8-羟基脱氧鸟苷在壳聚糖/石墨烯修饰电极上的电化学及DNA氧化损伤检测

采用循环伏安(CV)、线性扫描伏安(LSV)和示差脉冲伏安(DPV)等方法研究了8-羟基脱氧鸟苷(8-OHdG)在壳聚糖(Chi)/石墨烯(GR)修饰的玻碳电极(GCE)上的电化学行为,8-OHdG在该修饰电极上氧化峰电流与其浓度在3.5×10-7~1.4×10-4mol/L范围内呈良好的线性关系,检测限为6.4×10-8mol/L(S/N=3)。将Chi/GR/GCE用于检测DNA氧化损伤,8-OHdG在修饰电极上的氧化峰电流与损伤的DNA质量浓度在10~300 mg/L范围内呈良好的线性关系,损伤DNA检出限为0.026 mg/L(S/N=3)。     

石墨烯修饰的三唑磷分子印迹电化学传感器的制备

采用石墨烯作为电极增敏材料,制备三唑磷(TAP)分子印迹电化学传感器。采用自由基聚合法,在石墨烯修饰电极(GR/GCE)上合成分子印迹聚合物膜(MIP)。利用微分脉冲伏安法、电化学阻抗谱对不同修饰电极进行电化学表征,利用微分脉冲伏安法考察了MIP和非分子印迹聚合物膜(NIP)传感器的电化学性能。在最优实验条件下,TAP浓度在1.0×10~(-7)～2.0×10~(-5)mol·L~(-1)内和MIP膜传感器峰电流呈线性关系,检出限为4.3×10~(-8)mol·L~(-1)(S/N=3)。建立MIP膜传感器的动力学吸附模型,测得结合速率常数k为9.0580 s。     

石墨烯/聚硫堇膜修饰玻碳电极上沙丁胺醇的电化学行为研究

采用循环伏安法和差分脉冲伏安法研究了沙丁胺醇在石墨烯/聚硫堇修饰玻碳电极上的电化学行为,该电化学传感器对沙丁胺醇显示出良好的电化学响应。在pH 7.0,扫描范围为-0.6~0.4 V,扫速为80 mV/s条件下,沙丁胺醇的氧化峰电流与其浓度在3.1×10-7~8.5×10-5mol/L范围内呈良好线性关系,检出限达9.6×10-8mol/L。结果显示石墨烯/聚硫堇修饰玻碳电极具有良好的重现性和稳定性。     

基于钯/壳聚糖/氧化还原石墨烯修饰电极的制备 及对利发霉素的检测

制备了钯(Pd)/壳聚糖-还原氧化石墨烯(CS-RGO)修饰电极。采用循环伏安法研究了利发霉素在该修饰电极上的电化学行为,并利用示差脉冲伏安法对其进行测定。在0.1 mol·L~(-1)的磷酸盐缓冲溶液(PBS,pH=7.0)中,利发霉素的氧化峰电流大小与其浓度在1.0×10~(-7)～1.0×10~(-3) mol·L~(-1)浓度范围内成良好的一次线性关系,检出限为7.4×10~(-9) mol·L~(-1)(S/N=3)。此外,该修饰电极具有很好的稳定性和抗干扰能力。     

电还原氧化石墨烯/多壁碳纳米管复合修饰电极检测萘普生

将氧化石墨烯/多壁碳纳米管复合材料滴涂于玻碳电极表面,并运用恒电位还原法对氧化石墨烯进行直接电化学还原,制备了电还原氧化石墨烯/多壁碳纳米管复合修饰电极(rGO/MWCNTs-GCE),利用X-射线衍射(XRD)、扫描电镜(SEM)、拉曼光谱等对其进行初步表征。采用循环伏安法(CV)和差分脉冲伏安法(DPV)研究了萘普生在该复合修饰电极上的电化学响应,并对检测条件进行考察。结果表明,萘普生的浓度为2.0×10~(-4)～5.0×10~(-6) mol·L~(-1)间,氧化峰电流与其浓度成线性相关,检出限达到2.0×10~(-6) mol·L~(-1)。该复合修饰电极稳定性强、重现性好,可用于萘普生的快速检测。     

