Preparation of the Ordered Mesoporous Carbon/Fe304 and Its Application for the Direct Electrochemistry of Hemoglobin

采用微湿含浸法制备了有序中孔炭/四氧化三铁磁性材料.采用透射电镜和X射线衍射对复合材料进行了表征.将血红蛋白（Hb）固定于材料表面,对其直接电化学行为进行了研究,结果表明Hb在该材料内仍保持了其生物活性,在pH=7.0的PBS缓冲液中,血红蛋白表现出一对峰形良好的准可逆氧化还原峰,为Hb的Fe（Ⅲ）/Fe（Ⅱ）电对的特征峰,求出式电位E0＇为-0.306 V,电子转移数为n=1.226,电荷传递系数为α=0.51,表观异相电子转移速率常数为KS=0.0144s-1.在3.00×10-6到1.50×10-4mol/L浓度范围内,血红蛋白的浓度与其响应电流呈良好的线性关系,线性相关系数为R=0.9924,最低检测限为0.270×10-6mol/L.     

Hb/Fe3O4/CILE修饰电极的制备及应用

以类离子液体碳糊电极(CILE)为基体电极,采用滴涂法和利用静电吸附作用,制备了Hb/Fe3O4/CILE修饰电极,研究了Hb的直接电化学及其电催化行为,建立了H2O2的计时安培测定新方法。结果表明:Hb在该修饰电极上,Hb呈现了一对准可逆的氧化还原峰,且其在该修饰电极表面表观覆盖度为2.65×10-9moL/cm2;电子转移速率常数为1.35/s;表观米氏常数为1.59×10-5mol/L。在1.0×10-6~4.0×10-5mol/L范围内,催化电流与H2O2浓度呈线性关系(r=0.9976),检出限为3.0×10-7mol/L(S/N=3)。     

即抛型氧化石墨烯/血红蛋白传感器的制备及其对H_2O_2的测定

采用丝网印刷技术制备传感器(SPE),将制备好的氧化石墨烯(GO)修饰于SPE表面用以固载血红蛋白(Hb),构建氧化石墨烯/血红蛋白修饰传感器(Hb/GO/SPE)。Hb/GO/SPE配合实验室自制反应池,实现了对H_2O_2的电化学检测。结果表明,制备的GO具有良好的导电性和生物相容性,促进了Hb的直接电子转移,对H_2O_2的还原具有良好的电催化活性。Hb/GO/SPE对H_2O_2在6.0×10~(-6)～2.0×10~(-2) mol/L的浓度范围内表现出良好的线性关系,线性相关系数R=0.997,检测限(S/N=3)为3.5×10~(-6) mol/L。Hb/GO/SPE测定步骤简单、检测范围宽、稳定性和重现性较好,测定完成后Hb/GO/SPE即可抛弃,使用方便快捷。     

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。     

基于氮掺杂三维石墨烯/血红蛋白的丙烯酰胺电化学传感器制备及应用

本研究利用氮掺杂三维石墨烯/血红蛋白(3D N-RGO/Hb)修饰的玻碳电极,实现对食品中丙烯酰胺(AA)的电化学快速检测。以3D N-RGO作为玻碳电极上电子传递材料,利用其疏松多孔、吸附能力强及电子传输通道多等优势,增强了AA与Hb的相互作用,从而降低Hb的电化学信号,实现对AA的响应。实验采用示差脉冲伏安法(DPV)检测AA,所测得氧化还原峰电位为-350mV,峰电流值随AA浓度增大而逐渐减小。在AA浓度为1.4×10-12~1.4×10-4 mol/L范围内,峰电流强度与AA浓度呈现良好的线性关系(R2=0.9799),检出限(S/N=3)为1.0×10-12 mol/L。研究表明该方法制备的涂层厚度均一且不易脱落,能够实现对实际样品中AA的检测。     

