HA-[CePy][PF6]-Mb/GCE修饰电极的制备与应用

将肌红蛋白(Mb)包埋在十六烷基吡啶六氟磷酸盐([CePy][PF6])与透明质酸(HA)混合得到的复合膜内,采用滴涂法将其修饰在玻碳电极(GCE)表面,制备了HA-[CePy][PF6]-Mb/GCE修饰电极,研究了Mb的直接电化学及电催化行为,建立了H2O2的计时安培测定新方法。结果表明,在0.1 mol/LPBS(pH 7.0)中,该修饰电极上产生了一对准可逆的氧化还原峰,电子转移速率常数(ks)为3.9/s,电极表面表观覆盖度(Γ*)为4.36×10-9mol/cm2,表观米氏常数(Km)为2.6×10-5mol/L;该修饰电极上的Mb对H2O2的还原表现出良好的电催化作用,催化电流与H2O2浓度在2.5×10-6～5.0×10-5mol/L范围内呈线性关系,检出限为8.0×10-7mol/L(S/N=3)。     

亚铁氰化钾电催化氧化L-半胱氨酸的电化学行为研究

研究了在0.10 mol/L Na2SO4溶液中K4Fe(CN)6在玻碳电极(GCE)上电催化氧化L-半胱氨酸(L-Cys)的电化学行为。在-0.2~0.6 V的电位窗口内,L-Cys在GCE上的直接电化学氧化过程迟缓,不易直接发生氧化反应。在K4Fe(CN)6作用下,在0.23 V处出现一个不可逆的氧化峰,且氧化峰电流明显增大。研究结果表明,K4Fe(CN)6对L-Cys的氧化具有良好的电催化作用。电催化氧化峰电流Ipa随扫描速度的增大而增大,且与扫描速率平方根(v1/2)呈线性关系,表明该电催化氧化反应是受扩散控制的电化学过程。催化氧化峰电流与L-Cys浓度在4×10-5~2×10-3mol/L范围内呈良好的线性关系(R=0.9966)。该催化反应过程中电子转移系数α=0.5568,运用计时电流法(CA)得到该电催化氧化的速率常数k为(7.19±0.05)×102(mol/L)-1.s-1。     

曙红修饰电极对特丁基对苯二酚的灵敏检测

采用循环伏安法(CV)制备了曙红修饰玻碳电极(eosin Y/GCE),电化学交流阻抗法对修饰电极表面进行了表征,研究了特丁基对苯二酚(TBHQ)在该修饰电极上的电化学行为,建立了循环伏安法和差分脉冲伏安法(DPV)测定TBHQ的新方法。研究表明,修饰电极对TBHQ的氧化还原具有较好的电催化活性,在eosin Y/GCE上的氧化还原峰电位差从297 m V降至85 m V。在20~400 m V·s-1范围内,其氧化还原峰电流与扫速的平方根呈良好的线性关系,表明TBHQ在eosin Y/GCE上的电极反应受扩散控制。在0.10 mol·L-1磷酸盐缓冲溶液(p H 6.5)中,扫速为100 m V·s-1时,此修饰电极的DPV响应与TBHQ浓度在1~200μmol·L-1范围内呈线性关系,检出限(S/N=3)为0.1μmol·L-1。此修饰电极具有良好的选择性、重现性和稳定性,应用于油品中TBHQ的测定,回收率达95.0%~102.5%。该电极有望应用于多种食品中抗氧化剂的检测。     

聚四氨基镍酞菁膜修饰电极对甲巯咪唑的电催化氧化

用循环伏安法(CV)研究了聚四氨基镍酞菁膜修饰电极(p-NiTAPc/GCE)对甲巯咪唑的电催化氧化行为,在pH=2的磷酸盐缓冲溶液(PBS)中,与未修饰玻碳电极(GCE)相比,甲巯咪唑在p-NiTAPc/GCE上的氧化峰电位(Epa)负移157mV左右,氧化峰电流(Ipa)变为原来的2.6倍多,在2.0×10-5~1.0×10-3 mol·L-1范围内有良好的线性关系,回收率在90%以上,同时,p-NiTAPc/GCE对甲巯咪唑的电催化氧化活性有很高的稳定性。     

石墨烯-金纳米粒子复合膜修饰电极的制备及对双酚A的测定

采用电化学还原技术,通过一步电沉积制备了石墨烯-金纳米粒子复合膜修饰电极(ERGO-Au/GCE).采用透射电子显微镜(TEM)和循环伏安(CV)法对修饰电极进行了表征,并研究了双酚A(BPA)在该修饰电极上的电化学行为.结果表明,所制备的复合物修饰电极对双酚A有明显的电催化效果.在p H=6.0的磷酸盐缓冲溶液中,双酚A在0.3~1.0 V扫描电位范围内有1个不可逆的氧化还原峰出现.在优化的条件下,双酚A的浓度在3.00×10-8~1.30×10-5mol/L范围内与其氧化峰电流呈线性关系,检出限为1.0×10-8mol/L(S/N=3).将该修饰电极用于饮用水和塑料制品中双酚A含量的测定,回收率为96.4%~103.5%.     

