Applications of microfabrication techniques in electrochemical sensor development

Electrochemical sensors have been used either as a whole or as an integral part of a chemical and biological sensing device. Microfabrication technology has been used in the development of electrochemical sensors. The recent advancement of micromachining techniques adds new impetus to electrochemical sensor development. Most noticable is the application of anisotropic chemical etching, plasma etching, sacrificial layer methods, and high aspect ratio X-ray lithography to enhance the opportunity to produce scientifically and commercially viable electrochemical sensors. Examples will be used to illustrate the potential of microfabrication and micromachining techniques in electrochemical sensor development.     

Review on applications of carbon nanomaterials for simultaneous electrochemical sensing of environmental contaminant dihydroxybenzene isomers

Carbonaceous nanostructures stand out as an excellent electrode material to enhance the electrocatalytic, electroconductivity, and long-term stability of the electrochemical sensor in recent years. This review article focus on the important advancement in developing carbonaceous nanomaterials-based electrochemical sensors for simultaneous electrochemical sensing (binary and ternary mixtures) of environmental contaminants dihydroxybenzene isomers. The fabrication of electrochemical sensors such as graphene/carbon nanotubes hybrid composite, graphene/ carbon nanotubes supported nanomaterials, mesoporous carbon, carbon nanofiber, carbon nano-fragment and biochar modified electrode was presented coupled with suitable applications. This review discussed the selective reports on the application of dihydroxybenzene sensors during the period from 2015 to 2020.     

Glucose oxidase-incorporated hydrogel thin film for fast optical glucose detecting under physiological conditions

Hydrogel biosensors usually suffer from a slow response, which severely hinders their practical applications. Here a new optical glucose biosensor was designed, using glucose-sensitive hydrogel films as both glucose-sensing material and Fabry-Perot cavity. The film was fabricated by layer-by-layer assembly from partially oxidized dextran (PO-Dex), chitosan, and glucose oxidase (GOD). The film responds to glucose because the incorporated GOD converts glucose to gluconic acid, and thus lowers the local pH in the film, and, in turn, triggers the pH-sensitive film to swell. The glucose-induced swelling causes a shift of Fabry?Perot fringes on the reflection spectra of the film, from which the glucose concentration can be reported. The new sensor works well under physiological conditions. Potential interferents, such as diols for phenylboronic acid-based sensors and electroactive compounds for electrochemical sensors, do not influence the new sensor. The sensor can respond reversibly over a wide range of glucose concentration. Particularly, it responds linearly within the clinically relevant glucose range (0–20 mM). More importantly, because the film is very thin, the new sensor can respond quickly, making it potential for real-time, continuous glucose monitoring.     

Stretchable Electrochemical Sensor for Real‐Time Monitoring of Cells and Tissues

Stretchable electrochemical sensors are conceivably a powerful technique that provides important chemical information to unravel elastic and curvilinear living body. However, no breakthrough was made in stretchable electrochemical device for biological detection. Herein, we synthesized Au nanotubes (NTs) with large aspect ratio to construct an effective stretchable electrochemical sensor. Interlacing network of Au NTs endows the sensor with desirable stability against mechanical deformation, and Au nanostructure provides excellent electrochemical performance and biocompatibility. This allows for the first time, real‐time electrochemical monitoring of mechanically sensitive cells on the sensor both in their stretching‐free and stretching states as well as sensing of the inner lining of blood vessels. The results demonstrate the great potential of this sensor in electrochemical detection of living body, opening a new window for stretchable electrochemical sensor in biological exploration.     

Miniaturized back-side contact transducer for potentiometric sensors

A novel type of a miniature transducer for potentiometric sensors was designed and tested. The transducer is made from an ordinary printed circuit board using a typical technology. As a result, a back-side contact structure was obtained, which can be mounted in flow systems. The advantage of the fabrication process is its cheapness and flexibility in designing modified structures. The measurement properties of the transducer were tested as a chloride sensor. Then the structure was covered with polyHEMA and a potassium-selective membrane and tested as a potassium sensor. The performance and the long-term stability of the sensors with plasticized PVC and Siloprene based potassium-selective membranes were compared.     

