BOD微生物传感器的研制

本文是以BSA-GA为交联剂,将异常汉逊氏酵母菌(Hansenula anomalaVar.scheggil)菌体固定成膜,与氧电极偶合研制成BOD微生物传感器.在29.5℃、pH6.8的工作条件下,该传感器响应时间为2～3min,线性范围1～85mg/L,标准偏差0.91mg/L,变异系数4.2%,回收率94～107%,该电极操作简便、快速、测定的重现稳定性较好,能连续稳定测试一周以上,可作为各种污水中BOD测定的新方法.     

Quick and reliable estimation of BOD load of beverage industrial wastewater by developing BOD biosensor

An amperometric biosensor for determination of biochemical oxygen demand in wastewater has been developed to overcome the time consuming monitoring procedures. The performance and stability of the immobilized membrane have been investigated at 37 °C and pH 6.8. Immobilized microbial membranes maintain their stability and activity after intermittent use for 400 cycles when stored at 4 °C in sodium phosphate buffer pH 6.8. The response time of the BOD sensor was only 90 min, being independent of the concentration, and the lower detection limit was 1 mg/l. The obtained BOD values showed correlation with that of the conventional method for BOD determination (BOD5) with a deviation of ±10%. Moreover, the sensor exhibits good repeatability (3.39–4.45%) and reproducibility (1.85–2.25%). Software was added to upgrade this sensor and to make it a promising candidate for online monitoring.     

一种用于测定氧浓度的 荧光传感器的开发及研究

基于化学发光及氧及对荧光的猝灭作用，开发了一种荧光氧传感器。考虑到气体猝灭（氧）在高分子半透膜内同时存在吸附与溶解作用，一个新的荧光猝灭动力学模型建立起来了，该方程能够很好地说明荧光猝灭的机理，并能够非常准确地拟合实验数据。     

Influence of Matrices on Oxygen Sensing of Three Sensing Films with Chemically Conjugated Platinum Porphyrin Probes and Preliminary Application for Monitoring of Oxygen Consumption of Escherichia coli (E. coli)

Oxygen sensing films were synthesized by a chemical conjugation of functional platinum porphyrin probes in silica gel, polystyrene (PS), and poly(2-hydroxyethyl methacrylate) (PHEMA) matrices. Responses of the sensing films to gaseous oxygen and dissolved oxygen were studied and the influence of the matrices on the sensing behaviors was investigated. Silica gel films had the highest fluorescence intensity ratio from deoxygenated to oxygenated environments and the fastest response time to oxygen. PHEMA films had no response to gaseous oxygen, but had greater sensitivity and a faster response time for dissolved oxygen than those of PS films. The influence of matrices on oxygen response, sensitivity and response time was discussed. The influence is most likely attributed to the oxygen diffusion abilities of the matrices. Since the probes were chemically immobilized in the matrices, no leaching of the probes was observed from the sensing films when applied in aqueous environment. One sensing film made from the PHEMA matrix was used to preliminarily monitor the oxygen consumption of Escherichia coli (E. coli) bacteria. E. coli cell density and antibiotics ampicillin concentration dependent oxygen consumption was observed, indicating the potential application of the oxygen sensing film for biological application.     

Optical fiber sensing element based on luminescence quenching of silica nanowires modified with cryptophane-A for the detection of methane

An optical fiber sensing element based on luminescence quenching of cryptophane-A/silica nanowires was successfully constructed and used to dynamically monitor methane gas at low concentration below 3.5% (v/v). The optical fiber device was designed to operate via luminescence reflection. The sensing properties of optical sensing element to methane at room temperature were characterized. The sensing element shows an intensive and stable blue luminescence when excited by UV light source at wavelength of 380 nm, and it is efficiently quenched by molecular methane. The response of the sensing element demonstrates excellent linear Stern-Volmer behavior at the fixed wavelength 439 nm within the methane concentration range between 0.1% and 3.5% (v/v). A detection limit of below 0.1% (v/v) is estimated for the methane sensing element. This newly developed methane sensing element has significant advantages over the currently available methane sensors such as fast response and recovery (within seconds), good repeatability, selectivity, and long-term stability.     

Reaction-rate measurements by use of membraneless flow-through biosensors

Three different approaches to performing reaction-rate measurements by using flow-through optical biosensors are proposed. This type of biosensor consists of a special flow-cell located in a conventional spectrophotometer, on the inner walls of which a biocatalyst is immobilized. Reaction-rate measurements can be made by coupling the biosensor on-line to different flow-injection (FI) manifolds: a normal FI system in which the flow is halted while the sample plug is in the flow-cell; another where the flow direction is changed iteratively; and an open-closed configuration. The performance of the three manifolds is critically studied and compared by using the same biosensor (immobilized β- -glucuronidase) for the determination of glucuronide derivatives.     

