Potentiometric Urea Biosensor Based on Ion-Selective Electrode by Different Immobilization Procedures

Enzyme was immobilized on an ammonium ion-selective electrode by different methods.An ion-selective electrode is not completely ion-specific,and interfering ions react with the ion-selective electrode membrane,altering the measured potential.Therefore,the characteristics of the effect of other ions on ammonium ion-selective electrode-based urea biosensors are considered.Based on the experimental results,the urea biosensor based on entrapment had a high response voltage of around 189 mV and fast response time of around 16 sec.Moreover,selectivity of the urea biosensor in different interfering ions was considered to elucidate the characteristics of ammonium ion-selective electrode-based biosensors.

Tris(2,2'-bipyridyl)ruthenium(Ⅱ) electrochemiluminescence (ECL) enhanced by rutin on platinum electrode

Ru（bpy）3^2＋ electrochemiluminescence （ECL） was applied to determination of rutin. ECL intensity of Ru（bpy）3^2＋ could be enhanced in the presence of rufin in basic solution on platinum electrode. At pH 9.9, light emission intensity was found to be linear with rutin in the range of 1-50μmol/L.

A Kind of Electrode Enhanced the Electrochemiluminescence

Three kinds of platinum electrodes with different geometry were designed. The relation of the electrochemiluminescence (ECL) intensity with the geometry of these electrodes has been investigated. The optical character of these electrodes was directly studied by observation of ECL image and measurement of the ECL intensity. The results showed that the ECL not only concentrated on the edge of the electrode but also concentrated on the edge of holes, which contain in the electrode. The ECL intensity from Ru(bpy)3Cl2·6H2O on round electrode was about half of that on four-hole round disk electrode for a same concentration of Ru(bpy)3Cl2·6H2O, so the detection limit was improved to 10-18 mol/L Ru(bpy)3Cl2·6H2O on four-hole round disk electrode, three times higher than that on round disk electrode.

Disposable paper-based bipolar electrode array for multiplexed electrochemiluminescence detection of pathogenic DNAs

A novel disposable paper-based bipolar electrode （BPE） array is fabricated for multiplexed electrochemiluminescence （ECL） detection of pathogenic DNAs. This proposed BPE array device consists of 15 units, each consisting of six sensing cells and two reporting cells patterned using hydrophobic wax. A hairpin structure DNA assembled on the cathodes of BPEs hybridizes with Pt nanoparticles （NPs） labeled probe DNA in the presence of complementary target DNA. The introduction of Pt NPs catalyzes the reduction of dissolved 02 at cathodes and induces an enhanced ECL signal from Ru（bpy）32＋/tripropylamine （TPrA） at the anodes of BPEs. The dissolved 02 lost in reduction reaction could be promptly replenished due to the relatively large contact area of the paper-based cells with air, which ensures the stability of ECL signal. This obtained paper-based BPE array sensor showed excellent performances for the multiplexed analysis of the syphilis （Treponema pallidum） gene, the immunodeficiency virus gene （HIV） and hepatitis B virus gene （HBV）.

Determination of Amino Acids by Ru(bpy)_3^(2+) Cathodic Electrochemiluminescence with High Sensitivity

The unique cathodic electrochemiluminescence（ECL） emission of Ru（bpy）3^2＋（bpy=2,2′-bipyridine） was observed via Nation film at Au electrode[Au/Nafion/Ru（bpy）3^2＋] at about 0.20 V（vs. Ag/AgCl） and applied to the determination of several amino acids without prior derivatization with high sensitivity. The cathodic electrochemiluminescence（ECL） exhibits the detection limits and linear ranges of several amino acids comparable to or better than those of capillary electrophoresis with conventional ECL detection method（at 1.10-1.20 V vs. Ag/AgCl） based on precolumn derivatization. The results suggest that the cathodic ECL is promising for the detection of amino acids in bioanalysis.

Study of enzyme biosensor based on carbon nanotubes modified electrode for detection of pesticides residue

The paper describes a controllable layer-by-layer （LBL） self-assembly modification technique of multi-walled carbon nanotubes （MWNTs） and poly（diallyldimethylammonium chloride） （PDDA） towards glassy carbon electrode （GCE）, Acetylcholinesterase （ACHE） was immobilized directly to the modified GCE by LBL self-assembly method, the activity value of AChE was detected by using i-t technique based on the modified Ellman method. Then the composition of carbaryl were detected by the enzyme electrode with 0.01U activity value and the detection limit of carbaryl is 10^- 12 g L ^-1 so the enzyme biosensor showed good properties for pesticides residue detection.

