逐层交替自组装法制备葡萄糖氧化酶电极

采用了分子沉积法制备葡萄糖氧化酶电极.将带有正电荷的聚二甲基二丙烯铵盐(PDDA)和带有负电荷的葡萄糖氧化酶(GOD)交替沉积在修饰有3-巯基-1-丙基磺酸盐(MPS)的金电极表面.该电极以甲酸二茂铁衍生物(Fc-COOH)为电子媒介体,促进电子在葡萄糖氧化酶和金电极表面的传递.通过循环伏安法(CV)检测酶电极的活性,在0.332 V出现一对典型的可逆二茂铁氧化还原峰(见图1),其峰电流的大小和扫描速率的平方根成正比,即由扩散控制电流大小.该电极在溶液中对葡萄糖的线性响应范围上限为6.63 mmol/L(见图2),检测限为0.547mmol/L,响应时间为9.44s.在不同的pH值测试其对葡萄糖的响应,结果表明pH为7.0时为最佳反应条件.在同一浓度下重复测试电流响应,其标准偏差为0.152,其重复使用性能稳定.     

基于聚对苯二甲酸乙二醇酯薄膜的石墨烯/金纳米粒子/葡萄糖氧化酶柔性电极的制备及检测葡萄糖

采用化学气相沉积法生长多晶石墨烯(Graphene, G),转移至聚对苯二甲酸乙二醇酯(PET)薄膜表面,通过控制金溶胶蒸发速率,在多晶石墨烯表面组装均匀分布的亚单层金纳米粒子(AuNPs);然后修饰巯基乙酸,通过共价交联反应将葡萄糖氧化酶固定于AuNPs表面,构建基于PET膜的石墨烯/金纳米粒子/葡萄糖氧化酶(G/AuNPs/GOD)柔性电极.此电极在工作电位0.6 V(vs.SCE电极)、pH 7.0磷酸盐缓冲溶液、室温25℃条件下,差分脉冲伏安法响应电流与被测葡萄糖浓度在0.05~10.55 mmol/L范围内呈线性关系,线性方程为I(108A)=0.2629 C(mmol/L)+1.4149,线性相关系数 r=0.9955,检出限1 μmol/L (3σ). G/AuNPs/GOD柔性电极的制备可为特定环境和可穿戴设备的葡萄糖检测提供了新的途径和方法,拓展了葡萄糖检测的应用范围.     

镀金和碳纳米管修饰金电极上吸附态葡萄糖氧化酶比活性的EQCM研究

采用石英晶体微天平(EQCM)技术监测了裸金电极、镀金和碳纳米管修饰金电极上葡萄糖氧化酶(GOD)的吸附过程. 通过EQCM测量吸附固定的GOD质量, 并实时检测酶反应产物H2O2的氧化电量, 求算了各表面上吸附态GOD的比活性(ESAi). 结果表明, 各表面上均可吸附一定的GOD, 且吸附态GOD均有一定的酶活性; 修饰CNTs可增大酶吸附量和酶电极对葡萄糖的响应电流, 但ESAi随CNTs修饰量的增大而降低; Au电极上电镀金后, 酶吸附量和酶电极对葡萄糖的响应电流亦增大, 但ESAi与裸金电极上的基本一致.     

葡萄糖氧化酶在水溶性CdTe量子点上的直接电化学研究

利用合成的Cd Te量子点(QDs)作修饰材料,将葡萄糖氧化酶(GOD)固定在水溶性Cd Te量子点表面,制备了葡萄糖氧化酶Cd Te量子点修饰碳糊电极(GOD/Cd Te/CPE),实现了GOD在电极表面的直接电化学。Cd Te QDs能有效地加速葡萄糖氧化酶(GOD)与电极表面的直接电子转移,电子传递效率比无QDs Cd Te存在时提高约8倍;电子转移速率常数(K)为0.14 s-1,传递系数(α)为0.60,GOD在GOD/Cd Te/CPE表面的平均覆盖量(Γ)为7.9×10-8mol/cm2。GOD/Cd Te/CPE电极作为第三代葡萄糖电化学生物传感器,成功应用于葡萄糖浓度的检测,其线性范围为0.050~0.32 mmol/L,检出限为0.020 mmol/L。GOD/Cd Te/CPE的制备方法简单,稳定性强,具有优良的选择性和重现性,且响应速度快。     

壳聚糖-Cu^2＋复合物膜固定葡萄糖氧化酶用于葡萄糖传感

利用壳聚糖(CS)对Cu2 的配位吸附作用,制得壳聚糖-Cu2 复合膜修饰电极,进一步通过Cu2 与蛋白质的配位作用,再将葡萄糖氧化酶(GOD)固定在金电极上制得GOD-Cu2 -CS/Au电极.该酶电极检测葡萄糖的线性范围为0.03～2.5 mmol·L-1,线性相关系数为0.997,检出限(S/N=3)为1 μmol·L-1.以电化学石英晶体微天平(EQCM)技术监测了各修饰过程.     

