基于SOI基底的高通量细胞电融合芯片

提出了一种以MEMS技术为基础, 可在低电压驱动条件下工作的创新型细胞电融合芯片. 该芯片的设计原理在于通过缩短微电极间的间距, 在低电压条件下获得足够强度的排队和融合电场强度. 原型芯片以SOI硅片为加工材料, 通过刻蚀方式在顶层低阻硅形成微电极和微通道; 在微电极上沉淀2 μm厚的铝膜以降低电阻率, 提高导电性; 通过PECVD方法形成150 nm厚SiO2保障铝膜的抗腐蚀性及芯片生物相容性; 芯片最终采用DIP法进行封装. 在该芯片上进行了低电压(传统电融合设备工作电压的1/20)驱动条件下的基于介电电泳的细胞排队实验及后期的细胞电融合实验, 结果表明, 细胞多以两两结合的方式排列, 与传统的细胞融合电仪器相比较, 降低了多细胞排队概率, 进而减少了传统电融合设备多细胞融合的概率, 为细胞高效率融合奠定了基础. 在加载的低电压短脉冲信号后, 微通道中形成了高压短脉冲电场, 在脉冲作用下, 烟草原生质体细胞在微通道中发生了融合, 融合时间(2 min)远低于传统电融合方法(10~30 min), 融合率远远高于传统的PEG方法(融合率小于1%)和传统电融合方法(利用BTX ECM 2001细胞电融合系统得到, 融合率小于5%).     

叶绿素、染料体系光电效应的研究

叶绿素光电性质的研究有特殊意义.70年代开始国内外已有很多报道, 它们有整流、光导、光伏和光解水制取氢和氧等性质^[1-5].我们也报道过叶绿素a/聚乙烯醇夹层电池的研究^[6-8]。     

Electrogenerated chemiluminescence for potentiometric sensors

We report here on a generic approach to read out potentiometric sensors with electrogenerated chemiluminescence (ECL). In a first example, a potassium ion-selective electrode acts as the reference electrode and is placed in contact with the sample solution. The working electrode of the three-electrode cell is responsible for ECL generation and placed in a detection solution containing tris(2,2'-bipyridyl)ruthenium(II) [Ru(bpy)(3)(2+)] and the coreactant 2-(dibutylamino)ethanol (DBAE), physically separated from the sample by a bridge. Changes in the sample potassium concentration directly modulate the potential at the working electrode, and hence the ECL output, when a constant-potential pulse is applied between the two electrodes. A linear response of the ECL intensity to the logarithmic potassium concentration between 10 μm and 10 mM was found.     

Intact and permeabilized cells of the yeast Hansenula polymorpha as bioselective elements for amperometric assay of formaldehyde

Intact and permeabilized yeast cells were tested as the biorecognition elements for amperometric assay of formaldehyde (FA). For this aim, the mutant C-105 (gcr1 catX) of the methylotrophic yeast Hansenula polymorpha with a high activity of AOX was chosen. Different approaches were used for monitoring FA-dependent cell response including analysis of their oxygen consumption rate by the use of a Clark electrode, as well as assay of oxidation of redox mediator at a screen-printed platinum electrode covered by cells entrapped in Ca-alginate gel. It was shown that oxygen consumption rate of permeabilized cells reached its saturation at 4 mM of FA (23 °C). The detection limit was found to be 0.27 mM. In the presence of redox mediator 2,6-dichlorophenolindophenol (DCIP), the screen-printed platinum band electrode covered by permeabilized cells did not show any current output to FA. In contrast, well-pronounced amperometric response to FA was observed in the case of intact yeast cells in the presence of DCIP. It was shown that current output reached its maximum at 7 mM concentration of FA. The detection limit was found to be 0.74 mM. Obviously, it is necessary to perform a directed genetic engineering of the yeast cells to improve their bioanalytical characteristics in the corresponding biosensors.     

