氯过氧化物酶修饰电极对一氯二甲酮的催化氯化

通过将氯过氧化物酶溶液(Chloroperoxidase, CPO)与Nafion分散的单壁碳纳米管分散液混合后直接滴涂到玻碳电极表面制得修饰电极. 这个固定了氯过氧化物酶的碳纳米管修饰玻碳电极, 在pH=5.0的磷酸缓冲溶液中测得的循环伏安曲线上有一对准可逆的氧化还原电流峰, 经过与裸电极和没有固定氯过氧化物酶的碳纳米管修饰电极上测得的循环伏安行为对比后确认, 碳纳米管对氯过氧化物酶与电极之间的电子传递反应具有很好的促进作用. 利用该修饰电极能催化一氯二甲酮氯化为二氯二甲酮, 无需添加过氧化氢作为反应启动剂, 紫外光谱的测试结果表明, 每摩尔氯过氧化物酶可催化氯化4.0×105 mol 的一氯二甲酮, 表现出很高的催化效率.     

氯过氧化物酶-聚L-赖氨酸/GC电极的电化学特性

应用电化学方法在玻碳电极上修饰聚L-赖氨酸膜,以1-乙基-(3-二甲基氨基丙基)碳二亚胺盐酸盐做交联剂,固定氯过氧化物酶.修饰电极的循环伏安曲线呈现一对可逆的氧化还原峰,表明聚L-赖氨酸能够很好地促进氯过氧化物酶在电极表面的直接电子传递,这是一个受吸附控制并伴随有质子转移的准可逆电子传递过程.该电极有很好的稳定性,并能显著地电催化氧的电化学还原反应.     

辣根过氧化物酶生物传感器检测苯肼的研究

采用酸性溶胶法在碳纳米管(CNT)上负载纳米TiO2颗粒,制备了CNT-TiO2修饰电极,利用TiO2与辣根过氧化物酶(HRP)间的静电吸附及TiO2与羧基的高反应特性,实现了HRP在CNT-TiO2修饰电极表面的固定.实验发现,该生物传感器对邻氨基苯酚过氧化氢溶液的氧化还原有很好的催化作用,利用苯肼对HRP的抑制作用实现了对环境污染物苯肼的检测.该生物传感器寿命长,性能稳定且可以重复使用.     

基于固定化电子媒介体的漆酶电极的制备与应用

采用一种新方法引入媒介体,即将媒介体2,2-连氮-双(3-乙基苯并噻唑啉-6-磺酸)(ABTS)固定在多壁碳纳米管(MWCNTs)上,将壳聚糖与漆酶共同修饰在玻碳电极表面,制备了漆酶电极。实验发现,ABTS能够被牢固地吸附在多壁碳纳米管上,且吸附了ABTS的多壁碳纳米管在水中的分散性能大为改善。由于ABTS的存在,该漆酶电极能够更加有效地催化氧气还原,使氧气的还原电位从-0.1 V升至0.6 V。研究了修饰在多壁碳纳米管上的ABTS的电化学行为,并讨论了碳纳米管修饰量、pH值及温度对漆酶电极催化性能的影响。该方法简单,制备的漆酶电极对氧气还原的催化效率高,有望应用于植入型生物燃料电池。     

金电极表面聚赖氨酸固定微过氧化物酶-11的电化学研究

通过聚赖氨酸修饰将微过氧化物酶-11(MP-11)固定在金电极表面,制备成MP-11修饰电极.修饰在电极表面上的MP-11的血红素活性中心与电极之间可进行直接的电子传递反应,其氧化还原式电位为-0.39V.该修饰电极对氧的还原具有电催化活性.当MP-11与咪唑发生轴向配位反应时,其氧化还原式电位发生负移,此时对氧的还原不再具有电催化活性.     

