzyme sensors

Enzyme sensors for glucose and uric acid have been developed based on a solid-electrolyte cell using NASICON (Na₃Zr₂Si₂PO₁₂). These potentiometric devices respond reversibly to glucose and uric acid over a concentration range of two orders of magnitude with sensitivities of −54 and −52 mV/decade, respectively. The sensors can be used for a batch-type as well as a flow-through-type measuring system. Primarily the sensors respond to the H₂O₂ that is produced by the enzymatic reactions. The role of the three-phase region, electrolyte solution, sensing electrode metal and NASICON has been investigated. The liquid electrolyte/sensing electrode metal interface is found to work as a potential-determining as well as a rate-determining interface for the enzyme sensor.     

2,3-二巯基乙二酸自组装膜的电化学行为及应用研究

利用石英晶体微天平、电化学法、交流阻抗以及拉曼光谱法研究了2,3-二巯基乙二酸(DMSA)自组装膜的电化学性质及其在电极表面的组装过程.发现DMSA分子借助两个巯基自组装到了金电极表面.相对于在裸金电极表面,多巴胺和尿酸在此修饰电极表面的氧化峰电流均有明显的增加,且氧化峰电位大大降低,说明此自组装膜对于多巴胺和尿酸的氧化能够起到明显的电催化作用.     

基于青霉胺自组装膜的生物传感器及其应用研究

研究了青霉胺自组装膜在金电极上的电化学特性.在pH7.3的磷酸缓冲溶液中,利用差分脉冲法考察了多巴胺与尿酸在此修饰电极上的电化学行为.该电极可用于多巴胺与尿酸的同时测定,两者在修饰电极上的电位差可达到380 mV,且互不干扰.多巴胺与尿酸的氧化峰电流分别在1.0×10-4至1.0×10-3 mol/L,8.0×10-4至4.0×10-3 mol/L范围内与其浓度的大小呈良好的线性关系,检出限分别为6.5×10-6,2.1×10-5 mol/L.青霉胺自组装电极稳定性好,选择性高,可用于实际样品的测定,结果满意.     

基于微流控芯片的尿酸和抗坏血酸并行电化学检测研究

尿样和血样中的尿酸水平是诊断痛风等疾病的重要指标,传统检测方法存在时间长、需要其他辅助试剂等不足,开展了在微流控芯片上对尿酸进行电化学检测的研究：以碳纳米管修饰的丝网印刷电极片为检测单元,构建了PDMS微流控芯片。以微流控芯片为平台,采用微分脉冲伏安法（DPV）对尿酸和抗坏血酸分别进行检测,确定其原始峰值电位。最后,实验测试和分析比较了不同浓度尿酸和抗坏血酸对电化学检测信号的影响。研究结果表明：用DPV法分别检测尿酸和抗坏血酸,测得峰电流与样品浓度均有较好的线性度;从并行检测信号中能够分辨出尿酸和抗坏血酸的氧化峰位;尿酸和抗坏血酸对彼此的DPV峰位无明显影响,但对DPV电流峰值有一定抑制作用。     

NiO电极中YSZ添加量对NOx传感器气敏性能的影响

以钇稳氧化锆(简称YSZ,Yttria-Stabilized Zirco nia)为固体电解质,添加不同摩尔比例YSZ的NiO+YSZ混合体为敏感电极材料,通过丝网印刷技术制备了相应的混合电势型NOx传感器.采用XRD和SEM手段对NiO混合物进行了物理性能分析,利用电势和阻抗测量设备对传感器样品的输出电势(EMF)和交流阻抗等电学参数随NO浓度的变化进行了研究.结果显示:NiO+YSZ的混合体中,物相独立,没有新相产生;在相同NO检测环境下,敏感电极中YSZ所占摩尔比例为20mol%时传感器的响应电势最大且在0.O1 Hz～100 kHz范围内的阻抗谱最小,SEM也显示此时具有很好的TPB.     