碳纳米管修饰电极检测特丁基对苯二酚

利用碳纳米管修饰玻碳电极(MWCNTs/GCE),对特丁基对苯二酚(TBHQ)进行了检测,采用循环伏安法(CV)和差分脉冲伏安法(DPV)考察了TBHQ在裸电极和修饰电极上的电化学行为。M WCNTs/GCE对TBHQ的氧化具有较好的电催化活性,在修饰电极上的氧化还原峰电位差从261 m V减小到30 m V。在0.10 mol/L磷酸盐缓冲溶液(p H 7.0)中,扫速为50 m V/s时,此修饰电极的DPV响应与TBHQ浓度在2~250μmol/L范围内呈线性关系,检出限为0.1μmol/L(S/N=3)。此修饰电极可应用于食用油中TBHQ的测定,回收率为92.0%~104.0%。     

聚L-组氨酸/乙炔黑修饰电极上对乙酰氨基酚的电化学行为及测定

制备了聚L-组氨酸/乙炔黑修饰电极(Poly-(L-His)/AB/GCE),并用交流阻抗法(EIS)对其进行了表征。用循环伏安法(CV)研究了对乙酰氨基酚(PCT)在该修饰电极上的电化学行为。在p H 6.5的B-R溶液中,PCT在该修饰电极上出现一对氧化还原峰,在40~320 m V/s扫速范围内,氧化峰电流(Ipa)及还原峰电流(Ipc)均与扫速V呈线性关系,表明该电极过程受吸附控制。用差分脉冲伏安法(DPV)测定不同浓度的PCT溶液,在8.0×10-7~1.0×10-4mol/L浓度范围内,氧化峰电流Ipa与PCT浓度呈线性关系,检出限(S/N=3)为7.72×10-8mol/L。运用该方法对样品感冒灵颗粒进行了检测,回收率为97.8%~105.2%。     

多贝斯在石墨烯修饰玻碳电极上的电化学行为及其测定

制备了石墨烯修饰玻碳电极（GN/GCE）。 在0.05 mol/L H2SO4溶液中,用循环伏安法研究了多贝斯在GN/GCE上的电化学行为。 结果表明,GN/GCE对多贝斯的氧化还原反应有明显的电催化作用。 建立了测定多贝斯的新方法,用微分脉冲伏安法测得多贝斯的氧化峰电流与其浓度在2.0×10-9~1.2×10-6 mol/L范围内呈线性关系,检出限为1.0×10-9 mol/L(S/N=3)。 该法可用于胶囊中多贝斯的测定,修饰电极有较好的稳定性和重新性。     

桑色素/石墨烯修饰电极的制备及对多巴胺的选择性灵敏测定

在石墨烯纳米片修饰电极(GN/GCE)上,通过电聚合的方法制备了新颖的桑色素/石墨烯复合修饰电极(M/GN/GCE).以多巴胺(DA)和抗坏血酸(AA)为模型化合物,运用循环伏安法(CV)和差示脉冲伏安法(DPV)考察了该复合修饰电极的电催化行为.在pH 7.0的PBS中,DA和AA分别在0.172 V和-0.183 V产生氧化峰,峰位差达355 mV.与单一修饰电极(桑色素修饰电极(M/GCE)、石墨烯修饰电极(GN/GCE)及裸玻碳电极(GCE))相比,DA在M/GN/GCE上的峰电流显著增大.在优化的实验条件下,DA在2.0×l0-8～5.5×10-4 mol/L浓度范围内与其峰电流具有良好的线性关系,检出限达9.0×10-9 mol/L.     