Layer-by-layer construction of an active multilayer enzyme electrode applicable for direct amperometric determination of cholesterol

A biosensor for direct amperometric determination of cholesterol was constructed by a layer-by-layer nanothin film formation using cholesterol oxidase (COx) and poly(styrenesulfonate) on a monolayer of microperoxidase covalently-immobilized on Au–alkanethiolate electrodes. Cyclic voltammograms (CVs) of microperoxidase covalently-immobilized on mercaptopropionic acid- and aminoethanethiol-monolayer electrodes showed a redox wave with the formal potential of 0.40 V (versus Ag | AgCl | NaCl (sat.)). The formal potential and the apparent heterogeneous electron-transfer rate of immobilized microperoxidase were not specific with the inner Au–alkanethiolate layer. The biosensor shows a linear current response for cholesterol at the applied potential of 0 V in the concentration range of 0.2–3.0 mM with a correlation coefficient of 0.969. The current response of the biosensor for cholesterol was very rapid (response time <20 s) and was highly reproducible; sample standard deviation of the current response at the concentration of 1.5 mM in five individual determinations was 0.09. The magnitude of the amperometric response for cholesterol was 0.13 μA cm⁻² at the concentration of 1.5 mM. The inertness and stability of the biosensor towards the potential electrical interferents, -ascorbic acid, pyruvic acid and uric acid, was tested, and it was found that the biosensor rapidly responses to the addition of cholesterol even in the presence of these interferents.     

Application of a functionalized parylene film as a linker layer of SPR biosensor

The surface plasmon resonance (SPR) biosensors have been used to detect various target analytes by using highly specific antigen-antibody interactions. In this work, a parylene film modified to have primary amine groups was applied as a linker layer of the SPR biosensor, and the primary amine groups were used for the covalent immobilization of proteins to the SPR biosensor. The feasibility of the parylene film as a linker layer was presented by estimating the influence of the parylene film on the SPR measurement parameters, such as the sensitivity and the detection range. Then, a model protein called horseradish peroxidase (HRP) was used to demonstrate the improved immobilization efficiency as well as the sensitivity of the SPR biosensor with the parylene-A film. Additionally, a reconstruction method of the immunoaffinity layer was presented by using oxygen plasma.     

AChE/IL-GR/CHI/GCE结构酶电极的研制及其对毒死蜱农药的检测

利用氨基功能化离子液体修饰石墨烯(IL-GR)的独特性质,以壳聚糖(CHI)为交联剂,首先在玻碳电极表面固定IL-GR,然后吸附乙酰胆碱酯酶(AChE)制得新型有机磷检测酶电极(AChE/IL-GR/CHI/GCE),并用于卷心菜样品中毒死蜱农药残留的测定。采用透射电镜(TEM)表征了IL-GR的形貌,采用循环伏安法(CV)和差示脉冲伏安法(DPV)研究了酶电极的电化学性质。结果表明,在优化的实验条件下,抑制率(I%)与毒死蜱浓度的对数在1.0×10-10mol/L~1.0×10-5mol/L范围内呈良好的线性关系,检出限为7.0×10-12mol/L(S/N=3)。测定了卷心菜中毒死蜱的含量,回收率为92.3%~108.6%。     

A micro-machined thin film electro-acoustic biosensor for detection of pesticide residuals§

Increasing awareness concerning food safety problems has been driving the search for simple and efficient bio-chemical analytical methods. In this paper, we develop a portable electro-acoustic biosensor based on a film bulk acoustic reso-nator for the detection of pesticide residues in agricultural products. A shear mode ZnO film bulk acoustic resonator with a mi-cro-machining structure was fabricated as a mass-sensitive transducer for the real-time detection of antibody-antigen reactions in liquids. In order to obtain an ultra-low detection level, the artificial antigens were immobilized on the sensing surface of the resonator to employ a competitive format for the immunoassays. The competitive immunoreactions can be observed clearly through monitoring the frequency changes. The presence of pesticides was detected through the diminution of the frequency shift compared with the level without pesticides. The limit of detection for carbaryl （a widely used pesticide for vegetables and crops） is 2′10-10 M. The proposed device represents a potential alternative to the complex optical systems and electrochemical methods that are currently being used, and represents a significant opportunity in terms of simplicity of use and portability for on-site food safety testing.     