Tactile sensors based on conductive polymers

This paper presents results from a selection of tactile sensors that have been designed and fabricated. These sensors are based on a common approach that consists in placing a sheet of piezoresistive material on the top of a set of electrodes. We use a thin film of conductive polymer as the piezoresistive material. Specifically, a conductive water-based ink of this polymer is deposited by spin-coating on a flexible plastic sheet, giving it a smooth, homogeneous and conducting thin film. The main interest in this procedure is that it is cheap and it allows the fabrication of flexible and low cost tactile sensors. In this work, we present results from sensors made using two technologies. Firstly, we have used a flexible printed circuit board (PCB) technology to fabricate the set of electrodes and addressing tracks. The result is a simple, flexible tactile sensor. In addition to these sensors on PCB, we have proposed, designed and fabricated sensors with screen-printing technology. In this case, the set of electrodes and addressing tracks are made by printing an ink based on silver nanoparticles. The exhaustive characterization provides us insights into the design of these tactile sensors.     

Study of an amperometric glucose sensor based on Pd-Ni/SiNW electrode

An amperometric glucose sensor based on Pd-Ni/SiNW electrode has been investigated. The silicon nanowire (SiNW) electrodes were first fabricated by chemical etching, and then nickel and palladium particles were deposited onto the surfaces of SiNWs via electroless co-plating technique followed by annealing in nitrogen atmosphere at 350 °C for 300 s. The morphology of Pd-Ni/SiNW electrode was characterized by scanning electron microscope (SEM) and X-ray diffraction (XRD). The sensor performance was characterized by cyclic voltammetry (CV) and fixed potential amperometry techniques. In 0.1 M KOH alkaline medium with different glucose concentrations, the sensor shows an excellent sensitivity of 190.72 μA mM⁻¹ cm⁻² with the detection limit (S/N ratio = 3) of 2.88 μM. And it also exhibits superior anti-interference properties to the species including ascorbic acid (AA), uric acid (UA) and 4-acetamidophenol (AP). All results demonstrate that this Pd-Ni/SiNW electrode is a candidate with great potential for glucose detection.     

全血L􀀁乳酸􀀂生物传感器

全血L-广乳酸生物传感器适用于快速方便地测量全血中L-乳酸的浓度。它包括印有一对碳电极的基片，由L-乳酸氧化酶和作为电子传递剂的铁氰化钾构成的反应层和塑料薄膜形成的反应腔。将血样(2μL)滴在反应腔中，然后在电极两端施加一个300mV的恒电压，50s后读取电流值，即可得到对应的L-乳酸浓度。该传感器的线性范围为0-15mol。保存120d后，响应没有明显衰减。该传感器的测量结果和美国强生VITROS250 SYSTEM全自动干化学分析仪的测量结果有良好的相关性(r=0．9809)，该传感器适合大规模生产。     

Development of an amperometric sulfite biosensor based on sulfite oxidase with cytochrome c,as electron acceptor,and a screen-printed transducer

An amperometric biosensor for sulfite has been developed. The enzyme sulfite oxidase (SOD) and electron acceptor cytochrome c are mixed into the carbon ink that is deposited onto the working electrode of a screen-printed strip. A silver–silver chloride electrode is printed alongside the working electrode and serves as reference/counter electrode. The electrochemical behaviour of the biosensor surface in plain buffer has been investigated by cyclic voltammetry. In the voltage range −0.5 to +0.5 V, a well-defined anodic peak appeared at −0.15 V and a less well-defined anodic peak at about +0.2 V. In the presence of SO₃²⁻, the cyclic voltammogram obtained with the biosensor exhibited an increase in magnitude of the more positive peak; this was considered to result from the electrocatalytic oxidation of SO₃²⁻ involving SOD and the heme (Fe²⁺/Fe³⁺) centre of cytochrome c. Amperometry in stirred solution was used to construct a hydrodynamic voltammogram for SO₃²⁻ using the biosensor; this exhibited a single wave with a plateau beginning at +0.3 V. This wave corresponds to the electrocatalytic response observed by cyclic voltammetry. The pH and concentration of buffer components have been optimised for the determination of SO₃²⁻ by amperometry in stirred solution. Using these conditions, a detection limit of 4 ppm was obtained. The stability of the biosensors was examined after storage in 0.05 M phosphate buffer pH 7.4 at 4°C; it was found that the initial response was retained for at least 45 days. The proposed biosensors were evaluated on samples of unspiked and spiked estuarine, river and tap waters. The recovery and precision data indicated that the devices could be expected to give reliable data in these waters.     

