氮掺杂碳纳米管修饰电极的电化学行为

制备了氮掺杂改性的碳纳米管, 并用循环伏安法(CV)测定了多巴胺(DA)和抗坏血酸(AA)在不同氮含量的碳纳米管修饰电极上的电化学行为. 结果表明, 氮掺杂碳纳米管修饰电极对AA和DA有不同的电催化行为, 其中高氮含量修饰电极对AA的催化作用强, 而低氮含量修饰电极对DA的催化作用强. 微分脉冲伏安法(DPV)的结果显示, DA的氧化峰电流与其浓度在5.0×10^－6～2.0×10^－4 mol/L范围内呈良好的线性关系, 检出限达1.64×10^－6 mol/L (S/N＝3); AA氧化峰电流与其浓度在3.0×10^－5～1.0×10^－2 mol/L范围内呈良好的线性关系, 检出限达3.26×10^－6 mol/L (S/N＝3). 该修饰电极在AA大量存在(AA浓度为DA浓度两万倍)时可选择性地实现多巴胺的测定而不造成干扰.     

一种基于PVC膜电极的电位式葡萄糖传感器的研制

以三庚基十二烷基碘代季铵盐为电活性物质的PVC膜电极, 对过氧化氢和六价钼的络合物具有良好的电位响应. 将葡萄糖氧化酶固定到PVC膜电极表面, 制备成电位式葡萄糖传感器. 在优化的实验条件下, 该传感器在葡萄糖浓度为2×10^－4～5×10^－3 mol/L范围内有线性响应, 检测下限为5×10^－5 mol/L. 另外该传感器具有较高的稳定性和良好的选择性, 抗坏血酸、尿酸和一些氨基酸未对测定产生干扰.     

石墨烯/铁氰化钴复合膜修饰玻碳电极同时测定对苯二酚、邻苯二酚和间苯二酚

采用滴涂法和电沉积法制备了石墨烯/铁氰化钴复合膜修饰玻碳电极. 用扫描电镜对该纳米复合膜进行了表征.用循环伏安法研究了对苯二酚(HQ)、邻苯二酚(CT)和间苯二酚(RS)在修饰电极上的电化学行为. 实验结果表明, 相对于裸玻碳电极和石墨烯修饰电极, HQ, CT 和RS 在石墨烯/铁氰化钴修饰电极上的氧化峰电流显著提高. 利用差分脉冲伏安法测定, HQ, CT 和RS 分别在1.0×10^－6～1.5×10^－4 mol/L, 1.0×10^－6～2.0×10^－4 mol/L 和3.5×10^－6～2.5×10^－4 mol/L浓度范围内与氧化峰电流呈良好的线性关系, 相关系数分别为0.991, 0.993 和0.992. 信噪比为3 时, HQ, CT 和RS 检出限分别为2.0×10^－7, 2.1×10^－7 和3.5×10^－7 mol/L. 将该方法用于水样分析, 回收率为95.6%～106.1%.     

纳米银粒子修饰电极法测定血红蛋白

报道了一种利用纳米材料修饰电极检测血红蛋白的新方法。制作了以纳米银粒子修饰的银电极,并研究了血红蛋白在该修饰电极上的直接电化学行为。实验结果表明,血红蛋白在该修饰电极上具有良好的电流响应。在2.0×10-7~1.0×10-5mol/L浓度范围内,血红蛋白的氧化峰电流与其浓度呈良好线性关系;检出限为7.4×10-8mol/L。研究了该修饰电极对血红蛋白的催化机理,利用该电极所建立的方法实现了对血红蛋白的分析测定。     

基于2,3-丁二酮双缩氨基硫脲为中性载体的新型银离子选择性电极的研究

研究了基于2,3-丁二酮双缩氨基硫脲为中性载体的聚氯乙烯(PVC)膜电极, 该电极对银离子(Ag^＋)具有优良的电位响应性能. 在pH＝3.0的NaOH-HNO₃体系中, 该电极对Ag^＋电极电位呈现近能斯特响应, 线性响应范围为3.0×10^－6～1.0×10^－2 mol/L, 斜率为52.6 mV/decade (20 ℃), 检测下限为1.0×10^－6 mol/L. 相对于常见的阳离子, 该电极对Ag^＋表现出良好的选择性. 采用交流阻抗技术研究了电极响应机理, 并将电极初步应用于回收率实验, 结果令人满意.     

