基于纳米金探针和基因芯片的DNA检测新方法

运用荧光纳米金探针和基因芯片杂交建立一种新的DNA检测方法. 荧光纳米金探针表面标记有两种DNA探针: 一种为带有Cy5荧光分子的信号探针BP1, 起信号放大作用; 另一种为与靶DNA一部分互补的检测探针P532, 两种探针比例为5∶1. 当靶DNA存在时, 芯片上捕捉探针(与靶DNA的另一部分互补)通过碱基互补配对结合靶DNA, 将靶DNA固定于芯片上; 荧光纳米金探针通过检测探针与靶DNA及芯片结合, 在芯片上形成“三明治”复合结构, 最后通过检测信号探针上荧光分子的信号强度来确定靶DNA的量. 新方法检测灵敏度高, 可以检测浓度为1 pmol/L的靶DNA, 操作简单, 检测时间短. 通过改进纳米金探针的标记和优化杂交条件, 可进一步提高核酸检测的灵敏度, 这将在核酸检测方面具有重要的应用价值.     

A generalized probe selection method for DNA chips

The flaws in the present probe selection methods restrained the development of the DNA chip technology and its applications. The presented generalized probe selection method for the DNA chips elaborates the length of the probe, the melting temperatures, the specificity of the probe, and the position where the probe may bind to the targets.     

Multisample probe for fast-atom bombardment / mass spectrometry

An inexpensive multisample fast-atom bombardment (FAB) probe assembly was designed for high-throughput analysis of samples on a VG ZAB-SE mass spectrometer. The system consists of a vacuum lock system and a FAB probe whose tip contains five or more sample wells. The probe enters the mass spectrometer source region perpendicular to the secondary ion beam axis, The probe is maintained at high voltage on contact with a spring clip attached to the screen plate of the source block. Sample throughput with the multisample probe is twice that of a coaxial probe, with about twice the sensitivity and no sample cross contamination.     

Determination of the temperature of the graphite probe surface in graphite probe furnace atomic absorption spectrometry

An apparatus for determining the temperature of a graphite probe in graphite probe furnace atomic absorption spectrometry has been developed and tested. By measuring the change in the reflection of a laser beam from various pure metals which are deposited on the probe surface at the usual location for sample deposition, it has been found that the heating of the graphite probe surface occurs in two stages. When the probe is inserted into a pulse-heated, commercial graphite furnace after it has been heated to a steady-state temperature, the probe surface is initially rapidly heated by the radiation from the heated graphite tube wall, and thereafter the probe maintains that steady-state temperature for a short time. For a given graphite probe, the heating rate at the initial stage and the corresponding steady-state temperature at the final stage are mainly determined by the final tube wall temperature; the steady-state temperature of the probe is considerably lower than the final tube wall temperature because of thermal conduction by the probe to that part of its body which is lying outside the tube wall. The higher the final tube wall temperature, the higher is the heating rate of the probe at the initial stage, the higher is its steady-state temperature at the final stage, and the less is the difference between the final tube wall temperature and the steady-state temperature of the probe surface. The heating rate of the probe surface at 1600 K is 180 K s⁻¹, whereas at 2300 K it is 3600 K s⁻¹; the differences between the probe surface and tube wall temperatures at the former temperature is 700 K, whereas at the latter temperature it is 250 K.     

特异性识别半胱氨酸荧光探针的合成及细胞成像研究

基于光诱导电子转移(PET)机制,利用Cys亲核性较强,能够与探针分子发生亲核取代反应,使丙烯酰基离去,使探针分子体系内PET过程失效,合成了一种特异性识别半胱氨酸的荧光探针。当向探针溶液分别加入多种测试物时,除与Cys结构类似的Hcy和GSH会引起探针溶液微弱的荧光变化外,其他氨基酸均不会引起探针溶液荧光强度的变化,该探针对Cys具有良好的选择性和灵敏度,可在生理条件下检测Cys,并且区分Hcy和GSH。同时,该探针成功实现了细胞内Cys的荧光成像,为在生物学及医学中的实际应用建立了一种特异性识别Cys的分析方法。     

适宜于光聚合过程应用的荧光探针研究

研究了两种探针化合物在安息香醚引发烯类单体光聚合反应中的应用.发现在光聚合反应中,不同的探针化合物有着不同的光谱响应特征和溶致变色行为,显然,这对探针的灵敏度会带来影响.实验结果表明:探针化合物在光聚合反应中能否应用,其光照稳定性起着关键作用.本工作推荐了一种适宜在烯类单体光聚合反应中应用的探针化合物.     