石墨烯修饰电极电化学发光分析法测定甲巯咪唑

基于碱性介质中鲁米诺在石墨烯修饰玻碳电极(GCE)表面的弱电化学发光信号可被少量甲巯咪唑显著增敏的原理建立了一种灵敏测定甲巯咪唑的电化学发光新方法。实验考察了反应介质、石墨烯用量、鲁米诺浓度及电化学扫描速率对体系电化学发光信号的影响。结果发现:在8. 0μL的石墨烯用量、0. 01 mol·L~(-1)NaOH、0. 7μmol·L~(-1)鲁米诺及100 mV/s的扫描速率的优化条件下,甲巯咪唑浓度在6. 0×10~(-8)～1. 0×10~(-5)mol·L~(-1)范围内与其增敏的电化学发光强度呈良好的线性关系,检出限为2. 0×10~(-8)mol·L~(-1),其相对标准偏差(RSD)为3. 5%(c=0. 5μmol·L~(-1),n=11)。该方法可用于甲巯咪唑含量的临床测定,结果较为满意。     

水分散性石墨烯的制备及其电化学传感器在测定福莫特罗酒石酸盐中的应用

在碱性条件下用NaBH4还原氧化石墨烯(GO),成功制备水分散性良好的石墨烯。用制备的石墨烯修饰玻碳电极,并通过循环伏安法(CV)和差分脉冲伏安法(DPV)研究了福莫特罗酒石酸盐在该修饰电极上的电化学行为。优化DPV条件下,福莫特罗酒石酸盐的氧化峰电流与浓度在3.64×10-7~1.64×10-4 mol·L-1范围内呈线性关系(r=0.9978),检出限为7.89×10-8 mol·L-1。电化学测试结果表明,石墨烯修饰玻碳电极具有响应时间快、重现性和稳定性好的特点,可用于福莫特罗酒石酸盐的检测。     

长春地辛在硫化铜纳米花/石墨烯修饰玻碳电极上的电化学行为

通过改进的Hummers法和溶剂热法分别制备了石墨烯和硫化铜纳米花。采用滴涂法进一步依次将石墨烯和硫化铜纳米花修饰于玻碳电极,制备了硫化铜纳米花/石墨烯修饰玻碳电极(Nanoflower CuS/GR/GCE)。利用循环伏安法和差分脉冲伏安法等研究了长春地辛在该修饰电极的电化学行为。结果表明:长春地辛的浓度在1.0×10~(-8)~1.0×10~(-7) mol·L~(-1),1.0×10~(-7)~1.1×10~(-5) mol·L~(-1)及1.1×10~(-5)~1.0×10-4 mol·L~(-1)内与其对应的峰电流的减小量呈线性关系,检出限(3S/N)为4.9×10~(-9 )mol·L~(-1)。对1.0×10~(-6) mol·L~(-1)长春地辛标准溶液连续测定5次,测定值的相对标准偏差为1.2%。方法用于长春地辛药品样品的分析,加标回收率在97.1%~103%之间。     

百草枯在氧化石墨烯修饰玻碳电极上的电化学行为及其差分脉冲伏安测定

将氧化石墨烯悬浮液(1g·L~(-1))10μL滴涂于玻碳电极表面,烘干后,在0.10mol·L~(-1)的KH_2PO_4溶液中于-0.9V还原600s制备了氧化石墨烯修饰玻碳电极,用扫描电子显微镜、透射电子显微镜和电化学方法对修饰电极进行了表征。用差分脉冲伏安法研究了百草枯在氧化石墨烯修饰电极上的电化学行为,发现此修饰电极对百草枯的还原有明显的电催化作用。百草枯在pH 7.5的磷酸盐缓冲溶液中,在氧化石墨烯修饰电极上产生催化还原反应,在差分脉冲伏安曲线上先后在-0.6,-0.1V处出现2个还原峰。因后者与底液的还原峰重叠,故测定中采用-0.6V处的还原峰电流为测量值。经试验,百草枯在修饰电极上的富集电位为-0.6V,富集时间为200s,选用的扫描速率为50 mV·s~(-1)。在最佳试验条件下百草枯浓度在9.00×10~(-7)～1.00×10~(-5) mol·L~(-1)和1.00×10~(-5)～5.00×10~(-5) mol·L~(-1)内与其在-0.6V处的还原峰电流呈线性关系,检出限(3s/k)为1.64×10~(-7) mol·L~(-1)。方法应用于农药中百草枯含量的测定,测定值与标示值相符,对土壤样品进行加标回收试验,回收率在89.5%～114%之间。     

