Needle-tip effect promoted flexible electrochemical sensor for detecting chloride ions in food by in-situ deposited silver dendrimers

Salt plays a crucial role in food processing and consumption,and the rapid detection of chloride ions in food and feed has great significance for practical applications.In this work,Ag-based nanomaterials were deposited on the surface of a flexible integrated electrochemical sensor for the detection of Cl-in food.In order to enhance the detection performance,a unique needle-tip structure was formed by manipulating the electro-engraving process during the electrodeposition growth.Theoretical calculations and electrochemical investigations have demonstrated that the dendrimer’s rich tip structure significantly enhanced its electrochemical performance.A sensitive and flexible integrated electrochemical sensor was creatively developed for the detection of Cl-using needletip effect-promoted Ag micro dendrimers.The sensor achieved quantitative detection of Cl-over a dynamic range of 10.0μM–100.0 mM,with a low limit of detection of 0.148μM.The flexible electrochemical sensor proposed in this work exhibited good repeatability,selectivity and recoveries in real food samples.

Porous Silicon as a Carrier of Sensing Materials in Sensors

Novel potassium ion selective electrodes (K^+ISEs) and cDNA array sensors based on porous silicon (PS) have been developed.The calibration curve for the K^+ISEs is linear within a wide range of pK=2.0～6.0 with the slope of 56 mV per decade,which is near Nernst response.The response time and detection limit are within 31 s and 0.5μmol/L,respectively.The selective coefficient for Na^+ is-3.8,satisfies the requirement for the assay of blood potassium.The response variation is within 2 mV during 2 months.The binding capacity,the dynamic range and the detection limit of the DNA sensors were improved by replacing glass slide with PS substrates.The cDNA array sensors can bear 80℃of high temperature,75% of humidity,3.6 kLx of irradiation and keep stable within 10 days when they are exposed in air.Good performances of the K^+ISE and the cDNA array sensor are attributed to the large internal surface area and the easily modified microstructure of PS.

Electrochemical Investigation of P-Tert-Butylcalix[6]Arene Modified Gold Electrode for Ionic Detection

The aim of this work was to study the electrochemical behavior of gold electrode which was modified with p-tert-butylcalix[6]arene membrane and this in the presence of different nickel ions based concentrations in order to form a nickel electrochemical sensor. For that, impedance-spec- troscopy characteristics have been investigated. The obtained results were then modeled by appropriate equivalent circuit aiming at elucidating the electrical properties of the modified gold transducer. A correlation between the present impedimetric results and previous potentiometric ones was achieved traducing then a fast ionic transfer.

Noninvasive Label-Free Detection of Cortisol and Lactate Using Graphene Embedded Screen-Printed Electrode

A sensitive and specific immunosensor for the detection of the hormones cortisol and lactate in human or animal biological fluids, such as sweat and saliva, was devised using the label-free electrochemical chronoamperometric technique. By using these fluids instead of blood,the biosensor becomes noninvasive and is less stressful to the end user, who may be a small child or a farm animal.Electroreduced graphene oxide(e-RGO) was used as a synergistic platform for signal amplification and template for bioconjugation for the sensing mechanism on a screenprinted electrode. The cortisol and lactate antibodies were bioconjugated to the e-RGO using covalent carbodiimide chemistry. Label-free electrochemical chronoamperometric detection was used to analyze the response to the desired biomolecules over the wide detection range. A detection limit of 0.1 ng mL^(-1) for cortisol and 0.1 mM for lactate was established and a correlation between concentration and current was observed. A portable, handheld potentiostat assembled with Bluetooth communication and battery operation enables the developed system for point-of-care applications. A sandwich-like structure containing the sensing mechanisms as a prototype was designed to secure the biosensor to skin and use capillary action to draw sweat or other fluids toward the sensing mechanism. Overall, the immunosensor shows remarkable specificity, sensitivity as well as the noninvasive and point-of-care capabilities and allows the biosensor to be used as a versatile sensing platform in both developed and developing countries.

Chemically modified carbon-based electrodes for the determination of paracetamol in drugs and biological samples

Paracetamol is a non-steroidal, anti-inflammatory drug widely used in pharmaceutical applications for its sturdy, antipyretic and analgesic action. However, an overdose of paracetamol can cause fulminant hepatic necrosis and other toxic effects. Thus, the development of advantageous analytical tools to detect and determine paracetamol is required. Due to simplicity, higher sensitivity and selectivity as well as costefficiency, electrochemical sensors were fully investigated in last decades. This review describes the advancements made in the development of electrochemical sensors for the paracetamol detection and quantification in pharmaceutical and biological samples. The progress made in electrochemical sensors for the selective detection of paracetamol in the last 10 years was examined, with a special focus on highly innovative features introduced by nanotechnology. As the literature is rather extensive, we tried to simplify this work by summarizing and grouping electrochemical sensors according to the by which manner their substrates were chemically modified and the analytical performances obtained.