血红蛋白在裸银电极上的直接电化学及其分析应用

报道了血红蛋白(Hb)在裸银电极上的电化学氧化还原行为。在+0.4～-0.2V(vs.SCE)电位范围内于pH=4.5的0.1mol/LNaAc-HAc底液中,血红蛋白产生一对灵敏的氧化还原峰。峰电位之差△E为0.25V(扫描速度20mV/s).动力学研究表明:电极反应的电子转移数n为0.94,表现电子传递速率常数Ks为0.032.连续电位扫描30min,峰电流变化分别为0.2μA(还原峰)和0.15μA(氧化峰).两峰与血红蛋白浓度在2×10^-7～2×10^-6mol/L和2×10^-6～1.5×10^-5mol/L范围内均呈良好线性关系,已应用于血红蛋白的分析测定。     

盐酸吡哆辛在聚溴甲酚绿修饰电极的电化学特性

应用循环伏安法、线性电位扫描法研究盐酸吡哆辛(VB6)在聚溴甲酚绿修饰电极上的电化学特性.在pH=4 HAc-NaAc缓冲溶液,0.7~1.2 V电位区间,盐酸吡哆辛在聚溴甲酚绿电极有一不可逆氧化峰(0.978 V),转移电子数n为1,质子数m为1,传递系数α为0.37.VB6氧化峰电流与其浓度1×10-3~2×10-5mol/L范围内呈线性关系,相关系数0.9967,样品加标平均回收率为100.06%,检出下限为2×10-6mol/L.     

氧化铱膜修饰微电极的制备及痕量砷(Ⅲ)测定

通过在铱丝尖端电沉积氧化铱,制成氧化铱膜修饰微电极,研究了其电化学性质,测定了电极反应的动力学常数,电极反应的电子转移数为1,电子转移系数0.55,表观电子传递速率为0.1 s-1。在pH 4.5的磷酸缓冲溶液中,氧化铱膜修饰微电极对As(Ⅲ)的氧化有明显催化作用,可用于痕量As(Ⅲ)的测定,氧化峰电位为0.62 V。峰电流与As(Ⅲ)的浓度在5×10-8~8×10-5mol/L范围呈良好的线性关系,检出限5×10-9mol/L,响应时间小于1 s。该电极制作简单,稳定性和重复性好,已用于实际样品分析。     

百里香酚在聚甲苯胺蓝/多壁碳纳米管修饰电极上的电催化氧化动力学研究

采用电聚合、滴涂及多层修饰方法制备了4种修饰电极,百里香酚在几种修饰电极上均是不可逆电氧化反应,其中聚甲苯胺蓝/多壁碳纳米管修饰电极的电催化效果最佳,过电位降低了111mV,氧化峰电流增大了5倍。在pH为7.69的PBS溶液中,百里香酚在聚甲苯胺蓝/多壁碳纳米管修饰电极上是电子转移数和质子数均为1的扩散控制不可逆电氧化过程,扩散系数D=4.8470×10-4cm2/s,电极有效面积A=0.0383cm2。氧化峰电流ip与浓度c在9.0×10-6～5.0×10-4mol/L范围内呈良好的线性关系:ip(A)=-3.781×10-5-0.0491c(mol/L),相关系数R=-0.9958,样品测定回收率为96.88%～101.50%。     

氮氧自由基电催化氧化盐酸伪麻黄碱的电化学行为及其电化学动力学性质

运用循环伏安法(CV)、计时电流法(CA)在玻碳电极(GCE)上研究了以氮氧自由基(4-羟基-2,2,6,6-四甲基-哌啶-1-氧自由基,TEMPOL)为均相电子转移媒体电催化氧化盐酸伪麻黄碱(PEH)的电化学行为及其电化学动力学性质.研究结果表明,PEH在GCE上的电化学氧化过程十分迟缓,不易直接发生电化学氧化反应.而在TEMPOL存在时PEH在0.641 V处出现了一个不可逆的氧化峰,且峰电流大幅度增加,表明TEMPOL对PEH的电化学氧化具有良好的电催化作用.在5～1 000 mV/s扫描速度范围内,氧化峰电流(Ipa)与扫描速率平方根(v1/2)呈线性关系,此催化氧化反应是一受扩散控制的电极过程.测定了电催化氧化反应动力学参数:电子转移系数α为0.72,催化反应速率常数k为(2.26±0.05)×103(mol/L)/s.催化体系氧化峰电流与PEH浓度在2.0×10-5～2.0×10-3mol/L范围内呈良好的线性关系,检出限为1.0×10-5mol/L.     

