共价键合修饰壳聚糖pH传感器的研制

以共价键合的方法将壳聚糖修饰到玻碳电极上制成了pH传感器,探讨了该传感器的性能及作用机理.结果表明该传感器在pH 0.7～11.0的范围内电极电势与pH符合Nernst响应,斜率为58.3 mV/pH,可准确测定较高酸度溶液的pH,克服了玻璃pH传感器的"酸误差"的缺点.该传感器内阻小,易微型化,在一定的pH范围内对温度不敏感且具有较好的准确度和重现性,较快的响应速度.可用于雨水和饮料等实际样品溶液的pH的测定.     

One-pot synthesis of a new rhodamine-based dually-responsive pH sensor and its application to bioimaging

A new colorimetric and fluorescent sensor for the highly acidic pH was developed from rhodamine B, 1-(2-aminoethyl)piperazine, and 4-chloro-7-nitro-2,1,3-benzoxadiazole. The sensor could be synthesized in one pot with an 82.5% yield, and for the first time N,N-diisopropylethylamine was found to be crucial for the rhodamine spirolactam formation. The sensor responded to pH rapidly, visibly, reversibly, highly selectively, and sensitively. From pH 7.77 to 2.03, the absorption and fluorescence intensity of the sensor increased by 285 and 50.3 folds, respectively. The pK_a value based on the fluorescence titration was 2.87. Fluorescent imaging of living cells treated with the sensor in different pH media indicated that the sensor could provide intracellular pH information.     

Electroless Nickel Plating and Electroplating on FBG Temperature Sensor

Metal-coated fiber Bragg grating（FBG）temperature sensors were prepared via electroless nickel（EN）plating and tin electroplating methods on the surface of normal bare FBG.The surface morphologies of the metal-coated layers were observed under a metallographic microscope.The effects of pretreatment sequence,pH value of EN plating solution and current density of electroplating on the performance of the metal-coated layers were analyzed.Meanwhile, the Bragg wavelength shift induced by temperature was monitored by an optical spectrum analyzer.Sensitivity of the metal-coated FBG（MFBG）sensor was almost two times that of normal bare FBG sensor.The measuring temperature of the MFBG sensor could be up to 280℃,which was much better than that of conventional FBG sensor.     

A long lifetime chemical sensor: study on fluorescence property of fluorescein isothiocyanate and preparation of pH chemical sensor

The fluorescence property of fluorescein isothiocyanate (FITC) in acid-alkaline medium was studied by spectrofluorimetry. The characteristic of FITC response to hydrogen ion has been examined in acid-alkaline solution. A novel pH chemical sensor was prepared based on the relationship between the relative fluorescence intensity of FITC and pH. The measurement of relative fluorescence intensity was carried out at 362 nm with excitation at 250 nm. The excellent linear relationship was obtained between relative fluorescence intensity and pH in the range of pH 1-5. The linear regression equation of the calibration graph is F = 66.871 + 6.605 pH (F is relative fluorescence intensity), with a correlation coefficient of linear regression of 0.9995. Effects of temperature, concentration of FITC on the response to hydrogen ion had been examined. It was important that this chemical sensor was long lifetime, and the property of response to hydrogen ion was stable for at least 70 days. This pH sensor can be used for measuring pH value in water solution. The accuracy is 0.01 pH unit. The results obtained by the pH sensor agreed with those by the pH meter. Obviously, this pH sensor is potential for determining pH change real time in biological system.     

pH和温度敏感型聚合物荧光探针的合成及应用

以萘酰亚胺(NI)、N-异丙基丙烯酰胺(NIPAM)和多面体齐聚倍半硅氧烷(POSS)为原料,通过可逆加成断裂自由基聚合(RAFT)方法,设计合成了具有p H响应和温度敏感的聚合物荧光探针Poly(POSS-NINIPAM)。通过核磁共振波谱仪(NMR)、荧光发射光谱仪和质谱仪(MS)等技术手段表征了Poly(POSS-NINIPAM)的p H和温度的响应性能。结果表明,在p H值5.8~8.0范围内,探针Poly(POSS-NI-NIPAM)的荧光强度变化明显,与p H值呈现良好的线性相关(λem=520 nm,p Ka=6.51),对p H和温度的响应均呈现出良好的循环检测性能,可用于检测活细胞He La的p H值变化。探针Poly(POSS-NI-NIPAM)在检测生物样本中p H/温度变化方面具有潜在的应用前景。     