New insights into photosynthetic oscillations revealed by two-dimensional microscopic measurements of chlorophyll fluorescence kinetics in intact leaves and isolated protoplasts

Chlorophyll fluorescence kinetic microscopy was used to analyze photosynthetic oscillations in individual cells of leaves and in isolated leaf cell protoplasts. Four Brassicaceae species were used: Arabidopsis halleri (L.) O'Kane & Al-Shehbaz, Thlaspi fendleri (Nels.) Hitchc, Thlaspi caerulescens J.&C. Presl and Thlaspi ochroleucum Boiss et Helder. With the latter two, the measurements were extended also to isolated protoplasts. The oscillations were induced under the microscope by exposing dark-adapted samples to actinic irradiance. Detailed analysis of the induced transients revealed that they consist of several processes oscillating with different frequencies and not only one component as reported earlier. Furthermore, it was found that most of these processes are controlled inside each individual cell. This was shown by differences in oscillations in neighboring cells and protoplasts that share a uniform intercellular environment. The frequency of the dominant oscillation frequency depended neither on irradiance nor on CO2 concentration and is, therefore, not controlled by the photosynthetic rate. Characteristic differences in the frequency spectrum and damping of oscillations have been found among the plant species examined.     

Probing cell surface charge by scanning electrode potential

A static mercury electrode was used for measurement of double-layer charge displacement signals caused by living plant cells of the unicellular marine alga Dunaliella tertiolecta. By scanning the electrode potential a point is reached where the charge density of a plant cell compensates the electrode charge density. The experimentally determined values of surface charges for unicellular marine alga Dunaliella tertiolecta cells are -0.63 and -0.75 nuC/cm(2) in 0.1 M NaCl and 1 M NaCl solutions, respectively.     

Fast and Controlled Decorating of Metallic Nanoparticles Using Wall‐jet Configuration

A new method to decorate metallic nanoparticles (NPs) based on the wall‐jet configuration was developed. A homemade wall‐jet amperometric cell coupled to an electronic micropipette was used to decorate Pt NPs with Sb and Sn hydrodynamically through the injection of metallic precursor solutions onto an electrode modified with NPs under applied potential. The method allows the control of the coverage degree (θ) by changing easy handling parameters such as injection flow rate, injected volume and concentration of precursors. The decoration procedure is fast, reproducible, simple and economic, since it only uses a few microlitres of precursors to prepare each electrode composition. It is possible to prepare an average of 1000 electrodes using the same amount of precursors for each one prepared by a conventional method using a typical three‐electrode cell. Sb‐ and Sn‐decorated Pt/C NPs were first evaluated towards diluted glucose electrooxidation in buffer solution. These first insights reveal that the output current density increases with θ_Sb and θ_Sn; Sb‐decorated Pt/C shows the greatest improvement.     

钯/聚苯胺纳米多层膜的制备及对抗坏血酸和多巴胺的催化氧化

采用脉冲电位法(PPSM)结合聚苯胺(PANI)的层层自组装制备了Pd/PANI交替沉积纳米多层膜, 并用于抗坏血酸(AA)和多巴胺(DA)的检测. 实验发现, 多层膜结构形貌及催化性能受前躯体K₂PdCl₆浓度、 脉冲条件及膜厚度等影响. 当K₂PdCl₆浓度为2×10^-3 mol/L, 阴极脉冲电位为-0.3 V, 阶跃次数为17时, 5层Pd/PANI修饰玻碳电极对AA和DA的催化性能最佳; 在0.1 mol/L磷酸盐缓冲液中, AA和DA的氧化峰明显分离[ΔE_p(AA, DA)=160 mV], 其峰电流与浓度分别在5×10^-5～4×10^-4和4×10^-5～1×10^-4 mol/L范围内呈较好线性关系, 实现了对AA和DA的同时测定. 该修饰电极具有良好的抗干扰性和稳定性.     

