银掺杂L-脯氨酸修饰电极用于研究肾上腺素与DNA的相互作用

采用循环伏安方法将Ag~+与L-脯氨酸单体共聚合在玻碳电极表面制得银掺杂聚L-脯氨酸修饰电极,并应用该修饰电极研究了肾上腺素(EP)与双链DNA(dsDNA)之间的相互作用。试验发现:在pH 7.0磷酸盐缓冲溶液中,EP在修饰电板上有一个明显的氧化峰;当加入一定量的dsDNA后,EP的氧化峰电流明显下降。EP氧化峰电流的下降值(△i)与dsDNA的质量浓度在一定范围呈线性关系;dsDNA与EP相互作用形成了分子比为1比2的复合物,两者的结合常数为4.56×10~4。     

生物膜电极在以苯酚为燃料的微生物燃料电池中的应用

以苯酚为燃料, 生物膜电极为负极, Ti/SnO₂-Sb₂O₅/PbO₂电极为正极, 构建了双室微生物燃料电池. 利用微电流驯化法和自然驯化法分别制备了生物膜电极, 研究了微生物的挂膜方法、 挂膜时间和负极基底材料种类对微生物燃料电池产电能力的影响. 结果表明, 微电流驯化法优于自然驯化法, 微电流驯化法制备的生物膜电极更利于电池的产电; 微生物的挂膜时间为8 d时, 电池的产电能力最高, 其最大输出功率密度达到39 mW/m²; 不同基底材料生物膜电极所组建的微生物燃料电池产电能力高低顺序为碳毡>石墨>钛网>泡沫钛.     

用杯芳烃膜修饰碳纤维电极计时电流法测定过氧化氢

在含8.0×10-4mol·L-1杯芳烃的0.1 mol·L-1四丁基高氯酸铵溶液中,在-0.4～0.6 V电位下,在碳纤维电极表面电沉积一层杯芳烃膜,制得杯芳烃膜修饰碳纤维电极.采用扫描电镜和交流阻抗法对电极表面的性能进行了表征,采用循环伏安法和计时电流法对其电化学性能进行研究.试验发现:过氧化氢在杯芳烃膜修饰碳纤维电极上出现一个明显氧化峰,氧化峰电位为0.6 V,提出了用计时电流法测定过氧化氢的方法.在优化的试验条件下,氧化峰电流与过氧化氢的浓度在1.5×10-5～3.8×10-3mol·L-1范围内呈线性关系,检出限(3S/N)为5.0×10-6mol·L-1.修饰电极用于医用消毒水中过氧化氢的测定,所得结果与高锰酸钾滴定法测定值相一致,用标准加入法做回收率试验,所得结果在97%～104%之间,测定值的相对标准偏差(n=10)为4%.     

一种扩大汞膜电极可用电位范围的新方法及应用

研究了玻碳汞膜电极在次黄嘌呤溶液中的电化学行为及在此溶液中对抗坏血酸的电催化性能.结果表明:底液中加入一定量的次黄嘌呤能很好地抑制汞在较高的电位下溶出,并且汞膜电极在此溶液中有较好的稳定性,从而扩大了汞膜电极可用电位范围,为在较高电位下应用汞膜电极测定抗坏血酸提供了条件.在pH 1.81缓冲溶液中,抗坏血酸在汞膜电极上于0.25 V处出现灵敏的不可逆氧化峰(以银-氯化银电极作参比电极),峰电流在5×10-5～2.4×10-3mol·L-1范围内与浓度呈线性关系;检出限分别为8×10-6mol·L-1.该方法用于维生素C片剂中抗坏血酸含量的测定,分析结果的相对标准偏差(n=7)为1.3%,回收率在101.2%～104.5%之间.     

