一种基于静电吸附作用的直接检测补体C3新型可再生电容型免疫传感器

通过壳聚糖/褐藻酸钠体系实现抗体在电极上的固定,制得可多次再生的电容型免疫传感器,用于补体C₃的检测.先在金电极表面上组装一层半胱胺单分子层,通过戊二醛把壳聚糖修饰在金电极上,再用十二硫醇封闭电极,最后,利用壳聚糖与褐藻酸钠之间的强静电相互作用实现抗体的固定.使用交流阻抗法研究了溶液pH值和离子强度对电极膜层稳定性及对抗体固定性的影响.结果表明,所制备的传感器操作简便,易于再生,电容响应与补体C₃浓度在18.2～292.5ng/mL范围内呈线性关系,检出限为9.1ng/mL.     

光导纤维胆固醇生物传感器的研究

将胆固醇酯酶、胆固醇氧化酶和辣根过氧化物酶通过戊二醛交联反应,固定在牛血清蛋白上,制成光纤胆固醇生物传感器的传感膜.此传感器偶合了胆固醇酯水解、胆固醇的氧化和鲁米诺同过氧化氢的化学发光等3种酶催化反应,通过光纤输出的化学发光信号进行检测.测定总胆固醇和自由胆固醇的线性范围均为0.5～20μg/mL,检测下限为0.1μg/mL,响应时间为2min,寿命在2个月以上,适用于血清中总胆固醇和游离胆固醇的测定.     

基于碳纳米管固定抗原的电化学免疫传感器法测定IgG抗体

以1-萘酚磷酸酯为底物,将IgG抗原吸附固定在碳纳米管修饰玻碳电极的表面,利用待测IgG抗体和碱性磷酸酯酶标记IgG抗体共同竞争免疫传感器表面的IgG抗原,研制了一种新型的电化学免疫传感器用于IgG抗体的测定。碱性磷酸酯酶可以催化底物1-萘酚磷酸酯水解生成1-萘酚,在电极表面氧化产生电信号。在电位为+0.30 V(vs.SCE)时,响应电流与IgG抗体浓度在5.0×10-9～5.0×10-7g/mL范围内呈良好的线性关系,检出限为2.0×10-9g/mL。     

基于酶催化银沉积质量放大的血吸虫压电免疫传感器的研究

发展了一种基于酶催化金属银沉积信号放大的新型高灵敏气相压电免疫传感检测技术.先将血吸虫抗原(SjAg)共价固定在石英晶体表面,制备得到血吸虫压电免疫传感器.检测时,在晶振上滴加不同浓度的待测血吸虫抗体,再将碱性磷酸酶标记的二抗通过夹心方式结合到传感器表面.然后利用碱性磷酸酶催化磷酸化的抗坏血酸酯水解从而还原硝酸银,使金属银沉积在晶振表面上,放大传感器的质量响应信号.实验结果表明该传感检测方法可显著提高气相压电免疫传感器的检测灵敏度,传感器对血吸虫抗体的响应线性范围在1～225 ng/mL,检测下限为1 ng/mL.     

基于磁性纳米颗粒的日本血吸虫抗体荧光免疫分析

研究了一种基于磁性纳米颗粒的日本血吸虫荧光免疫分析方法。日本血吸虫抗原通过共价吸附到核壳结构的磁性颗粒表面,与待测抗体结合后,再与酶标二抗夹心反应,最后以3,3′,5,5′-四甲基联苯胺(TMB)为底物,通过测定酶催化下TMB氧化生成无荧光的二聚体化合物,使溶液荧光强度降低来间接测定日本血吸虫抗体的浓度。应用本方法测定了兔血清中日本血吸虫抗体,荧光强度(If)与抗体浓度(C)在5.0~100μg/L之间呈线性关系,线性回归方程为If=225.8-1.6C(r=0.9976),检出限达1.5μg/L。方法简单实用,具有良好的检测灵敏度和重现性。     

