基于硫堇/碳纳米管修饰电极的新型过氧化氢电化学传感器

基于碳纳米管(CNTs)和硫堇(Th)的协同效应,将辣根过氧化物酶(HRP)通过戊二醛(GA)交联作用固定在硫堇(Th)/CNTs修饰电极上,构造了一种新型酶电极(HRP/GA-Th/CNTs/GC)。CNTs静电吸附正电荷的Th,而Th不仅可以促进电极和酶的氧化还原活性中心之间的电子传递,而且能使CNTs氨基(—NH2)功能化,从而利于HRP的固定。基于HRP/GA-Th/CNTs/GC电极的过氧化氢传感器具有较好的传感性能,且检出限低(0.3μmol.L-1)、响应时间短(5 s内)、抗干扰能力强。     

Amperometric biosensor for hydrogen peroxide based on the co-electrodeposition of horseradish peroxidase and methylene blue on an ITO electrode modified with an anodic aluminum oxide template

We report on a nano-array sensor for hydrogen peroxide (H₂O₂) that is based on a nanoporous anodic aluminum oxide template. This was used as a matrix for the co-immobilization of horseradish peroxidase (HRP) and methylene blue (MB) on the surface of an indium tin oxide electrode. The immobilized HRP retained its natural activity and MB is capable of efficiently shuttle electrons between HRP and the electrode. The new electrode was characterized by SEM and electrochemical methods. It exhibits fast response, long-term stability, high sensitivity and good selectivity to H₂O₂. Under optimized conditions, it linearly responds to H₂O₂ in the concentration range from 1.0?μM to 26?mM, with a detection limit of 0.21?μM (at S/N?=?3).

Direct electrochemistry and electrocatalysis of horseradish peroxidase immobilized in hyaluronic acid and single walled carbon nanotubes composite film

Direct electrochemistry and electrocatalysis of horseradish peroxidase (HRP) immobilized on a hyaluronic acid (HA)-single walled carbon nanotubes (SCNs) composite film coated glassy carbon electrode (GCE) was studied for the first time. HRP entrapped in the SCNs-HA composite film exhibited a pair of well-defined, quasi-reversible cyclic voltammetric peaks in a 0.1 M phosphate buffer solution (pH 7.0). Formal potential vs. standard calomel electrode (E°′) was −0.232 V, and E°′ was linearly dependent on the solution pH indicating that the electron transfer was proton-coupled. The current is linearly dependent on the scan rate, indicating that the direct electrochemistry of HRP in that case is a surface-controlled electrode process. UV-VIS spectrum suggested HRP retained its original conformation in the SCNs-HA film. Immobilized HRP showed excellent electrocatalysis in the reduction of hydrogen peroxide (H₂O₂).     

HRP在大孔笼状介孔分子筛FDU-12上的固定及直接电化学

用吸附的方法将辣根过氧化物酶(HRP)固定到三维笼状介孔分子筛FDU-12中, 傅立叶变换红外光谱(FTIR)和电化学交流阻抗谱结果表明, 固定后的HRP没有变性, 并表现出良好的直接电化学性质, 其式量电位(E0')为-0.325 V, 在40-300 mV·s-1范围内, 它不随扫描速率变化而变化. 电化学反应速率常数(ks)为1.200 s-1. 固定后的HRP对H2O2有稳定的电催化活性, 该固定酶的方法具有简单、易操作和电极稳定性良好等优点, 可用于获得其他酶或氧化还原蛋白质的直接电子转移以及第三代生物传感器电极的制备.     

基于石墨烯-壳聚糖-辣根过氧化物酶的H2O2生物传感器的研制

制备了石墨烯-壳聚糖(GR-CS)纳米复合材料,并将之与辣根过氧化物酶(HRP)混合,构建了基于石墨烯-壳聚糖-辣根过氧化物酶的生物传感器(GR-CS-HRP/GC)。探针及循环伏安研究表明,该界面具有优异的电子传导能力、较大的比表面积和良好的生物相容性,对H2O2的还原显示出较好的电催化活性,在工作电位为-0.2 V,0.05 mol/L的磷酸盐缓冲盐溶液(PBS,pH 6.8)中,该酶传感器对过氧化氢响应灵敏度高,检测范围宽,测定H2O2的线性范围为5.0×10-7～2×10-3mol/L(相关系数为0.998)。检出限为2.0×10-7mol/L(S/N=3)。并且表现出良好的稳定性和高选择性。该电极用于实际样品中H2O2的测定,结果令人满意。     