血红蛋白在壳聚糖修饰碳纳米管上的电化学特性及对过氧化氢的电催化分析

用壳聚糖对多壁碳纳米管进行修饰,构建了一种用于固定血红蛋白的新型复合材料,并研究了血红蛋白在该碳纳米管上的电化学性质及其对过氧化氢的电催化活性.扫描电镜结果表明,壳聚糖修饰的多壁碳纳米管呈单一的纳米管状,并能均匀分散在玻碳电极表面.紫外光谱分析表明血红蛋白在该复合膜内能很好地保持其原有的二级结构.将该材料固定在玻碳电极上后,血红蛋白能成功地实现其直接电化学.根据峰电位差随着扫描的变化,计算得到血红蛋白在壳聚糖修饰的碳纳米管膜上的电荷转移系数为0.57,表观电子转移速率常数为7.02 s-1.同时,该电极对过氧化氢显示出良好的催化性能,电流响应信号与H2O2浓度在1.0×10-6 ～1.5×10-3 mol/L间呈线性关系,检出限为5.0×10-7 mol/L.修饰电极显示了良好的稳定性.     

Liquid phase deposition of hemoglobin/SDS/TiO2 hybrid film preserving photoelectrochemical activity

This work demonstrates that liquid phase deposition (LPD) technique provides a novel approach to the immobilization of hemoglobin (Hb) in TiO(2) film for studying the direct electron transfer of Hb. Using the LPD process, a hybrid film composed of Hb, TiO(2) and sodium dodecylsulfonate (SDS) is successfully prepared on the electrode surface. The surface morphology of as-deposited Hb/SDS/TiO(2) film shows a flower-like structure. The cyclic voltammetric measurement indicates that the LPD hybrid film facilitates the electron transfer of Hb, which yields a pair of redox peaks prior to the characteristic voltammetric peaks of TiO(2). Due to the electrocatalytic activity of Hb towards H(2)O(2), the Hb/SDS/TiO(2) hybrid LPD film can be utilized as an H(2)O(2) sensor, showing a sensitive response linearly proportional to the concentration of H(2)O(2) in the range of 5.0×10(-7)-4.0×10(-5) mol/L. At the same time, the Hb/SDS/TiO(2) hybrid film preserves the photoelectrochemical activity of TiO(2). The photovoltaic effect on the electrochemical behavior of Hb/SDS/TiO(2) film is observed after long-time UV irradiation on the film, which could improve the calibration sensitivity for H(2)O(2).     

Direct electron transfer and electrocatalysis of hemoglobin in layer-by-layer films assembled with Al-MSU-S particles

In this paper, layer-by-layer (LBL) {MSU/Hb}(n)/PDDA films assembled by alternate adsorption of positively charged hemoglobin (Hb) and negatively charged mesoporous molecular sieves of Al-MSU-S onto a glassy carbon electrode (GCE) were reported. Al-MSU-S was synthesized by the precursor of zeolite Y and ionic liquids 1-hexadecane-3-methylimidazolium bromide (CMIMB) as a template in basic medium. It exhibited larger pore diameter, pore volume and surface area. Direct electrochemical and electrocatalytic properties of Hb in these layer-by-layer films were investigated. A pair of well-defined nearly reversible cyclic voltammetric peaks was observed and the formal potential of the heme Fe(III)/Fe(II) redox couple was found to be -0.295V (vs. SCE). The influences of layer's number and the pH of the external solution to the electron transfer behavior of Hb in {MSU/Hb}(n)/PDDA films were also estimated by cyclic voltammetry and a set of optimized conditions for film fabrication was inferred. The hemoglobin in{MSU/Hb}(n)/PDDA films displayed a good electrocatalytic activity to the reduction of hydrogen peroxide, which had linear current responses from 1.0 x 10(-6) to 1.86 x 10(-4)mol/L with the detection limit of 5.0 x 10(-7)mol/L (S/N=3). The apparent Michaeli-Menten constant (K(m)(app)) was 0.368 mmol/L. Thus, this methodology shows potential application of the preparation of third-generation biosensors.     