氧化石墨烯修饰碳糊电极的方波溶出伏安法测定锌

实验采用改进的Hummers法合成氧化石墨烯并将其修饰在碳糊电极(CPE)的表面制备了氧化石墨烯修饰碳糊电极(GO/CPE),以该修饰电极为工作电极,采用方波溶出伏安法对锌离子进行测定。结果表明:在十二烷基苯磺酸钠的增敏作用下,在0.1mol·L~(-1)KCl溶液中,该修饰电极对锌的氧化溶出有良好的催化作用,溶出峰电流与Zn~(2+)的浓度在4.0×10-8mol·L~(-1)~2.0×10-7mol·L~(-1)呈良好的线性关系,检出限为1.8×10~(-10)mol·L~(-1).该修饰电极用于实际样品中锌的含量分析,结果令人满意。     

Progress in electrochemistry of hybrid diamond/sp2-C nanostructures

Hybrid diamond/sp²-C nanostructures have aroused growing interests in electrochemistry currently owing to the good chemical/physical properties, including high electrical conductivity, mechanical robustness, and high specific surface area, as well as the unique electrochemical properties, namely, an enhanced electrochemical activity while retaining a wide potential window and low background currents when properly engineering the microstructure. This mini-review presents the recent electrochemistry process of diamond/sp²-C nanostructures. In particular, the synthetic methods, microstructures, and possible growth mechanism of diamond/sp²-C nanostructures are briefly summarized. Then, the electrochemical property tailoring is addressed in detail, and subsequently, their potential applications in electrochemistry including electrochemical sensors, supercapacitors, electrocatalysis, and other applications are discussed. The future perspectives of diamond/sp²-C nanostructures in electrochemistry finally conclude this review.     

Electrochemical sensitive determination of acetaminophen in pharmaceutical formulations at iron oxide/graphene composite modified electrode

Acetaminophen (AC) is one of the most commonly prescribed analgesic and antipyretic drug, which is considered to be safe as well as effective. Rational use of AC does not pose any toxicity or adverse effects, however, an overdose or prolonged use could lead to nephrotoxicity and severe hepatoxicity. Thus, monitoring of AC is essential for drug safety. In this work, a facile Fe₂O₃/reduced graphene oxide (Fe₂O₃/RGO) nanocomposite was synthesized for improved electrochemical detection of AC. The material was synthesized through a simple one-step process. For characterization of synthesized Fe₂O₃/RGO composite, energy-dispersive X-ray spectroscopy (EDX), field emission-scanning electron microscopy (FE-SEM) and electrochemical impedance spectroscopy (EIS) were employed. To verify the electrochemical performance of Fe₂O₃/RGO nanocomposite, GCE was modified with this nanocomposite and utilized for quantification of AC. The detection limit of AC was 21 nM in a linear range from 1.0 × 10⁻⁷ to 74 × 10⁻⁶ M. Furthermore, the sensor also unveiled good stability, promising sensitivity and selectivity. Hence, Fe₂O₃/RGO could be applied as a sensing material for electrochemical detection of AC. Finally, the analytical utility of the method was also verified in human urine and drug samples with some preliminary treatments.     

