小分子荧光探针在蛋白质标记与成像分析中的应用

小分子荧光探针由于其体积小、合成简单等特点在蛋白质成像技术中扮演着越来越重要的角色。此领域的研究融合了生物化学、有机合成、分析化学等相关学科,是当今化学发展的一个重要方向,有着广阔的前景。目前,能够专一性地与目标蛋白质(POI)结合的小分子探针较少,设计和合成方法的缺乏已经成为制约该领域进一步发展的瓶颈。本文概括地介绍了近年来出现的一些小分子荧光探针,关注它们在活体标记中的应用。     

数码成像比色法测定水样中的总磷

在酸性介质中,磷酸二氢钾与钼酸铵、酒石酸锑钾及抗坏血酸作用,生成蓝色的络合物。随着磷酸二氢钾浓度的增加,溶液颜色加深,其数码成像的RGB值亦随着磷酸二氢钾浓度的增加而增加,由此建立数码成像比色法(DIC)测定水样中总磷的新方法。考察了DIC法的影响因素和最佳反应条件。与钼酸铵分光光度法对照,该方法简单,快速。用于实际水样的测定,相对标准偏差为1.8%~3.4%,回收率为99.7%~102.5%,结果与分光度法一致。     

CT、MRI对良恶性甲状腺结节的鉴别价值

本文探讨了计算机断层扫描（CT）、磁共振成像（MRI）对良恶性甲状腺结节的鉴别价值。方法：选取2015年3月至2018年3月本院收治的甲状腺结节患者150例，依据病理结果分为恶性48例、良性102例，所有患者均给予CT、MRI检查，分析CT、MRI对良恶性甲状腺结节的鉴别价值。结果发现，MRI总病灶、形态不规则、边界不清/毛糙、信号/密度不均检出率明显高于CT，MRI钙化灶检出率明显低于CT，差异有统计学意义（P<0.05），CT、MRI淋巴结转移检出率比较，差异无统计学意义（P>0.05）；在鉴别良恶性甲状腺结节的敏感度、特异度、准确度中，CT为79.17%、74.51%、76.00%，MRI为83.33%、80.39%、81.33%，CT联合MRI为95.83%、96.08%、96.00%，CT联合MRI明显高于CT、MRI，差异有统计学意义（P<0.05）。说明CT、MRI可作为鉴别良恶性甲状腺结节的重要方法，CT对钙化灶有较高的分辨能力，MRI对软组织及小病灶有较高的分辨能力，CT联合MRI可有效提高其鉴别价值。     

Dielectric analysis of polystyrene microcapsules using scanning dielectric microscope

 A dielectric imaging technique with a scanning dielectric microscope was applied to polystyrene microcapsules in an aqueous environment to study the electrical properties of individual ones. The dielectric images obtained over a frequency range from 10 kHz to 10 MHz showed frequency dependence, which indicated dielectric dispersion (or relaxation) due to interfacial polarization or the build up of charge on the boundaries between the microcapsule shell and the aqueous phases. The dielectric dispersion was analyzed based on an equivalent electrical circuit model and a shell-sphere model in which a spherical core is covered with an insulating shell. Received: 26 September 1997 Accepted: 26 December 1997     

Inhomogeneity in Distribution and Conformation of Bovine Serum Albumin in Sol–Gel: A Closer Look with a Near-Infrared Multispectral Imaging Technique

Concentration distributions and conformations of bovine serum albumin (BSA) entrapped in sol–gels were successfully determined for the first time by use of the recently developed NIR multispectral imaging instrument. It was found that BSA molecules were inhomogeneously distributed within the sol–gel matrix, independent of its concentration. At relatively high concentration (366 mg/mL) the encapsulation process does not seem to produce any observable changes in the conformation of BSA. However, when the concentration of BSA was decreased to 220 mg/mL, pronounced changes in the spectra of the protein were observed as a function of (sol–gel reaction) time. The observed inhomogenity might be traced to both a non-uniform concentration distribution of BSA and changes in protein native conformation resulting from interactions between the charged protein and the silicate anions. Results obtained seem to suggest that the protein molecules might adapt themselves to accommodate evolving geometry and sites of the silica network.     