无酶葡萄糖电化学传感器的研究进展

随着各种新型材料的层出不穷及其在葡萄糖电化学传感器方面应用的发展,无酶葡萄糖电化学传感器的研制成为葡萄糖电化学传感器的另一个研究热点.本文综述了近年来无酶葡萄糖电化学传感器的研究进展,重点介绍了电流型无酶葡萄糖传感器所使用的各种电极材料,总结了最近五年各种新型结构材料在该类传感器研制方面的应用,并对无酶葡萄糖电化学传感器发展方向和趋势进行了展望.     

适配体电化学传感器检测汞离子进展

适配体是一小段经体外筛选得到的寡核苷酸序列。适配体中的胸腺嘧啶(T)碱基可与Hg~(2+)形成比双链DNA更加稳定的T-Hg~(2+)-T结构。利用该性质结合电化学测量方法可制作检测Hg~(2+)的特异性强、灵敏度高的适配体电化学传感器,并建立微量Hg~(2+)的检测方法。该文对近年来发展的检测Hg~(2+)的适配体电化学传感器进行了综述和总结,对文献报道的几类传感器的构建过程和检测机理进行了详述,对检测方法的优缺点进行了分析。最后,对此类传感器今后的发展方向提出了展望,引用文献83篇。     

基于磁性分子印迹聚合物的电化学传感器的研究进展

分子印迹聚合物与磁性纳米材料结合,制备成磁性分子印迹纳米敏感膜,这样做不仅可以发挥分子印迹聚合材料的优势,而且磁性纳米粒子可有效提高电化学传感器的灵敏度、稳定性以及生物相容性等。近年来将磁性分子印迹纳米敏感膜应用于电化学传感器制备成的磁性分子印迹电化学传感器得到了较快的发展。本文就近5年来磁性分子印迹电化学传感器敏感膜所用的磁性材料、敏感膜制备方法以及磁性分子印迹电化学传感器在环境、食品以及临床方面的应用进行了综述总结。     

Synthesis of Ferrosoferric Oxide‐graphene Oxide Nanocomposite by Isoelectric Point Method for the Detection of Catechol

Ferrosoferric oxide functionalized graphene oxide nanocomposite with layer by layer structure was synthesized by isoelectric point method in this work. The prepared material was characterized by Fourier transform infrared spectroscopy, X‐ray diffraction, scanning electron microscopy, transmission electron microscopy and Raman spectroscopy. Then the material was used to modify a glassy carbon electrode to fabricate an electrochemical sensor for the detection of catechol. The electrochemical sensor exhibited excellent electrochemical performance towards the detection of catechol with a linear response in the range of 5–205 μM and a detection limit of 2.32 μM. Furthermore, the electrochemical sensor showed excellent selectivity, stability and repeatability. These results revealed ferrosoferric oxide functionalized graphene oxide nanocomposite has potential applications in the fabrication of electrochemical sensors.     

纳米氧化铜修饰的苯巴比妥分子印迹传感器的制备及其电化学性能

为了改善分子印迹传感器的灵敏度,在四丁基高氯酸铵的支持电解质溶液中,以甲基丙烯酸为功能单体,马来松香丙烯酸乙二醇酯为交联剂在纳米氧化铜修饰过的玻碳电极上电聚合了一种苯巴比妥(PB)识别性能的分子印迹传感膜.采用循环伏安(CV)法、差分脉冲伏安(DPV)法及交流阻抗(EIS)法对这种纳米氧化铜修饰过的印迹及非印迹电极的电化学性能进行了研究,结果显示纳米氧化铜修饰过的印迹及非印迹电极的电化学性能完全不同.X射线衍射(XRD)证实纳米粒子为氧化铜.采用扫描电镜(SEM)对纳米氧化铜修饰过的印迹传感器的形貌进行分析,发现纳米氧化铜分散在电极表面,改善了修饰印迹传感器的识别点.差分脉冲伏安法(DPV)表明苯巴比妥的浓度在1.0×10-8-1.8×10-4mol·L-1范围内呈现良好的线性关系(线性相关系数R=0.9994);检出限2.3×10-9mol·L-1(信噪比(S/N)=3).研究结果表明纳米氧化铜修饰过的印迹传感器具有较高灵敏度及选择性.此印迹传感器能用于实际样品中苯巴比妥的检测,加标回收率在95.0%-102.5%.     