Multiparameter Sensor Chip with Barium Strontium Titanate as Multipurpose Material

It is well known that biochemical and biotechnological processes are strongly dependent and affected by a variety of physico‐chemical parameters such as pH value, temperature, pressure and electrolyte conductivity. Therefore, these quantities have to be monitored or controlled in order to guarantee a stable process operation, optimization and high yield. In this work, a sensor chip for the multiparameter detection of three physico‐chemical parameters such as electrolyte conductivity, pH and temperature is realized using barium strontium titanate (BST) as multipurpose material. The chip integrates a capacitively coupled four‐electrode electrolyte‐conductivity sensor, a capacitive field‐effect pH sensor and a thin‐film Pt‐temperature sensor. Due to the multifunctional properties of BST, it is utilized as final outermost coating layer of the processed sensor chip and serves as passivation and protection layer as well as pH‐sensitive transducer material at the same time. The results of testing of the individual sensors of the developed multiparameter sensor chip are presented. In addition, a quasi‐simultaneous multiparameter characterization of the sensor chip in buffer solutions with different pH value and electrolyte conductivity is performed. To study the sensor behavior and the suitability of BST as multifunctional material under harsh environmental conditions, the sensor chip was exemplarily tested in a biogas digestate.     

Development of a novel fluorescent sensor to detect a specific range of pH

A novel fluorescent sensor for monitoring the change of pH was developed, based on a structure containing two hydroxyl groups that are sequentially deprotonated as the pH is increased: the first deprotonation increases the fluorescence intensity and the second decreases it. Compared with most reported pH sensors that can detect only whether or not the pH is below or above a specific value, our sensor could detect a specific range of pH (centered on pH 8–9) that should be useful for the study of biological microenvironment.     

Development of an iridium-based pH sensor for bioanalytical applications

A new iridium-based planar pH sensor for bioanalytical purposes is introduced. The fabrication of the sensor was carried out by a two-stage coating process of different iridium solutions on a platinum thick film surface. The pH response behaviour and the Nernstian characteristics of the double-layer electrode exhibited better results than the single iridium depositions. An almost theoretical Nernstian slope could be obtained as well as a pH response time of about 3 to 5 min in a pH range of 4.01 to 9.18. Furthermore, a biofilm growth of different microorganisms onto the iridium-coated electrodes could be achieved. Afterwards, the viability of the microorganisms was demonstrated via cell plating studies.     

A liver tissue-based electrochemical sensor for hydrogen peroxide

A slice of bovine liver covering an oxygen electrode is used to provide a selective sensor for > 10^-5 M hydrogen peroxide. The sensor is less susceptible to temperature and pH changes than a similar electrode covered with catalase, and it has a much longer lifetime.     

An amperometric sensor for carbon dioxide based on immobilized bacteria utilizing carbon dioxide

A biosensor consisting of a CO₂-utilizing autotrophic bacterium (strain S-17, Pseudomonas type) and an oxygen-sensing electrode was constructed for the amperometric determination of CO₂. The correlation between current decrease and CO₂ concentration was linear in the range 5–200 mg l^?1 CO₂. The optimum temperature and pH for operation of the biosensor were 30°C and 5.5, respectively. The sensor did not respond to other volatile compounds except for acetic acid. The sensor could be operated continuously for about a month.     

Glucose Oxidase Electrode Based on Graphite and Methylthio Tetrathiafulvalene as Mediator

Abstract

A glucose sensor based on glucose oxidase and a new mediator - 4,5-dimethyl-4′-methylthio-Δ 2,2′-bi-1,3-dithiole (MTTTF) is described. The background for sensor action is the effective MTTTF cation interaction (apparent bimolecular constant (2.0+/-0.5)?10⁶ M^?1 s^?1 at 25°C and pH 7.0) with reduced glucose oxidase and the high electrochemical rate of mediator transformation.