壳聚糖-纳米金-葡萄糖氧化酶生物传感器的制备及其应用于葡萄糖的测定

采用了一种简便快捷的电沉积方法制备了壳聚糖-纳米金复合膜并应用于葡萄糖生物传感器的构建.氯金酸和壳聚糖的混合液在玻碳电极表面电化学还原为金纳米粒子,再将葡萄糖氧化酶通过戊二醛交联的方式固定在纳米金复合膜修饰的玻碳电极表面,制成一种新型的葡萄糖氧化酶生物传感器.该传感器对葡萄糖的响应十分快速,在5 S内即达到平衡.测定葡萄糖的线性范围为20μmol·L-1～5 mmol·L-1,检出限(3S/N)为12μmol·L-1.     

以对乙酰氨基酚为媒介体的葡萄糖传感器研究

电化学葡萄糖传感器检测血浆中的葡萄糖时,血浆中的电活性物质-对乙酰氨基酚会严重干扰检测结果。本研究以对乙酰氨基酚(ACP)为电子转移媒介体,研究了葡萄糖氧化酶(GOD)修饰电极的电化学行为,并探讨了不同pH条件下该修饰电极催化葡萄糖氧化的能力。研究发现ACP能有效地促进酶活性中心与电极间的电子转移,且Nafion涂覆的GOD修饰电极能有效排除尿酸(UA)和抗坏血酸(AA)的干扰。实验结果表明Nafion/GOD电极的氧化电流与葡萄糖浓度在0.6～15mmol/L范围内呈良好的线性关系,且对葡萄糖的检测限为59μmol/L。     

表面形貌对螺旋线形跨尺度电化学葡萄糖传感器性能的影响

将键合金丝以螺旋方式紧密绕制在光纤纤芯上,用水浴法在其表面合成氧化锌纳米线,再将葡萄糖氧化酶物理吸附在纳米线上,得到了螺旋线形跨尺度葡萄糖酶电极。提取了该跨尺度结构及相应酶电极的表面形貌,表征了该批酶电极的电化学性能。结果表明,氧化锌纳米线的合成参数对跨尺度结构的表面形貌、葡萄糖氧化酶的固定效果、跨尺度电化学葡萄糖传感器的性能有显著影响;当生长液Zn2+浓度为25 mmol/L时,跨尺度结构表面形貌的粗糙度为0.10μm、相关长度0.29μm,此时葡萄糖氧化酶的固定效果最好,对应的葡萄糖传感器灵敏度为2.15μA/(mmol/L·cm2)、线性范围0~4.5 mmol/L、检出限9.2μmol/L、Michaelis-Menten常数3.68 mmol/L。研究结果不但有助于螺旋线形跨尺度酶电极的批量制备,还可显著提高其测量精度。     

纳米级微带金电极上葡萄糖氧化酶的固定.性质及应用

实现了葡萄糖氧化酶以及葡萄糖氧化酶和电子传递媒体Fe(CN)^3^-~6同时在纳米级微带电极上的固定,用红外光谱和循环伏安对GOD/PPy微电极进行了表征, 研究了微带金电极上聚吡咯恒电位形成过程的动力学及葡萄糖氧化酶对其动力学过程的影响,探讨了微酶电极GOD/Fe(CN)^3^-~6/PPy对葡萄糖氧化的催化作用, 考察了PPy膜厚度和溶液中氧的存在对GOD/Fe(CN)^3^-~6/PPy微电极测定葡萄糖的影响.     

利用层层累积技术制备基于纳米碳管的葡萄糖生物传感器

以多壁纳米碳管(MWNTS)为电子媒介体和酶的吸附载体,利用层层累积的自组装技术固定葡萄糖氧化酶(GOX)的多层(MWNTa/GOx).复合薄膜修饰电极,制备了一种新型葡萄糖生物传感器.结果表明,传感器对葡萄糖的响应电流值随着MWNTa//GOx复合薄膜层数的不同而变化,当MWNTa//GOx复合薄膜的层教为6时,响应电流值迭到最大.(MWNTs/GOx).复合薄膜修饰的葡萄糖生物传感器对30mmol/L葡萄糖的响应电流为1.63μA,响应时间仅为6.7 s.该生物传感器检测的线性范围为0.5～15 mmol/L,最低检测浓度可达0.09 mmol/L.     