基于纳米金与碳纳米管-纳米铂-壳聚糖纳米复合物固定癌胚抗原免疫传感器的研究

采用纳米金(nano-Au)、多壁碳纳米管-纳米铂-壳聚糖的纳米复合物(MWNT-Pt-CS)及电子媒介体硫堇(Th)固载抗体制得高灵敏癌胚抗原免疫传感器．首先, 于壳聚糖溶液中用NaBH4还原H2PtCl6, 并将多壁碳纳米管分散于其中制得碳纳米管-纳米铂-壳聚糖纳米复合物, 并将其滴涂在玻碳电极上成膜; 然后, 吸附电子媒介体硫堇制得硫堇/碳纳米管-纳米铂-壳聚糖(Th/MWNT-Pt-CS)修饰电极．利用壳聚糖和硫堇分子中大量的氨基固定纳米金并吸附癌胚抗体(anti-CEA); 最后, 用辣根过氧化物酶(HRP)封闭活性位点从而制得高灵敏电流型免疫传感器．在优化的实验条件下, 该传感器响应的峰电流值与癌胚抗原(carcinoembryonic antigen)浓度在0.5～10和10～120 ng/mL的范围内保持良好的线性关系, 检测限为0.2 ng/mL．     

白藜芦醇作辣根过氧化物酶底物的布氏杆菌抗体酶联免疫传感器研究

一种纯天然产物白藜芦醇用作辣根过氧化物酶(HRP)底物。对其化学性质的研究证实,白藜芦醇在空气中较稳定,对HRP、H2O2的电化学响应性能优于传统HRP底物,对人体无毒害。白藜芦醇在HRP催化下可被H2O2氧化成醌,产物醌在电极上于-376 mV处可被还原,其电流的大小与HRP的浓试在一定浓度范围内呈线性相关。将兔布氏杆菌抗原包埋在石墨-石蜡基质中制备了测定兔布氏杆菌抗体的电化学酶联免疫传感器,该传感器测定兔布氏杆菌抗体的线性范围为3×10-4~1.65×10-2g/L;检出限为1×10-4g/L;RSD为4.6%。本方法制备免疫传感器的电化学性能稳定,抗原活性保持良好。     

石墨烯-壳聚糖复合物修饰电极构建电化学免疫传感器对1-芘丁酸的检测研究

采用石墨烯(GS)和壳聚糖(CS)复合膜修饰玻碳电极(GS-CS/GCE),利用1-乙基-(3-二甲基氨基丙基)碳二亚胺盐酸盐(EDC)和N-羟基丁二酰亚胺(NHS)(4∶1)活化GS-CS/GCE,共价固定多环芳烃抗体(anti-PAHs),构建灵敏度高、稳定性好的非标记电流型免疫传感器,用于1-芘丁酸(PBA)的检测。运用扫描电子显微镜对GS-CS复合膜的形貌进行表征。在pH 7.0含10 mmol/L K3Fe(CN)6和0.1 mmol/L KCl的磷酸盐溶液中,通过循环伏安法和示差脉冲伏安法研究修饰电极表面的电化学性质,并考察了免疫传感器的电化学性能。研究表明,由于石墨烯和壳聚糖的协同作用,GS-CS修饰的玻碳电极在Fe(CN)64-/3-溶液中的峰电流明显增大,有利于提高免疫传感器的灵敏度。在优化实验条件下,电极表面的anti-PAHs抗体固定量显著提高,增强了电极的分子识别性能。由于anti-PAHs抗体-抗原结合物的导电性较差,免疫传感器的峰电流随着待测溶液中PBA浓度的增大而减小,PBA浓度在0.1～80μg/L范围内呈良好的线性关系,检出限为0.03μg/L。该免疫传感器重现性好、特异性强,用于实际样品的测定,回收率为90%～105%。     

