基于Fe_3O_4-Au磁性纳米粒子及碳纳米管修饰电极的对氧磷生物传感器研究

采用化学共沉淀技术制备磁性Fe3O4-Au纳米粒子复合物(Fe3O4-AuNPs),并以此磁性纳米复合物和碳纳米管(CNTs)构建用于快速检测对氧磷的乙酰胆碱酯酶(AChE)生物传感器。通过磁力作用将Fe3O4-AuNPs纳米粒子固定在自制的磁铁/玻碳电极(MGCE)上,并以此作为AChE的载体。分别通过X射线衍射、振动样品磁强和透射电镜表征了磁性纳米粒子复合物Fe3O4-AuNPs的成分、磁性及其形貌特征。利用电化学交流阻抗(EIS)、循环伏安法和微分脉冲伏安法(DPV)表征了自制的MGCE修饰电极以及生物传感器(AChE/Fe3O4-AuNPs/CNTs/MGCE)的电化学特征,建立了用该生物传感器微分脉冲伏安法检测对氧磷的方法。在最佳实验条件下,酶抑制率与对氧磷浓度的对数在3.6×10-6~2.9×10-2mol/L范围内呈线性关系,检出限为1.6×10-7mol/L。用提出的方法对实际水样中的对氧磷进行加标回收实验,回收率为98.0%~107%。     

基于褐藻酸钠-纳米金复合物作非酶标记的新型电化学免疫传感器的研制

比较了用三碘甲状腺氨酸抗体(T3抗体)、褐藻酸钠(AS)标记T3抗体及褐藻酸钠-纳米金复合物(ASN)标记的T3抗体,在通过免疫反应结合到免疫电极表面后,引起的电极表面微环境发生改变的程度;用Fe(CN)3-/4-6为电化学探针,用循环伏安法获取金电极表面微环境改变的电流信息来检测 T3抗体,检测的线性范围为100～1 600ng·ml-1,检出限为45ng·ml-1.     

无机纳米材料表面引发自由基可控聚合反应

无机纳米-高分子杂化材料具有优异的性能及广阔的应用前景,引起人们的广泛关注.本文综述了无机纳米材料表面引发自由基可控聚合反应在合成无机-高分子纳米杂化材料方面的广泛应用,包括表面引发原子转移自由基聚合(ATRP)、表面引发可逆加成-断裂链转移自由基聚合(RAFT)、表面引发稳定氮氧自由基聚合(NMP). 着重总结了近几年来这类杂化材料在功能性研究上新的进展,并对今后研究的发展趋势进行了展望.     

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.     

16-n-16型双子表面活性剂稳定纳米金的制备及其催化性能

双子表面活性剂由于其特殊的两亲结构可以作为纳米金颗粒(AuNPs)的表面稳定剂,但双子表面活性剂结构中的连接基团对AuNPs的粒径大小及稳定性有显著影响。本文制备了16-n-16(n=2,3,4和6)型双子表面活性剂稳定的金纳米溶胶,考察了体系pH对AuNPs稳定性的影响,并测试了其对4-硝基苯酚加氢还原体系的催化效果。结果表明,16-4-16和16-3-16对AuNPs的稳定性效果较好,所制备的AuNPs中,16-3-16-AuNPs在不同pH的环境中稳定性最好,而16-4-16-AuNPs在4-硝基苯酚加氢还原反应中的催化活性最佳。     

无金属可见光诱导原子转移自由基聚合法制备聚丙烯酰胺@氧化石墨烯/纳米钯复合物修饰电极及其对乙醇的检测

在金电极表面,用无金属可见光诱导原子转移自由基聚合(MVL ATRP)的方法制备聚丙烯酰胺@氧化石墨烯/纳米钯复合物修饰电极(Au/PAM@GO/Pd)。采用电化学循环伏安法(CV)、交流阻抗法(EIS)、扫描电子显微镜(SEM)、能量色散X射线光谱法(EDS)对Au/PAM@GO/Pd电极进行表征,结果表明在金电极表面成功制备了复合物。利用Au/PAM@GO/Pd电极作为电化学传感器,该传感器能成功地检测溶液中的乙醇。在最佳条件下,利用差分脉冲伏安法(DPV)该传感器检测乙醇的线性范围为1.0×10-8~1.0 mol/L,检出限(S/N=3)为1.3×10-9 mol/L,线性相关系数为0.996。     