纳米铜修饰电极对多巴胺和抗坏血酸的同时测定

用电沉积方法制备了纳米铜修饰电极并将其用于混合溶液中多巴胺(DA)和抗坏血酸的同时测定。在优化的实验条件下,修饰电极对多巴胺和抗坏血酸具有良好的电催化响应,多巴胺的峰电流与浓度在8.0×10-7mol/L~1.0×10-4mol/L范围内成很好的线性关系,抗坏血酸的氧化峰电流与其浓度在8.0×10-6mol/L~1.0×10-3mol/L的范围成良好的线性关系。该修饰电极制备简单、稳定性好,用于样品检测,效果良好。     

新型双核铜金属配合物为中性载体的硫氰酸根离子高选择性电极的研究

研制了基于N,N'-亚乙基(μ-5,5-亚甲基-二水杨醛根)(乙酰丙酮根)合二铜(II) [Cu₂(II)-MDSBAE]金属配合物为中性载体的阴离子选择性电极. 试验表明, 以Cu₂(II)-MDSBAE金属配合物为中性载体的电极对SCN^－具有良好的电位响应特性, 且呈现反Hofmeister行为,其选择性序列为: SCN^－＞Sal^－＞I^－＞ClO₄^－＞NO₃^－＞Br^－＞NO₂^－＞Cl^－≈SO₃^2－＞SO₄^2－. 在pH 5.0的磷酸盐缓冲体系中, 电极电位呈现近能斯特响应, 线性响应范围为1.0×10^－6～1.0×10^－1 mol/L, 斜率为－53. 6 mV/dec (25 ℃), 检测下限为8.1×10^－7 mol/L. 用交流阻抗研究了电极的响应机理, 并用紫外可见光谱技术测定了电极载体与SCN^－, Sal^－, I^－, ClO₄^－和NO₃^－离子间的配位数及缔合常数. 将该电极用于实验室废水和工业废水中硫氰酸根的检测, 其结果令人满意.     

碳纳米管修饰金电极检测特定序列DNA

利用化学偶联法将末端修饰氨基的寡聚核苷酸固定在表面修饰有羧基化碳纳米管(CNTs-COOH)的金电极表面, 制备新型核酸探针, 可以特异性结合目标单链寡聚核苷酸. 以阿霉素作为嵌合指示剂, 利用示差脉冲法测定杂交的结果. 经过实验条件的优化, 测定DNA浓度在1.0×10^－6～1.0×10^－9 mol/L呈良好的线性关系. 检测限为: 2.54×10^－10 mol/L. 碳纳米管特有的纳米结构对检测结果的放大作用, 提高了该传感器的检测限和灵敏度.     

基于纳米金和硫堇固定酶的过氧化氢生物传感器

在铂电极上自组装一层纳米金(GNs), 构建负电荷的界面, 然后通过金-硫、金-氮共价键合作用和静电吸附作用自组装一层阳离子电子媒介体硫堇(Thio). 再以同样的作用自组装一层GNs和辣根过氧化酶(HRP)的混合物, 最后在电极最外层滴加一层疏水性聚合物壳聚糖(Chit), 由此制备了一种新型的过氧化氢生物传感器. 研究了工作电位、检测底液pH、温度对响应电流的影响, 以及GNs和HRP之间的相互作用, 探讨了传感器的表面形态、交流阻抗、重现性和稳定性. 该传感器的酶催化反应活化能为12.4 kJ/mol, 表观米氏常数为6.5×10^－4 mo/L, 在优化的实验条件下, 所研制的传感器对H₂O₂的线性范围为5.6×10^－5～2.6×10^－3 mol/L, 检出限为1.5×10^－5 mol/L. 应用此方法制备了HRP和葡萄糖氧化酶(GOD)双酶体系葡萄糖生物传感器, 并应用于实验样品葡萄糖含量的测定.     