L—谷氨酰胺动物组织电极的研制及应用

将含有谷氨酰胺酶的猪肾组织切片固定于聚酯膜和聚碳酸酯膜之间,并与氨电极偶合制成L-谷氨酰胺传感器。线性范围10~(-4)～5×10~(-2)mol/L,响应时间5min。测量细胞培养基RPMI—1640,结果与实际值吻合。标准加入回收率98.75％。     

基于聚间苯二胺-壳聚糖复合膜的葡萄糖电化学生物传感器

采用循环伏安法在铂电极表面形成聚间苯二胺-壳聚糖复合膜;以戊二醛为交联剂将葡萄糖氧化酶共价固定在复合膜上形成葡萄糖电化学生物传感器;运用扫描电镜考察复合膜的形貌特征;考察了壳聚糖用量和电位循环圈数对膜特性的影响;采用电流-时间法考察了该传感器对葡萄糖的电化学响应特性。结果表明,该传感器对葡萄糖有较快的响应速度(3.5s),在0.02m mol·L-1~1.27mmol·L-1浓度范围内响应电流与葡萄糖浓度成正比,检测极限为0.01m mol·L-1,样品测定的加标回收率为97.1%~102.5%。该传感器具有较好的选择性,对葡萄糖的测定具有较高的准确度与精密度。     

巯基丁二胺铜单层修饰金电极上HIV-p24抗原的电化学免疫检测

制备了用巯基丁二胺铜(CuL)修饰的金电极并用作HIV-p24抗原蛋白(简称p24)免疫检测的化学传感器。CuL通过单层自组装固定在金电极表面,其覆盖率为1.02×10-11mol.cm-2,在含有1.0 mmol.L-1过氧化氢并在pH 6.2的磷酸盐缓冲溶液中,制备的校正曲线的线性范围为0.5-150μg.L-1p24对相应的伏安响应,方法的检出限为0.2μg.L-1。在10μg.L-1p24浓度水平作精密度试验,得RSD值为3.5%,于试样中分别加入5,15,20及30μg.L-1p24进行回收率试验,所得结果在98%-102%之间。此方法毋需另加电子传递媒介体。应用此方法于临床血清分析,所得结果与放射性免疫法的结果一致,且所得RSD值均小于0.3%。     

单壁碳纳米管修饰电极循环伏安法测定盐酸利多卡因

将单壁碳纳米管(SWCNT′s)分散在10g.L-1十二烷基磺酸钠溶液中并滴涂在玻碳电极表面,红外灯烘干后,制备了单壁碳纳米管修饰电极。采用循环伏安法研究了盐酸利多卡因在修饰电极上的电化学行为。结果表明:盐酸利多卡因在该修饰电极上出现了一个灵敏的氧化峰,其峰电流比在裸玻碳电极上增大了5倍。据此提出了用循环伏安法测定盐酸利多卡因的方法。盐酸利多卡因的浓度在0.9～50.0μmol.L-1范围内,氧化峰电流与其浓度呈线性关系,检出限(3S/N)为0.3μmol.L-1。修饰电极用于盐酸利多卡因注射液中盐酸利多卡因的测定,测定值与标示值相符,加标回收率在98.0%～105%之间。     

以伴刀豆球蛋白为固定基质的脲酶生物传感器

本文制备了一种以溶剂聚合膜pH电极作原电极,利用伴刀豆球蛋白(Con A)与糖蛋白间的特异性识别作用,将Con A和脲酶表面的麦芽糖残基结合,采用交替沉积Con A和脲酶,进行多层脲酶膜组装的脲酶生物传感器。研究了酶固定化条件的影响,优化了实验条件,测试了传感器对尿素的生物电化学响应。在6.9×10-5~1.0×10-3mol.L-1的浓度范围内传感器响应的电极电位与尿素浓度的对数成正比,检出限为4.5×10-5mol.L-1。将传感器用于牛奶样品中回收率的测定,结果满意。     