Experimental Study on Denitrification Using Coated Electrode of Immobilized Denitrifying Bacteria

Objective To develop a coated electrode of immobilized denitrificants and to evaluate the performance of a bioelectrochemical reactor to enhance and control denitrification, Methods Denitrifying bacteria were developed by batch incubation and immobilized with polyvinyl alcohol （PVA） on the surface of activated carbon fiber （ACF） to make a coated electrode. Then the coated electrode （cathode） and graphite electrode （anode） were transferred to the reactor to reduce nitrate. Results After acclimated to the mixtrophic and autotrophic denitrification stages, the denitrifying bacteria could use hydrogen as an electron donor to reduce nitrate, When the initial nitrate concentration was 30.2 mg NO3-N/L, the denitrification efficiency was 57.3% at an applied electric current of 15 mA and a hydraulic retention time （HRT） of 12 hours. Correspondingly, the current density was 0.083 mA / cm^2. The nitrate removal rate of the reactor was 34,4 g NO3-N / m^3,d, and the surface area loading was 1.34 g NO3-N / m^2.d. Conclusion The coated electrode may keep high quantity of blomass, thus achieving a high denitrification rate. Denitrification efficiencies are related to HRT, current density, oxidation reduction potential （ORP）, dissolved oxygen （DO）, pH value, and temperature,

Potential control of horseradish peroxidase immobilization on gold electrode

A new approach based on potential control was firstly used for the immobilization of horseradish peroxidase (HRP) as the model protein. The self-assembly monolayer (SAM) was prepared with 2-aminoethanethiol (AET) on the gold electrode. The charge on HRP was adjusted by means of the acidity of the phosphate buffer solution (PBS) for dissolving the HRP. The in-fluence of electric potential on HRP immobilization was investigated by means of colorimetric immunoassay of enzyme-substrate interaction (CIESI) using an automatic plate reader. The HRP modified electrodes were characterized with X-ray photoelectron spectroscopy (XPS) as well as atomic force microscope (AFM) on template-stripped gold surface. The potential for maximum immobilization of HRP was near the zero charge potential. The result indicates that controlled potential can affect the course of HRP immobilization without the loss of enzymic activity. It is of great significance for the control of biomolecular self-assembly and the intrinsic electric device.

The electrochemiluminescent behavior of nickel phthalocyanine(NiTSPc)/H_2O_2 system on a heated ITO electrode

In this study, the electrochemiluminescent （ECL） behavior of Nickel（II） tetrasulfophthalocyanine （NiTSPc）/H2O2 on a heated indium tin oxide （ITO） electrode was investigated. The effect of pH value, electrochemical scan mode, concentration of NiTSPc and electrode surface temperature on the ECL intensities had been studied in detail. Based on the fact that the ECL of NiTSPc can be greatly enhanced by hydrogen peroxide at the ITO electrode, a new ECL biosensor for hydrogen peroxide has been developed. The possible mechanism for the ECL of NiTSPc has also been proposed.

Tris（2,2＇-bipyridyl） Ruthenium（Ⅱ） Doped Silica Film Modified Indium Tin Oxide Electrode and Its Electrochemiluminescent Properties

An approach was reported to synthesize silica hybridized ruthenium bipyridyl complex through amidation reaction by covalent attachment of bis（bipyridyl）-4,4＇-dicarboxy-2,2＇-bipyridyl-ruthenium to （3-aminopropyl）-triethoxysilane. The hybrid complex then was gelatinized through acid catalytic hydrolysis method and a sol-gel modified indium tin oxide electrode was prepared via spin coating technique. As prepared indium tin oxide electrode possesses good stability therein with excellent electrochemiluminescence behavior.