Pd纳米粒子敏化的纳米单层TiO_2-Ru(Ⅱ)螯合物修饰电极对单磷酸鸟苷的电催化氧化行为

利用LB膜技术可控制备了纳米单层的二氧化钛-有机钌螯合物杂化膜,并研究了上述无机-有机杂化膜修饰电极在Pd纳米粒子敏化后对单磷酸鸟苷(GMP)的电催化氧化行为.实验结果表明:(1)纳米单层TiO2/[Ru(phen)2(dC18bpy)]2+(简称为TiO2-Ru)杂化膜的平均厚度为(3.2±0.5)nm;(2)在光照条件下TiO2-Ru杂化膜能有效催化还原[Pd(NH3)4]2+形成粒径位于20～200nm之间的Pd纳米粒子;(3)纳米单层TiO2-Ru/Pd杂化膜能高效催化氧化具有供电子能力的单磷酸鸟苷(GMP),与纳米单层TiO2-Ru杂化膜修饰的ITO电极(ITO/TiO2-Ru)相比,当工作电压为1200mV时,ITO/TiO2-Ru/Pd电极在含有1×10-3molL-1GMP的磷酸盐缓冲液中,单位面积的催化氧化电流提高了约36倍;(4)Pd纳米粒子的引入消除了金属钌螯合物中配体对电子传递的阻碍作用,改变了电子传递途径,从而有效减少了电子空穴对的复合,提高了杂化膜修饰电极(ITO/TiO2-Ru/Pd)的电子传递效率.     

单极脉冲一步合成聚苯胺/铁氰化镍杂化膜及其过氧化氢电催化还原活性

采用单极脉冲法在铂基体表面一步合成聚苯胺/铁氰化镍 (PANI/NiHCF) 有机-无机杂化膜,并分析了杂化膜高电势静电吸引沉积机理. 高电压聚合杂化膜避免了Fe(CN)₆^3-的还原,并形成单一“不可溶”结构NiHCF. 用扫描电镜（SEM）、X射线能谱仪（EDS）和傅立叶变换红外（FT-IR）光谱研究了杂化膜表面形貌及组成,并考察了不同单极脉冲电压制得杂化膜的电化学性能. 结果表明,单极脉冲电压1.0 V制得的PANI/NiHCF杂化膜有最佳的电活性和良好的稳定性. 使用计时电流法考察了杂化膜电极的过氧化氢（H₂O₂）的电催化还原活性,在0.5 mol·L^-1 KCl + 0.5 mol·L^-1 HCl电解液中,PANI/NiHCF杂化膜电极过氧化氢催化还原电流与其浓度（4.0×10^-4 ~ 1.6×10^-2 mol·L^-1）呈良好的线性关系,相关性系数R = 0.9991,检出限为6.09×10-5 mol·L-1,灵敏度为1075 mA·(mol·L-1)-1·cm-2.     

基于Dy_2(MoO_4)_3-AuNPs复合纳米材料的葡萄糖生物传感器

采用水热法合成了纳米材料钼酸镝[Dy_2(MoO_4)_3],并制备了Dy_2(MoO_4)_3-AuNPs复合材料,利用该复合材料固定葡萄糖氧化酶(GOD)构建了葡萄糖生物传感器.通过透射电子显微镜(TEM)、紫外-可见光谱(UV-Vis)和能谱分析(EDS)等手段对所制备的材料进行了表征,并利用电化学阻抗谱(EIS)和循环伏安(CV)曲线研究了该传感器的电化学性能.结果表明,Dy_2(MoO_4)_3-AuNPs复合材料具有较好的生物相容性,能增强固定化的GOD的生物活性,并促进GOD在电极表面的电子传递速率;该传感器在葡萄糖浓度为0.01~1.0 mmol/L范围内葡萄糖浓度与响应电流呈较好的线性关系,最低检出限为3.33μmol/L(S/N=3),该生物传感器还具有较好的稳定性和重现性.     