基于纳米银/聚L-谷氨酸修饰玻碳电极的电化学传感器用于泡菜中亚硝酸钠含量的测定

采用电沉积和电聚合的方式,将纳米银和L-谷氨酸修饰在玻碳电极上,制得纳米银/聚L-谷氨酸修饰玻碳电极(Poly-L-Glu/Nano-Ag/GCE)。以0.2 mol·L^(-1)磷酸盐缓冲溶液(pH 7.0)为支持电解质,以Poly-L-Glu/Nano-Ag/GCE为工作电极,饱和甘汞电极为参比电极,铂电极为辅助电极,在最佳检测条件下,采用循环伏安法进行测定。结果表明:Poly-L-Glu/Nano-Ag/GCE对亚硝酸钠具有较好的选择性,亚硝酸钠的浓度在4.14×10^(-6)~1.35×10^(-3) mol·L^(-1)内与对应的氧化峰电流的绝对值呈线性关系,检出限(3s/k)为4.14×10^(-7) mol·L^(-1),并且该电极的制备方法具有较好的重复性。将PolyL-Glu/Nano-Ag/GCE用于泡菜样品中亚硝酸钠的测定,检出量为1.33×10^(-5) mol·L^(-1),加标回收率为98.9%~103%。

基于MPSO-BP算法的四电极电化学气体传感器温度补偿研究

针对四电极电化学气体传感器的测量精度极易受环境温度影响的问题,提出一种基于粒子群优化BP神经网络算法(PSO-BP)的温度补偿方法。利用改进的PSO算法(MPSO)对BP神经网络的权值和阈值进行优化,构造四电极电化学气体传感器的温度补偿模型,并设计了气体传感器测试系统。实验结果表明,MPSO-BP算法可有效提高BP神经网络的收敛速度和泛化能力;基于MPSO-BP算法的四电极气体传感器温度补偿模型,可将温度补偿误差控制在0.1%以内。

基于柔性电极和信号放大技术构建检测磷脂酶C的电化学传感器

磷脂酶C(PLC)是动植物中重要的脂质水解酶,在哺乳动物细胞的代谢、生长、炎症、分化、衰老和凋亡中起着重要作用,与许多癌症的发生、发展显著相关。蛋白质催化原子转移自由基聚合(PATRP)是高分子设计、制备的有效手段,可通过链式反应将数百个电活性单体连接成一个高相对分子质量的聚合物链,从而使分子识别信号大大增强。首先,在柔性碳布(CC)电极表面修饰纳米金(AuNPs),之后通过3-巯基丙酸、碳二亚胺盐酸盐和N-羟基丁二酰亚胺,将PLC的特异性底物磷脂酰乙醇胺(PE)固定在电极上,经过PLC对PE的特异性水解产生磷酸基团,引入Zr^(4+),通过Zr^(4+)的配位作用将聚合引发剂α-溴苯乙酸修饰到电极表面,最后在蛋白质催化作用下进行2,2,6,6-四甲基哌啶氧化物(TEMPO)的PATRP聚合反应,在电极表面引入电活性聚合物分子链,构建信号放大型电化学传感器P(TEMPO)/PE/AuNPs/CC,用于磷脂酶C的高灵敏度检测。结果表明,该传感器检测PLC的线性范围为10~1×10^(5)mU/L,检出限为3.568 mU/L(S/N=3)。与其他检测PLC的方法相比,该传感器具有较宽的检测范围和较低的检出限,且在检测实际乳腺癌细胞中的PLC方面有巨大的实际应用潜力。

基于可植入电极的活体脑化学电分析研究进展

基于可植入电极的活体电化学传感研究一直是推动脑神经化学领域分析方法发展的重要助力。脑内结构的复杂性和各项生理活动的实时性对分析方法提出了严苛的要求。分析测量方法的高特异性、高灵敏度、较强的抗干扰能力以及良好的生物相容性是活体原位分析的前提。随着新功能材料的研发和电化学研究方法的进步,可植入电极的活体电化学研究得到了一定的发展,但该领域仍然存在着一系列的挑战。本文综述了目前可植入电极,如酶修饰电极、核酸适配体修饰电极、离子选择性电极、基于液-液界面的电极、离子电流整流类电极在活体电化学传感领域中的应用以及其兼容性、响应性等关键性能研究的主要进展,以期为未来的复杂脑内环境下的精准检测研究提供有益借鉴。