Amperometric glucose biosensor based on integration of glucose oxidase with platinum nanoparticles/ordered mesoporous carbon nanocomposite

This article reports a new amperometric glucose biosensor based on ordered mesoporous carbon (OMC) supported platinum nanoparticles (Pt/OMC) modified electrode. The Pt/OMC nanocomposite modified electrode exhibited excellent electrocatalytic activities towards the reduction and oxidation of H₂O₂ as well. This feature allowed us to use it as bioplatform on which glucose oxidase (GOD) was immobilized by entrapment in electropolymerized pyrrole film for the construction of the glucose biosensor. The biosensor showed good analytical performances in terms of low detection (0.05 mM), high sensitivity (0.38 μA/mM) and wide linear range (0.05-3.70 mM). In addition, the effects of pH value, applied potential, electroactive interference and the stability of the biosensor were discussed. The applicability to blood analysis was also evaluated.     

基于氧化石墨烯修饰的DNA生物传感器用于苯酚的检测

作为一种典型的优先控制污染物,苯酚一直是环境监测和污染控制的重要对象。基于氧化石墨烯大的比表面积、优良的电子传导性等特性,以其为桥梁,为DNA在玻碳电极上的固定提供了可能,并加大了DNA在电极上的电化学响应信号,由此而构建了一种性能优良的DNA生物传感器。将该传感器浸在含有苯酚的溶液中,由于苯酚对DNA的损伤作用,降低了DNA在电极上的电化学响应。实验发现,响应信号与苯酚的浓度对数呈现良好的线性关系,响应范围为1.0×10-8～1.0×10-4mol/L,此外,该生物传感器表现出良好的稳定性和重现性。     

Conducting polymers with benzothiadiazole and benzoselenadiazole units for biosensor applications

Poly(4,7-di(2,3)-dihydrothienol[3,4-b][1,4]dioxin-5-yl-benzo[1,2,5]thiadiazole) (PBDT) and poly(4,7-di(2,3)-dihydrothienol[3,4-b][1,4]dioxin-5-yl-2,1,3-benzoselenadiazole) (PESeE) were electrochemically deposited on graphite electrodes and used as immobilization matrices for biosensing studies. After electrochemical deposition of the polymeric matrices, glucose oxidase (GOx) was immobilized on the modified electrodes as the model enzyme. In the biosensing studies, the decrease in oxygen level as a result of enzymatic reaction was monitored at −0.7 V vs Ag/AgCl (3.0 M KCl) and correlated with substrate concentration. The biosensor was characterized in terms of several parameters such as operational and storage stabilities, kinetic parameters (K_m and I_max) and surface morphologies. The biosensor was tested on real human blood serum samples.     

Catalytic determination of traces of Rh(III) using an optode based on immobilization of methyl violet on a triacetylcellulose membrane

The characterization of an optical sensor membrane is described for determination of rhodium. The optode sensing reagent is methyl violet which is immobilized on triacetylcellulose membrane. It has been found that oxidation of methyl violet with periodate is very slow. Presence of trace amount of Rh(III) catalyzes the reaction and causes a significant increase in the reaction rate. The reaction of periodate with the immobilized methyl violet in the presence of rhodium in acidic media causes a decrease in the absorbance of the film at 594 nm which is directly proportional to the concentration of rhodium. This sensing phase has a linear range of 1-110 μg mL⁻¹ for Rh(III) ions. The one-shot sensor can readily be fully regenerated with methyl violet solution, and the color is fully reversible.     

生物传感器BOD快速测定仪电气控制系统

生物需氧量(BOD)是一种表征水体有机污染程度的综合指标,广泛用于水体检测和污水处理厂的运行控制.概述了生物传感器BOD快速测定仪电气控制系统的工作原理,详细介绍了该仪器的硬件配置和软件设计,其用户界面设计为人机友好的视窗模式,从而实现自动检测实时显示等功能,能够满足水体有机污染快速准确检测的要求,对于我国水质评价、合...     

