微流控高通量试样引入技术的研究进展

如何实现外部宏观系统与芯片微观系统之间的衔接一直是微流控芯片分析领域中一个重要的研究课题。本文结合作者所在研究组的工作及成果,介绍了当前微流控高通量试样引入技术的研究进展。其中分别介绍了基于固定储液池、流通池和取样探针3种模式的微流控芯片系统试样引入系统,以及基于毛细管的微流控高通量试样引入系统。此外,还对该领域研究发展的前景进行了展望。     

磁场控制技术在微流控芯片中的应用*

磁场作为除了电场和力场之外的另一个有力的驱动和控制手段,由于不需与溶液接触即可实现对被分析物的操纵,极大降低污染的可能,近年来被越来越广泛地用于微流控芯片系统,尤其在细胞、病毒甚至单分子的捕获、分选以及操纵等方面显示出较大优势。本文综述了微流控芯片系统中磁场控制技术的最新进展,分别从理论分析,磁场加工技术、泵阀的实现,微流体控制和磁分离等方面介绍了该领域近几年的发展状况,并重点分析了微流控芯片磁场操控技术在临床分析和现场检测方面的应用,及其未来发展趋势和需解决的主要问题。     

微流控芯片高通量试样引入系统的研究

基于微流控芯片试样引入技术的研究是目前微流控芯片分析领域内的重要研究方向之一,其目的是实现宏观外部系统(进行10^-6～1L级液体的操作)与芯片系统(进行10^-12～10^-9 L级液体的操作)的衔接(world-to-chip interfacing)．目前文献报道的微流控分析系统,包括芯片流动注射系统,     

精准入微——将微流控技术引入分析化学教学的探讨

微流控技术凭借其优异的微尺度操控能力,在分析化学和其他诸多领域得到了广泛而快速的发展。在本科阶段的分析化学课程引入微流控技术有助于提高分析化学教学的前沿性和趣味性,促进创新型人才的培养。本文回顾了微流控技术的发展史并挖掘了其中蕴含的课程思政元素,简要介绍了微流控技术的重要理论和微流控芯片的基本制作方法,讨论了微流控技术与分析化学的联系。在此基础上介绍了近年来微流控技术在分析化学领域,尤其是生命分析科学领域的研究进展,以期为分析化学教学引入微流控技术提供参考。     

微流控芯片系统在单细胞研究中的应用

微流控芯片具有网络式通道结构,扩展了在细胞和亚细胞水平进行生命科学研究的能力,为单细胞研究提供了一个新的平台.在微流控芯片通道中,人们利用气压、液压和电压,或利用介电电泳、光学陷阱、行波介电电泳以及磁场等技术,可以操纵细胞通过或驻留在通道内的任意位置,从而使单细胞计数、筛选以及胞内组分分析等操作大大简化.本文对微流控芯片系统在血液流变学、单细胞操纵与计数以及单细胞胞内组分分析中的应用进行了综述,介绍了用于单细胞研究的多种微芯片系统,讨论了芯片上进行单细胞操纵的各种方法     

基于流体动力单细胞高效捕获的微流控芯片结构研究进展

单细胞分析对于重大疾病的早期诊断及治疗、药物筛选和生理病理过程的研究具有重要意义。微流控芯片能够精确控制单细胞的微环境,实时监测单细胞的行为,已成为单细胞分析的强大工具。单细胞捕获是单细胞分析的重要步骤。目前已报道了多种微流控芯片用于单细胞捕获的方法,其中基于流体动力的微流控芯片单细胞捕获方法具有操作方便、单细胞捕获效率高等优点,受到研究人员的广泛关注及使用。为了全面了解基于流体动力的微流控芯片单细胞捕获方法的研究现状,掌握单细胞高效捕获的微流控芯片结构设计,实现单细胞精准快速分析,本文综述了基于流体动力的单细胞高效捕获（>70%）原理及微流控芯片结构,根据结构设计不同分为微井结构、微柱结构和旁路通道结构,介绍了单细胞高效捕获的微流控芯片优化过程,总结了微流控芯片的材质、结构特点及单细胞捕获效率等,对不同单细胞捕获结构的优势及不足进行了分析。最后,对基于流体动力的微流控芯片单细胞捕获方法的发展趋势进行了展望。     

微流控芯片上的免疫分析

近20年来,随着微流控芯片加工技术的不断发展,微流控分析已从一个概念发展为当前世界上最前沿的科技领域之一,微流控芯片上免疫分析的方法研究也取得重要进展。这些芯片包含传输流体的微通道和免疫分析程序中部分或全部的必要组件。微流控技术用于免疫分析在减少试剂用量、缩短分析时间、自动化等方面提高了分析性能。本文综述了微流控芯片上免疫分析的发展、分类,并评述了各类微流控免疫分析芯片的性能及优缺点。     

