New developments in Western blot technology

Western blotting is a highly valued method for protein identification and relative quantitation in complex samples. It combines size-based electrophoretic separation with immunoaffinity to identify specific proteins. This technique remains popular and has become a workhorse in biochemical research and clinical laboratories. Despite its utility and popularity, this method has many limitations including slow analysis, incompatibility with limited sample application, low throughput and low information content. Recently there has been significant success in improving different aspects of Western blotting. In this review, we provide an overview of the developments in the area of improving conventional Western blotting methods with a focus on recent developments in microfluidic Western blotting. We overview different separation platforms, and discuss studies on protein transfer methods as well as protein immobilization methods and chemistries. We also describe integrated miniaturized platforms that can perform rapid separations and immunodetections.     

Precise measurement and control of the pressure-driven flows for microfluidic systems

The pressure-driven device is designed and the flow rates of the microfluidic systems can be supplied by the pressure-driven flows, which can significantly reduce the flow-rate fluctuations coming from the pump source. For pressure-driven flows, the flow rates of the fluids can be predicted by measuring the pressure drop along a polytetrafluoroethylene (PTFE) tubing. Especially, by varying the geometrical parameters of the PTFE tubing, the predicted flow rates of the fluids are compared with the experimental measurements, and the testing precision of the pressure-driven flows can be obtained. Meanwhile, the dynamic characteristics of the open-loop and closed-loop control pressure-driven device are comparatively studied. Particularly, a proportional and integral (PI) controller is integrated with the closed-loop control pressure-driven device, and the effects of the parameters of the PI controller on the dynamic characteristics of the pressure-driven devices are mainly discussed. Most importantly, by improving the dynamic characteristics of the pressure-driven devices, precise measurement and control of the pressure-driven flows can be achieved for microfluidic systems.     

Low-cost automated capillary electrophoresis instrument assembled from commercially available parts

A CE instrument that can be assembled from commercially available components with minimal construction effort is described. Except for the electronic control circuitry no specially made parts are required. It is based on a flexible design of microfluidic, electropneumatic, and electronic sections and different configurations can easily be implemented. Automated injection into the capillary is performed hydrodynamically by the application of a pressure for a controlled length of time. The performance of the device was tested with a contactless conductivity detector by separating different metal ions. In addition, nine metal cations related to the quality of honey were separated in 2.3 min and four honey samples were analysed quantitatively to demonstrate the applicability of the method.     

Synthesis of fused indolines by interrupted Fischer indolization in a microfluidic reactor

This study describes our development of a microfluidic reaction scheme for the synthesis of fused indoline ring systems found in several bioactive compounds. We have utilized a continuous-flow microfluidic reactor for the reaction of hydrazines with latent aldehydes through the interrupted Fischer indolization reaction to form fused indoline and azaindoline products. We have identified optimal conditions and evaluated the scope of this microfluidic reaction using various hydrazine and latent aldehyde surrogates. This green chemistry approach can be of general utility to rapidly produce indoline scaffolds and intermediates in a continuous manner.     

基于侧向磁泳的微流控芯片对两种磁性纳米球的同时分选

基于磁性纳米球在微流控芯片上的侧向磁泳, 利用微流控芯片分选了不同磁响应性的磁球. 提出了包含磁性纳米球聚集与偏移的理论模型, 用于分析磁球在芯片上的侧向位移. 在理论分析的基础上设计了芯片系统, 使不同磁响应性的磁纳米球可以在芯片系统上依次被分选. 实验结果表明, 2种磁性纳米球的分选效率均可接受, 且实验操作简单; 磁响应性强的磁球可被完全分离, 这对于珍贵分析样品的分选很有价值. 该分选系统被成功用于同时分选样品中乙型肝炎病毒的DNA与丙型肝炎病毒的反转录DNA, 在生化分析中具有广阔的应用前景.     

Microalgae separation by inertia-enhanced pinched flow fractionation

To improve the accuracy and efficiency of ships’ ballast water detection, the separation of microalgae according to size is significant. In this article, a method to separate microalgae based on inertia-enhanced pinched flow fractionation (iPFF) was reported. The method utilized the inertial lift force induced by flow to separate microalgae according to size continuously. The experimental results show that, as the Reynolds number increases, the separation effect becomes better at first, but then stays unchanged. The best separation effect can be obtained when the Reynolds number is 12.3. In addition, with the increase of the flow rate ratio between sheath fluid and microalgae mixture, the separation effect becomes better and the best separation effect can be obtained when the flow rate ratio reaches 10. In this case, the recovery rate of Tetraselmis sp. is about 90%, and the purity is about 86%; the recovery rate of Chlorella sp. is as high as 99%, and the purity is about 99%. After that, the separation effect keeps getting better but very slowly. In general, this study provides a simple method for the separation of microalgae with different sizes, and lays a foundation for the accurate detection of microalgae in the ballast water.     