Fiber-optic chlorine probe based on fluorescence decay of N-(6-methoxyquinolyl)acetoethyl ester

A fiber-optic probe for measuring chlorine in aqueous solution is evaluated. The probe uses a microporous gas-permeable membrane to trap a small volume of aqueous internal solution made of N-(6-methoxyquinolyl)acetoethyl ester (MQAE) in front of a fiber-optic assembly. The working principle of this probe is based on a combination of fluorescence quenching and redox reaction of MQAE by chloride ion and chlorine, respectively. While the magnitude of total fluorescence decay is independent of the sample concentration, the initial rate of decrease in fluorescence intensity is linearly proportional to the chlorine concentration over the range from 8.4 to 418 microM. Once the probe is exposed to a chlorine sample, the probe tip must be refilled with a fresh aliquot of the internal solution before the next measurement. In this mode, the probe displays excellent reproducibility; the relative standard deviation of the initial rate of fluorescence decay (n = 3) is only 1 percent. This probe can also be used for the measurement of hypochlorous acid (HOCl) in aqueous solution. The response properties are identical to those of the chlorine probe.     

A sensitive and label-free impedimetric biosensor based on an adjunct probe

A highly sensitive and label-free impedimetric biosensor is achieved based on an adjunct probe attached nearby the capture probe. In this work, the adjunct probe was co-assembled on the surface of gold electrode with the capture probe hybridized with the reporter probe, and then 6-mercapto-1-hexanol was employed to block the nonspecific binding sites. When target DNA was added, the adjunct probe functioned as a fixer to immobilize the element of reporter probe displaced by the target DNA sequences and made the reporter probe approach the electrode surface, leading to effective inhibition of charge transfer. The increase in charge transfer resistance is related to the quantity of the target DNA in a wide range. The linear range for target DNA with specific sequences was from 0.1 nM to 0.5 μM with a good linearity (R = 0.9988) and a low detection limit of 6.3 pM. This impedimetric biosensor has the advantages of simplicity, sensitivity, good selectivity, and large dynamic range.     

Two thermospray probe insert designs that allow clogged probes to be rapidly replaced

Thermospray has been widely accepted as a reliable technique for the analytical scientist. Many manufacturers provide thermospray as an option on their mass spectrometers. One difficulty experienced with thermospray is the clogging of the probe inserts. This report describes two new probe insert designs that minimize the problems associated with clogged probe inserts. Both of these new designs minimize the expense and downtime associated with clogged probe inserts. The capillary can be easily and quickly replaced to ensure optimum performance. The new fused-silica probe insert design that is described worked. adequately; there was, however, some beam instability caused by rapid oscillation of the fused-silica tubing near the tip. This oscillation also caused the tip to become brittle, necessitating frequent replacement. The stainless steel probe insert described did not exhibit these problems. Last, a comparison is made between the two new designs and the standard Kratos thermospray probe insert.     

Grazing-exit electron probe X-ray microanalysis (GE-EPMA): Fundamental and applications

Electron probe microanalysis (or Scanning electron microscope-energy dispersive X-ray spectrometry) has been studied under grazing-exit conditions. That is, characteristic X-rays are detected at a very small take-off (exit) angle; the technique is known as grazing-exit electron probe microanalysis (GE-EPMA). Fundamental aspects, instrumentation, and characteristics of grazing-exit electron probe X-ray microanalysis method are described here. Since the observation depth decreases as the exit angle decreases, theoretically to a few nanometers, surface analysis is possible in grazing-exit electron probe X-ray microanalysis. Of course, the size of the electron beam is also small—less than 1 μm, enabling localized surface analysis. In the case of total reflection X-ray spectrometry that allows surface analysis, the whole sample surface must be flat. However, the requirement for flatness is not as strict in grazing-exit electron probe X-ray microanalysis. Grazing-exit electron probe X-ray microanalysis measurements can easily be applied using a commercially available electron probe microanalysis (or Scanning electron microscope-energy dispersive X-ray spectrometry) instrument. To change and control the exit angle in grazing-exit electron probe X-ray microanalysis, the inclination of the sample stage or movement of the X-ray detector is all that is required. Theoretically, this study shows that grazing-exit electron probe X-ray microanalysis would be useful in improving the lateral resolution of the sample surface. In addition, the study demonstrates that grazing-exit electron probe X-ray microanalysis can be applied successfully for surface, thin-film, and particle analyses. As an optional method of electron probe microanalysis, grazing-exit electron probe X-ray microanalysis will be useful in expanding the research fields of normal electron probe microanalysis.     