Superoxide sensor based on hemin modified electrode

A hemin modified pyrolytic graphite (PG) electrode was prepared and applied for the electrochemical determination of superoxide. The rate constant of heterogeneous electron transfer of adsorbed hemin was determined with cyclic voltammetry (CV) to be 15 s⁻¹. The hemin modified electrode was applied to detect superoxide radicals produced by xanthine oxidase (XOD) catalyzed hypoxanthine oxidation. Sensitivity was higher than compared to the established cytochrome c (cyt c)-based sensor. The antioxidative activity of superoxide dismutase (SOD) and uric acid was also investigated.     

基于Au—Ni复合材料的新型葡萄糖传感器的研究

利用新型Au—Ni复合材料,通过壳聚糖将Au—Ni复合材料修饰到电极表面．制备了一种新型的用于葡萄糖检测的电化学传感器。以XRD表征了Au—Ni材料,以循环伏安法,交流阻抗法,计时电流等电化学方法研究了此传感器的电化学特性。研制的电极对葡萄糖检测的线性范围为2．5×10^-9．5×10^-4mol／L,检测限为lxl0...     

Whole blood assay of glucose-6-phosphate dehydrogenase: potential for simplified immunoassay

Enzyme labels combined with electrochemical product detection have considerable advantages in the development of non isotopic immunoassays. In particular, there is the possibility of signal detection in whole blood samples using cheap, robust and ultimately portable instrumentation. In this study the amperometric measurement, in whole blood, of glucose-6-phosphate dehydrogenase (G6PDH), an enzyme commonly employed in homogeneous immunoassays, has been investigated using a simple membrane covered electrode. On comparison of several compounds for electrochemical mediation of the enzyme cofactor NADH, in whole blood, napthoquinone sulphonic acid has been found to be optimal giving lower background responses (<1 nA vs. Ag/AgCl) whilst mediating effectively NADH detection at low overpotentials (≤0.15 V vs. Ag/AgCl). Employing this mediator it is possible to measure electrochemically NADH and subsequently G6PDH at concentrations down to 0.6 U ml⁻¹ in the presence of whole blood. This simplified G6PDH detection system will facilitate greatly the development of dehydrogenase based amperometric immunoassays in whole blood.     

铜掺杂聚L-天冬氨酸修饰电极同时测定多巴胺和尿酸

用循环伏安法制备了铜掺杂聚L-天冬氨酸修饰玻碳电极,研究了多巴胺（DA）和尿酸（UA）在该修饰电极上的电化学行为,建立了同时测定DA和UA的新方法。在pH3．5的磷酸盐缓冲溶液中,扫描速率为120mV]s时,DA和UA在该电极上产生氧化还原峰,峰电位分别为Eps=0．429V、Epc=0．336V（DA）和Eps=0．617V（UA）,DA和UA的氧化峰分开达0．188V。采用循环伏安法（CV法）和示差脉冲伏安法（DPVs法）同时测定DA和UA的线性范围分别为：DA：3．00×10^-6-4．00×100mol／L、4．00×10^-5～1．00×10^-4mlo/L（CV）、3．00×10^-7～3．00×10^-6mol／L、3．00×10^-6—1．00×10^-5mol／L（DPVs）,UA：8．00×10^-6～5．00×10^-5mol／L、5．00×10^-5-2．00×10^-4mol／L（CV）、3．00×10^-7～5．00×10^-5mol／L、5．00×10^-5．2．00×10^-4mol／L（DPVs）;检出限分另U为8．0×10^-7mol／L、1．0×10^-6mol／L（CV）和3．0×10^-7mol/L、3．0×10^-7mol／L（DPVs）。用于人体尿液中DA和UA的同时测定,结果满意。     

三维泡沫石墨烯在抗坏血酸的干扰下检测尿酸

该文采用化学气相沉积法在泡沫镍上生长石墨烯,通过扫描电镜、X射线衍射、拉曼光谱对生成产物的形貌和结构分别进行了表征。结果表明：所制得的石墨烯为具有三维网状结构且层数较少的石墨烯。将三维泡沫石墨烯转移到ITO玻璃上制成生物传感器的工作电极,利用电化学工作站对尿酸和抗坏血酸进行检测．电化学测试结果表明：三维泡沫石墨烯修饰电极在抗坏血酸的干扰下可以准确的检测尿酸,其灵敏度为0．274μA／（μmol／L）,线性范围为10-100μmol／L。