Highly sensitive electrochemical impedance spectroscopic detection of DNA hybridization based on Aunano-CNT/PANnano films

A polyaniline nanofibers (PAN_nano)/carbon paste electrode (CPE) was prepared via dopping PAN_nano in the carbon paste. The nanogold (Au_nano) and carbon nanotubes (CNT) composite nanoparticles were bound on the surface of the PAN_nano/CPE. The immobilization and hybridization of the DNA probe on the Au_nano-CNT/PAN_nano films were investigated with differential pulse voltammetry (DPV) and cyclic voltammetry (CV) using methylene blue (MB) as indicator, and electrochemical impedance spectroscopy (EIS) using [Fe(CN)₆]^3−/4− as redox probe. The voltammetric peak currents of MB increased dramatically owing to the immobilization of the probe DNA on the Au_nano-CNT/PAN_nano films, and then decreased obviously owing to the hybridization of the DNA probe with the complementary single-stranded DNA (cDNA). The electron transfer resistance (R_et) of the electrode surface increased after the immobilization of the probe DNA on the Au_nano-CNT/PAN_nano films and rose further after the hybridization of the probe DNA. The remarkable difference between the R_et value at the DNA-immobilized electrode and that at the hybridized electrode could be used for the label-free EIS detection of the target DNA. The loading of the DNA probe on Au_nano-CNT/PAN_nano films was greatly enhanced and the sensitivity for the target DNA detection was markedly improved. The sequence-specific DNA of phosphinothricin acetyltransferase (PAT) gene and the polymerase chain reaction (PCR) amplification of nopaline synthase (NOS) gene from transgenically modified beans were determined with this label-free EIS DNA detection method. The dynamic range for detecting the PAT gene sequence was from 1.0 × 10⁻¹² mol/L to 1.0 × 10⁻⁶ mol/L with a detection limit of 5.6 × 10⁻¹³ mol/L.     

乙酰胆碱/胆碱电化学生物传感器研究进展

本文综述了近年来乙酰胆碱/胆碱电化学生物传感器的研究状况及其在分析化学中的应用进展。     

ELECTROCHEMICAL COPOLYMERIZATION OF ANILINE AND AZURE B*

The electrochemical copolymerization of aniline and N,N,N'-trimethylthionin (azure B) in aqueous solutions hasbeen carried out using the potential sweep method, The optimum conditions for the coelectrodeposition are that the pH valueand the temperature of the electrolytic solution are controlled at 5.57 and 30℃, respectively, and the scan potential range isset between - 0.25 and 1.10 V (versus SCE). The copolymerization rate of aniline and azure B is about 3 times larger thanthat of aniline in the absence of azure B. The copolymerization of aniline and azure B was verified from the results of visiblespectra during electrolysis, FTIR spectra and the atomic force microscopy (AFM) images of the polymers. The in situ visiblespectrum for the electrolysis of the solution containing aniline and azure B is different from that of the respective aniline andazure B. The FTIR spectrum of the copolymer is not a superposition of that of polyaniline and poly(azure B). The AFMimage of the copolymer is different from those of polyaniline and poly(azure B) and is not a mixture of individual polymers.The conductivity of thc copolymer synthesized at pH 5.57 is four orders of magnitude higher than that of polyanilinesynthesized under the same conditions, bat in the absence of azure B. The clectrochemical properties of the copolymer aremainly attributed to polyaniline, but the copolymer has a better electrochemical reversibility and a much faster charge transferthan those of polyaniline.     

Recent developments in electrochemical flow detections—A review: Part I. Flow analysis and capillary electrophoresis

Recent years have provided numerous new examples of applying flow-through electrochemical detectors in chemical analysis. This review, based on about 250 original research papers cited from the current analytical literature, presents their application in flow analysis and capillary electrophoretic methods. Example applications are also given for arrays of electrochemical sensors in flow analysis and electrochemical detection in microfluidic systems. Potentiometric detection with ion-selective electrodes predominates in flow analysis carried out mostly in a flow-injection system, while amperometric and conductivity detections are most commonly employed in capillary electrophoresis.     

Reduced Graphene Oxide/Carbon Nanotube/Gold Nanoparticles Nanocomposite Functionalized Screen‐Printed Electrode for Sensitive Electrochemical Detection of Endocrine Disruptor Bisphenol A

We fabricated a highly sensitive electrochemical sensor for the determination of bisphenol A (BPA) in aqueous solution by using reduced graphene oxide (RGO), carbon nanotubes (CNT), and gold nanoparticles (AuNPs)‐modified screen‐printed electrode (SPE). GO/CNT nanocomposite was directly reduced to RGO/CNT on SPE at room temperature. AuNPs were then electrochemically deposited in situ on RGO/CNT‐modified SPE. Under optimized conditions, differential pulse voltammetry (DPV) produced linear current responses for BPA concentrations of 1.45 to 20 and 20 to 1,490 nM, with a calculated detection limit of an ultralow 800 pM. The sensor response was unaffected by the presence of interferents such as phenol, p‐nitrophenol, pyrocatechol, 2,4‐dinitrophenol, and hydroquinone.     