Novel Carbohydrate‐Appended Metal Complexes for Potential Use in Molecular Imaging

Seven discrete sugar‐pendant diamines were complexed to the {M(CO)₃}⁺ (^99mTc/Re) core: 1,3‐diamino‐2‐propyl β‐D ‐glucopyranoside ( L ¹ ), 1,3‐diamino‐2‐propyl β‐D ‐xylopyranoside ( L ² ), 1,3‐diamino‐2‐propyl α‐D ‐mannopyranoside ( L ³ ), 1,3‐diamino‐2‐propyl α‐D ‐galactopyranoside ( L ⁴ ), 1,3‐diamino‐2‐propyl β‐D ‐galactopyranoside ( L ⁵ ), 1,3‐diamino‐2‐propyl β‐(α‐D ‐glucopyranosyl‐(1,4)‐D ‐glucopyranoside) ( L ⁶ ), and bis(aminomethyl)bis[(β‐D ‐glucopyranosyloxy)methyl]methane ( L ⁷ ). The Re complexes [Re( L ¹ – L ⁷ )(Br)(CO)₃] were characterized by ¹H and ¹³C 1D/2D NMR spectroscopy which confirmed the pendant nature of the carbohydrate moieties in solution. Additional characterization was provided by IR spectroscopy, elemental analysis, and mass spectrometry. Two analogues, [Re( L ² )(CO)₃Br] and [Re( L ³ )(CO)₃Br], were characterized in the solid state by X‐ray crystallography and represent the first reported structures of Re organometallic carbohydrate compounds. Conductivity measurements in H₂O established that the complexes exist as [Re( L ¹ – L ⁷ )(H₂O)(CO)₃]Br in aqueous conditions. Radiolabelling of L ¹ – L ⁷ with [^99mTc(H₂O)₃(CO)₃]⁺ afforded in high yield compounds of identical character to the Re analogues. The radiolabelled compounds were determined to exhibit high in vitro stability towards ligand exchange in the presence of an excess of either cysteine or histidine over a 24 h period.     

离子速度成像方法研究二溴甲烷的紫外光解动力学

利用二维离子速度成像(Ion-Velocity Imaging)方法对二溴甲烷分子在234和267 nm附近的光解动力学行为进行了研究. 实验中得到了二溴甲烷光解产生的Br^*(²P_1/2)和Br(²P_3/2)在不同波长下的角度和平动能分布. 在平动能分布中发现两个高斯分布, 推测其中主要是C—Br的快速解离, 而高能宽分布则来自于CH₂Br自由基的二次解离过程. 通过角度分布得到了Br^*与Br中来自直接解离和非绝热交叉跃迁两种来源的比例. 结果表明Br^*原子主要来自于B₁态的直接解离, 而Br则绝大部分是从B₁态向A₁的非绝热交叉跃迁得到, 并导致了两种解离通道能量分布的差别.     

Detection of stress whitening in plastics with the help of X-ray dark field imaging

The processing of thermoplastics can induce a wide range of defects such as stress whitening, cavitation and porosity, which can adversely affect the reliability of the final products. Hence, fast and effective non-destructive detection methods for such defects are highly important for quality assurance on production lines. In this paper, X-ray dark field imaging is presented as a new non-destructive testing method that allows the visualization of stress whitening or cavitation efficiently. The performance of the method is demonstrated for the case of an injection-moulded polyvinylidene fluoride part that exhibits stress whitening. Whereas the stress whitening could not be detected by conventional X-ray imaging, it was localized by an X-ray dark field image acquired within a few minutes. Once the precise location of the stress whitening was known, it was possible to verify the result by local micro X-ray computed tomography and by a micro section image.     

Gadolinium‐Decorated Silica Microspheres as Redox‐Responsive MRI Probes for Applications in Cell Therapy Follow‐Up

The redox microenvironment within a cell graft can be considered as an indicator to assess whether the graft is metabolically active or hypoxic. We present a redox‐responsive MRI probe based on porous silica microparticles whose surface has been decorated with a Gd‐chelate through a disulphide bridge. Such microparticles are designed to be interspersed with therapeutic cells within a biocompatible hydrogel. The onset of reducing conditions within the hydrogel is paralleled by an increased clearance of Gd, that can be detected by MRI.     

Predicting future duration from present age: A critical assessment

Using a temporal version of the Copernican principle, Gott has proposed a statistical predictor of future longevity based on present age (Gott III, J. R., 1993, Nature, 363, 315) and applied the predictor to a variety of examples, including the longevity of the human species. Although Gott's proposal contains a grain of truth, it does not have the universal predictive power that he attributes to it.