Nano-Particle Sizing in a Thermal Plasma Synthesis Reactor

The radio frequency inductively coupled thermal plasma synthesis process, based on the use of solution precursors as the process feedstock, has been employed for the production of ceria (CeO₂) nano-powders. A sampling probe has been developed to continuously withdraw synthesized nano-powders from all desired positions within the plasma chamber for subsequent analysis. Using this probe, it was possible to study the 3D mapping of the plasma synthesis process. A flow of helium was introduced into the sampling probe to quench sampled particles and to prevent further particle growth within the sampling probe. Numerical simulations of the plasma flow were performed to study the influence of the probe tip geometry on the plasma flow. The reactor wall product collection method was also applied for sampling probe performance verification. The effects of selected plasma power and reactor pressure on the synthesized nano-powders size were investigated with this sampling probe. The results indicated that size distribution of the synthesized nano-powders is locally monomodal, with particles sizes as small as 4 nm being synthesized.     

A double-stranded molecular probe for homogeneous nucleic acid analysis

This paper reports the design and optimization of a double-stranded molecular probe for homogeneous detection of specific nucleotide sequences. The probes are labeled with either a fluorophore or a quencher such that the probe hybridization brings the two labels into close proximity, and this diminishes the fluorescence signal in the absence of a target. In the presence of a target, the fluorophore probe is thermodynamically driven to unzip from its hybridized form and bind with the target. An equilibrium analysis, which successfully describes all the major features of the assay without any fitting parameter, is performed to generalize the design of the probe. Several key parameters affecting the performance of the assay are examined. We show that the dynamic range and the signal-to-noise ratio of the assay can be optimized by the probe concentration, the quencher-to-fluorophore ratio, and the probe strand sequence. By proper design of the sequence, the probe discriminates single nucleotide mismatches in a single step without any separation step or measurement of melting profile.     

A Novel Microsensor for Measuring Angular Distribution of Radiative Intensity

This article presents the design, construction and characterization of a novel type of light probe for measuring the angular radiance distribution of light fields. The differential acceptance angle (DAA) probe can resolve the directionality of a light field in environments with steep light gradients, such as microbial mats, without the need to remove, reorient, and reinsert the probe, a clear advantage over prior techniques. The probe consists of an inner irradiance sensor inside a concentric, moveable light‐absorbing sheath. The radiative intensity in a specific zenith direction can be calculated by comparing the irradiance onto the sensor at different acceptance angles. We used this probe to measure the angular radiance distribution of two sample light fields, and observed good agreement with a conventional radiance probe. The DAA probe will aid researchers in understanding light transfer physics in dense microbial communities and expedite validation of numerical radiative transfer models for these environments.     

On the application of an oxygen probe in chemical kinetics: The influence of the probe response on kinetic measurement

Membrance covered oxygen probes are frequently used to monitor the progress of chemical reactions involving dissolved oxygen. For reactions that are comparable in rate to the response of the oxygen probe it is difficult to obtain the correct kinetic constants directly from the probe signal with traditional kinetic data manipulation methods. In this article, we apply the method of impulse response function to describe the probe signal of an oxygen probe for three different types of simple chemical reactions. The impulse response function is obtained experimentally. Using the impulse response function we have obtained the relationships between the probe signal and the kinetic parameters of these reactions. The slow response of the probe has two effects on the kinetic curves of the reaction studied: a time-lag and distortion of the shape of the kinetic curve throughout the reaction. The latter effect becomes significant when the reaction is fast. Procedures to obtain the correct kinetic information from the oxygen probe signal are described. © 1995 John Wiley & Sons, Inc.     