Amperometric measurement of ds-DNA content using a peroxidase-modified electrode

An enzyme electrode with a chemically amplified response for methylene blue (MB) was constructed from a glassy carbon electrode and a layer containing immobilized horseradish peroxidase (HRP). MB is reduced on the electrode but regenerated through the HRP-catalyzed reaction in the presence of H(2)O(2). The electroreduction/regeneration cycle for MB resulted in an amplified electrode response. The enzyme electrode was applied to the highly sensitive measurement of ds-DNA. The current for MB decreased in association with its complexation with DNA, and the current response caused by DNA was also amplified through the recycling processes. The detection limit of ds-DNA (from salmon testes) was as low as 5 ng ml(-1).     

Voltammetric Determination of Folic Acid Using Adsorption of Methylene Blue onto Electrodeposited of Reduced Graphene Oxide Film Modified Glassy Carbon Electrode

This work presents a sensitive voltammetric method for determination of folic acid by adsorbing methylene blue onto electrodeposited reduced graphene oxide film modified glassy carbon electrode (MB/ERGO/GCE) in 100 mM KCl‐10 mM sodium phosphate buffer solution (pH 7.40). The surface morphology of the MB/ERGO/GCE modified electrode was characterized using scanning electron microscopy, displays that both MB and ERGO distributed homogeneously on the surface of GCE. The MB/ERGO/GCE modified electrode shows more favorable electron transfer kinetics for potassium ferricyanide and potassium ferrocyanide probe molecules, which are important electroactive compounds, compared with bare GCE, MB/GCE, and ERGO/GCE. The electrochemical behaviors of folic acid at MB/ERGO/GCE were investigated by cyclic voltammetry, suggesting that the modified electrode exhibited excellent electrocatalytic activity towards folic acid compared with other electrodes. Under physiological condition, the MB/ERGO/GCE modified electrode showed a linear voltammetric response from 4.0 μM to 167 μM for folic acid, and with the detection limit of 0.5 μM (S/N=3). The stability, reproducibility and anti‐interference ability of the modified electrode were examined. The developed method has been successfully applied to determination of FA in tablets with a satisfactory recovery from 96 % to 100 %. The work demonstrated that the electroactive MB adsorbing onto graphene modified electrode showed an enhanced electron transfer property and a high resolution capacity to FA.     

水滑石负载的钯纳米粒子对水合肼的电催化氧化

利用共沉淀方法制备了载体水滑石(LDH), 通过离子交换法将PdCl2₄^- 插入水滑石层间, 再用水合肼将其还原, 制备得到了水滑石负载的分散状钯纳米粒子(LDH-Pd⁰). 利用X射线衍射(XRD)、透射电镜(TEM)和X射线电子能谱(XPS)等手段对所得样品进行了表征, 结果表明钯纳米粒子能很好地分散在水滑石上. 将该纳米材料修饰的玻碳电极(GCE)用于水合肼的电催化氧化, 该修饰电极表现出很好的电化学催化活性. 用循环伏安法(CV)、计时库仑法(CC)和计时安培法(i-t)对修饰电极的催化活性、有效表面积和水合肼的催化氧化机理等进行了研究. 结果表明水合肼在-0.1 V附近有明显的氧化峰, 在1.0×10^-5-2.0×10^-4 mol·L^-1范围内, 阳极峰电流与水合肼浓度间有良好的线性关系, 其检测限为9.5×10^-7 mol·L^-1. 计算得到GCE, LDH-Pd⁰/GCE 和LDH/GCE电极活化面积分别为0.02089, 0.02762 和0.02496 cm². 推知水合肼的氧化过程有4 电子和4 质子参与, 并且其在电极上的反应是受扩散控制的不可逆过程.     