3D Nano‐structure L‐cysteine/AuNPs/Bi2O3 Modified Glass Carbon Electrode as Chemical Sensor for Highly Sensitive and Selective Detection Cu (II)

It was first time using the l‐cysteine self‐assembled on the surface of gold nanoparticles and Bi₂O₃ nano‐structured materials modified GCE composed l‐cysteine/AuNPs/Bi₂O₃/GCE sensor. The sensor possessed three‐dimensional nanostructure and exhibited a higher ratio of activity sites, large active surface, fast electron transfer rate, excellent catalytic, sensing characteristics and larger affinity to Cu (II). The sensor was determined to have an excellent sensitivity and selectivity for the detection of Cu (II). The characterization of sensor as well as the optimization of the analytical procedure was reported. The optimized conditions parameters allowed the detection of Cu (II) concentration following short analysis time, a detection limit of 5×10^?11 M at 80 s of preconcentration time was obtained using the as‐prepared sensor, and also show excellent stability and good repeatability, and, thus, could be used for detection of Cu (II) in environment.     

电极/离子液体界面电容

用电化学阻抗方法研究了铂片电极在BMIMPF6,BMIMBF4,BMIMClO4,BMIMTf2N,BMIMCl,BMIMBr,C3OHMIMBF4,C3OHMIMClO4和BMMIMPF6(BMIM:1-butyl-3-methylimidazolium;C3OHMIM:1-(3-hydroxypropyl)-3-methylimidazolium;BMMIM:1-butyl-2-methyl-3-methylimidazolium;Tf2N:bis(trifluoromethylsulfonyl)amide)等离子液体中的界面电容及结构.结果表明:当阴、阳离子半径相差不大且不存在特性吸附时,在零电荷电势附近,电极/离子液体界面的电容-电势曲线将出现电容单峰或者双峰.电极的零电荷电势对应于单峰的峰电势或者双峰之间的谷电势.当电极电势远离零电荷电势时,电极/离子液体界面成紧密层结构,可由紧密层理论来描述.如果存在离子的特性吸附,相应的电容峰可能不再出现,而表现为双层电容随电极电势对零电荷电势的偏离而单调增加.还研究了添加小的Li+离子对电极/离子液体界面电容的影响.通过向BMIMTf2N中加入LiTf2N,发现Li+离子可以改变电极/离子液体界面的双层结构,但无助于界面电容的提高,甚至可能引起电容的降低.最后探讨了不同条件下,尤其考虑阴阳离子特性吸附时,电极/离子液体的界面结构.     

基于静电吸附作用制备PPy/CNTs复合材料

通过添加十二烷基苯磺酸钠(SDBS), 在碳纳米管(CNTs)表面引入具有静电吸附作用的基团, 使吡咯单体附着于CNTs表面, 然后发生化学原位聚合, 得到了由片状聚吡咯(PPy)包覆CNTs所构成的PPy/CNTs复合材料, 开辟了一条易于工业化生产制备PPy/CNTs复合材料的途径. 所得材料和CNTs借助傅立叶变换红外光谱、扫描电子显微镜、透射电子显微镜等设备进行了成分和形貌的表征; 并将所得材料组装成电化学超级电容器, 进行了电化学性能测试. 研究结果表明, 加入SDBS后, 吡咯单体能很好地吸附于CNTs表面; CNTs的应用细化了PPy的颗粒, 改善了PPy的导电性能和机械性能, 使PPy/CNTs复合材料呈现出多孔状; 其电化学容量达到101.1 F·g-1(有机电解液), 是同样制备条件下所得纯PPy电化学容量(19.0 F·g-1)的5倍多, 约是所用纯CNTs电化学容量(25.0 F·g-1)的4倍.