纳米材料在电化学检测亚硝酸盐的应用研究进展

亚硝酸盐作为一种常见的食品添加剂,能够稳定肉制品的色泽、提高风味、延长货架期。然而,亚硝酸盐同时又是一种有毒的污染物,长期过量摄入将会严重危害人体健康,因此,实现对其高灵敏度、高选择性的快速检测具有十分重要的意义。相较于其他传统检测方法,电化学检测法具有操作简单、选择性好、灵敏度高的优势。而电极材料作为电化学传感器的核心组成,其功能和界面性能都将影响到传感器的综合性能。文章详细介绍了碳、金属、金属氧化物、导电聚合物等纳米复合材料在亚硝酸盐电化学检测中的研究进展,重点详述了构建方法和检测结果,最后对亚硝酸盐传感器的未来发展趋势进行了讨论。

构建5-氟尿嘧啶电化学传感器电极材料的研究进展

电化学检测方法具有准确度高、成本低、操作简单易行的特点,广泛应用于各种药物含量的分析测定。5-氟尿嘧啶在肿瘤的治疗中起着重要作用,但药物过量会引起许多显著的不良反应,因此,5-氟尿嘧啶的含量测定是很有必要的。本文结合国内外文献对5-氟尿嘧啶的报道,综述了近几年电化学检测5-氟尿嘧啶的电极修饰材料、检测方法及其检测结果,认为运用生物提取物作为修饰材料是5-氟尿嘧啶电化学传感器的重要研究方向。

基于氮掺杂介孔碳修饰玻碳微球糊电极的双酚A电化学传感器的构建及性能研究

制备了一种由氮掺杂介孔碳修饰的玻碳微球糊电极,用于双酚A的灵敏、快速检测。利用循环伏安法对修饰电极进行了表征,采用方波伏安法研究了双酚A在修饰电极上的电化学行为;根据不同扫速下峰电流与扫速的关系讨论了双酚A在电极表面的反应过程。在最优的实验条件下,双酚A的响应电流与浓度在0.3~2μM和2~30μM范围内时呈线性关系,检测限是0.01μM(S/N=3)。该方法具有良好的重现性和抗干扰性,可用于实际样品的检测,样品回收率为97.5%~101.5%。

Recent advances in electrochemical sensors for antibiotics and their applications

The abuse of antibiotics will cause an increase of drug-resistant strains and environmental pollution,which in turn will affect human health.Therefore,it is important to develop effective detection techniques to determine the level of antibiotics contamination in various fields.Compared with traditional detection methods,electrochemical sensors have received extensive attention due to their advantages such as high sensitivity,low detection limit,and good selectivity.In this mini review,we summarized the latest developments and new trends in electrochemical sensors for antibiotics.Here,modification methods and materials of electrode are discussed.We also pay more attention to the practical applications of antibiotics electrochemical sensors in different fields.In addition,the existing problems and the future challenges ahead have been proposed.We hope that this review can provide new ideas for the development of electrochemical sensors for antibiotics in the future.

基于电极修饰材料的重金属离子电化学传感器

在传统检测重金属的基础上,电化分析法在检测重金属领域有着不可比拟的发展前景。将电化学传感器与电化学分析技术有机地结合起来,可以为高效地检测重金属离子提供一种新的方法。在电化学传感器中,电极的修饰一直是人们关注的焦点。本文着重从金属及金属氧化物纳米材料、碳纳米材料和高分子聚合物材料修饰电极对重金属离子的电化学传感器研究进展。通过一些具有代表性的实例,讨论了这些电极的设计和传感机理。最后,对其未来的研究方向进行了总结和展望。

羧基化纳米多孔碳电化学适配体传感器的构建及其在维生素C检测中的应用

目的建立一种简单、灵敏度高、选择性好的电化学适配体传感器用于维生素C(vitamin C,VC)的快速检测。方法将羧基化纳米多孔碳材料(carboxylated nanoporous carbon powder,NCP-COOH)修饰在丝网印刷电极(screen printed electrode,SPCE)表面,为结合氨基修饰的适配体提供大量的活性位点,构建新型适配体传感器。当VC存在时,传感器表面的适配体与VC特异性结合导致差分脉冲伏安(differential pulse voltammetry,DPV)响应信号下降,根据信号的变化实现对VC的定量检测。采用循环伏安法和交流阻抗法对传感器的构建过程及电化学性能进行考察,并通过对NCP-COOH材料浓度、适配体浓度、缓冲液pH、孵育时间等条件的优化,确定传感器对VC的最佳检测条件。结果NCP-COOH具有大的比表面积,良好的导电性和生物相容性,能显著提高传感器的电化学性能。在最佳的实验条件下,传感器在0.1~1000.0μg/L范围内对VC有良好的响应,检出限为0.01μg/L,用于实际样品的测定时回收率为92.5%~100.5%,测定结果与GB5009.86—2016《食品安全国家标准食品中抗坏血酸的测定》相符。结论该方法方便快捷、灵敏度高、选择性好,能够应用于蔬菜样品中VC的准确测定,为农产品中VC的快速检测提供了一种新方法。