Amperometric Biosensor for Hydrogen Peroxide Based on Electrodeposited Sub-micrometer Gold Modified Glassy Carbon Electrode

IntroductionAmperometricbiosensorofhydrogenperoxideisofpracticalimportancebecauseofitswideapplicationsinchemical,biological,clinical,environmentalandmanyotherfields.Forimprovementofsensor抯quality,vari-ouskindsofchemicalmodificationmethodshavebeendevelopedforreducingredoxoverpotentialsofH2O2atelectrodesurfaces,increasingthedetectionsensitivity,linearrange,stabilityandlivetime.Ithasbeenshownthattheuseofsub-micrometersizedmetalparticlessuchasPt-blackcansignificantlyimprovethequalityofthebiosens…     

辣根过氧化物酶活性膜结构及生物电催化性能

通过分子沉积法研究了在聚对苯二甲酸乙二醇酯（PET）表面及金电极表面组装辣根过氧化物酶（HRP）/聚对苯乙烯磺酸钠（PSS）多层生物活性膜，用原子力显微镜(AFM)研究了组装膜的表面形貌，并研究了组装膜的形貌、粗糙度和活性关系.应用循环伏安法（CV）研究了组装HRP膜后电极对H2O2的电化学催化还原作用.实验发现，采用亚甲基蓝（MB）溶液为介质，在H2O2浓度为0.2～5.0 mmol•L－1时，其响应电流对H2O2浓度变化基本呈线性.     

Carbon felt-based bioelectrocatalytic flow detectors: highly sensitive amperometric determination of hydrogen peroxide using adsorbed peroxidase and thionine.

Horseradish peroxidase (HRP) and thionine (TN) were co-adsorbed onto a porous carbon felt (CF), and the resulting HRP and TN-adsorbed CF (HRP-TN-CF) was successfully used as a working electrode unit of a novel bioelectrocatalytic flow detector for a highly sensitive amperometric determination of hydrogen peroxide (H(2)O(2)). Co-adsorbed TN was essential to enhance the cathodic peak current of H(2)O(2), and the current responses of the HRP-TN-CF-based detector were much larger than those of the HRP-CF-based detector (without TN). When air-saturated 0.1 M phosphate buffer (pH 7.0) was used as a carrier at a flow rate of 3.9 ml/min, cathodic peak currents of H(2)O(2) (sample injection volume, 200 microl) obtained at an applied potential of 0 V (vs. Ag/AgCl) increased linearly up to 50 microM with a detection limit of 0.1 microM. Repetitive 100 sample injection of 100 microM H(2)O(2) induced no serious current decrease, and RSD was 0.41 to 1.21% (n = 100). The HRP-TN-CF retained 42% of its original activity after 8 days of storage in 0.1 M phosphate buffer at 4 degrees C.     

Study of carbon nanotubes-HRP modified electrode and its application for novel on-line biosensors

In this paper, multi-walled carbon nanotubes (MWCNTs) were successfully immobilized on the surface of a glassy carbon electrode by mixing with horse-radish peroxidase (HRP). The electrochemical behavior of H2O2 was also studied with the MWCNTs-HRP modified electrode as a working electrode. The MWCNTs-HRP modified electrode showed excellent response of reduction current for the determination of H2O2 at the potential of -300 mV (vs. Ag/AgCl). We assembled the MWCNTs-HRP modified electrode in a thin-layer flow cell and the H2O2 solution was continuously introduced into the cell with a syringe pump. We optimized the sensitivity of the H2O2 sensor by adjusting the working potential and the pH of the buffer solution. The peak current increased linearly with the concentration of H2O2 in the range 3.0 x 10(-7) to approximately 2.0 x 10(-4) mol L(-1). The detection limit is 1.0 x 10(-7) mol L(-1) (S/N = 3). The interferences from ascorbic acid, uric acid and other electroactive substances can be greatly excluded since the sensor can be operated at -300 mV. Stability and reproducibility of the MWCNTs-HRP chemically modified electrode were also studied in this paper. Fabricated with glucose and lactate oxidase, the MWCNTs-HRP electrode was also applied to prepare the on-line glucose and lactate biosensors because of the high sensitivity for the determination of H2O2.     