具有不对称孔道结构的小介孔二氧化硅粒子的合成及其高分子杂化膜的构建

利用手性阴离子酸表面活性剂, 采用软模板法制备了具有不对称孔道结构的小介孔二氧化硅(SiO₂)粒子. 将小介孔SiO₂粒子引入聚偏四氟乙烯(PVDF)和聚酰亚胺(PI)中构建了两种有机/无机杂化膜. 利用傅里叶变换红外光谱(FTIR)、 透射电子显微镜(TEM)、 扫描电子显微镜(SEM)和比表面积分析等表征了小介孔SiO₂粒子和有机/无机杂化膜的微结构, 并通过超滤实验和气体渗透实验分别考察两种杂化膜的性能. 研究结果表明, 表面含有大量亲水基团的小介孔SiO₂粒子具有规则有序排列的孔道结构, 该孔道结构呈现螺旋扭曲和不对称性. 构建的两种有机/无机杂化膜的极性显著提升, 进而有效增强了PVDF杂化膜的膜通量和抗污染性能及PI杂化膜对CO₂气体的分离性能, 克服了高分子膜的博弈效应(Trade-off效应). 另外, SiO₂的小介孔孔道还可以在PI杂化膜中引入优先通过CO₂分子的限域传质通道, 加速了CO₂气体在杂化膜中扩散. 但过多小介孔SiO₂粒子的加入导致其在高分子基质中团聚, 削弱杂化膜的极性和亲水性, 从而降低了两种杂化膜的分离性能.     

A novel strategy for immobilization of thionine based on calcium carbonate-gold nanoparticles inorganic hybrid composite and its application in hydrogen peroxide sensor

A novel strategy for efficient immobilization of electroactive Thionine(Th)on the gold(Au)electrode surface based on calcium carbonate-gold nanoparticles(CaCO3-AuNPs)inorganic hybrid composite was proposed and conducted by the strong electrostatic interaction between positively charged Th and negatively charged CaCO3-AuNPs composite.The hybrid composite was obtained by the adsorption of AuNPs onto the surface of CaCO3 microspheres through electrostatic interaction.Due to the microporous architecture,large s...     

Prussian Blue electrodeposited on MWNTs-PANI hybrid composites for H2O2 detection

A Prussian Blue (PB)/polyaniline (PANI)/multi-walled carbon nanotubes (MWNTs) composite film was fabricated by step-by-step electrodeposition on glassy carbon electrode (GCE). The electrode prepared exhibits enhanced electrocatalytic behavior and good stability for detection of H₂O₂ at an applied potential of 0.0 V. The effects of MWNTs thickness, electrodeposition time of PANI and rotating rate on the current response of the composite modified electrode toward H₂O₂ were optimized to obtain the maximal sensitivity. A linear range from 8 × 10⁻⁹ to 5 × 10⁻⁶ M for H₂O₂ detection has been observed at the PB/PANI/MWNTs modified GCE with a correlation coefficient of 0.997. The detection limit is 5 × 10⁻⁹ M on signal-to-noise ratio of 3. To the best of our knowledge, this is the lowest detection limit for H₂O₂ detection. The electrode also shows high sensitivity (526.43 μA μM⁻¹ cm⁻²) for H₂O₂ detection which is more than three orders of magnitude higher than the reported.     

Composite film of carbon nanotubes and chitosan for preparation of amperometric hydrogen peroxide biosensor

A new amperometric biosensor for hydrogen peroxide was developed based on cross-linking horseradish peroxidase (HRP) by glutaraldehyde with multiwall carbon nanotubes/chitosan (MWNTs/chitosan) composite film coated on a glassy carbon electrode. MWNTs were firstly dissolved in a chitosan solution. Then the morphology of MWNTs/chitosan composite film was characterized by field-emission scanning electron microscopy. The results showed that MWNTs were well soluble in chitosan and robust films could be formed on the surface. HRP was cross-linked by glutaraldehyde with MWNTs/chitosan film to prepare a hydrogen peroxide biosensor. The enzyme electrode exhibited excellent electrocatalytic activity and rapid response for H₂O₂ in the absence of a mediator. The linear range of detection towards H₂O₂ (applied potential: −0.2 V) was from 1.67 × 10⁻⁵ to 7.40 × 10⁻⁴ M with correction coefficient of 0.998. The biosensor had good repeatability and stability for the determination of H₂O₂. There were no interferences from ascorbic acid, glucose, citrate acid and lactic acid.     