Gold nanoparticles-coated eggshell membrane with immobilized glucose oxidase for fabrication of glucose biosensor

This work reports the fabrication and application of a glucose biosensor based on the catalytic effect of gold nanoparticles (AuNPs) on enzymatic reaction for blood glucose determination. AuNPs were initially in situ synthesized on the surface of an eggshell membrane (ESM) which was subsequently immobilized with glucose oxidase (GO_x) to produce a GO_x-AuNPs/ESM. The GO_x-AuNPs/ESM was positioned on the surface of an oxygen electrode to form a GO_x-AuNPs/ESM glucose biosensor. The effects of pH, concentration of phosphate buffer solution and amount of GO_x on the response of the GO_x-AuNPs/ESM glucose biosensor were studied in detail. AuNPs on GO_x/ESM can improve the calibration sensitivity (30% higher than GO_x/ESM without AuNPs), stability (87.3% of its initial response to glucose after 10-week storage) and shortens the response time (<30 s) of the glucose biosensor. The linear working range for the GO_x-AuNPs/ESM glucose biosensor is 8.33 μM to 0.966 mM glucose with a detection limit of 3.50 μM (S/N = 3). The biosensor has been successfully applied to determine the glucose in human blood serum samples and the results compared well to a standard spectrophotometric method commonly used in hospitals. Our work demonstrates that the developed GO_x-AuNPs/ESM glucose biosensor has potential in biomedical analysis.     

Transducer mechanisms for optical biosensors. Part 1: The chemistry of transduction

The first stage of optical biosensor transduction involves a chemical interaction between the analyte and an indicator phase to produce an optically detectable signal. This stage is critical because it determines stability, selectivity and sensitivity as well as establishing the wavelengths required for the optical measurement. Several types of analyte/indicator interaction are possible. Direct indicators such as those used in optical pH sensors are in equilibrium with the analyte in the sample. They may be used for continuous measurements and can be coupled to the sensing of other analytes such as acidic and basic gases like carbon dioxide and ammonia. Integrating reagents react irreversibly with analyte and require that the rate of product formation be measured. Sensors based on catalysis by an immobilised enzyme involve a steady-state measurement of optically detectable substrate or product. High selectivity can be achieved using antibodies as reagents and basing sensing on competitive binding; however, response time is a serious problem. A variety of methods have been employed to immobilize the indicator phase including adsorption on solid substrates, covalent bonding to a substrate and confinement by membranes permeable to analyte but not to indicator.     

基于二氧化锆纳米粒子固定乙酰胆碱酯酶的甲基对硫磷传感器

先在金电极表面电沉积二氧化锆纳米粒子并固定乙酰胆碱酯酶(AChE),将此电极浸入含有不同浓度的有机磷溶液中,根据电极在底物氯化乙酰巯基胆碱中电化学信号强度的大小来实现溶液中有机磷的定量检测.以甲基对硫磷为分析目标物,研究了传感器的主要响应特性、选择性及再生性能,考察了底物浓度、工作电位及溶液pH值对分析性能的影响.结果表明,该有机磷传感器在5.0×10-7～5.0×10-4 g/L浓度范围内对目标分析物有线性响应,检出限为1.0×10-7 g/L.该传感器灵敏度高,非特异性吸附小,再生性好,所用的二氧化锆纳米粒子层制备简单、操作方便,具有较大的应用潜力.     

Design and performances of immunoassay based on SPR biosensor with Au/Ag alloy nanocomposites

A novel method for detecting human IgG is reported, which is based on Au/Ag alloy nanocomposites for amplifying surface plasmon resonance response. Au/Ag alloy nanocomposites were characterized in detail by transmission electron microscopy (TEM), UV-vis absorption spectroscopy and X-ray photoelectron spectroscopy (XPS). Covalent immobilization of about 24 nm diameter of Au/Ag alloy nanocomposites on the Au film results in a large shift in resonance wavelength, which is due to the increase of the thickness of the sensing membrane, high dielectric constant of Au/Ag nanoparticles, and electromagnetic coupling between Au/Ag alloy nanocomposites and Au film. The SPR biosensor based on Au/Ag alloy nanocomposites exhibits a satisfactory response for human IgG in the concentration range of 0.15-40.00 μg mL⁻¹. While the biosensor based on Au nanoparticles shows a response in the concentration range of 0.30-20.00 μg mL⁻¹ and the biosensor based on Au film shows a response for human IgG in the concentration range of 1.25-20.00 μg mL⁻¹.     

CO-sensing properties of hafnium oxide thin films prepared by electron beam evaporation

Thin films of hafnium oxide were deposited by electron beam evaporation. The effects of the film thickness and preparation conditions (films prepared on the heated substrate with or without the presence of oxygen environment during deposition) on the optical and carbon monoxide sensing properties of the films were studied. The films were characterized using X-ray diffraction and X-ray photoelectron spectroscopy and optical spectroscopy techniques. Films deposited on unheated substrates were amorphous, whereas those deposited on heated substrates showed a mixture of amorphous and polycrystalline structure. It was found that the sensitivity of the films to CO increased with the thickness and the porosity (as reflected by the refractive indices) of the films.