A glucose sensor was prepared by adsorbing mediator (MTTTF) and glucose oxidase on graphite rods. The sensor responds to glucose at electrode potentials higher than 50 mV vs SCE, but the maximal activity is obtained at a potential of 250 mV. In air saturated solution the electrode shows a non-linear calibration curve with a half-saturation concentration 10.4 mM and Hill coefficient 2.08 at 250 mV. Sensor response changes little at pH 6.5–8.0. The energy of activation of the sensor response calculated from the Arrhenius equation was 64.5 kJ/mol, and the temperature coefficient at 25°C was 9.2%.     

Internally-referenced resonant mirror for chemical and biochemical sensing

The resonant mirror sensor is a planar optical sensor platform that uses frustrated total internal reflection to couple light into and out of a leaky waveguiding layer. The evanescent wave associated with the dielectric structure is very sensitive to changes in surface refractive index caused by the binding of macromolecules to immobilised proteins or other biorecognition species such as antibodies. However, such variations can also be generated by variations in the bulk analyte solution, via changes in the composition or temperature. In the device described here, an additional buried resonant mirror layer is incorporated into the sensor structure generating an internal reference resonant mirror. The efficacy of this internal reference system is demonstrated in both chemical and immunological systems--as a pH sensor monitoring the absorption of an encapsulated sulfonephthalein dye, and as a refractive index sensor measuring the adsorption of anti-protein A and binding of its corresponding antigen. In both cases the internally referenced resonant mirror provides a means by which errors due to fluctuations in light intensity, temperature and bulk composition may be accounted for.     

Thermodynamic Foundation for High Temperature Electrochemistry

Thermodynamic concepts required for the thermodynamic calculation of the potentials of electrodes for high temperature applications are briefly reviewed. A thermodynamic approach to the calculation of half cell potentials and the standard chemical potential of an electron at high temperatures which are related to the Standard Hydrogen Electrode(SHE) is discussed. As examples, an external Ag/AgCl reference electrode and a YSZ(Ag|O2) pH sensor for high temperature applications are analyzed by using the thermodynamic ap-proach to derive a high temperature pH measurement equation. The two electrodes are employed to measure high temperature pH and the measured pH was compared with the calculated pH by using a solution chem-istry method. Concepts and principles for electrode kinetics are also briefly introduced and a modification to the Tafel equations is suggested.     

Preparation and Properties of a Micro Enzyme Sensor for Creatine

Abstract

A micro enzyme sensor using creatine amidinohydrolase (EC 3. 5. 3. 3) and sarcosine oxidase (EC 1. 5. 3. 1) was developed for measuring creatine. The sensor consisted of platinum and silver wires fixed in a glass tubing with epoxy resin adhesive, and creatine amidinohydrolase and sarcosine oxidase immobilized on their tip by cross-linking method. The calibration curve for measurement of creatine, the effects of pH, temperature, the amount of flavin adenine dinucleotide and compounds on the sensitivity, and the life-time of the sensor were examined. Under optimal conditions, the response of the sensor was linear in the concontration range of 10 μ M ～ 0.65 mM creatine.     

Detection of Adrenaline in Blood Plasma as Biomarker for Adrenal Venous Sampling

An amperometric bi‐enzyme biosensor based on substrate recycling principle for the amplification of the sensor signal has been developed for the detection of adrenaline in blood. Adrenaline can be used as biomarker verifying successful adrenal venous sampling procedure. The adrenaline biosensor has been realized via modification of a galvanic oxygen sensor with a bi‐enzyme membrane combining a genetically modified laccase and a pyrroloquinoline quinone‐dependent glucose dehydrogenase. The measurement conditions such as pH value and temperature were optimized to enhance the sensor performance. A high sensitivity and a low detection limit of about 0.5–1 nM adrenaline have been achieved in phosphate buffer at pH 7.4, relevant for measurements in blood samples. The sensitivity of the biosensor to other catecholamines such as noradrenaline, dopamine and dobutamine has been studied. Finally, the sensor has been successfully applied for the detection of adrenaline in human blood plasma.     