Fluorometric method for the determination of hydrogen peroxide and glucose with Fe3O4 as catalyst

In this paper, we utilized the instinct peroxidase-like property of Fe₃O₄ magnetic nanoparticles (MNPs) to establish a new fluorometric method for determination of hydrogen peroxide and glucose. In the presence of Fe₃O₄ MNPs as peroxidase mimetic catalyst, H₂O₂ was decomposed into radical that could quench the fluorescence of CdTe QDs more efficiently and rapidly. Then the oxidization of glucose by glucose oxidase was coupled with the fluorescence quenching of CdTe QDs by H₂O₂ producer with Fe₃O₄ MNPs catalyst, which can be used to detect glucose. Under the optimal reaction conditions, a linear correlation was established between fluorescence intensity ratio I₀/I and concentration of H₂O₂ from 1.8 × 10⁻⁷ to 9 × 10⁻⁴ mol/L with a detection limit of 1.8 × 10⁻⁸ mol/L. And a linear correlation was established between fluorescence intensity ratio I₀/I and concentration of glucose from 1.6 × 10⁻⁶ to 1.6 × 10⁻⁴ mol/L with a detection limit of 1.0 × 10⁻⁶ mol/L. The proposed method was applied to the determination of glucose in human serum samples with satisfactory results.     

A Novel NH2/ITO Ion Implantation Electrode: Preparation,Characterization, and Application in Bioelectrochemistry

A novel NH₂⁺ ion implantation‐modified indium tin oxide (NH₂/ITO) electrode was prepared. Acid‐pretreated, negatively charged MWNTs were firstly modified on the surface of NH₂⁺ ion implantation electrode, then, positively charged Mb was adsorbed onto MWNTs films by electrostatic interaction. The assembly of MWNTs and Mb was characterized with electrochemical impedance spectroscopy (EIS) and cyclic voltammetry (CV). The immobilized Mb showed a couple of quasireversible cyclic voltammetry peaks in pH 7.0 phosphate buffer solution (PBS). The apparent surface concentration of Mb at the electrode surface was 1.06×10^?9 mol cm^?2. The Mb/MWNTs/NH₂/ITO electrode also gave an improved electrocatalytic activity towards the reduction of hydrogen peroxide. The catalysis currents increased linearly to the H₂O₂ concentration in a wide range from 9×10^?7 to 9.2×10^?5 M with a correlation coefficient of 0.999. The detection limit was 9.0×10^?7 M. The experiment results demonstrated that the modified electrode provided a biocompatible microenvironment for protein and supplied a necessary pathway for its direct electron transfer.     

Rapid determination of telmisartan in pharmaceuticals and serum by the parallel catalytic hydrogen wave method

The polarographic characteristics of telmisartan have been investigated in 0.8 mol L^–1 NH₃.H₂O–NH₄Cl (pH 8.9)–0.01 mol L^–1 H₂O₂ as supporting electrolyte. The results demonstrate that the polarographic reduction wave at ca. –1.30 V in the absence of H₂O₂ is a catalytic hydrogen wave, and the reduction wave enhanced by H₂O₂ is a so-called parallel catalytic hydrogen wave. The analytical sensitivity of the parallel catalytic hydrogen wave is ca. 60 times higher than that of the corresponding catalytic hydrogen wave. Based on the parallel catalytic hydrogen wave a novel method has been developed for determination of telmisartan by linear sweep polarography. The calibration curve is linear in the range 2.0×10^–8–2.0×10^–6 mol L^–1 and the detection limit is 1.0×10^–8 mol L^–1. The precision is excellent with relative standard deviations of 2.6% at a concentration of 1.0×10^–7 mol L^–1 telmisartan. The proposed method has been applied to the direct determination of the telmisartan in capsule forms and biological samples. The proposed method has been proved to be advantageous over existing CZE and MEKC methods in simplicity, rapidity, and reproducibility.     

Electrochemical synthesis of Fe3O4-PB nanoparticles with core-shell structure and its electrocatalytic reduction toward H2O2

The Fe₃O₄-Prussian blue (PB) nanoparticles with core-shell structure have been in situ prepared directly on a nano-Fe₃O₄-modified glassy carbon electrode by cyclic voltammetry (CV). First, the magnetic nano-Fe₃O₄ particles were synthesized and characterized by X-ray diffraction. Then, the properties of the Fe₃O₄-PB nanoparticles were characterized by CV, electrochemical impedance spectroscopy, and superconducting quantum interference device. The resulting core-shell Fe₃O₄-PB-modified electrode displays a dramatic electrocatalytic ability toward H₂O₂ reduction, and the catalytic current was a linear function with the concentration of H₂O₂ in the range of 1 × 10⁻⁷~5 × 10⁻⁴ mol/l. A detection limit of 2 × 10⁻⁸ (s/n = 3) was determined. Moreover, it showed good reproducibility, enhanced long-term stability, and potential applications in fields of magnetite biosensors.     