聚黄苓苷/还原氧化石墨烯修饰电极的制备及对羟胺的检测

通过电聚合的方法制备了聚黄苓苷/还原氧化石墨烯修饰电极,采用扫描电子显微镜和循环伏安法对制备的电极进行了表征和研究。结果表明:该修饰电极对羟胺具有明显的电催化作用。采用计时电流技术对羟胺进行检测,在1.0×10~(-7)~1.1×10~(-4)mol/L的浓度范围内,羟胺的计时电流响应信号和其浓度成良好的线性关系,检测限为52 nmol/L(S/N=3)。该修饰电极能够用于羟胺的样品分析。     

磁性普鲁士蓝纳米颗粒的合成及其化学修饰电极的制作

利用FeSO₄与FeCl₃合成了超细磁性Fe₃O₄纳米颗粒, 并进一步利用该纳米颗粒与铁氰酸钾在酸性溶液(pH～2)中的化学反应成功制备了一种新型的磁性普鲁士蓝纳米颗粒; 研究了该磁性颗粒的磁学性能, 通过磁力将其修饰于固体石蜡碳糊电极表面制成了化学修饰电极, 考察了该电极对过氧化氢的电催化还原及对水合肼的电催化氧化特性. 该化学修饰电极可对过氧化氢和水合肼进行测定, 线性范围分别为过氧化氢2×10^－6～5×10^－3 mol/L, 水合肼7.2×10^－7～3.6×10^－4 mol/L. 利用磁性普鲁士蓝纳米颗粒制得的修饰电极具有催化性能高、稳定性好、表面易更新等优点.     

Simultaneous determination of oxalate, thiosulfate, and thiocyanate in urine by ion-exclusion chromatography with electrochemical detection

Summary A sensitive ion-exclusion chromatographic method has been developed for determination of oxalate, thiosulfate, and thiocyanate. The method is based on separation of these anions on a polymethacrylate-based, weakly acidic cation-exchange resin (TSKgel OApak-A) and detection by means of a glassy carbon (GC) electrode electrochemically modified with polyvinylpyridine (PVP), palladium, and iridium oxide (PVP/Pd/IrO₂). The electrochemical behavior of oxalate, thiosulfate, and thiocyanate at this chemically modified electrode (CME) have been investigated by cyclic voltammetry. The results indicated that electrocatalytic oxidation of these anions by the electrode was efficient and that the sensitivity, stability, and lifetime of the electrode were relatively high. Combined with ion-exclusion chromatography the PVP/Pd/IrO₂ electrode was used as the working electrode for amperometric detection of these anions. All linear ranges were over two orders of magnitude and detection limits, defined asS/N=3, were 9.0×10⁻⁷ mol L⁻¹ for oxalate, 6.7×10⁻⁷ mol L⁻¹ for thiosulfate, and 5.6×10⁻⁷ mol L⁻¹ for thiocyanate. Correlation coefficients were all>0.998. Coupled with microdialysis sampling the method has been successfully applied to the determination of oxalate, thiosulfate, and thiocyanate in urine.     