普鲁士蓝/氧化锆复合材料的电化学行为及对H2O2的电催化

通过一步电沉积技术制备了普鲁士蓝/氧化锆修饰玻碳电极。采用电化学阻抗技术表征修饰电极。采用循环伏安法研究了pH值和扫描速率对该修饰电极的电化学行为的影响。结果表明:普鲁士蓝的峰电流与其扫描速率的一次方在一定范围内呈良好的线性关系。此外,该修饰电极在含有KCl(1.0mol/L)的磷酸盐缓冲溶液(0.1mol/L,pH=7.0)中,对H2O2具有明显的电催化作用,在无酶检测H2O2领域具有潜在的应用价值。     

ss—DNA在纳米金上固载和杂化的化学传感研究

将２－氨乙基硫醇（ＡＥＴ）固载到玻碳电极（ＧＣＥ）表面,进而化学吸附纳米金（ＮＧ）,并在纳米金上固载ss－ＤＮＡ得到ss－ＤＮＡ／ＮＧ／ＡＥＴ／ＧＣＥ,以Ｃo（ｂｐ ｙ）３＾３＋,但用pＨ７．０的磷酸缓冲液浸泡可基本上避免这种变性,并时显提高杂化反应的识别能力。结合在ds－ＤＮＡ／ＮＧ／ＡＥＴ／ＧＣＥ上的Ｃo（bpy）３＾３＋的峰电流与扫速的线性关系可保持到８０mＶ／s,与电沉积法固载纲米金相比较,本电极更稳定     

Electrochemical properties of myoglobin deposited on multi-walled carbon nanotube/ciprofloxacin film

We report the direct electrochemical and electrocatalytic properties of myoglobin (MB) on a multi-walled carbon nanotube/ciprofloxacin (MWCNT/CF) film-modified electrode. A highly homogeneous MWCNT thin-film was prepared on an electrode surface using ciprofloxacin (CF) as a dispersing agent. MB was then electrochemically deposited onto the MWCNT/CF-modified electrode. The MB/MWCNT/CF film was characterized by scanning electron microscopy and UV-visible spectroscopy (UV-vis). UV-vis spectra confirmed that MB retained its original state on the MWCNT/CF film. Direct electrochemical properties of MB on the MWCNT/CF film were investigated by cyclic voltammetry. The formal potential and electron transfer rate constant were evaluated in pH 7.2 buffer solution as -0.327V and 300s(-1), respectively. In addition, the MB/MWCNT/CF-modified electrode showed excellent electrocatalytic properties for the reduction of hydrogen peroxide (H(2)O(2)). The MB/MWCNT/CF-modified electrode was used for the detection of H(2)O(2) at concentrations from 1×10(-6)M to 7×10(-4)M in pH 7.2 buffer solution. Overall, the MB/MWCNT/CF-modified electrode was very stable and has potential for development as a H(2)O(2) sensor.     

Electrochemical study of Meldola's blue,methylene blue and toluidine blue immobilized on a SiO<Subscript>2</Subscript>/Sb<Subscript>2</Subscript>O3 binary oxide matrix obtained by the sol-gel processing method

SiO₂/Sb₂O₃ (SiSb), having a specific surface area, S _BET, of 788 m² g⁻¹, an average pore diameter of 1.9 nm and 4.7 wt% of Sb, was prepared by the sol-gel processing method. Meldola's blue (MeB), methylene blue (MB) and toluidine blue (TB) were immobilized on SiSb by an ion exchange reaction. The amounts of the dyes bonded to the substrate surface were 12.49, 14.26 and 22.78 μmol g⁻¹ for MeB, MB and TB, respectively. These materials were used to modify carbon paste electrodes. The midpoint potentials (E _m) of the immobilized dyes were −0.059, −0.17 and −0.18 V vs. SCE for SiSb/MeB, SiSb/MB and SiSb/TB modified carbon paste electrodes, respectively. A solution pH between 3 and 7 practically did not affect the midpoint potential of the immobilized dyes. The electrodes presented reproducible responses and were chemically stable under various oxidation-reduction cycles. Among the immobilized dyes, MeB was the most efficient to mediate the electron transfer for NADH oxidation in aqueous solution at pH 7. In this case, amperometric detection of NADH at an applied potential of 0 mV vs. SCE gives linear responses over the concentration range of 0.1–0.6 mmol L⁻¹, with a detection limit of 7 μmol L⁻¹.     

