Detecting proteins complex formation using steady-state diffusion in a nanochannel

In this work, we present theoretical and experimental studies of nanofluidic channels as a potential biosensor for measuring rapid protein complex formation. Using the specific properties offered by nanofluidics, such as the decrease of effective diffusion of biomolecules in confined spaces, we are able to monitor the binding affinity of two proteins. We propose a theoretical model describing the concentration profile of proteins in a nanoslit and show that a complex composed by two bound biomolecules induces a wider diffusion profile than a single protein when driven through a nanochannel. To validate this model experimentally, we measured the increase of the fluorescent diffusion profile when specific biotinylated dextran was added to fluorescent streptavidin. We report here a direct and relatively simple technique to measure the affinity between proteins. Figure We present theoretical and experimental studies of nanofluidic channels as potential biosensors for rapidly measuring protein complex formation. Our system is based on steady-state diffusion effects which are observed inside a nanoslit.     

Coupling of size-exclusion chromatography to a continuous assay for subtilisin using a fluorescence resonance energy transfer peptide substrate: testing of two standard inhibitors

Liquid chromatography (LC) was coupled on-line to a homogeneous continuous-flow protease assay using fluorescence resonance energy transfer (FRET) as a readout for the screening of inhibitors of an enzyme (e.g., Subtilisin Carlsberg). The inhibitors aprotinin (a protein of approximately 6500 g/mol) and 4-(2-aminoethyl)benzenesulfonyl fluoride hydrochloride (AEBSF, 240 g/mol) were mixed with other, non-active compounds and separated on a size-exclusion chromatography column. After the separation, the analytes were eluted to the postcolumn reactor unit where the enzyme solution and subsequently the FRET peptide substrate were added; by measuring the fluorescence intensity the degree of inhibition was monitored on-line. As expected, only the two inhibitors caused a change in the FRET response. Detection limits for aprotinin were 5.8 microM in the flow injection analysis (FIA) mode and 12 microM in the on-line LC mode. System validation was performed by determining IC50 values for aprotinin for the FIA mode (19 microM) and the on-line mode (22 microM). These IC50 values were in line with the value determined in batch experiments (25 microM). With this system, chemical information (i.e., chromatographic retention time) and biological information (i.e., enzyme inhibition) can be combined to characterize mixtures.     

毒剂的生化分析技术

本文论述了酶法分析、核酸探针、免疫分析法特别是生物传感器在毒剂检测中的应用，提出了毒剂生化分析的发展方向。     

Monitoring arsenic in the environment: a review of science and technologies with the potential for field measurements

This review examines available field assays and other technologies with the potential to measure and monitor arsenic in the environment. The strengths and weaknesses of the various assays are discussed with respect to their sensitivity, ability to detect the chemical states of arsenic, performance in various media, potential interferences, and ease of operation. The state of the science and development efforts of selected technologies is presented.     

4H—1,2,4—三唑—4—基酮和醇的合成及其生物活性

1-(4H-1,2,4-三唑-4-基)频哪酮(2)与卤代烃在相转移催化条件下反应,得到具有较高产率的4H-1,2,4-三唑-4-基酮(3);进一步用硼氢化钾还原,得到近乎定量产率的醇(4)。初步的生物活性测定表明3和4有一定的延缓植物生长的作用和杀菌活性。     

二恶英类化学物质的检测方法

本文介绍了20世纪60年代以来二恶英类化学物质的检测方法。重点介绍了色谱法、免疫法和生物法，并对各种分析方法的优缺点进行了评述，提出了各方法运用的适用范围，为建立二恶英类化学物质分析方法提供了依据。     

N,N′-二烷基-氨基甲酰基膦酰胺酯类化合物的合成

据Jelinek报道,N,N-二烷基-氨基甲酰基膦酰胺酯类化合物具有抑制植物生长的活性,能影响多种植物的开花和坐果。为探讨这类化合物的合成方法、结构与活性的关系,从而筛选出高效低毒的除草剂,本文合成了通式为RO(R′NH)P(O)C(O)-NHR~2的10种新化合物(表1)。对于合成方法进行了初步探讨,其中方法Ⅱ未见文献报道。     

Nanoscale potentiometry

Potentiometric sensors share unique characteristics that set them apart from other electrochemical sensors. Potentiometric nanoelectrodes have been reported and successfully used for many decades, and we review these developments. Current research chiefly focuses on nanoscale films at the outer or the inner side of the membrane, with outer layers for increasing biocompatibility, expanding the sensor response, or improving the limit of detection (LOD). Inner layers are mainly used for stabilizing the response and eliminating inner aqueous contacts or undesired nanoscale layers of water. We also discuss the ultimate detectability of ions with such sensors and the power of coupling the ultra-low LODs of ion-selective electrodes with nanoparticle labels to give attractive bioassays that can compete with state-of-the-art electrochemical detection.     

基于化学荧光测定的板蓝根抗病毒效价检测方法的建立

荧光测定法在化学分析和生物检测中已广泛应用,将该法引用到中药的生物效价检测中则是一种新的尝试。而生物效价检测与药效直接相关联,是研究中药质量控制与品质评价方法的新趋势。为了建立与抗病毒药效相关的板蓝根质量控制和评价方法,采用化学荧光测定法考察了板蓝根提取物对流感病毒神经氨酸酶(NA)的体外抑制活性,分析了其药理作用的量效曲线变化趋势和作用规律。在此基础上并根据生物检定的统计学原理,以“质反应平行线”法设计和优化检测条件,建立了板蓝根抗病毒生物效价荧光检测方法。实际测试结果能够灵敏、定量表征样品间的品质差异,方法的可靠性和可重复性较好。以此作为板蓝根质量生物控制和评价方法,能够体现中药药效特点。