Direct Electrochemistry of Hemoglobin Entrapped in Composite Electrodeposited Chitosan‐Multiwall Carbon Nanotubes and Nanogold Particles Membrane and Its Electrocatalytic Application

Hemoglobin was entrapped in composite electrodeposited chitosan‐multiwall carbon nanotubes (MCNTs) film by assembling gold nanoparticles and hemoglobin step by step. In phosphate buffer solution (pH 7), a pair of well‐defined and quasireversible redox peaks appeared with formal potential at ?0.289 V and peak separation of 100 mV. The redox peaks respected for the direct electrochemistry of hemoglobin at the surface of chitosan‐MCNTs‐gold nanoparticles modified electrode. The parameters of experiments have also been optimized. The composite electrode showed excellent electrocatalysis to peroxide hydrogen and oxygen, the peak current was linearly proportional to H₂O₂ concentration in the range from 1×10^?6 mol/L to 4.7×10^?4 mol/L with a detection limit of 5.0×10^?7 mol/L, and this biosensor exhibited high stability, good reproducibility and better selectivity. The biosensor showed a Michaelis–Menten kinetic response as H₂O₂ concentration is larger than 5.0×10^?4 mol/L, the apparent Michaelis–Menten constant for hydrogen peroxide was calculated to be 1.61 μmol/L.     

柔红霉素修饰的纳米金电极的制备及其对DNA检测

利用双硫醇分子作为连接剂, 将纳米金颗粒固定于金电极上, 用伏安法、紫外-可见光谱和电化学交流阻抗对其组装过程以及活性进行了表征. 制备的纳米金修饰电极用于DNA测定及其对DNA损伤的检测. DNA的检测限为 1.2×10^－9 mol/L. 该法灵敏、简便.     

Direct Electrochemistry of Hemoglobin at Silver Electrode Modified by Lipoic Acid Monolayer

Abstract

The direct electrochemistry of hemoglobin (Hb) was studied by cyclic voltammetry(CV) and flow injection analysis(FIA) on a silver electrode modified by a self-assembled monolayer of lipoic acid(LA). Lipoic acid molecules can strongly adsorb onto the Ag electrode surface through the cleavage of the S-H bond and the formation of the Ag-S bond. The observed adsorption coverage of LA demonstrates that the LA molecules spontaneously form a self-assembled monolayer. Experimental data show that LA can promote the redox process of Hb at the modified electrode surface. This chemically modified electrode (CME) exhibits good stability in the CV and FIA. Linear sweep voltammetric measurement of Hb at the CME reveals a linear relationship between the oxidative peak current and the concentration of Hb in the range of 5.0×10^?7-1.5×10^?5 mol/L. The relative standard derivation (RSD) for six replicate measurements of 5.0×10^?6 mol/L Hb in FIA is 2.8%. The detection limit is 2.0×10^?7 mol/L. The reaction mechanism involves the hydrogen bond/ salt bridge formation between the carboxylate of LA and the protonated lysine residues of Hb that can enhance the electron transfer reaction. It can be used to detect Hb in real examples.     

An Electrochemical Aptasensor for Detection of Thrombin based on Target Protein‐induced Strand Displacement

A sensitive electrochemical aptasensor for detection of thrombin based on target protein‐induced strand displacement is presented. For this proposed aptasensor, dsDNA which was prepared by the hybridization reaction of the immobilized probe ssDNA (IP) containing thiol group and thrombin aptamer base sequence was initially immobilized on the Au electrode by self‐assembling via Au? S bind, and a single DNA labeled with CdS nanoparticles (DP‐CdS) was used as a detection probe. When the so prepared dsDNA modified Au electrode was immersed into a solution containing target protein and DP‐CdS, the aptamer in the dsDNA preferred to form G‐quarter structure with the present target protein resulting that the dsDNA sequence released one single strand and returned to IP strand which consequently hybridized with DP‐CdS. After dissolving the captured CdS particles from the electrode, a mercury‐film electrode was used for electrochemical detection of these Cd²⁺ ions which offered sensitive electrochemical signal transduction. The peak current of Cd²⁺ ions had a good linear relationship with the thrombin concentration in the range of 2.3×10^?9–2.3×10^?12 mol/L and the detection limit was 4.3×10^?13 mol/L of thrombin. The detection was also specific for thrombin without being affected by the coexistence of other proteins, such as BSA and lysozyme.