Flexibly regulated electrochemiluminescence of all-inorganic perovskite CsPbBr_(3)quantum dots through electron bridge to across interfaces between polar and non-polar solvents

All-inorganic perovskite quantum dots(QDs)have attracted great interests due to its outstanding properties.But their poor stability in polar solvents seriously hampered wide applications in analytical chemistry.In this work,strong,stable and flexibly regulated the electrochemiluminescence(ECL)emission form CsPbBr(_3)QDs was successfully obtained and applied in the analysis of polar solvents through the unique structure of closed bipolar electrode(BPE).To demonstrate the feasibility,it was successfully used in the detection of tetracycline(Tc)aqueous solution.CsPbBr(_3)QDs was immersed into organic solution in anode microcell of closed BPE while Tc aqueous solution was added into cathode microcell.The two microcells were physically separated and would not interfere with each other.But the bio-recognition event between aptamer and Tc in cathode microcell would induce the ECL signal change in anode microcell through the electrons conducted by BPE as the bridge.The ECL emission can be flexibly regulated by environmental factors of both polar and non-polar solvents and the interface status of the BPE.Compared with traditional methods to overcome the intrinsic instability in polar medium,the reported method does not need any further surface modifications,has no limitations on the targets and can provide wide development space for further deep research,which may open a new direction for the ECL sensing of CsPbBr(_3)QDs.

Deciphering electrochemiluminescence generation from luminol and hydrogen peroxide by imaging light emitting layer

Electrochemiluminescence(ECL)of luminol is a luminescence process that proceeds in the presence of reactive oxygen species(e.g.hydrogen peroxide(H_(2)O_(2)))at a suitable electrode potential,the reaction mechanism of which is complicated and remains ambiguous.In this work,we report a visualization approach for measuring the thickness of the ECL layer(TEL)of the luminol/H_(2)O_(2) system to decipher the reaction process by combined use of the microtube electrode,ECL microscopy,and finite element simulations.With the increase of solution pH,the ECL image captured with the microtube electrode tends to vary from spot to ring,corresponding to the decrease of TEL from>9.1𝜇m to ca.4.3𝜇m.We propose that different intermediates are involved in the course of ECL reaction.At a low pH(e.g.pH<9),a relatively large TEL is most likely determined by the diffusion of oxidized and deprotonated luminol intermediate that is neutral and has a long lifetime.While at a high pH(e.g.pH in the range of 10 to 12),the ECL reaction is controlled by short-lived radical intermediates of both luminol and superoxide anion.The proposed mechanism is proved theoretically by finite element simulations and experimentally by the apparent effect of concentration ratio of luminol/H_(2)O_(2).

双极电化学发光-分子印迹传感器检测水环境中全氟辛烷磺酸

结合分子印迹聚合物(MIP)的特异性识别能力及双极电化学发光传感(BPECL)的高灵敏、抗干扰特点,构建了一种MIP/BPECL传感器,用于水样中全氟辛烷磺酸(PFOS)的检测.以PFOS为模板分子,邻苯二胺(o-PD)为功能单体,在双极电极的阴极端电聚合分子印迹聚合物以特异性识别PFOS,采用扫描电子显微镜(SEM)和循环伏安法(CV)对电极进行了表征;在双极电极的阳极端以钌联吡啶/三正丙胺[Ru(bpy)_(3)^(2+)/TPr A]为输出信号,构筑了传感与信号分离的MIP/BPECL传感体系.在最优条件下,该传感器对PFOS浓度在1~1000nmol/L范围内呈现良好的线性关系,检出限为0.43 nmol/L(S/N=3).将该传感器应用于实际环境水样的加标回收检测,结果良好,表明所构建的MIP/BPECL传感器具有灵敏度高、特异性好及抗干扰能力强的优点.通过改变分子印迹的模板分子,有望实现该传感器在其它环境污染物检测上的应用.

基于电还原鲁米诺电化学发光分析法测定水样中钼Ⅵ

基于钼 对鲁米诺电化学发光体系的电还原发光信号的增敏作用 ,建立了一种测定钼 的电化学发光新方法。在最佳的实验条件下 ,相对电化学发光强度与钼 的浓度在 5 .0× 1 0 - 4～ 1 .0× 1 0 - 2 g L范围内呈线性关系 ;检出限为 0 .1 3mg L ;相关系数为 0 .992 0。