罗丹明6G衍生物基偏酸性“关开型”pH荧光探针

以罗丹明6G和水合肼为原料,先制备罗丹明6G酰肼,接着在乙醇中滴加少量冰醋酸做催化剂后与2,5-二甲氧基苯甲醛反应,合成了一种新型的pH荧光分子探针(RGSBD),进行了结构表征及荧光性能研究。结果表明,原本在氢离子浓度较低,即体系pH较高时(pH≥4.0),探针RGSBD内酰胺螺环闭环导致不显示荧光并且无色,然而在氢离子浓度较大即体系pH较低时(pH<4.0)时,其内酰胺螺环闭环产生了明显的颜色变化,发出强烈的荧光。pH 1.9时,探针的荧光强度达到最大,最大荧光峰发生显著的红移。进一步研究表明,探针RGSBD的荧光峰强度差值与pH在1.9~3.2范围内呈良好的线性关系,探针RGSBD识别H^+的选择性高,稳定性与可逆性强,可发展用作生物体内pH荧光传感材料。     

A Chemodosimetric Probe Based on a Conjugated Oxidized Bis‐Indolyl System for Selective Naked‐Eye Sensing of Cyanide Ions in Water

A new bis‐indolyl‐based colorimetric probe has been synthesized. This allows a Michael‐type adduct formation for the detection of cyanide ions. The probe shows a remarkable color change from red to colorless upon addition of the cyanide ions in pure water. The cyanide ion reacts with the probe and removes the conjugation of the bis‐indolyl moiety of the probe with that of the 4‐substituted aromatic ring. This renders the probe colorless. The mechanism of the reaction of the probe with the cyanide ion was established by using ¹H and ¹³C NMR spectroscopy, mass spectrometry, and kinetic studies.     

pH响应型近红外菁类荧光探针的合成及细胞成像

癌症的早期诊治是提高癌症患者治愈率的关键。但传统的"always on"型显影剂存在自身背景干扰且易造成"假阳性"等问题。本文利用肿瘤细胞具有弱酸性这一特性,设计合成了p H激活型不对称菁类荧光探针,并选用氨基葡萄糖作为修饰基团以增强探针母体的水溶性并赋予其肿瘤靶向性。该探针具有p H调控的"off-on"可逆的近红外荧光特性,以及与肿瘤弱酸性微环境相吻合的p H响应范围。此外,探针的浓度高达1.0×10~(-5)mol/L时仍未表现出明显的细胞毒性。该探针在细胞水平实现了肿瘤细胞弱酸性微环境的特异性成像。     

CD20靶向Cy7-Rituximab分子探针的制备及在小鼠活体荧光成像中的应用

以B淋巴细胞表面CD20抗原靶向的单克隆抗体Rituximab为载体, 通过共价键偶联荧光基团菁染料Cy7, 获得了新型荧光分子探针Cy7-Rituximab. 利用全光谱紫外-可见分光光度仪、SDS-聚丙烯酰胺凝胶电泳和基质辅助激光解析电离飞行时间质谱等对该探针结构进行表征, 并通过激光共聚焦显微镜观察了其在弥漫大B细胞淋巴瘤(DLBCL)细胞中的摄取情况. 选用BALB/C裸鼠为模型, 尾静脉注射 Cy7-Rituximab, 通过活体荧光成像系统观察了其在小鼠体内的分布情况. 研究结果表明, 修饰后的Cy7-Rituximab保持了原有抗体的免疫活性. 活体荧光成像结果表明, 在CD20高表达的脾脏部位监测到该分子探针的特异性浓集.     

Study on the Interaction of Mitomycin C with ct-DNA by Pd-Porphin Room Temperature Phosphorescence Probe

Study of the interaction of drugs with calf thymus DNA (ct-DNA) in molecular level1-4 is helpful to understand the fundamental aspects of activation of anticancer drugs and provide the valuable information for designing and developing new antitumor agents. Mitomycin C (MMC) is an anticancer drugs being widely used in clinic with high activity and effectiveness for many cancers. DNA has been proved to be the main target molecule of MMC in the body. The activated MMC can hinder the rep…     

A novel sensor based on the porous plastic probe for determination of dissolved oxygen in seawater

A new sensor based on the porous plastic probe has been developed for the detection of dissolved oxygen. This probe was prepared by co-polymerization of monomer, cross-linking reagent, porogent and luminescent ruthenium(II)diimine complex. The porous plastic probe exhibits good response to dissolved oxygen and resistance to indicator leaching out due to its high hydrophobicity. The preparation and characteristics of the probe were investigated in detail. This porous plastic probe serves as analyte-sensitive function as well as optical wave-guide, which make it easy to assemble the fiber-optical chemical sensor (FOCS). The developed sensor has been applied to the determination of dissolved oxygen in seawater with satisfactory results compared with the standard method.