血红蛋白在离子液体[BMIM]PF6碳糊电极上的直接电化学

制备了离子液体[BMIM]PF6修饰碳糊电极(CILE), 并对其形貌和电化学行为进行了表征. 采用涂布法利用壳聚糖-皂土有机-无机复合膜将血红蛋白(Hb)固定于CILE电极表面, 利用紫外可见光谱、红外光谱和电化学方法等手段对包埋于膜内的Hb的性质进行了表征. 结果表明, Hb在薄膜内保持了其原始构象与生物活性, 循环伏安实验表明, 在pH=7.0的Britton-Robinson (B-R)缓冲液中, Hb表现出一对峰形良好的准可逆氧化还原峰, 为Hb Fe(III)/Fe(II)电对的特征峰, 对其直接电化学行为进行了研究, 求出式电位为-0.352 V(vs SCE), 电子转移数为0.885, 电荷传递系数为0.578, 表观异相电子转移速率常数为0.149 s-1.     

以碳纳米管为支撑电沉积制备高电活性与电催化性能的六氰合铁酸钴纳米多孔薄膜

以碳纳米管(MWNTs)修饰的碳糊电极为基底电极,通过电沉积方法制备了六氰合铁酸钴(CoHCF)纳米多孔生物传感平台。考察了MWNTs对CoHCF沉积的影响,优化了CoHCF沉积的各种实验条件(0.5mol/L KCl,1 mmol/L CoCl2和0.9 mmol/L K3Fe(CN)6混合溶液,在循环伏安电压范围0～1.1 V内扫20圈,扫速100 mV/s),借助循环伏安法、交流阻抗法和扫描电镜法对修饰电极进行了表征。由于MWNTs的支撑作用,电沉积得到的CoHCF呈现出多孔结构和良好的电化学稳定性。具有纳米多孔结构的MWNTs-CoHCF薄膜能有效地促进生物小分子在电极上的电子交换,维生素B2在纳米多孔CoHCF/MWNTs上具有优异的氧化还原行为,其测定线性范围为1.2×10-7～2.6×10-7mol/L,检出限为8.9×10-8mol/L。     

Studies on direct electron transfer and biocatalytic properties of hemoglobin in polyacrylonitrile matrix

The direct electrochemistry of hemoglobin (Hb) immobilized in polyacrylonitrile (PAN) modified glassy carbon electrode was described. The protein-PAN film exhibited a pair of well-defined and quasi-reversible cyclic voltammetric peaks for Hb Fe(III)/Fe(II) redox couple in a pH 7.0 phosphate buffer. The formal potential of Hb heme Fe(III)/Fe(II) couple varied linearly with the increase of pH in the range of 5.0-9.0 with a slope of 54 mV pH(-1), which implied that a proton transfer was accompanied with each electron transfer in the electrochemical reaction. Position of Soret absorption band of Hb-PAN film suggested that the Hb kept its secondary structure similar to its native state in the PAN matrix. The Hb in PAN matrix acted as a biologic catalyst to catalyze the reduction of hydrogen peroxide. The electrocatalytic response showed a linear dependence on the H(2)O(2) concentration ranging from 8.3 x 10(-6) to 5 x 10(-4) mol L(-1) with a detection limit of 8.3 x 10(-6) mol L(-1) at 3 sigma. The apparent Michaelis-Menten constant K(M)(app) for H(2)O(2) sensor was estimated to be 0.9 mmol L(-1).     

Application of NiMoO4 Nanorods for the Direct Electrochemistry and Electrocatalysis of Hemoglobin with Carbon Ionic Liquid Electrode