微流控系统在生化分析领域的新应用

微流控芯片是近年来新兴的研究领域,它由微米级别的微通道及辅助器件构成,并且有着低试剂消耗量、响应时间短、高精度、高灵敏度、高集成度和独特的微观物理现象等特性。微流控芯片的独特优势为生物样品的处理与分析、生物模拟、药物传递和多组分分析等领域提供了前所未有的机会。为获得理想、完善的微流控平台,还需进一步挖掘微流控芯片的潜在应用。本文回顾了微流控芯片在生化分析领域中的新应用,分析了其优劣势与存在的挑战,并预测了微流控芯片未来可能的发展趋势,指出了微流控芯片"走出实验室"投入实际应用的可能。     

微流控芯片-质谱联用细胞分析方法研究进展

细胞分析和代谢物分析在生物系统中起着重要的作用。微流控技术已成为细胞生物学研究的一个重要工具。该文总结了最近微流控芯片在细胞和代谢物的分析,尤其是微流控芯片与质谱联用技术的应用。同时对微流控芯片上细胞的生物学研究提出了见解和看法,希望能对感兴趣者提供一些启发。     

微流控芯片检测技术进展

介绍了目前微流控芯片应用的3种主要检测手段:质谱检测器、电化学检测器和光学检测器。微流控芯片是微全分析系统(μ-TAS)中最活跃的领域和发展前沿。人们在微流控芯片的研究中已经取得了很大的进展,研制出了多种微型化、集成化的芯片,而与微流控芯片配套的高灵敏度微型检测系统更是研制的热点。     

Methodology for determination of magnetic force of polymeric nanocomposites

Magnetic nanocomposites present several interesting uses. They are very useful in environmental recovery, drug delivery and sensor applications. However, sophisticated magnetic measurements are very complex and present high costs, which may sometimes prevent research on these materials. Therefore, this paper presents a magnetic force test, which can be performed at relatively low cost and produces interesting results, which are very useful to support the development of these magnetic materials. Specifically, polylactic acid (PLA)/maghemite nanocomposites were prepared and characterized using Fourier transform infrared (FTIR) spectroscopy, wide-angle X-ray scattering (WAXS), small-angle X-ray scattering (SAXS) and size-exclusion chromatography (SEC). Our results demonstrate that nanocomposites, were obtained, which were also subjected to the magnetic force and magnetic susceptibility tests. The results of these latter tests were found to be linearly related, which proves the utility of the magnetic force test as a practical characterization technique.     

Chemical analysis of size-tailored magnetic colloids using slurry nebulization in ICP-OES

In this work, inductively coupled plasma emission spectroscopy was utilized to directly determine the chemical composition of magnetic fluids constituted of size-sorted ferrite nanoparticles in aqueous solution. Nickel and cobalt nanoferrites were chemically synthesized following a bottom-up route and dispersed under various pH conditions. Size and structural characteristics of nanograins were investigated by X-ray diffraction using a synchrotron source. Chemical analysis was then carried out by directly introducing diluted magnetic fluid samples (slurries) into the spectrometer. To achieve reliable measurements, sample conditions and apparatus parameters were carefully investigated. Slurry stability must be optimized in order to obtain reproducible and accurate analysis. The instrument must also be calibrated to minimize the difference between the signal produced by slurries and that of aqueous ordinary solutions. Furthermore, slurry sample introduction offers many advantages over conventional sample digestion, including reduced sample pretreatment time, less possibility of contamination and the use of direct calibration with aqueous solutions.     

Review: A gentle introduction to magnetism: units,fields, theory,and experiment

We present an introduction to the workings, units of measure, and general properties of magnetic materials. This is intended as a “primer to interpretation of magnetic data” for those who are entering the field, or those who are encountering magnetic measurements in the literature. We expect this work will serve as an initial guide to the reader to familiarize them with the basics in the hope that those working in the field of magnetochemistry will wish to explore additional, more detailed literature as their specific investigations demand. Topics covered include: magnetic fields and units (SI and cgs), paramagnetism (magnetization and magnetic susceptibility), Curie and Curie–Weiss behavior, magnetic exchange interactions, magnetic anisotropy, dimeric systems and exchange-coupled networks (including chains, ladders, and layers), and long-range order.     