Effect of molecular crowding on the response of an electrochemical DNA sensor

E-DNA sensors, the electrochemical equivalent of molecular beacons, appear to be a promising means of detecting oligonucleotides. E-DNA sensors are comprised of a redox-modified (here, methylene blue or ferrocene) DNA stem-loop covalently attached to an interrogating electrode. Because E-DNA signaling arises due to binding-induced changes in the conformation of the stem-loop probe, it is likely sensitive to the nature of the molecular packing on the electrode surface. Here we detail the effects of probe density, target length, and other aspects of molecular crowding on the signaling properties, specificity, and response time of a model E-DNA sensor. We find that the highest signal suppression is obtained at the highest probe densities investigated, and that greater suppression is observed with longer and bulkier targets. In contrast, sensor equilibration time slows monotonically with increasing probe density, and the specificity of hybridization is not significantly affected. In addition to providing insight into the optimization of electrochemical DNA sensors, these results suggest that E-DNA signaling arises due to hybridization-linked changes in the rate, and thus efficiency, with which the redox moiety collides with the electrode and transfers electrons.     

Comparison of the signaling and stability of electrochemical DNA sensors fabricated from 6- or 11-carbon self-assembled monolayers

We have characterized the solution-phase and dry storage stability of electrochemical E-DNA sensors fabricated using mixed self-assembled monolayers (SAMs) composed of 6- or 11-carbon (C6 and C11, respectively) alpha,omega-thiol alcohols and the analogous C6- or C11-thiol-terminated stem-loop DNA probe. We find that the solution-phase and dry storage stability of C6-based E-DNA sensors are limited and poorly reproducible. The use of stabilizing agents bovine serum albumin plus either glucose or trehalose significantly improves the dry storage shelf life of such sensors: when using these preservatives, we observe only 7-9% sensor degradation after 1 month of storage in air at room temperature. In comparison, the stability of C11-based E-DNA sensors is significantly greater than that of the C6-based sensors; we observe only minor (5-8%) loss of signal upon storing these sensors for a week under ambient solution conditions or for more than a month in air in the presence of preservatives. Moreover, whereas the electron-transfer rate through C11 SAMs is slower than that observed for C6 SAMs, it is rapid enough to support good sensor performance. It thus appears that C11 SAMs provide a reasonable compromise between electron-transfer efficiency and sensor stability and are well suited for use in electronic DNA-sensing applications.     

Nanomolar Detection of Glutamate at a Biosensor Based on Screen-Printed Electrodes Modified with Carbon Nanotubes

The amperometric glutamate biosensor based on screen-printed electrodes containing carbon nanotubes (CNT), and its integration in a flow injection analysis system, is described herein. The sensor was fabricated by simply adsorbing enzyme glutamate oxidase (GlutOx) on a commercial substrate containing multi-wall CNT. The resulting device displayed excellent electroanalytical properties toward the determination of L-glutamate in a wide linear range (0.01-10 μM) with low detection limit (10 nM, S/N≥3), fast response time (≤5 s), and good operational and long-term stability. The CNT modified screen-printed electrodes have a potential to be of general interest for designing of electrochemical sensors and biosensors.     

以马来松香丙烯酸乙二醇酯为交联剂的咖啡因分子印迹电化学传感器

以咖啡因为模板分子, 含菲环骨架的马来松香丙烯酸乙二醇酯为交联剂, 甲基丙烯酸为功能单体, 在玻碳电极表面以自由基热聚合的方式制备分子印迹聚合物敏感膜, 构建了测定咖啡因的新型分子印迹膜电化学传感器. 通过循环伏安法、 差分脉冲伏安法及电化学交流阻抗法研究了传感器对咖啡因的响应特性. 结果表明, 在最佳的实验条件下, 传感器的峰电流与咖啡因浓度在3.00×10^-3~2.73 mmol/L范围内呈现良好的线性关系, 检出限(S/N=3)为1.12×10^-4 mmol/L. 传感器具有良好的选择性和重现性. 将该传感器用于可口可乐饮料中咖啡因含量的测定, 平均回收率为98.7%.     

脉冲电势调制型电化学气体传感器

根据暂态电化学原理 ,使用微电极并融合计算机控制的快速电势调制技术和数据采集、处理功能 ,提出并建立了一类全新的集信号提取、处理与结果显示等功能于一体的“脉冲电势调制型气体传感器” .在优化传感器性能及其新的功能开发和集成方面取得了重要进展 ,是一类为常规电化学气体传感器无法比拟而有发展前景的暂态电化学多组份气体传感器 .     