咖啡酸在多壁碳纳米管修饰玻碳电极上的电化学行为及其测定

制备了多壁碳纳米管(MWNT)修饰玻碳电极,并研究了咖啡酸在该电极上的电化学行为及其测定方法,与裸玻碳电极(GCE)相比,MWNT膜修饰电极(MWNT/GCE)能显著提高咖啡酸的氧化峰电流.在pH=3.29的B-R缓冲溶液中,咖啡酸在MWNT/GCE电极上出现1对准可逆的氧化还原峰,Epa=0.47 V,Epc=0.32 V,峰电流与其浓度在5.0×10-7～2.0×10-5 mol/L范围内成线性关系,检出限为5.0×10-7mol/L.实际样品测定的相对标准偏差(RSD)为0.82％(n=5),平均回收率为100.7％.MWNT膜对咖啡酸的电化学氧化有明显的催化作用.该法是一种快捷、可靠、灵敏的检测方法,可以用于咖啡酸含量的测定.     

Direct Electrochemistry of Myoglobin in a Nafion‐Ionic Liquid Composite Film Modified Carbon Ionic Liquid Electrode

In this paper two kinds of ionic liquids (ILs) were used for the construction of a myoglobin (Mb) electrochemical biosensor. Firstly a hydrophilic ionic liquid of 1‐ethyl‐3‐methylimidazolium tetrafluoroborate (EMIMBF₄) was used as binder to prepare a carbon ionic liquid electrode (CILE), then a Nafion and hydrophobic ionic liquid of 1‐butyl‐3‐methylimidazolium hexafluorophosphate (BMIMPF₆) composite film was applied on the surface of the CILE. The direct electrochemistry of Mb in the Nafion‐BMIMPF₆/CILE was achieved with the cathodic and anodic peak potentials located at ?0.345 V and ?0.213 V (vs. SCE). The formal potential (E°′) was located at ?0.279 V, which was the characteristic of Mb Fe^III/Fe^II redox couples. The electrochemical behaviors of Mb in the Nafion‐ionic liquid composite film modified CILE were carefully investigated. The Mb modified electrode showed good electrocatalytic behaviors to the reduction of trichloroacetic acid (TCA) and NaNO₂. Based on the Nafion‐BMIMPF₆/Mb/CILE, a new third generation reagentless biosensor was constructed.     

Myoglobin/arylhydroxylamine film modified electrode: Direct electrochemistry and electrochemical catalysis

The adsorption processes and electrochemical behavior of 4-nitroaniline (4-NA) adsorbed onto glassy carbon electrodes (GCE) have been investigated in aqueous 0.1 M nitric acid (HNO₃) electrolyte solutions using cyclic voltammetry (CV). 4-NA adsorbs onto GCE surfaces, and upon potential cycling past −0.2 V, is transformed into the arylhydroxylamine (ArHA) derivative which exhibits a well-behaved pH dependent redox couple centered at 0.32 V at pH 1.5. It is noted as arylhydroxylamine modified glassy carbon electrodes (HAGCE). This modified electrode can be readily used as an immobilization matrix to entrap proteins and enzymes. In our studies, myoglobin (Mb) was used as a model protein for investigation. A pair of well-defined reversible redox peaks of Mb (Fe(III)-Fe(II)) was obtained at the Mb/arylhydroxylamine modified glassy carbon electrode (Mb/HAGC) by direct electron transfer between the protein and the GCE. The formal potential (E^0′), the apparent coverage (Γ^*) and the electron-transfer rate constant (k_s) were calculated as −0.317 V, 8.26 × 10⁻¹² mol/cm² and 51 ± 5 s⁻¹, respectively. Dramatically enhanced biocatalytic activity was exemplified at the Mb/HAGC electrode by the reduction of hydrogen peroxide (H₂O₂), trichloroacetic acid (TCA) and oxygen (O₂). The Mb/arylhydroxylamine film was also characterized by UV-visible spectroscopy (UV-vis), scanning electron microscope (SEM) indicating excellent stability and good biocompatibility of the protein in the arylhydroxylamine modified electrode. This new Mb/HAGC electrode exhibited rapid electrochemical response (2 s) for H₂O₂ and had good stability in physiological condition, showing the potential applicability of the films in the preparation of third generation biosensors or bioreactors based on direct electrochemistry of the proteins.     