基于中性红电聚合膜的伏安型甲胎蛋白免疫传感器

用循环伏安法在玻碳电极上电聚合一层稳定的中性红聚合物膜,再通过共价键合作用将戊二醛和甲胎蛋白抗体自组装到电极表面,最后用辣根过氧化物酶封闭电极上的非特异性吸附位点,并同时起到放大响应电流信号的作用,制得高灵敏伏安型甲胎蛋白抗原免疫传感器。实验结果表明,该传感器对甲胎蛋白抗原具有良好的电流响应,该传感器的线性范围为1.00～10.0ng/mL和10.0～200ng/mL,检出限(3σ)为0.40ng/mL。     

基于酶标抗体和媒介体共吸附于金胶壳聚糖膜的PSA免疫传感器的制备

本文研制了一种用金胶壳聚糖仿生膜来同时固定四甲基联苯胺（TMB）和酶标抗体的新型电化学免疫传感器,用于检测血清肿瘤标志物前列腺特异性抗原（PSA）的含量。固定的TMB作为电子传递媒介体,在扫速小于45 mV/s时,电极表现为一个表面控制过程,而在扫速大于45 mV/s时则表现为一个扩散控制过程。将固定有酶标抗体和TMB的免疫传感器与待测PSA抗原一起培育,在该传感器上形成的免疫复合物通过TMB-H₂O₂-HRP电化学体系进行了测定。在优化实验条件下,PSA的线性检测范围为5-30 ng·mL^-1,检测限为1.0 ng·mL^-1。该PSA免疫传感器制备方法简单,成本低廉,具有较好的稳定性和重现性。     

Preparation, Properties and Mechanism of Inhomogeneous Calcium Alginate Ion Cross-linking Gel Microspheres

Inhomogeneous calcium alginate ion cross-linking gel microspheres,a novel ion absorbent,were prepared by dropping a sodium alginate solution to a calcium chloride solutioin via an electronic droplet generator.Calcium alginate microspheres have uniform particle sizes.a smooth surface and a microporous structure.The electrode probe reveals the inhomogeneous distribution of calcium ions with the highest concentration on the surface,and the lowest concentration in the cores of the spheres.As a novel ion adsorbent,calcium alginate gel microspheres have a lower limiting adsorption mass concentration,a higher enrichment capacity and a higher adsorption capacity for Pb^2 than usual ion exchange resins.The highest percentage of the adsorption is 99.79%.The limiting adsorption mass concentration is 0.0426mg/L.The adsorption capacity for Pb^2 is 644mg/g,Calcium alginate gel microspheres have a much faster ion exchange velocity than D418 chelating resin and D113 polyacrylate resin.The moving boundary model was employed to interpret the ion exchange kinetics process,which indicates that the ion exchange process is controlled by intraparticle diffusion of adsorbable ions.So the formation of inhomogeneous gel microspheres reduces the diffusion distance of adsorbable ions within the spheres and enhances the ion exchange velocity.Alginate has a higher selectivity for pb^2 than for Ca^2 and the selectivity coefficient KCa^Pb is 316. As an ion cross-linking gel,calcium alginate inhomogeneous microspheres can effectively adsorb heavy metal Pb^2 at a higher selectivity and a higher adsorption velocity.It is a novel and good ion adsorbent.     

A piezoelectric immunoassay based on self-assembled monolayers of cystamine and polystyrene sulfonate for determination of Schistosoma japonicum antibodies

A piezoelectric immunosensor based on an improved immobilization strategy combining self-assembled monolayers (SAM) of cystamine (Cys) and polystyrene sulfonate (PSS) has been developed for the determination of Schistosoma japonicum antibodies (SjAb) in rabbit serum. Cys SAM were first applied to the gold electrode surface of the crystal, serving as a positively-charged base. Schistosoma japonicum antigen (SjAg) was then electrostatically immobilized on the crystal by means of a negatively-charged PSS layer. When sealed by use of an appropriately selected blocking reagent for BSA and normal rabbit serum (NRS), non-specific adsorption could be substantially reduced.The immunosensor was used to determine SjAb in optimized buffer medium with addition of poly(ethylene glycol) (PEG), which served as an immunoreaction enhancer. It was shown experimentally that SjAg immobilized by the Cys-PSS adsorption procedure had higher immunological activity or binding efficiency than those immobilized by the glutaraldehyde (GLU) binding or direct attachment procedures. The immunosensor developed had satisfactory sensitivity and detection limit, and regeneration of the piezoelectric quartz-crystal was easy. Analytical results obtained with infected rabbit serum samples indicated that the proposed immunosensor is a promising alternative for qualitative and quantitative determination of SjAb in clinical diagnosis of infection with Schistosoma japonicum.     