微流控纸芯片在环境分析检测中的应用

近年来,微流控纸芯片由于低成本、便携化、检测快等优点,在需要快速检测的环境分析领域中展现出了巨大的应用前景。该综述从微流控纸芯片在环境分析中的应用角度,总结归纳了微流控纸芯片在环境分析中的最新研究进展,并展望了其在未来的发展趋势与挑战。论文内容引用150余篇源于科学引文索引(SCI)与中文核心期刊中的相关论文。该综述包括微流控纸芯片在环境检测中的优势与制造方法介绍;电化学法、荧光法、比色法、表面增强拉曼法、集成传感法等基于纸芯片的先进分析方法介绍;根据环境分析目标物种类,如重金属离子、营养盐、农药、微生物、抗生素以及其他污染物等,对纸芯片的最新应用现状进行了举例评述;基于微流控纸芯片的环境分析研究的未来发展趋势和前景展望。通过综述近期相关研究,表明微流控纸芯片从提出至今虽然只有十几年的发展历程,但其在环境分析研究中的发展却十分迅速。微流控纸芯片可以根据不同的环境条件和检测要求灵活选择制作与分析方法,实现最佳的检测效果。但是微流控纸芯片也面临一些挑战,如纸张机械强度不足、流体控制程度不佳等问题。这些问题指出了微流控纸芯片在环境检测领域的发展趋势,相信随着不断深入的研究,纸芯片将会在未来的环境分析中发挥更大作用。     

微流控芯片液滴生成与检测技术研究进展

微流控芯片液滴技术是一种操控微小体积液体的新技术,既可实现高通量微观样本的生成及控制,也可进行独立液滴的操作。分散的微液滴单元可作为理想的微反应器,在生物医药中的药物筛选、材料筛选和高附加值微颗粒材料合成领域展现出巨大的应用潜力。液滴微流控芯片是利用流体剪切力的改变,使互不相溶的两相流体在其界面处生成稳定、有序的液滴,目前微液滴的生成方法主要有水动力法、气动法、光控法和电动法等。基于液滴的微流控系统越来越多地被应用于执行复杂的多重反应、测量和分析,可以进行超小体积和超高吞吐量的化学和生物实验。对液滴微流控系统而言,液滴的速度、大小和内容物含量会影响最终的检验结果,因此对液滴形成速率和液滴的内容物含量的实时检测至关重要,目前最常用的液滴检测方法有光学检测技术与电学传感检测技术。对两相流液滴生成机理以及现有液滴生成技术开展了讨论分析,同时对液滴检测技术进行了评述。     

基于介电电泳的微流控细胞分离芯片的研究进展

细胞分离技术是细胞分选和细胞种群纯化的重要手段,在生物、医学、农业、环境等许多领域都有重要的应用,是当前生化分析领域的国际研究热点。本文介绍了基于介电电泳的微流控细胞分离芯片的研究现状,阐述了介电电泳的工作原理,并依据细胞尺寸、电极形状、外加信号方式等影响细胞介电电泳的关键因素对不同类型的微流控细胞分离芯片进行了详细介绍,并对该技术的未来发展趋势做了展望。     

微流控芯片上的肿瘤组织微阵列构建

研发了一种多层复合微流控芯片,包含64细胞培养微孔阵列,该微阵列集成了细胞进样、水凝胶三维支架形成和持续灌流培养的过程.以MCF-7乳腺癌细胞为模型,连续培养中监测细胞存活率、细胞密度、增殖率和细胞内pH值,并同时进行冰冻切片后免疫组化染色.实验结果显示,乳腺癌细胞在水凝胶微球中增殖形成了类组织结构.E-cadherin及Vinculin在细胞内、细胞间隙均出现较强表达,提示水凝胶微球中细胞建立了细胞-细胞、细胞-间质连接.芯片上连续培养15天内细胞存活率保持在85％以上,细胞增殖率随时间延长而递减.细胞内pH值检测显示芯片3D培养细胞内部呈现明显的酸化,其程度随着细胞密度增大而增加.这种芯片肿瘤组织微阵列构建方法简单高效,有望发展成为肿瘤研究的有力工具.