线性扫描伏安法测定辣椒制品中苏丹红Ⅰ含量

基于苏丹红Ⅰ分子中的-C=C-和-N=N-基团的电活性,在悬汞电极上还原产生还原波,其还原峰高与苏丹红的浓度呈线性关系。据此提出用线性扫描伏安法测定辣椒制品中苏丹红Ⅰ的含量。试验中用悬汞电极为工作电极,饱和甘汞电极为参比电极,铂微电极为对电极,饱和硼砂缓冲溶液(pH 9.2)为支持电解质,并以丙酮作为样品的溶剂,记录在-1 050mV处还原峰电流ip。测得苏丹红Ⅰ的质量浓度在0.1~1.4mg·L-1范围内与其峰高呈线性关系,检出限(3s/k)为9.8μg·L-1。用标准加入法进行回收试验,测得回收率在88.0%~98.4%之间,测定值的相对标准偏差(n=5)在0.72%~5.4%之间。     

Microbial electrode sensor for vitamin B12

A microbial sensor consisting of immobilized Escherichia coli 215 and an oxygen electrode is described for the determination of vitamin B₁₂. When the sample solution is injected into the microbial electrode system, the increased consumption of oxygen by the micro-organisms causes a decrease in the dissolved oxygen around the porous membrane of the oxygen electrode and the current decreases gradually with time until a steady state is reached. The response time for a rate measurement is 2 h. When 0.5 mg of Escherichia coli 215 is immobilized, a linear relationship is obtained between the current decrease and the vitamin B₁₂ concentration between 5 × 10^?9 and 25 × 10^?9 g ml^?1.     

生化需氧量微生物传感器的研究进展

生化需氧量(biochemical oxygen demanded，BOD)是衡量水污染程度必须测定的重要指标之一。然而，传统的5d法不能及时反映排放水的污染程度。因此，能够快速、准确测定BOD的微生物传感器近年来得到了迅速发展。本文综述了BOD微生物传感器及其商品化仪器的发展，并对能使BOD传感器与传统的5d法得到更为一致的结果的方法做了总结。     

Ammonium ion sensor based on immobilized nitrifying bacteria and a cation-exchange membrane

The ammonium ion sensor is based on nitrifying bacteria isolated from activated sludge. The sensor comprises a cation-exchange membrane, an alkaline solution layer (pH 10), a gas-permeable membrane, an immobilized microbial membrane, and an oxygen electrode. This novel combination provides accurate amperometric determinations of ammonium ions in aqueous solutions within 7 min in the range 10^-4– 4.5 × 10^-2 M. Volatile amines or other ions do not interfere. The relative error is within 4% and the sensor can be used continually for more than 10 days.     

Response Characteristics of a Glucose Electrode with a Sensing Membrane Prepared by Plasma Polymerization

A glucose electrode was composed of a dissolved oxygen electrode and an immobilized glucose oxidase membrane prepared by plasma polymerization of propargyl alcohol as a monomer. Fairly good precision of the electrode response to sample solutions was obtained by measurements using the steady-state method or the reaction rate method. Activity of the glucose oxidase immobilized within the membrane and mounted on the electrode lasted for 50 consecutive measurements over 5 days, and, if the membrane was stored in a buffer solution of pH 7.0 at a temperature of 0°C, the activity was preserved for more than 2 months. Such immobilization of the glucose oxidase with the plasma polymer effectively suppressed interference from Cu²⁺ions, which would seriously interrupt oxidation of the glucose in homogeneous solutions, in the sample solutions.     

Microbial Membrane Electrode for Steroid Assay

Abstract

Polyacrylamide - immobilized Nocardia opaca was coupled to a rotating glassy carbon electrode to form a microbial membrane electrode for the estimation of steroid hormones. The principle of assay is baaed on the detection of reduced artificial electron acceptor. The concentration dependence for 3 keto- 4- enesteroids solubilized in methanol was demonstrated.     

Immobilization of creatinine deiminase on a substituted poly(methylglutamate) membrane and its use in a creatinine sensor

A substituted poly(γ-methyl-l-glutamate) membrane is used for chemical immobilization of creatinine deiminase. The permeability of the membrane is controlled by the conditions used for membrane preparation. The creatinine sensor based on the immobilized enzyme membrane with immobilized nitrifying bacteria and an oxygen electrode exhibited greater sensitivity than the sensor previously reported which had a 1,8-diamino-4-amino-methyloctane membrane. The sensor gave a linear response to creatinine over the range 1–10 mg dl^?1; responses remained stable for two weeks.     