Hydrogen Peroxide Biosensor Based on the Electrochemistry of the Myoglobin‐TATP Composite Film

Abstract

Direct electrochemistry of the myoglobin‐triacetone triperoxide (Mb‐TATP) composite on carbon paste (CP) electrode is reported. This electrode gives a well‐defined and quasi‐reversible cyclic voltammogram for the Mb Fe^III/Fe^II redox coupled with the formal potential (E?′) of ?0.302 V (vs. Ag/AgCl) in pH 6.92 phosphate buffer. Electronic and vibrational spectroscopies show that the Mb in the composite retains a structure similar to its native form. The enzymatic reactivity to the reduction of H₂O₂ has been studied for the Mb‐TATP film. The analytical performances have been obtained with the linear range of 78.32–1135.64 µM, the detection limit of 55 µM (S/N=3), and the apparent Michaelis‐Menten constant (K _m) of 662.8 µM. This H₂O₂ biosensor based on the electrocatalysis of the immobilized Mb presents a higher stability within two weeks.     

Myoglobin‐Clay Electrode for Nitric Oxide (NO) Detection in Solution

Sodium montmorillonite was prepared via a colloidal chemical approach and deposited onto glassy carbon electrodes (GCE). Myoglobin was immobilized on the clay membrane modified electrode by spontaneous adsorption. Characterization of the myoglobin/clay/glassy carbon electrode (Mb/clay/GCE) showed a quasi‐reversible, electrochemical redox behavior of the adsorbed protein with a formal potential of ?0.380±0.010 V (vs. Ag/AgCl). The heterogeneous electron transfer rate constant was found to be strongly influenced by the buffer concentration. The Mb/clay/GCE was stable for several days in solution. The interaction of the immobilized Mb with nitric oxide (NO) is characterized by coordination chemistry. The reaction was found to be reversible and could be applied for NO detection in the nanomolar concentration range by a voltammetric analysis. In addition a mixed protein electrode with co‐immmobilized myoglobin (Mb) and cytochrome c (Cyt.c) was developed. By choice of the electrode potential both proteins can be addressed independently.     

Direct Electrochemistry and Electrocatalysis of Myoglobin with Ionic Liquid through Multilayers Film on Carbon Ionic Liquid Electrode

Multilayers of myoglobin (Mb) with ionic liquid 1‐ethyl‐3‐methylimidazolium tetrafluoroborate ([EMIM]BF₄) was assembled on carbon ionic liquid electrode (CILE) based on the electrostatic attraction between the negatively charged Mb and the positively charged imidazolium ion of IL. The CILE was fabricated with 1‐ethyl‐3‐methylimidazolium ethylsulfate ([EMIM]EtOSO₃) as the modifier, which exhibited imidazolium ion on the electrode surface. Then Mb molecules were assembled on the surface of CILE step‐by‐step to get a {IL/Mb}_n multilayer film modified electrode. UV‐Vis adsorption and FT‐IR spectra indicated that Mb remained its native structure in the IL matrix. In deaerated phosphate buffer solution (pH 7.0) a pair of well‐defined quasi‐reversible redox peaks appeared with the apparent formal potential (E^0′) as ‐0.212 V (vs. SCE), which was the characteristic of Mb heme Fe(III)/Fe(II) redox couples. The results indicated that the direct electron transfer of Mb was realized on the modified electrode. The {IL/Mb}_n/CILE displayed excellent electrocatalytic ability to the trichloroacetic acid reduction in the concentration range from 2.0 to 22.0 mmol/L with the detection limit of 0.6 mmol/L (3σ). The proposed method provides a new platform to fabricate the third generation biosensor based on the self‐assembly of redox protein with ILs.     

Direct electrochemistry of myoglobin in a layer-by-layer film on an ionic liquid modified electrode containing CeO2 nanoparticles and hyaluronic acid

We describe an ionic liquid modified electrode (CPE-IL) for sensing hydrogen peroxide (HP) that was modified by the layer-by-layer technique with myoglobin (Mb). In addition, the surface of the electrode was modified with CeO₂ nanoparticles (nano-CeO₂) and hyaluronic acid. UV-vis and FTIR spectroscopy confirmed that Mb retains its native structure in the composite film. Scanning electron microscopy showed that the nano-CeO₂ closely interact with Mb to form an inhomogeneously distributed film. Cyclic voltammetry reveals a pair of quasi-reversible redox peaks of Mb, with the cathodic peak at ?0.357?V and the anodic peak at ?0.269?V. The peak separation (??E _p) and the formal potential (E ^0??) are 88?mV and ?0.313?V (vs. Ag/AgCl), respectively. The Mb immobilized in the modified electrode displays an excellent electrocatalytic activity towards HP in the 0.6 to 78.0???M concentration range. The limit of detection is 50?nM (S/N?=?3), and then the Michaelis-Menten constant is 71.8???M. We believe that such a composite film has potential to further investigate other redox proteins and in the fabrication of third-generation biosensors.