In Situ Amperometric Detection of Vesicles and Microgel Phases in an Aggregating System: Calcium Alginate

In situ amperometric characterization of an aggregating system in terms of molecular adsorption and single microparticle interactions at the electrode interface is demonstrated using a model system: alginate/Ca(II) in an aqueous electrolyte solution. Recording of chronoamperometric curves of oxygen reduction at the dropping mercury electrode is designed for detection of dip‐shaped signals of individual gel microparticles. By addition of Ca(II) decrease of alginate adsorption is accompanied by appearance of signals indicating vesicle type association of alginate molecules and microparticles of gel phase. AFM imaging provided evidence of initial stage in calcium alginate gel formation.     

Determination of creatinine with a sensor based on immobilized glutamate dehydrogenase and creatinine deiminase

Glutamate dehydrogenase and creatinine deiminase are immobilized by adsorption on wet poly(vinyl chloride) membranes. Creatinine is determined by a sensor consisting of the two membranes placed over an ammonia-sensing electrode. Endogenous ammonia is removed as it passes through the glutamate dehydrogenase layer. Creatinine (1–50 mg dl^?1) is converted to ammonia in the inner creatinine deiminase layer and is detected by the ammonia electrode. The assay requires 3 min, the minimum detectable concentration is 1 mg dl^?1 at pH 8.5, and the precision is ca. 5%. Endogenous ammonia can be tolerated up to 2 × 10^?4 M.     

An amperometric immunosensor based on a conducting immunocomposite electrode for the determination of Schistosoma japonicum antigen.

A renewable amperometric immunosensor based on a graphite-paraffin-Schistosoma japonicum antibody (SjAb) biocomposite electrode has been prepared for the detection of Schistosoma japonicum antigen (SjAg). Competitive ELISA was employed involving HRP-SjAg as a tracer and 3,3',5,5'-tetramethylbenzidine (TMB) as a substrate. The product of an enzyme catalytic reaction was detected at +0.1 V (vs. Ag/AgCl reference electrode) for measuring the amount of HRP-labeled SjAg binding to the electrode surface. The assay conditions were optimized, including the amount of SjAb loading in the electrode and HRP-SjAg in the incubation solution, the pH of the measuring solution and the incubation time. The measuring range was 0.5-30 microg/ml under the optimum conditions. Rabbit serum samples of different infection degree were measured, which demonstrated that the immunosensor meets the demands of clinical analysis. It exhibits some advantages, such as simplicity of fabrication, rapidity of measurement, and satisfactory sensitivity and reproducibility.     

微囊化海藻酸离子移变凝胶的制备、结构与性能

通过静电脉冲技术制备了海藻酸-壳聚糖-海藻酸(Alginate-Chitosan-Alginate,ACA)微胶囊,红外光谱分析表明,ACA是一种以聚电解质配合物为囊膜,以海藻酸钠离子吸附剂为囊心物的微胶囊型离子吸附体系.扫描电镜测试表明,ACA吸附重金属离子的过程是微胶囊囊内海藻酸凝胶化的过程,其解吸附过程是海藻酸凝胶转变成海藻酸溶液的过程.与传统离子交换树脂相比,ACA对Pb²⁺的吸附具有较高的去除率、很强的富集能力和较低的极限吸附浓度,并且能够被多次重复使用.ACA的离子交换速率比传统离子交换树脂快得多,离子交换过程中,交换离子和吸附剂海藻酸分子的相互扩散大大提高了离子交换速率.     