The direct electrochemistry of glucose oxidase based on the synergic effect of amino acid ionic liquid and carbon nanotubes

Amino acid ionic liquids (AAILs) have attracted much attention due to their special chemical and physical properties, especially their outstanding biocompatibility and truly green aspect. In this work, a novel electrochemical biosensing platform based on AAILs/carbon nanotubes (CNTs) composite was fabricated. AAILs were used as a novel solvent for glucose oxidase (GOD) and the GOD-AAILs/CNTs/GC electrode was conveniently prepared by immersing the carbon nanotubes (CNTs) modified glassy carbon (GC) electrode into AAILs containing GOD. The direct electrochemistry of GOD on the GOD-AAILs/CNTs/GC electrode has been investigated and a pair of reversible peaks was obtained by cyclic voltammetry. The immobilized glucose oxidase could retain bioactivity and catalyze the reduction of dissolved oxygen. Due to the synergic effect of AAILs and CNTs, the GOD-AAILs/CNTs/GC electrode shows excellent electrocatalytic activity towards glucose with a linear range from 0.05 to 0.8 mM and a detection limit of 5.5 μM (S/N = 3). Furthermore, the biosensor exhibits good stability and ability to exclude the interference of commonly coexisting uric and ascorbic acid. Therefore, AAILs/CNTs composite can be a good candidate biocompatible material for the direct electrochemistry of the redox-active enzyme and the construction of third- generation enzyme sensors.     

Polymerized ionic liquid-wrapped carbon nanotubes: The promising composites for direct electrochemistry and biosensing of redox protein

Polymerized ionic liquid-wrapped carbon nanotubes (PIL-CNTs) were firstly designed for direct electrochemistry and biosensing of redox proteins. The CNTs were coated successfully with polymerized ionic liquid (PIL) layer, as verified by transmission electron microscopy (TEM), thermogravimetric analysis (TGA) and Fourier transform infrared (FT-IR) spectroscopy. The PIL-CNTs were dispersed better in water and showed superior electrocatalysis toward O₂ and H₂O₂ comparing to pristine CNTs and the mixture of IL monomer and CNTs. With glucose oxidase (GOD) as a protein model, the direct electrochemistry of the redox protein was investigated on the PIL-CNTs modified glassy carbon (GC) electrode and excellent direct electrochemical performance of GOD molecules was observed. The proposed biosensor (GOD/PIL-CNTs/GC electrode) displayed good analytical performance for glucose with linear response up to 6 mM, response sensitivity of 0.853 μA mM⁻¹, good stability and selectivity.     

Reagentless Glucose Biosensor Based on the Direct Electrochemistry of Glucose Oxidase on Carbon Nanotube‐Modified Electrodes

The direct electrochemistry of glucose oxidase (GOD) was revealed at a carbon nanotube (CNT)‐modified glassy carbon electrode, where the enzyme was immobilized with a chitosan film containing gold nanoparticles. The immobilized GOD displays a pair of redox peaks in pH 7.4 phosphate buffer solutions (PBS) with the formal potential of about ?455 mV (vs. Ag/AgCl) and shows a surface‐controlled electrode process. Bioactivity remains good, along with effective catalysis of the reduction of oxygen. In the presence of dissolved oxygen, the reduction peak current decreased gradually with the addition of glucose, which could be used for reagentless detection of glucose with a linear range from 0.04 to 1.0 mM. The proposed glucose biosensor exhibited high sensitivity, good stability and reproducibility, and was also insensitive to common interferences such as ascorbic and uric acid. The excellent performance of the reagentless biosensor is attributed to the effective enhancement of electron transfer between enzyme and electrode surface by CNTs, and the biocompatible environment that the chitosan film containing gold nanoparticles provides for immobilized GOD.     

Direct electrochemistry of glucose oxidase on a graphite nanosheet–Nafion composite film modified electrode

The direct electrochemistry of glucose oxidase (GOD) immobilized in a modified electrode based on a composite film of exfoliated graphite nanosheets (GNSs) and Nafion has been investigated for the first time. Direct electron communication between GOD and the electrode was achieved with a fast electron transfer rate (12.6 s^?1). In addition, the bioactivity of GOD was retained after immobilization in the composite film and glucose could be determined based on the decrease of the electrocatalytic response of the reduced form of GOD to dissolved oxygen. The resulting biosensor exhibited higher sensitivity (3.4 μA mM^?1). Considering much lower cost of GNSs and ready preparation from graphite, the GNSs-based modified electrode described here is superior to the carbon nanotubes (CNTs)-based modified electrodes and should have wide applications in third-generation biosensors, bioelectronics and electrocatalysis.     