基于聚亚甲基蓝-碳纳米管复合膜固载血红蛋白的H2O2生物传感器

采用吸附和电化学聚合修饰方法,制得了聚亚甲基蓝-碳纳米管聚合膜玻碳电极(PMB-MWNTs/GCE),再将血红蛋白(Hb)固定在PMB-MwNTs/GCE表面,制备了稳定的Hb/PMB-MwNTs//GCE的H2O2生物传感器,并用循环伏安法对修饰电极的生物电催化行为进行了表征.研究结果表明,固定在PMB-MWNTs/...     

ss-DNA在纳米金上固载和杂化的电化学传感研究

将2-氨乙基硫醇(AET)固载到玻碳电极(GCE)表面,进而化学吸附纳米金(NG),并在纳米金上固载ss-DNA得到ss-DNA/NG/AET/GCE,以Co(bpy)₃³⁺为电化学指示剂可以识别研究ss-DNA的杂化反应.结果表明,纳米金能使固载其上的ss-DNA发生部分变性而结合Co(bpy)₃³⁺,但用pH7.0的磷酸缓冲液浸泡可基本上避免这种变性,并明显提高杂化反应的识别能力.结合在ds-DNA/NG/AET/GCE上的Co(bpy)₃³⁺的峰电流与扫速的线性关系可保持到80mV/s.与电沉积法固载纳米金相比较,本电极更稳定和可靠.     

Affinity interactions between phenylboronic acid-carrying self-assembled monolayers and flavin adenine dinucleotide or horseradish peroxidase

A method is provided for the recognition of glycated molecules based on their binding affinities to boronate-carrying monolayers. The affinity interaction of flavin adenine dinucleotide (FAD) and horseradish peroxidase (HRP) with phenylboronic acid monolayers on gold was investigated by using voltammetric and microgravimetric methods. Conjugates of 3-aminophenylboronic acid and 3,3'-dithiodipropionic acid di(N-hydroxysuccinimide ester) or 11-mercaptoundecanoic acid were prepared and self-assembled on gold surfaces to generate monolayers. FAD is bound to this modified surface and recognized by a pair of redox peaks with a formal potential of -0.433 V in a 0.1 M phosphate buffer solution, pH 6.5. Upon addition of a sugar to the buffer, the bound FAD could be replaced, indicating that the binding is reversible. Voltammetric, mass measurements, and photometric activity assays show that the HRP can also be bound to the interface. This binding is reversible, and HRP can be replaced by sorbitol or removed in acidic solution. The effects of pH, incubation time, and concentration of H(2)O(2) were studied by comparing the catalytic reduction of H(2)O(2) in the presence of the electron-donor thionine. The catalytic current of the HRP-loaded electrode was proportional to HRP concentrations in the incubation solution in the range between 5 microg mL(-1) and 0.1 mg mL(-1) with a linear slope of 3.34 microA mL mg(-1) and a correlation coefficient of 0.9945.     

An amperometric biosensor using toluidine blue as an electron transfer mediator intercalated in α-zirconium phosphate-modified horseradish peroxidase immobilization matrix

A novel H₂O₂ biosensor was constructed employing α-zirconium phosphate as a new support substrate to hold an electron shuttle toluidine blue between a glassy carbon electrode and horseradish peroxidase. Toluidine blue was intercalated into α-zirconium phosphate-modified horseradish peroxidase immobilization matrix cross-linked on a glassy carbon electrode surface via bovine serum albumin-glutaraldehyde. This co-immobilization matrix of the mediator and the enzyme was formed from the α-zirconium phosphate (α-ZrP)-toluidine blue (TB) inclusion colloid in which horseradish peroxidase (HRP) was dissolved. Intercalation of TB in layered α-ZrP was investigated by scanning electron microscopy (SEM), X-ray powder diffraction (XRD) and electrochemical measurements. TB immobilized in this way underwent a quasi-reversible electrochemical redox reaction at the electrode. Cyclic voltammetry and amperometric measurements demonstrated good stability and efficiently-shuttled electrons between HRP and the electrode. The sensor responded rapidly to H₂O₂ with a detection limit of 3.0 × 10^–7 mol/L.