基于明胶-碳纳米管的辣根过氧化物酶修饰电极在离子液体中的直接电化学

制备了明胶(Gel)-多壁碳纳米管(MWCNTs)纳米复合物,将其修饰在玻碳电极表面,再吸附辣根过氧化物酶(HRP),制得明胶-多壁碳纳米管-辣根过氧化物酶修饰电极(Gel-MWCNTs-HRP/GCE).该修饰电极在PBS中的循环伏安图上出现了一对峰形良好、几乎对称的氧化还原峰,式量电位为-0.356 V(vs.SCE),表明包埋在Gel-MWCNTs中的HRP与电极之间发生了直接电子传递.当扫速在20 ～ 180 mV/s时,氧化峰电流(Ipa)与还原峰电流(Ipc)均与扫速成正比,表明电极过程是受电子传递速率控制的表面传质过程.运用循环伏安法研究了修饰电极的电化学特性,探讨了工作电位、pH值、干扰物质等对修饰电极的影响.实验结果表明,HRP在修饰电极表面能有效和稳定地进行直接电子转移,并保持了其对过氧化氢(H2O2)的生物催化活性.进一步研究发现,在含有亲水性离子液体1-丁基-3-甲基咪唑四氟硼酸([BMIM]BF4)的溶液中,修饰电极对H2O2显示出更灵敏的催化活性,其线性范围为2.0×10-7～0.13 mol/L,检出限(S/N =3)为2.3×10-8 mol/L.该电极具有灵敏度高、重现性及稳定性好、使用寿命较长等优点,同时还显示了较好的抗干扰能力.     

聚芳酰胺-多壁碳纳米管混合物固定漆酶电极的电化学行为

以聚芳酰胺-多壁碳纳米管混合物为载体,利用漆酶表面氨基与聚芳酰胺主链端羧基的共价偶联以及碳纳米管与漆酶间的疏水作用,构筑了具有较高稳定性和电催化活性的漆酶修饰电极.并对该固酶修饰电极的固酶量、酶活力、电化学行为及其电催化氧还原的性能进行了表征.对漆酶分子具有亲和力的聚芳酰胺芳环结构及聚芳酰胺端羧基与漆酶表面氨基的共价偶联避免了漆酶的脱落和变性.而碳纳米管与聚芳酰胺的混合使得该三维修饰电极具有良好的电子导电性,并成功地实现了漆酶的氧化还原活性位与电极之间的直接电荷转移,这一点可由在0.73和0.38V附近观察到漆酶的T1和T2(漆酶的T1,T2铜活性位的形式电位分别为0.78和0.39V(vsNHE))铜活性位的两对氧化还原峰确认.漆酶的担载量为56.0mg·g-1,具有电化学活性的漆酶占总担载漆酶量的68%.在pH=4.4磷酸盐缓冲溶液中,该修饰电极上氧气还原的起始电位为0.55V,其对氧气的米氏常数KM为55.8μmo·lL-1,对氧气的检测限为0.57μmo·lL-1.在4℃下保存两个月后能实现直接电荷转移的漆酶量仅下降了14%左右而氧还原超电势提高了约50mV.结果表明该修饰电极有望用作酶基生物燃料电池的阴极和电流型氧气传感器.     

辣根过氧化物酶/多壁碳纳米管修饰铂电极生物传感器用于过氧化氢的循环伏安测定

将1mg多壁碳纳米管(MWCNT's)分散在5mL的0.5g·L~(-1)壳聚糖溶液中后,滴涂在铂电极表面,制得多壁碳纳米管修饰电极。将上述修饰电极在辣根过氧化物酶(HRP)溶液中浸泡8h,在MWCNT's修饰电极表面静电吸附辣根过氧化物酶,制成过氧化氢生物传感器,用于过氧化氢的测定。试验结果表明:在pH 6.0的磷酸盐缓冲溶液中,HRP/MWCNT's修饰电极对过氧化氢具有明显的电催化还原作用,过氧化氢的浓度在3.5×10~(-5)～9.0×10~(-3)mol·L~(-1)范围内与其还原峰电流呈线性关系,检出限(3S/N)为2.4×10~(-5)mol·L~(-1)。用标准加入法作回收试验,回收率在96.0%～101.8%之间。     

基于金纳米链标记抗体及HRP信号增强的电流型免疫传感器

酶联免疫分析将抗原-抗体反应的特异性与酶的高效催化放大作用相结合,因而极大地提高了免疫分析的灵敏度~([1]).本研究将均匀分散的碳纳米管修饰到预处理的电极表面,通过电化学还原氯金酸制成碳纳米管-纳米金复合基质用以固载抗体.同时制备了金纳米链(Au NCs)并标记二抗,结合辣根过氧化物酶(HRP),采用双抗体夹心分析模式,以心血管疾病标志物血清人N末端脑钠尿肽前体(NT-proBNP)为免疫蛋白模型,构建了高灵敏电流型酶免疫传感器.     