Different methods for the fractionation of magnetic fluids

 Magnetic fluids are used in many fields of application, such as material separation and biomedicine. Magnetic fluids consist of magnetic nanoparticles, which commonly display a broad distribution of magnetic and nonmagnetic parameters. Therefore, upon application only a small number of particles contribute to the desired magnetic effect. In order to optimize magnetic fluids for applications preference is given to methods that separate magnetic nanoparticles according to their magnetic properties. Hence, a magnetic method was developed for the fractionation of magnetic fluids. Familiar size-exclusion chromatography of two different magnetic fluids was carried out for comparison. The fractions obtained and the original samples were also magnetically characterized by magnetic resonance and magnetorelaxometry, two biomedical applications. The size-exclusion fractions are similar to those of magnetic fractionation, despite the different separation mechanisms. In this respect, magnetic fractionation has several advantages in practical use over size-exclusion chromatography: the magnetic method is faster and has a higher capacity. The fractions obtained by both methods show distinctly different magnetic properties compared to the original samples and are therefore especially suited for applications such as magnetorelaxometry. Received: 12 July 1999/Accepted in revised form: 9 November 1999     

Magnetic Field and Magnetic Isotope Effects upon Reactions of Heavy Atom-Centered Radicals

We present our recent studies on magnetic field effects (MFEs) observed in reactions of heavy atom-centered radicals such as Si-,P-, Ge-, and Sn-radicals with a ns-laser photolysis technique under magnetic fields of 0–10 T. Although the MFES of heavy atom-centered radicals are much smaller than those of C-radicals due to the spin-orbit interaction of heavy atoms, we have found appreciable MFEs in many reactions of such heavy atom-centered radicals. Comparing the MFES of C-radicals with those of heavy atom-centered ones, we have explained the MFEs of heavy atom-centered radicals in terms of the Δg and relaxation mechanisms. We have found that the separation between the MFES due to the Δg mechanism and those due to the relaxation one is possible with the enhancement of spin relaxation by the addition of a paramagnetic ion. We have also tried to enrich magnetic isotopes of heavy atoms with the magnetic isotope effect (MIE), using the reactions which show fairly large MFES. Recently, we have succeeded in enriching ⁷³Ge. This is the heaviest isotope which has so far been enriched with the MIE from samples of natural abundance.     

磁性珠状纤维素制备工艺研究

本文较系统地研究了在采用反相悬浮包埋技术制备磁性珠状纤维素的过程中，纤维素的分子量、分散介质的性质、搅拌速度和O／W值等诸因素对磁性纤维素珠体的粒径、粒径分布和磁性材料包封率的影响。得到平均粒径在300微米以下，粒径分布指数小于1．4的磁性珠状纤维素，收率可达90％以上，且磁性材料（γ－Fe2O3）包封率较高。     

Mn0.6 Zn0.4 Fe2 O4 磁性亚微球的可控合成及磁性能

采用溶剂热法制备了单分散Mn0.6Zn0.4Fe2O4磁性亚微米球, 研究了反应工艺参数对磁性亚微米球结构形貌、 直径和静磁性能的影响规律. 研究发现, 随着反应时间的延长, 体系中的金属离子首先水解沉淀, 形成羟基氧化铁及Mn, Zn氢氧化物, 然后脱水转化为Mn0.6Zn0.4Fe2O4球形纳米粒子, 这些纳米粒子发生团聚, 形成结构疏松、 大小不均匀的亚微米粒子, 最后通过Ostwald熟化过程, 形成致密的单分散亚微米球. 降低反应溶液的pH值、 增加乙二醇或聚乙二醇的用量, 均会使亚微球的直径增大, 并可在150~500 nm范围内调控微球的粒径; 但组成磁性亚微球的纳米粒子的粒径逐渐减小, 产物的饱和磁化强度增大, 矫顽力和剩磁减小.     

磁性珠状纤维素的性能表征

本文采用反相悬浮包埋技术制各了磁性珠状纤维素（magneticcellulosebead缩写MCB），并对MCB各方面的性能进行了全面的评价：湿态孔度高达80％以上，磁化率在10-3emu／g数量级，磁性铁分布均匀，且磁稳定性较高。     

Advances in Molecular Diamagnetism

At the present state of instrumentation and quantum-mechanical approximations, diamagnetic measurements can supply information on chemical structure which complements the result of other approaches, such as infrared and NMR spectroscopy. General applicability and relatively low cost of equipment are among the advantages of this technique. There is growing interest in the relation to chemical shifts in NMR spectra and in the possibility offered by this technique for testing quantum-chemical approximations.     

Review: Preparation and Application of Magnetic Chitosan Derivatives in Separation Processes

Chitosan is one of the most abundant natural polysaccharide in nature. Due to its unique properties, chitosan has fascinated the scientific community since its discovery. When modified with other materials and combined with magnetic particles, the resulting composite material, a magnetic chitosan derivative, is provided with three significant characteristics. First, chitosan has excellent properties for preconcentration/extraction, such as adsorption and chelating effects, low cost, and nontoxicity. Second, new functional groups have enhanced the properties of chitosan that include water solubility, stability, recyclability, and enhanced adsorption capacity. Finally, due to the efficient and fast adsorption processes, as well as simple and convenient magnetic separation, the magnetic adsorbents greatly reduce the time of sample handling. In this article, recent synthesis and modification methods of magnetic chitosan derivatives are reviewed along with some applications in analytical separations.