Photoelectrocatalytic degradation of 3-nitrophenol at surface of Ti/TiO2 electrode

The widely utilization of phenol and its derivatives such as 3-nitrophenol (3-NP) has led to the worldwide pollution in the environment. In this study, Ti/TiO₂ photoelectrode was prepared with anodic oxidation of Ti foil electrode and then the photoelectrocatalytic (PEC) degradation of 3-NP was performed via this electrode, comparing with photocatalytic (PC), electrooxidation and direct photolysis by ultraviolet light. A significant photoelectrochemical synergetic effect in 3-NP degradation was observed on the Ti/TiO₂ electrode and rate constant for the PEC process of Ti/TiO₂ electrode was about three times as high as its PC degradation process. 3-NP concentration monitoring was carried out with differential pulse voltammetry. Results showed that PEC degradation has highest effect on concentration decreasing of 3-NP at solution and degraded it about 38 %, while other processes degradation efficiencies were about 4, 7, and 12 % for electrooxidation, direct photolysis and photocatalytic degradation, respectively. Finally, effects of solution pH and applied potential on degradation efficiency were studied and results showed that optimum pH for degradation is equal 4.00 and optimum potential is 1.2 V vs. Ag|AgCl|KCl (3M) reference electrode.     

W-C Synthesis in a Pulsed Arc Submerged in Liquid

Pulsed arc production of tungsten carbide (W-C) powders in deionized water and analytical (99.8%) ethanol was studied. The arc was ignited between two submerged electrodes: one of 99.99% graphite (C) and the other of 99.5% W. The pulse energy and duration were in the ranges of 7.7–192 mJ and 25–65 μs, respectively. The WC_1−x production rate was maximized by configuring the C electrode as the anode and the W electrode as the cathode. The rate was greater in ethanol than in water. The rate of producing ∼10 nm particles in ethanol was two orders of magnitude greater when using W anode -C cathode configuration, than with the opposite polarity.     

Design of a New Carbon Paste Electrode Modified with TiO2 Nanoparticles to Use in an Electrochemical Study of Codeine and Simultaneous Determination of Codeine and Acetaminophen in Human Plasma Serum Samples

A new electrochemical sensor was fabricated via TiO₂ nanoparticles onto a carbon paste electrode. Cyclic voltammetry (CV) and differential pulse voltammetry (DPV) studied the response of the modified electrode toward codeine. The effects of pH, modifier amount, pulse amplitude, and scan rate of potential have been examined. Using DPV, we could measure simultaneously codeine and acetaminophen in one mixture. The detection limits of 0.018 and 0.050 µmol L^?1 were achieved for codeine and acetaminophen, respectively. The electrooxidation pathway, transfer coefficient, and standard rate constant, are estimated. The proposed voltammetric sensor was successfully applied to determination of codeine and acetaminophen in human plasma serum samples.     

Direct zinc determination in commercial sulphuric acid by dpasv. Comparison of rotating disc and stationary graphite electrodes

A striking gas technique employed made a direct Zn determination possible at extremely low pH in commercial acid solutions when a stationary impregnated graphite-based mercury film electrode was used. The original Zn(II) concentrations were determined quantitatively by differential pulse anodic stripping voltammetry on 0.5M and 1M sulphuric acid solutions by standard addition and were found to be 2 x 10(-8)M and 4.1 x 10(-8)M, respectively. The influence of mercury ion concentration, pulse amplitude, potential step and pulse repetition time on analytical data was studied and optimized. A rotating disc graphite electrode was also used as a working electrode and was found unreliable for this purpose as hydrogen bubbles were not removed effectively and blocked the working electrode surface.     