Electrochemical sensing platform based on covalent immobilization of thionine onto gold electrode surface via diazotization-coupling reaction

A novel electrochemical sensing platform by modification of electroactive thionine (Th) onto gold electrode surface was constructed, which was realized by diazotization of 4-aminothiophenol (ATP) self-assembled monolayer, followed by coupling of Th with the diazonium group to form a covalent diazo bond. A pair of well-defined redox peaks of Th was observed in the cyclic voltammetric measurement. The resulting diazo-ATP monolayer displayed superior electrical conductivity, which contributed to the sensitive detection of hydrogen peroxide (H₂O₂). The immobilized Th also showed a remarkable stability, which may benefit from the π-π stacking force and the covalent diazo bond between diazo-ATP and Th molecules. Under the optimized experimental conditions, the current fabricated non-enzyme and reagentless sensor could show a rapid response to H₂O₂ within 3 s and a linear calibration plot ranged from 1.0 × 10⁻⁶ to 6.38 × 10⁻³ M with a detection limit of 6.7 × 10⁻⁷ M. The current fabrication strategy of electroactive interface is expected to be used as a versatile route for the immobilization of more electroactive molecules and offer more opportunities for the applications in electrochemical sensor, biosensor, electrocatalysis, etc.     

An H2O2 Biosensor Based on Immobilization of Horseradish Peroxidase Labeled Nano‐Au in Silica Sol‐Gel/Alginate Composite Film

Abstract

A novel approach to assemble an H₂O₂ amperometric biosensor was introduced. The biosensor was constructed by entrapping horseradish peroxidase (HRP) labeled nano‐scaled particulate gold (nano‐Au) (HRP‐nano‐Au electrostatic composite) in a new silica sol‐gel/alginate hybrid film using glassy carbon electrode as based electrode. This suggested strategy fully merged the merits of sol‐gel derived inorganic‐organic composite film and the nano‐Au intermediator. The silica sol‐gel/alginate hybrid material can improve the properties of conventional sol‐gel material and effectively prevent cracking of film. The entrapment of HRP in the form of HRP‐nano‐Au can not only factually prevent the leaking of enzyme out of the film but also provide a favorable microenvironment for HRP. With hydroquinone as an electron mediator, the proposed HRP electrode exhibited good catalytic activity for the reduction of H₂O₂. The parameters affecting both the qualities of sol‐gel/alginate hybrid film and the biosensor response were optimized. The biosensor exhibited high sensitivity of 0.40 Al mol^?1 cm^?2 for H₂O₂ over a wide linear range of concentration from 1.22×10^?5 to 1.46×10^?3 mol L^?1, rapid response of <5 s and a detection limit of 0.61×10^?6 mol L^?1. The enzyme electrode has remarkable stability and retained 86% of its initial activity after 45 days of storage in 0.1 mol L^?1 Tris‐HCl buffer solutions at pH 7.     

Electrochemical reduction and flow detection of iodate on (Bu<Subscript>4</Subscript>N)<Subscript>2</Subscript>Mo<Subscript>6</Subscript>O<Subscript>19</Subscript> self-assembled monolayer

A stable monolayer of the inorganic–organic hybrid polyoxometalate (Bu₄N)₂Mo₆O₁₉, denoted as Mo₆O₁₉, was formed on a sodium-3-mercapto-1-propanesulfonate (MPPS)-covered gold electrode surface, interlaced with an anionic poly(dimethyldiallylammonium chloride) (PDDA) binding layer based on the electrostatic self-assembled (ESA) technique. Electrochemical characterization of the Mo₆O₁₉ self-assembled thin films on the solid surface by cyclic voltammetry and AC impedance spectroscopy revealed a stable and sensitive electrocatalytic response to the reduction of iodate. Iodate was determined amperometrically through a flow injection cell at the modified electrode in the concentration range of 1.0×10^–6 to 1.0×10^–1 M with a detection limit of 8×10^–8 M (signal-to-noise ratio = 3). Performance was improved to meet practical needs compared with previously reported analogues.