In this paper NiMoO₄ nanorods were synthesized and used to accelerate the direct electron transfer of hemoglobin (Hb). By using an ionic liquid (IL) 1‐butylpyridinium hexafluorophosphate (BPPF₆) modified carbon paste electrode (CILE) as the basic electrode, NiMoO₄ nanorods and Hb composite biomaterial was further cast on the surface of CILE and fixed by chitosan (CTS) to establish a modified electrode denoted as CTS/NiMoO₄‐Hb/CILE. UV‐vis and FT‐IR spectroscopic results showed that Hb in the film retained its native structures without any conformational changes. Electrochemical behaviors of Hb entrapped in the film were carefully investigated by cyclic voltammetry with a pair of well‐defined and quasi‐reversible redox voltammetric peaks appearing in phosphate buffer solution (PBS, pH 3.0), which was attributed to the direct electrochemistry of the electroactive center of Hb heme Fe(III)/Fe(II). The results were ascribed to the specific characteristic of NiMoO₄ nanorods, which accelerated the direct electron transfer rate of Hb with the underlying CILE. The electrochemical parameters of Hb in the composite film were further carefully calculated with the results of the electron transfer number (n) as 1.08, the charge transfer coefficient (α) as 0.39 and the electron‐transfer rate constant (k_s) as 0.82 s^?1. The Hb modified electrode showed good electrocatalytic ability toward the reduction of trichloroacetic acid (TCA) in the concentration range from 0.2 to 26.0 mmol/L with a detection limit of 0.072 mmol/L (3σ), and H₂O₂ in the concentration range from 0.1 to 426.0 µmol/L with a detection limit of 3.16×10^?8 mol/L (3σ).     

Preparation and Electrochemical Behaviors of AA-PEGMA Copolymer Film Electrode

A new kind of comblike copolymer film composed of acrylic acid-polyethylene glycol monomethyl ether acrylate copolymer(AA-PEGMA copolymer) was successfully synthesized to immobilize hemoglobin(Hb). FTIR, UV-Vis and CD spectra suggest that Hb kept its original structure in the AA-PEGMA copolymer film without denaturation. A pair of well-defined, quasi-reversible cyclic voltammetric peaks at around –270 mV vs. saturated calomel electrode(SCE) for the Hb Fe(Ⅲ)/Fe(Ⅱ) redox couple was observed on the film-modified electrode in phosphate buffer solution(PBS, pH=7.0). The formal potential of Hb/AA-PEGMA copolymer film-modified electrode is linearly dependent on solution pH with a slope of –46.3 mV/pH, illustrating that one-proton transfer was accompanied with each electron transfer. Furthermore, the modified electrode displayed electrocatalytic response to the reduction of H₂O₂ with a linear range of 3.5―126 μmol/L and a detection limit of 1.17 μmol/L. In conclusion, the AA-PEGMA copolymer film was proved to be an excellent matrix for the immobilization and electrochemistry of proteins.     

维生素B1的电化学聚合及催化作用

用循环伏安法在石墨电极上制备了VB1聚合膜修饰电极,VB1聚合膜在pH5的PBS中有一对氧化还原峰,峰电位Epd=350mV,Epc=325mV,峰电流与扫描速率的平方根成正比,表明电子在膜中的传递为扩散控制,且聚合膜与VB1单体有不同的电化学性质。实验表明VB1聚合膜对多巴胺、肾上腺素等神经递质有显著的电催化作用。     

Direct Electrochemistry of Hemoglobin on Single‐Walled Carbon Nanotubes Modified Carbon Ionic Liquid Electrode and Its Electrocatalysis

In this article we report on the fabrication of a carbon ionic liquid electrode (CILE) by using a room temperature ionic liquid of 1‐butyl‐3‐methylimidazolium hexafluorophosphate (BMIMPF₆) as binder. It was further modified by single‐walled carbon nanotubes (SWCNTs) to get a SWCNTs modified CILE denoted as SWCNTs/CILE. The redox protein of hemoglobin (Hb) was further immobilized on the surface of SWCNTs/CILE with the help of Nafion film. UV‐vis and FT‐IR spectra indicated that the immobilized Hb retained its native conformation in the composite film. The direct electrochemistry of Hb on the SWCNTs/CILE was carefully studied in pH 7.0 phosphate buffer solution (PBS). Cyclic voltammetric results indicated that a pair of well‐defined and quasireversible voltammetric peaks of Hb heme Fe(III)/Fe(II) was obtained with the formal potential (E°') at ?0.306 V (vs. SCE). The electrochemical parameters such as the electron transfer coefficient (α), the electron transfer number (n) and the apparent heterogeneous electron transfer rate constant (k_s) were calculated as 0.34, 0.989 and 0.538 s^?1, respectively. The fabricated Hb modified electrode showed good electrocatalytic ability to the reduction of trichloroacetic acid (TCA) in the concentration range from 20.0 to 150.0 mmol/L with the detection limit of 10.0 mmol/L (3σ).