分子印迹-电化学发光技术研究进展

分子印迹-电化学发光技术具有分子印迹技术的高选择性及电化学发光技术的高灵敏性,以及发光易于调控、稳定性好、便于微型化和仪器操作简单等优点,已被广泛地应用于重金属检测、免疫传感技术、基因传感技术、酶传感技术、食品安全与药物分析等领域。该文结合本实验室的研究工作介绍了分子印迹电化学发光传感器的原理和构建思路。在此基础上,着重介绍了分子印迹电化学发光技术在食品安全与药物分析中的应用,并对其今后的研究趋势进行了展望。     

Synthesis and characterization of high-integrity solid-contact polymeric ion sensors

High-integrity solid-contact (SC) polymeric ion sensors have been produced by using spin casting and electropolymerization techniques in the preparation of the SC employing the conductive polymer, poly(3-octylthiophene) (POT). The physical and chemical integrity of the POT SCs have been evaluated using scanning electron microscopy (SEM), atomic force microscopy (AFM), secondary ion mass spectrometry (SIMS), and X-ray photoelectron spectroscopy (XPS). Furthermore, the electrochemical stability of SC polymeric ion sensors has been investigated using electrochemical impedance spectroscopy (EIS). The results of this study demonstrate that electropolymerization and spin casting methods also comprising annealing of the synthesized SC film are capable of producing SCs that are relatively free of imperfections such as pores and pinholes. This leads to electrochemically stable and robust polymeric ion sensors where the SC/sensor interface is resistant to the formation of a detrimental water layer that normally gives rise to spurious ion fluxes and a degradation in the sensitivity and selectivity of the SC polymeric ion sensor.     

一种利用离子交换膜研制的电化学氧传感器

利用聚苯乙烯阴离子交换膜研制的金为催化剂，采用碱性体系的新型控制电位电解型氧传感克服了以往电化学氧传感器的缺点，具有响应时间快、稳定性好、噪声低、本底电流小、温度系数低等优点。     

纳米氧化铜修饰的苯巴比妥分子印迹传感器的制备及其电化学性能

为了改善分子印迹传感器的灵敏度, 在四丁基高氯酸铵的支持电解质溶液中, 以甲基丙烯酸为功能单体, 马来松香丙烯酸乙二醇酯为交联剂在纳米氧化铜修饰过的玻碳电极上电聚合了一种苯巴比妥(PB)识别性能的分子印迹传感膜. 采用循环伏安(CV)法、差分脉冲伏安(DPV)法及交流阻抗(EIS)法对这种纳米氧化铜修饰过的印迹及非印迹电极的电化学性能进行了研究, 结果显示纳米氧化铜修饰过的印迹及非印迹电极的电化学性能完全不同. X射线衍射(XRD)证实纳米粒子为氧化铜. 采用扫描电镜(SEM)对纳米氧化铜修饰过的印迹传感器的形貌进行分析, 发现纳米氧化铜分散在电极表面, 改善了修饰印迹传感器的识别点. 差分脉冲伏安法(DPV)表明苯巴比妥的浓度在1.0×10^-8-1.8×10^-4 mol·L^-1 范围内呈现良好的线性关系(线性相关系数R=0.9994); 检出限2.3×10^-9 mol·L^-1 (信噪比(S/N)=3). 研究结果表明纳米氧化铜修饰过的印迹传感器具有较高灵敏度及选择性. 此印迹传感器能用于实际样品中苯巴比妥的检测, 加标回收率在95.0%-102.5%.     

Electrochemical sensing of gases based on liquid collection interfaces

Although many electrochemical gas sensors have been reported, electrochemical gas sensors based on liquid collection constitute a smaller subset. Minimally, a liquid interface based electrochemical gas sensor is composed of two electrodes and an ion conducting electrolyte. There is a large number of possible arrangements of these parts, and many choices exist for their composition and preparation methods. This results in a diverse and rich technology now available for gas sensing. The measurement of some analyte gases of interest, notably ozone, nitrogen oxides, hydrogen peroxide, formaldehyde, ammonia, sulfur dioxide and hydrogen sulfide are specifically discussed. Finally, the recent reviews that are likely to be the most relevant to the further development of electrochemical detection approaches for gases with a liquid collection interface are cited and discussed.