Differential pulse anodic stripping voltammetry of lead (lI) benzoylacetonate in chloroform: Application to the analysis of free-lead gasoline and gas oil samples

The voltammetric characteristics of lead(II) benzoylacetonate in chloroform at the mercury electrode are investigated. The conditions for nearly reversible reduction of lead(II) were optimized. Anodic stripping voltammetry for the determination of trace-lead was developed using differential pulse technique to strip amalgamed lead from hanging mercury drop electrode. The experimental conditions, such as scanning rate of electrode potential and deposition time of lead were optimized. The calibration graph was linear over concentration range 5x10(-8)-10(-6) M of lead(II). The detection limit was 2.5x10(-9) and the relative standard deviation for the determination of 4x10(-7) M Pb(II) was 2%. Preceded by decomposition of organolead compounds with concentrated nitric acid, then ashing at 300 degrees C and a solvent extraction of Pb(II) benzoylacetonate in chloroform, the suitability of the proposed method for the determination of lead in free-lead gasoline and gas oil was demonstrated as a typical example of application.     

Ag/TiO2对含酚废水的光电催化降解

Ag/TiO2对含酚废水的光电催化降解;Ag/TiO2; 光电催化; 苯酚;电解质     

Determination of ascorbic acid content of some fruit juices and wine by voltammetry performed at pt and carbon paste electrodes

A method was developed for assessing ascorbic acid concentration in fruit juices and wine by differential pulse voltammetry. The oxidation peak for ascorbic acid occurs at about 530 mV (versus SCE) on a Pt strip working electrode and at about 470 mV on a carbon paste working electrode. The influence of the operational parameters like the pulse amplitude and the pulse period on the analytical signal was investigated. The obtained calibration graph shows a linear dependence between the peak height and ascorbic acid concentration within the range 0.31-20 mM with a Pt working electrode, and within the range 0.07-20 mM with a carbon paste working electrode. The equation of the calibration graph was y = 21.839x + 35.726, r2 = 0.9940, when a Pt strip electrode was used (where y represents the value of the current intensity measured for the peak height, expressed as μA and x the analyte concentration, as mM). R.S.D. = 2.09%, n = 10, C(ascorbic acid) = 2.5 mM. The equation of the calibration graph was y = 3.4429x + 5.7334, r2 = 0.9971, when a carbon paste electrode was used (where y represents the value of intensity measured for the peak height, expressed as μA and x the analyte concentration, as mM). R.S.D. = 2.35%, n = 10, C(ascorbic acid) = 2.5 mM. The developed method was applied to ascorbic acid assessment in fruit juices and wine. The ascorbic acid content determined ranged between 6.83 mg/100 mL juice for soft drinks (Fanta Madness) and 54.74 mg/100 mL for citrus (lemon) juices obtained by squeezing fruit. Different ascorbic acid concentrations (from standard solutions) were added to the analysed samples, the degree of recovery being comprised between 94.74 and 104.97%. The results of ascorbic acid assessment by differential pulse voltammetry were compared with those obtained by cyclic voltammetry. The results obtained by the two methods were in good agreement.     

Immobilization of barley protoplasts on a polyelectrolyte modified electrode for measuring the photoelectric behavior of protoplasts

A novel method to immobilize barley protoplasts on the poly(diallyl dimethyl ammonium chloride) gold/(PDADMAC) electrode was developed for the purpose to measure the photoelectric behavior of barley protoplasts. The electrochemical quartz crystal microbalance (EQCM) results show that the thickness of the adsorbed PDADMAC layer is 2.4 nm. The barley protoplasts are immobilized on the surface of gold/PDADMAC electrode due to the electrostatic adsorption between negatively charged protoplasts and positively charged PDADMAC. The fluorescence image taken by laser scanning confocal microscope shows that the attached barley protoplasts are integrity. For the gold/PDADMAC/barley protoplast electrode an anodic photocurrent was observed under the irradiation of white light (wavelength of 200–800 nm) and its properties are discussed. This novel method may provide a convenient technique for immobilizing cells or other bio-particles on the surface of electrode for studying their electrochemical characters.     