海藻酸钠水凝胶固载细胞色素c的蛋白膜伏安法研究

用海藻酸钠(SA)水凝胶将细胞色素c(cyt-c)固定在棱面热解石墨电极(EPPGE)表面,形成稳定的SA-cyt-c/EPPGE电极,采用蛋白膜伏安法(PFV)研究了cyt-c与电极之间的直接电化学和离子强度、pH、外加金属离子对其电化学行为的影响及其电催化性能。结果表明:cyt-c中血红素辅基Fe(Ⅲ)/Fe(Ⅱ)电对表现出准可逆行为,pH7.0、NaCl浓度为0.1 mol/L时电化学活性最高,外加金属离子则有抑制作用,SA-cyt-c/EPPGE可催化还原O2,有可能发展成为一种溶解氧的生物传感器。     

氧化钯作为电位型传感器中敏感电极的工作机理

This paper describes the sensing properties of a potentiometric sensor based on a palladium oxide (PdO) electrode. Our investigation of the sensing mechanism is also discussed. We studied carbon monoxide (CO) sensing performance of a PdO electrode doped with Mg, Ni, and La, printed on zirconia. The results indicated that defects on the surface of PdO, which allow adsorption of CO, can effectively enhance the sensitivity of the sensors. To explore the source of the signal, a PdO-based electrode was printed on an alumina disc and a zeolite pellet for CO detection at 450℃. Notably the zeolite coupled with the PdO-based electrode to generate potentiometric responses to changes in CO concentration. According to the resistance and impedance measurements, the response to CO was ascribed to the changing interfacial potential between the PdO electrode and electrolyte. A model based on an electrochemical double layer between the PdO and electrolyte was determined to explain the behavior of the potentiometric sensor. It may be possible to harness these effects at PdO electrodes for the development of electrochemical sensors.     

Development of a disposable miniature l-lysine sensor

A hybrid l-lysine sensor consisting of an immobilized l-lysine decarboxylase and a miniature bacterial CO₂ sensor was fabricated using semiconductor techniques. The bacteria was immobilized in a calcium alginate gel in a miniature oxygen electrode cell together with the electrolyte. The enzyme was immobilized in a bovine serum albumin matrix on a gas-permeable membrane. The cell was formed on a silicon substrate by anisotropic etching and had a two-gold-electrode configuration. The response time of the l-lysine sensor was 1–3 min. The optimum pH was 6.0 and the optimum temperature was 33°C. The response to l-lysine concentration was linear from 25 to 400 μM. Reproducible responses were obtained by adding more than 1 μM pyridoxal-5′-phosphate. The sensor had excellent selectivity for l-lysine and a stable response for more than 25 repetitive operations.     

Sensor–actuator system for dynamic chloride ion determination

Chloride is a crucial anion for various analytical applications from biological to environmental applications. In order to measure the chloride ion concentration, a measurement system is needed which can detect this concentration for prolonged times reliably. Chronopotentiometry is a technique which does not need a long term stable reference electrode and is therefore very suitable for prolonged ion concentration measurements. As the used electrode might be fouled by reaction products, this work focuses on a chronopotentiometric approach with a separated sensing electrode (sensor) and actuating electrode (actuator). Both actuation and sensor electrode are made of Ag/AgCl. A constant current is applied to the actuator and will start the reaction between Ag and Clˉ, while the resulting Clˉ ion concentration change is observed through the sensor, which is placed close to the actuator. The time it takes to locally deplete the Clˉ ions is called transition time. Experiments were performed to verify the feasibility of this approach. The performed experiments show that the sensor detects the local concentration changes resulting from the current applied to the actuator. A linear relation between the Clˉ ion concentration and the square root of the transition time was observed, just as was predicted by theory. The calibration curves for different chips showed that both a larger sensor and a larger distance between sensor and actuator resulted in a larger time delay between the transition time detected at the actuator and the sensor.