Steady-state oxidation of cholesterol catalyzed by cholesterol oxidase in lipid bilayer membranes on platinum electrodes

Cholesterol oxidase is immobilized in electrode-supported lipid bilayer membranes. Platinum electrodes are initially modified with a self-assembled monolayer of thiolipid. A vesicle fusion method is used to deposit an outer leaflet of phospholipids onto the thiolipid monolayer forming a thiolipid/lipid bilayer membrane on the electrode surface. Cholesterol oxidase spontaneously inserts into the electrode-supported lipid bilayer membrane from solution and is consequently immobilized to the electrode surface. Cholesterol partitions into the membrane from buffer solutions containing cyclodextrin. Cholesterol oxidase catalyzes the oxidation of cholesterol by molecular oxygen, forming hydrogen peroxide as a product. Amperometric detection of hydrogen peroxide for continuous solution flow experiments are presented, where flow was alternated between cholesterol solution and buffer containing no cholesterol. Steady-state anodic currents were observed during exposures of cholesterol solutions ranging in concentration from 10 to 1000 μM. These data are consistent with the Michaelis-Menten kinetic model for oxidation of cholesterol as catalyzed by cholesterol oxidase immobilized in the lipid bilayer membrane. The cholesterol detection limit is below 1 μM for cholesterol solution prepared in buffered cyclodextrin. The response of the electrodes to low density lipoprotein solutions is increased upon addition of cyclodextrin. Evidence for adsorption of low density lipoprotein to the electrode surface is presented.     

流动注入式乳酸生物传感器

研制了一种测定L－乳酸的生物传感器,将乳酸氧化酶（LOD）通过共价键固定在尼龙钢上制备乳酸氧化酶膜,将制得的酶膜固定在氧电极上构成乳酸生物传感器;将透析膜放在氧化酶膜上产生对L－乳酸扩散高度限制来改变该生物传感器的响应;酶膜机械强度高,在氧电极上反复装卸而不损坏,所构成的乳酸生物传感器的校正曲线的乳酸定量上限达5mmol/L,响应时间小于30s;初步血样测试的结果显示该乳酸生物传感器用于临床血乳酸的测定具有可行性。     

Amperometric determination of acetic acid with immobilized Trichosporon brassicae

A microbial sensor consisting of immobilized Trichosporon brassicae, a gas-permeable Teflon membrane and an oxygen electrode is suitable for the continuous determination of acetic acid in fermentation broths. When an acetic acid solution is pumped through the flow system, the current decreases to a steady state with a response time of 8 min; shorter pumping times give peaks which can also be measured. The relationship between the current decrease and the acetic acid concentration is linear up to 54 mg l^-1, with a relative standard deviation of about 6% at the higher concentrations. Selectivity is satisfactory. Results obtained with this sensor and by gas chromatography for a glutamic acid fermentation broth were in good agreement (regression coefficient 1.04). The sensor was stable for more than 3 weeks and 1500 assays.     

Development of cholesterol biosensor based on immobilized cholesterol esterase and cholesterol oxidase on oxygen electrode for the determination of total cholesterol in food samples

The development of a cholesterol biosensor by co-immobilization of cholesterol esterase (ChEt) and cholesterol oxidase (ChOX) on oxygen electrode is described. The electrode consists of gold cathode and Ag/AgCl anode. The enzymes were immobilized by cross-linking with glutaraldehyde and Bovine Serum Albumin (BSA). The immobilized enzymatic membrane was attached to the tip of the electrode by a push cap system. The optimum pH and temperature of the sensor was determined, these are 6 and 25 degrees C respectively. The developed sensor was calibrated from 1-75 mg/dl of cholesterol palmiate and found linear in the range of 2-50 mg/dL. The calibration curve was drawn with V(i) (ppm/min)(initial velocity) vs different concentrations of cholesterol palmiate (mg/dL). The application of the sensor to determine the total cholesterol in different real food samples such as egg, meat was investigated. The immobilized enzymatic layer can be reused over 30 times and the stability of the enzymatic layer was studied up to 9 weeks.