Expression of integrins, cyclooxygenases and matrix metalloproteinases in three-dimensional human endometrial cell culture system

The objective of this investigation was to establish a three-dimensionally cultured human endometrium which could be used as a tissue model for the mechanism study of implantation in vitro. By using human endometrial stromal (ES) and epithelial cells (EE) from hysterectomy specimens, reconstruction of endometrium in culture was established by first layering a collagen gel containing ES cells, then overlaying with the Matrigel containing endometrial epithelial (EE) cells. Ultrastructural examination of the 48 h-endometrial cell culture revealed monolayered columnar EE cells with microvilli on the collagen layer containing ES cells and appearance of the tight junctions and desmosomes between EE cells, a cell layer closely resembling the native endometrium. Immunohistochemical characterization of the reconstructed endometrium showed a strong immunoreactivity for cytokeratin, integrin alpha1, alpha4 and beta3 subunits, cyclooxygenases-1 and -2, matrix metalloproteinases-1, -2, -3 and -9, and tissue inhibitor of metalloproteinases-1 and -2 in the EE cells comparable to the native endometrial epithelium. ES cells also showed stronger immunoreactivity for cyclooxygenases, integrins and MMPs, but less for cytokeratin. Gelatin zymographic analyses of the media obtained from the reconstructed endometrium model showed gelatinase activity bands at 57, 60, 72, 92 and 97 kDa molecular weight, respectively. The present study provides a possibility that our three-dimensionally cultured endometrium model could mimic the morphological and functional characteristics of the native endometrium. The model could be used to clarify the roles of various molecules involved in the human implantation.     

An Electrochemical Sensing Platform for the Detection of Lead Ions Based on Dicarboxyl‐Calix[4]arene

A simple and highly sensitive electrochemical sensor COOH−C4 derived from dicarboxyl‐calix[4]arene modified on a screen printed gold electrode (Au) was developed for the determination of lead ions in water samples. A 3‐mercaptopropionic acid (MPA) monolayer was used as a template on the gold electrode for the surface modification with dicarboxyl‐calixarene. The modified electrodes were surface‐characterized using Fourier Transform infrared spectroscopy (FTIR). The data obtained proved the confirmation of each stage of the electrode modification. The electrochemical analyses of the COOH−C4 electrode showed an enhanced electrocatalytic activity and higher current towards Pb²⁺ ions as compared to the bare Au and MPA/Au electrodes. Under optimum conditions, the differential pulse voltammetry response of COOH−C4 displayed a wide linear response ranging from 280–2500 μg/L for Pb²⁺ with a detection limit of 6.2 μg/L. In addition, the fabricated electrode showed a high selectivity and stability towards the Pb²⁺ ions in presence of possible interfering species. The present method was successfully applied to determine Pb²⁺ ions in real samples with satisfactory precision, with a relative standard deviation of 3.12 % and an acceptable recovery of 92 %, which demonstrated the potential application of dicarboxyl‐calix[4]arene modified on electrodes for heavy‐metal sensing.     

From salmon pink to blue natural sensitizers for solar cells: Canna indica L., Salvia splendens, cowberry and Solanum nigrum L.

Study on dye-sensitized solar cells (DSSCs) with extracts of Canna indica L., Salvia splendens, Solanum nigrum L. as sensitizers is firstly reported in this paper. DSSCs were assembled by using natural dyes extracted from C. indica L., S. splendens, cowberry and S. nigrum L. as sensitizers. The energy conversion efficiency of the cells sensitized with dyes of C. indica L., S. splendens, cowberry and S. nigrum L. was 0.29%, 0.26%, 0.13% and 0.31%, respectively. A novel technique was taken to fabricate TiO₂ electrode films by electrophoresis. We present FTIR and UV–vis spectroscopy studies of structures and light absorption of these four kinds of natural dyes. The electrochemical impedance spectroscopy (EIS) was used to analyze the interface resistance of cells. The result indicated that high resistance existed in the interfaces of cell with cowberry extract as sensitizer.