Electrochemical behavior of hydrogen peroxide sensor based on new methylene blue as mediator

A novel amperometric hydrogen peroxide sensor was proposed by co-immobilizing new methylene blue (NMB) and Horseradish peroxidase (HRP) on glassy carbon electrode through covalent binding. The electrochemical behavior of the sensor was studied extensively in 0.1 mol/L phosphate buffering solution (pH = 7.0). The experiments showed NMB could effectively transfer electrons between hydrogen peroxide and glassy carbon electrode. The electron transfer coefficient and apparent reaction rate constant were determined to be 0.861 and 1.27 s⁻¹. The kinetic characteristics and responses of sensor on H₂O₂ were investigated. The Michaelis constant is 8.27 mol/L and the linear dependence of current on H₂O₂ is in the range of 2.5–100 μmol/L. At the same time, the effects of solution pH, buffer capacity, and temperature on the sensor were examined. Translated from Chemistry, 2006, 23(8): 916–920 [译自: 化学通报]     

A novel hydrogen peroxide sensor based on the redox of ferrocene on room temperature ionic liquid film

A novel sensor was constructed based on the catalytic activity of ferrocene (Fc) that was immobilized on a room temperature ionic liquids (RTILs), 1-ethyl-3-methyl imidazolium tetrafluoroborate ([EMIM][BF₄]), film. Electrochemical behavior of ferrocene was investigated by electrochemical impedance spectroscopy (EIS) and cyclic voltammetry (CV). A pair of stable, well-defined and quasi-reversible redox peak of ferrocene could be obtained at pH 7.0 phosphate buffer. Further investigations reveal that both anodic and cathodic peak currents of ferrocene vary linearly with the concentration of hydrogen peroxide (H₂O₂). Based on this, a new sensor for the measurement of H₂O₂ can be fabricated facilely. This sensor allowed us to measure H₂O₂ by polarizing the electrode under ether anodic or cathodic potential with an excellent stability and anti-interfering ability.     

8-羟基喹啉-5-磺酸修饰电极pH传感器的制备及应用

制备了8-羟基喹啉-5-磺酸(HQS)修饰铂丝电极pH传感器,对其pH响应范围,斜率,线性相关系数,响应时间等进行了考察.将该电极用于表面修饰氨基纳米二氧化硅的测定,取得了满意结果.     

Surface acoustic wave sensor system applied to the kinetic study of urease in plant seeds

A new type of the surface acoustic wave (SAW) sensor system was delivered. Ure-ase from several kinds of plant seeds was extracted with different extracting solvents. The urease activity, Michaelis constant and other kinetic parameters were estimated for the first time by means of the new device-SAW sensor system. Some factors such as pH, temperature, activators and inhibitors are also discussed. The method can be applied to the determination of urea content in human urine and the experimental results consist with those reported.     

A Novel Colorimetric and Fluorescent pH Sensor Derived from Iminocoumarin and Thiophene‐Carboxaldehyde

A novel colorimetric and fluorescent pH sensor derived from iminocoumarin and thiophene‐carboxaldehyde was designed and synthesized. The structures of the dye and related compounds were characterized by IR, ¹H NMR, ¹³C NMR, and mass spectra. Color change from green to yellow of the new sensor solution in ethanol–water with the decrease in the pH value from 7 to 2 was observed by the naked eye. Under acidic conditions, the intensity of the maximum fluorescence emission peak of the sensor increased gradually with the decrease in the acidity of the solution (the increase in the pH value from 2 to 7) and attained to the maximum value at about pH 6. Under basic conditions, the fluorescence intensity of the emission peak of the sensor did not exhibit a distinct change at pH ≤ 11.85, and the fluorescence was quenched at pH 13.36, concomitant with the green color of the solution turning pale. The sensor can be used as a fluorescent pH probe in the presence of common metal cations and anions without interference.