Improved particle-packed HPLC/MS microchips for proteomic analysis

The influence of packing process parameters (packing pressure, application of ultrasound) and the stationary phase particle size (3.5 and 5 μm) on the chromatographic performance of HPLC/MS chips was systematically investigated for proteomic samples. First, reproducibility and detection limits of the separation were evaluated with a low‐complexity sample of tryptic BSA peptides. The influence of adsorbent packing quality on protein identification was then tested with a typical proteomics sample of high complexity, a human plasma protein fraction (Cohn fraction IV‐4). All HPLC/MS chips provided highly reproducible separations of these proteomic samples, but improved packing conditions and smaller particle sizes resulted in chromatograms with narrower peaks and correspondingly higher signal intensities. Improved separation performance increased the peak capacity, the number of identified peptides, and thus the sequence coverage in the proteomic samples, particularly for low sample amounts.     

Motion‐Based,High‐Yielding,and Fast Separation of Different Charged Organics in Water

We report a self‐propelled Janus silica micromotor as a motion‐based analytical method for achieving fast target separation of polyelectrolyte microcapsules, enriching different charged organics with low molecular weights in water. The self‐propelled Janus silica micromotor catalytically decomposes a hydrogen peroxide fuel and moves along the direction of the catalyst face at a speed of 126.3 μm s^?1. Biotin‐functionalized Janus micromotors can specifically capture and rapidly transport streptavidin‐modified polyelectrolyte multilayer capsules, which could effectively enrich and separate different charged organics in water. The interior of the polyelectrolyte multilayer microcapsules were filled with a strong charged polyelectrolyte, and thus a Donnan equilibrium is favorable between the inner solution within the capsules and the bulk solution to entrap oppositely charged organics in water. The integration of these self‐propelled Janus silica micromotors and polyelectrolyte multilayer capsules into a lab‐on‐chip device that enables the separation and analysis of charged organics could be attractive for a diverse range of applications.     

Characterization of Diamond Nanoparticles by High-Speed Micro-Thermal Field-Flow Fractionation

Micro-thermal field-flow fractionation was used to characterize the particle size distribution of nanometer-sized diamond nanoparticles. Although the experimental conditions were chosen to perform high-speed separation, and, consequently, the resolution achieved experimentally was not very high, the application of the original correction method for the zone spreading allowed for obtaining of very good calculated particle size distribution or, explicitly, a true polydispersity index of the diamond nanoparticle sample. The future use of several samples of diamond nanoparticles of different average sizes and different surface chemistries should allow deeper insight into the effect of these particulate characteristics on the retention in micro-thermal field-flow fractionation.     

整体柱富集技术在微流控芯片系统中的应用

样品预处理技术是微流控芯片技术发展的瓶颈之一。整体材料是近几年在色谱领域发展起来的一种新型色谱填料,具有结构均匀、传质速度快、通透性好、制备过程简单等优点,被广泛用于微流控芯片系统中。该文综述了整体柱富集技术在微流控芯片系统中的应用进展,引用文献80篇。     

生命分析微流控芯片的多尺度应用:从分子水平到个体水平

微流控芯片技术是多学科、多领域交叉的新兴分析技术,具有微型化、集成化、高通量、低消耗、高灵敏、分析速度快等特点。如今,微流控芯片技术已发展成为自然科学研究中不可或缺的技术平台,展现出巨大的优势,尤其在生命科学研究中得到了广泛应用。该文概述了近年来微流控芯片技术在分子水平、细胞水平、组织器官水平和生物个体水平等多个尺度上的应用,并对其发展前景进行了展望。     

裂解-气相/质谱法分析木屑物证

木屑是一种在各种案件现场中出现几率较高的微量物证,但由于其化学组成复杂、难溶,高分子组分之间的差异不显著,所以一直未建立有效的鉴定方法.采用裂解-气相/质谱技术(PY-GC/MS)对不同树种木屑难溶物进行分析,结果发现:不同树种木屑难溶物的总离子流图特征相似,即每种木屑难溶物的总离子流图中都有一组特征峰.但个别组分有差异.     

Field-flow fractionation in microfluidic channels of low aspect ratio

The shape of the steady-state three-dimensional flow velocity profile established in carrier liquid flowing inside the rectangular cross-sectional channel for field-flow fractionation should be taken into account to optimize the separation. The central parts of this profile in the planes parallel to the main channel walls are flat with almost identical flow velocities which drop down to zero at the side walls. The separated species transported by the flow in the close-to-side walls regions move with lower average velocities compared to the species transported in the central part of the channel and are undesirably broadened. The hydrodynamic splitting of the carrier liquid at the entry of the channel where the sample is injected only into the central part of the channel eliminates the excessive zone broadening. The aspect ratio of the breadth to the thickness of the channel ratio can thus be reduced. The effect of various aspect ratios on the shape of the flow velocity profile is calculated and the results are used to optimize the aspect ratio of microfluidic channels. The experiments carried out by microthermal field-flow fractionation confirmed that the aspect ratio cannot be reduced to a value of 1, proposed by other authors.     

三种典型磨粒磨损磨屑形成过程的研究

作者利用扫描电子显微镜、光学显微镜和计算机图象分析系统,对3种典型磨粒磨损磨屑的形成特点和典型试验条件下材料的磨粒磨损过程进行了研究。结果表明,在磨粒磨损条件下,典型的磨屑形态主要是切屑和块状屑,同时还有极少量的球状屑和花状屑。作者指出,切屑和块状屑分别是磨粒与被磨材料表面一次和多次相互作用的产物。在三体磨粒磨损条件下,切削是造成编号为2M和3M等硬质材料磨损的主要原因,也是4M和几种奥氏体锰钢在高载荷下磨损的重要形式;块状屑的形成是塑性较好的材料在各种磨损条件下磨损的主要形式。球状屑的形成是磨粒与被磨材料表面的接触点产生高温致使材料熔化的结果。球状屑一般是中空且表面有很多孔洞的球壳,其形成与气体有关。     

基于声表面波技术实现数字微流体多基片间输运

建立了声表面波实现多基片间输运微流体的新方法.由3个128(0)YX-LiNbO3压电基片组成,一个基片为接口基片,另两个为工作基片,每个基片光刻一个中心频率为27.5 MHz叉指换能器和一个反射栅.采用微量进样器将待输运的数字微流体进样到工作基片2,调节接口基片使得其与工作基片2位于同一高度,并使其间隙尽可能小,在工...     

基于液滴微流控接口的高效液相色谱-毛细管电泳二维分离平台初探

蛋白质组体系的高度复杂性需要更高分辨率的多维分离技术。近年兴起的液滴技术在微纳尺度样品操控方面具有微体积、低扩散、无返混等独特优势,有望为多维分离平台的接口提供解决方案。通过采用不同结构的液滴微流控芯片可以实现“液滴生成”与“油相排除”功能,进行样品由连续流-非连续流-连续流的高效转移,将不同的分离模式进行二维耦联。本研究利用液滴作为接口技术耦联高效液相色谱与毛细管电泳构建二维分离系统,以蛋白质降解的复杂多肽混合物为样品,考察了液滴接口二维分离平台的可行性和有效性,并获得3000以上的峰容量,初步展示了该接口技术在多维分离分析领域的应用潜力。