纸基电极制备方法的研究进展

在过去的十年中,基于纸张的传感器受到了越来越多的关注,已被广泛应用于食品及药物分析、环境监控、临床病理诊断等多个领域。纸张因其用途广泛、低成本、重量轻、环境友好性、可回收性和可弯曲性等优点,是一种很有前途的电极材料。目前开发基于纸张的高性能、低检测限,快速响应的电极制备方面已进行了广泛的研究。因此,本文结合本实验室相关研究内容重点介绍近年来一些常见的纸基电极的制备方法并简述其优缺点。

Coulometric Response of H-Selective Solid-Contact Ion-Selective Electrodes and Its Application in Flexible Sensors+

The analytical performance of H+-selective solid-contact ion-selective electrodes(SCISEs)based on solid contact polyaniline doped with chloride(PANI(Cl))and poly(3,4-ethylenedioxythiophene)doped with poly(styrene sulfonate)(PEDOT(PSS))was characterized by a developed coulometric signal transduction method.PEDOT(PSS)solid contact is covered by PVC based H+-selective membrane.The obtained coulometric signal demonstrates that the cumulated charge can be amplified by increasing the capacitance of solid contact.SCISEs covered with spin-coated membrane behave faster amperometric response than electrodes with drop-cast mem-brane.In contrast to earlier works,the amperometric response and impedance spectrum demonstrates H+transfer through SCISEs is independent from the thickness of membrane.The exceptional behavior of PANI(Cl)H+-SCISEs shows that the capacitance estimated from impedance spectrum at low frequency 10 mHz and coulometric signal of PANI(Cl)based SCISEs is influenced by the applied po-tentials,whereas PEDOT(PSS)solid contact is independent from the chosen applied potentials.Furthermore,preliminary investiga-tions of coulometric signal transduction on flexible pH sensor implies its potential applications in wearable sensors for sweat ion concentration detection.

海水重金属电化学传感器检测系统

研制了一种新型的海水重金属电化学传感器流动分析系统。通过在线过滤、紫外线消解、电化学富集以及离子选择性电极电位测定等过程,实现对海水重金属的高灵敏、高选择性的快速检测。在海水基体条件下,对于镉、铅和铜的测定线性范围分别为1.0×10-9～1.0×10-7 mol/L,3.0×10-9～1.0×10-7 mol/L和1.0×10-9～1.0×10-7 mol/L,相应检出限为2.8×10-10,6.6×10-10和5.1×10-10 mol/L,连续6次测定的RSD均小于5%,全程分析在25min内完成。应用于实际海水样品分析,其测定结果与溶出伏安法一致。此传感器性能可靠、成本低廉,在海水重金属现场快速监测方面具有良好的应用前景。

三电极电化学传感器的恒电位仪设计

三电极电化学传感器在化学、生物和环境监测等领域的应用越来越广泛,为了充分发挥其性能,并实现测量仪器的便携性,选用AT89S8252单片机和A/D、D/A转换器等IC芯片,设计了一种用于传感器电流信号检测的便携式恒电位仪。该恒电位仪通过电压负反馈调节系统使电化学传感器的工作电压等于基准电压,并保持恒定。为检测仪器的性能,用一个电路模型等效三电极电化学传感器进行了测试,实验结果表明该恒电位仪具有很好的精度。

水杨酸分子印迹膜电化学传感器的制备

以水杨酸为模板分子,采用循环伏安法电聚合形成聚吡咯膜,以固定电位过氧化法去除印迹分子,制备了水杨酸分子印迹膜电极。本印迹电极能促进水杨酸电氧化过程,有效地避免结构类似物(如苯甲酸)对其测定的干扰。循环伏安法用于电化学检测,当富集时间为10min,磷酸盐缓冲溶液的pH=6.86时,在1.0×10-6～2.0×10-3mol/L浓度范围内,水杨酸氧化峰电流与其浓度呈良好的线性关系,检出限为0.8μmol/L,用分子印迹膜电极对加标样品进行分析,回收率为94.6%～103.4%。