Direct Electron Transfer and Electrocatalysis of Myoglobin Based on its Direct Immobilization on Carbon Ionic Liquid Electrode

Direct electron transfer of myoglobin (Mb) was achieved by its direct immobilization on carbon ionic liquid electrode (CILE) with a conductive hydrophobic ionic liquid, 1‐butyl pyridinium hexaflourophosphate ([BuPy][PF₆]) as binder for the first time. A pair of well‐defined, quasi‐reversible redox peaks was observed for Mb/CILE resulting from Mb redox of heme Fe(III)/Fe(II) redox couple in 0.1 M phosphate buffer solution (pH 7.0) with oxidation potential of ?0.277 V, reduction potential of ?0.388 V, the formal potential E°′ (E°′=(E_pa+E_pc)/2) at ?0.332 V and the peak‐to‐peak potential separation of 0.111 V at 0.5 V/s. The average surface coverage of the electroactive Mb immobilized on the electrode surface was calculated as 1.06±0.03×10^?9 mol cm^?2. Mb retained its bioactivity on modified electrode and showed excellent electrocatalytic activity towards the reduction of H₂O₂. The cathodic peak current of Mb was linear to H₂O₂ concentration in the range from 6.0 μM to 160 μM with a detection limit of 2.0 μM (S/N=3). The apparent Michaelis–Menten constant (K and the electron transfer rate constant (k_s) were estimated to be 140±1 μM and 2.8±0.1 s^?1, respectively. The biosensor achieved the direct electrochemistry of Mb on CILE without the help of any supporting film or any electron mediator.     

Electrochemical and spectroelectrochemical properties of manganese reconstituted myoglobin

Electrochemical and spectroelectrochemical properties of manganese(III) reconstituted myoglobin (Mn(III)–Mb) have been investigated. No redox wave of Mn(III)–Mb was observed at a highly hydrophilic indium oxide electrode on which rapid direct electron transfer of native myoglobin took place, suggesting the electron transfer reaction of Mn(III)–Mb at an indium oxide electrode is very slow. The rate constant of the chemical reduction of Mn(III)–Mb with dithionite was ca. 20 times smaller than that of native Mb. Using an optically transparent thin layer electrode (OTTLE) cell and Oxazine-170 perchlorate, 5,9-bis(diethylamino)-10-methyl-benzo[a]phenoxazonium perchlorate, as an electron transfer mediator, the redox potential for the Mn(III) Mn(II)–Mb couple was estimated to be −0.32 V versus Ag AgCl (sat. KCl) at 25°C.     

Electrochemical analysis of the coordination sphere of ruthenium(ii) as electron transfer mediator in glucose oxidase catalysis in aqueous solutions

The redox potentials of the cis-[Ru(LL)₂XY]ⁿ⁺ complexes (LL = 2,2"-bipyridyl (bpy), 1,10-phenanthroline (phen), and 4,4"-dimethyl-2,2"-bipyridyl (Me₂bpy); X, Y = Cl^–, Br^–, CO₃ ^2–, NO₂ ^–, SCN^–, N₃ ^–, H₂O, and DMSO) in aqueous buffer solutions were measured and analyzed in the framework of the Lever theory on the additivity of contributions of ligands (E _L) to the apparent redox potential of the complex (E ^o"). The complexes manifest the properties of reversible or quasireversible redox systems, whose formal redox potentials lie in the 0.2—0.5 V range. The complexes are efficient electron transfer mediators between the active center of glucose oxidase (GO) from Aspergillus niger and an electrode.     

Direct electrochemistry and electrocatalysis of hemoglobin in gelatine film modified glassy carbon electrode

Direct electrochemical and electrocatalytic behavior of hemoglobin (Hb) immobilized on glass carbon electrode (GCE) containing gelatine (Gel) films was investigated. The characteristics of Hb/Gel film modified GC electrode were performed by using SEM microscopy, UV-vis spectroscopy and electrochemical methods. The immobilized Hb showed a couple of quasi-reversible redox peak with a formal potential of −0.38 V (versus SCE) in 0.1 M pH 7.0 PBS. The formal potential changed linearly from pH 4.03 to 8.41 with a slope value of −52.0 mV pH⁻¹, which suggested that a proton transfer was accompanied with each electron transfer (ET) in the electrochemical reaction. The Hb/gelatine/GCE displayed a rapid amperometric response to the reduction of H₂O₂ and nitrite.