单链脱氧核糖核酸在石墨电极表面固定化的研究

用5%(V/V)3-氨基丙基三乙氧基硅烷(PrNH_2硅烷Ⅱ)在石墨电极表面硅烷化以导入氨基(—NH_2),然后用乙基-(3-二甲基丙基)碳二亚胺盐酸盐(EDC)作为偶联活化剂,将单链DNA(ssDNA)共价固定在石墨电极表面.采用显微分光光度法、红外光谱法和电化学方法对电极表面的ssDNA层进行了表征,并用紫外-可见光谱法对电极表面固定化ssDNA的杂交特性进行了研究.结果表明,ssDNA可以比较均匀地固定在石墨电极表面,而且ssDNA是通过5’端磷酸基以磷酸氨基酯键的形式共价结合在电极表面,固定在电极表面的ssDNA的杂交特性未发生变化,能够有效地与溶液中的互补链cDNA进行杂交反应.

磁性纳米粒子固定葡萄糖氧化酶修饰电极电致化学发光葡萄糖传感器

通过交联剂将葡萄糖氧化酶(GOD)固定在Fe3O4磁性纳米粒子上,在磁力作用下将该磁性复合粒子修饰在石蜡碳糊电极(SPCE)表面,制成易更新酶电极。GOD催化氧化葡萄糖生成过氧化氢,并使鲁米诺产生电致化学发光(ECL),据此首次构建了易更新型电致化学发光葡萄糖传感器。其电致发光强度与葡萄糖浓度在1×10-5～1.0×10-2mol/L范围内呈线性关系,线性回归方程I=65.4374C+23.9017(r=0.9987);检出限为1.0μmol/L。此传感器响应快,稳定性高,表面易更新,已用于测定人血清中葡萄糖的含量。

纳米石墨烯修饰电极电化学发光法测定盐酸氯丙嗪的研究

基于盐酸氯丙嗪对联吡啶钌电化学发光的增敏作用,以石墨烯(Graphene)和Nafion复合膜修饰的玻碳电极(GCE)为工作电极,建立了一种直接测定盐酸氯丙嗪的电化学发光新方法。最佳实验条件下,盐酸氯丙嗪浓度在8.0×10-7~1.2×10-4mol/L范围内与其相对发光强度呈良好线性关系(r=0.998 8),且在该修饰电极上的检出限(S/N=3)为4.0×10-7mol/L。连续测定4.0×10-6mol/L盐酸氯丙嗪溶液11次,发光强度值的相对标准偏差(RSD)为1.4%,表明该修饰电极具有较好的重复性和灵敏度。盐酸氯丙嗪的加标回收率为93%~104%,RSD(n=5)为4.1%。将该方法应用于药片中盐酸氯丙嗪的检测,结果满意。

壳聚糖凝胶材料固定葡萄糖氧化酶制电极的研究

以壳聚糖为载体研究凝胶法固定葡萄糖氧化酶制电极。试验研究了载体壳聚糖的降解性；交联剂戊二醛的浓度、用量；电极的载酶量等固定化条件对所组建的传感器性能的影响。通过影响规律的分析、优化固定化条件的研究，找出了根据壳聚糖溶液粘度适当调整交联剂戊二醛的用量和铂丝在酶膜母液中浸涂时间，克服壳聚糖的降解性对酶电极性能的影响，建立了制备性能相近的ＧＯＤ传感器的方法。

毛细管电泳-电致化学发光检测法分离测定中药马尿泡中的托烷类生物碱成分

以铕离子掺杂类普鲁士蓝（Eu-PB）化学修饰铂电极为工作电极,采用毛细管电泳-电致化学发光检测法对4种托烷类生物碱成分（如山莨菪碱、东莨菪碱、阿托品和樟柳碱）进行了分离检测。考察了氧化电位值、运行缓冲液酸度、盐浓度和甲醇含量等实验条件对电泳分离效果及检测灵敏度的影响。在优化的实验条件下,以20mmol/L的磷酸盐（pH8.0）-7%（体积分数）甲醇为运行液,各组分在6min内可达到基线分离,其峰面积的相对标准偏差小于5.0%,迁移时间的相对标准偏差小于1.1%（n=12）。并将该法成功地应用于测定中药马尿泡根茎中的山莨菪碱和东莨菪碱的含量,其含量平均值分别为27.8g/kg和4.43g/kg。样品的加标回收率为97.8%~102%。