氯过氧化物酶修饰电极用于岩白菜素的电催化氯化

将氯过氧化物酶(CPO)与双十二烷基二甲基溴化铵(DDAB)混合后滴涂于玻碳(GC)电极表面, 制得CPO-DDAB/GC修饰电极. 循环伏安结果显示, 固定在电极表面的CPO可与电极之间发生直接的电子传递作用. 利用高效液相色谱-质谱联用技术对反应产物进行表征, 结果显示, 以该CPO修饰电极为工作电极, 在氧气饱和的氯化钾-岩白菜素溶液中, 利用CPO催化氧还原生成的过氧化氢可进一步驱动CPO对岩白菜素的催化氯化反应. 经估算总转化数(TTN)达到13600, 即1 mol CPO可催化13600 mol岩白菜素.     

Electrochemical studies of chloroperoxidase on poly-L-lysine film modified GC electrode

<正>Poly-L-lysine(PLL) was first electrodeposited onto the surface of a glassy carbon(GC) electrode.The PLL modified electrode was used to immobilize chloroperoxidase(CPO) via 1-[(3-dimethylamino)propyl]-3-ethylcarbodiimide hydrochloride(EDC).The electrochemical behaviors of immobilized CPO on PLL/GC electrode were investigated by cyclic voltammetry(CV).The CV results obtained showed that CPO was successfully immobilized on the PLL/GC electrode and a fast direct electron transfer between CPO and PLL-GC electrode was achieved with a formal redox potential of -0.23 V vs.SCE.The CPO-PLL/GC modified electrode showed a good catalytic activity for electrocatalytical reduction of O_2,promising for a broad range of CPO-catalyzed transformations.     

Ionic liquid modified GC electrode for the direct electrochemistry of chloroperoxidase

Chloropcroxidase （CPO） was immobilized by konjac glucomannan （KGM） on the 1-butyl-3-methyl imidazolium tetrafluoroborate [BMIM][BF4]/Nafion modified glassy carbon eloctrode. The electrochemical behaviors of the immobilized CPO were investigated by cyclic voltammetry. The results showed that CPO was successfully immobilized on the GCE and underwent fast direct electron transfer reactions with the formal potential at -0.3 V vs. SCE. The modified electrode showed a good catalytic activity for elcctrocatalytical reduction of O2 and H2O2.     

A New Amperometric Hydrazine Sensor Based on Prussian Blue/Single‐walled Carbon Nanotube Nanocomposites

A slow reaction process has been successfully used to synthesize Prussian blue/single‐walled carbon nanotubes (PB/SWNTs) nanocomposites. Electrochemical and surface characterization by cyclic voltammetry (CV), scanning electron microscopy (SEM), transmission electron microscopy (TEM), UV‐vis absorption spectroscopy, Fourier transform infrared (FTIR) spectroscopy and X‐ray diffraction (XRD) confirmed the presence of PB nanocrystallites on SWNTs. PB/SWNTs modified glassy carbon electrode (GCE) exhibits efficient electron transfer ability and high electrochemical response towards hydrazine. The fabricated hydrazine sensor showed a wide linear range of 2.0×10^?6–6.0×10^?3 M with a response time less than 4 s and a detection limit of 0.5 μM. PB/SWNTs modified electrochemical sensors are promising candidates for cost‐effective in the hydrazine assays.     