The Amperometric Glucose Enzyme Electrode by Immobilized Glucose Oxidase in Glucose Oxidase/N-ethyl-Poly (4-vinyl)pyridine Multilayer

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基于室温离子液体的有序多孔金膜葡萄糖传感器

将1-丁基-3-甲基咪唑四氟硼酸盐（[BMIm][BF4]）、N,N-二甲基甲酰胺（DMF）与葡萄糖氧化酶（GOD）的混合物修饰于三维有序大孔（3DOM）金膜电极上,构建了一种新型的葡萄糖传感器．固定的GOD在pH7．0的磷酸缓冲液（PBS）中展现出一对可逆性好的氧化还原峰,这归因于GOD的活性中心黄素腺嘌呤二核苷酸（FAD）的直接电化学行为．研究表明,离子液体（IL）、DMF以及3DOM金膜对GOD的直接电化学都起到了重要的作用．3DOM金膜修饰电极作为基底提高了酶的负载量,加速了GOD与电极表面的电子传递;IL的应用增加了固定GOD的电化学活性;DMF与IL、GOD的协同作用更好地保持了GOD的生物活性．固定在电极表面的GOD对葡萄糖显示出良好的催化性能,其检测线性范围为10～125nmol／L,检测限为3．3nmol／L（S／N=3）,酶催化反应的表观米氏常数Km为0．018mmol／L．     

Preparation of the glucose sensor based on three-dimensional ordered macroporous gold film and room temperature ionic liquid

A novel type of glucose sensor was fabricated based on a glucose oxidase (GOD)-N,N-dimethtylformamide (DMF)-[BMIm][BF₄] composites modified three-dimensional ordered macroporous (3DOM) gold film electrode. The immobilized GOD exhibits a pair of well-defined reversible peaks in 50 mM pH 7.0 phosphate buffer solutions (PBS), which could be attributed to the redox of flavin adenine dinucleotide (FAD) in GOD. The research results show that ionic liquid ([BMIm][BF₄]), DMF and 3DOM gold film are crucial for GOD to exhibit a pair of stable and reversible peaks. It is believed that the large active area of 3DOM gold film can increase the amount of immobilized GOD. Simultaneously, the application of IL enhances the stability of GOD and facilitates the electron transfer between GOD and the electrode. The synergetic effect of DMF can help the GOD to maintain its bioactivity better. GOD immobilized on the electrode exhibits the favorable electrocatalytic property to glucose, and the prepared sensor has a linear range from 10 to 125 nM with a detection limit of 3.3 nM at a signal-to-noise ratio of 3σ. The apparent K _m (Michaelis- Menten constant) for the enzymatic reaction is 0.018 mM.     

Facile Fabrication of a Graphene‐based Electrochemical Biosensor for Glucose Detection

A simple and effective glucose biosensor based on immobilization of glucose oxidase (GOD) in graphene (GR)/Nafion film was constructed. The results indicated that the immobilized GOD can maintain its native structure and bioactivity, and the GR/Nafion film provides a favorable microenvironment for GOD immobilization and promotes the direct electron transfer between the electrode substrate and the redox center of GOD. The electrode reaction of the immobilized GOD shows a reversible and surface‐controlled process with the large electron transfer rate constant (k_s) of 3.42±0.08 s^?1. Based on the oxygen consumption during the oxidation process of glucose catalyzed by the immobilized GOD, the as‐prepared GOD/GR/Nafion/GCE electrode exhibits a linear range from 0.5 to 14 mmol·L^?1 with a detection limit of 0.03 mmol·L^?1. Moreover, it displays a good reproducibility and long‐term stability.     

Immobilized Fullerene C60‐Enzyme‐Based Electrochemical Glucose Sensor

A mixed‐valence cluster of cobalt(II) hexacyanoferrate and fullerene C60‐enzyme‐based electrochemical glucose sensor was developed. A water insoluble fullerene C60‐glucose oxidase (C60‐GOD) was prepared and applied as an immobilized enzyme on a glassy carbon electrode with cobalt(II) hexacyanoferrate for analysis of glucose. The glucose in 0.1 M KCl/phosphate buffer solution at pH = 6 was measured with an applied electrode potential at 0.0 mV (vs Ag/AgCl reference electrode). The C60‐GOD‐based electrochemical glucose sensor exhibited efficient electro‐catalytic activity toward the liberated hydrogen peroxide and allowed cathodic detection of glucose. The C60‐GOD electrochemical glucose sensor also showed quite good selectivity to glucose with no interference from easily oxidizable biospecies, e.g. uric acid, ascorbic acid, cysteine, tyrosine, acetaminophen and galactose. The current of H₂O₂ reduced by cobalt(II) hexacyanoferrate was found to be proportional to the concentration of glucose in aqueous solutions. The immobilized C60‐GOD enzyme‐based glucose sensor exhibited a good linear response up to 8 mM glucose with a sensitivity of 5.60 × 10² nA/mM and a quite short response time of 5 sec. The C60‐GOD‐based glucose sensor also showed a good sensitivity with a detection limit of 1.6 × 10^‐6 M and a high reproducibility with a relative standard deviation (RSD) of 4.26%. Effects of pH and temperature on the responses of the immobilized C60‐GOD/cobalt(II) hexacyanoferrate‐based electrochemical glucose sensor were also studied and discussed.