Electorchemical Studies of Cytochrome c on Electodes Modified by Single—Wall Carbon Naotubes

Single-wall carbon nanotubes(SWNTs) modified gold electrodes were prepared by using two different methods.The electrochemical behavior of cytochrome c on the modified gold electrodes was investigated.The first kind of SWNT-modified electrode (noted as SWNT/Au electrode)was prepared by the adsorption of carboxylterminated SWNTs from DMF dispersion on the gold electrode.The oxidatively processed SWNT tips were covalently modified by coupling with amines (AET) to form amide linkage.Via Au-S chemical bonding,the self-assembled monolayer of thiol-unctionalized nanotubes on gold surface was fabricated so as to prepare the others SWNT-modified electrode (noted as SWNT/AET/Au electrode).It was shown from cyclic voltammetry cxperiments that cytochrome c exhibited direct electrochemical responses on the both electrodes, but only the current of controlled diffusion existed on the SWNT/Au electrode while both the currents of controlled diffusion and adsorption of cytochrome c occurred on the SWNT/AET/Au electrode.Photoelastic Modulation Infared Reflection Absorpthion Spectroscopy (PEM-IRRAS) and Quartz Crystal Microbalance (QCM) were employed to verify the adsorption of SWNTs on the gold electrodes.The results proved that SWNTs could enhance the direct electron transfer proecss between the electrodes and redox proteins.     

多巴胺在氧化锌纳米棒嵌入石墨修饰电极上的电化学行为及测定

采用水热法制备了氧化锌纳米棒,用扫描电子显微镜、红外光谱等测试方法对其进行表征,通过嵌入式修饰方法,将制备出的氧化锌纳米棒嵌入到石墨电极中制成修饰电极。 用循环伏安法和差分脉冲伏安法研究了多巴胺在修饰电极上的伏安行为和反应机理。 结果表明,该修饰电极对多巴胺显示出良好的响应,不仅使峰电流增加,并使多巴胺的氧化峰电位负移68 mV。 该电极过程的动力学参数：电子转移数n=2,电子转移系数α=0.48。 多巴胺的脉冲峰电流与其浓度在5.0×10-7~1.0×10-4 mol/L内呈良好的线性关系,检出限为1.0×10-7 mol/L(S/N=3)。 对1.0×10-5 mol/L的多巴胺平行测定8次的相对标准偏差（RSD）为3.42%。 用本法测定了盐酸多巴胺注射液中多巴胺的含量,加标回收率为94.83%~104.5%。     

单壁碳纳米管修饰的高灵敏纳米碳纤维电极

碳纳米管已被应用于电极材料,但未得到良好的电化学伏安行为;且由于碳纳米管的直径很小(几到数十纳米),制作单根的碳纳米管电极非常困难,难以实际应用.碳纳米管用于修饰电极已得到更多重视,但都在常规尺寸(毫米级)的电极上进行,这样的电极不适于在生物微环境和毛细管电泳电化学检测中应用.     

The influence of cetyltrimethyl ammonium bromide on electrochemical properties of thyroxine reduction at carbon nanotubes modified electrode

The effect of cetyltrimethyl ammonium bromide (CTAB) on the electrochemical behaviors of thyroxine at a glassy carbon electrode (GCE) modified with single-walled carbon nanotubes (SWNTs) was investigated. At the SWNTs film-coated GCE, a well-defined oxidation peak of thyroxine at 0.78 V was obtained, but the reduction peak of thyroxine was indiscernible. When trace CTAB was added to the working solution, the reduction current could be greatly enhanced and the oxidation current remained stable. The reaction mechanisms for the reduction of thyroxine were explored by chronocoulometry. Thyroxine might form particular ion complex with CTAB via the interaction between iodine atoms on thyroxine and bromide ions in CTAB, which made the concentration of thyroxine at the surface of the modified electrode increased and the electron transfer rate enhanced. The proper mechanisms for the enhanced reduction of thyroxine in the present of CTAB were explored by several electrochemical techniques including cycle voltammetry linear sweep voltammetry and others. It was concluded that the special interactions between the thyroxine CTAB and SWNTs resulted in the increase of the reduction peak current. All results indicated that two iodine atoms on the thyroxine and four electrons were involved the reduction process which was irreversible and two iodine ions produced. In this system, the sensitive reduction peak of thyroxine at 0.3 V was employed to determine thyroxine and a low detection limit of 2x10(-8) mol/L was obtained for 2 min accumulation at 0.9 V. The SWNTs coated GCE had good stability and reproducibility.