Departamento de Biotecnología e Ingeniería de Alimentos y Centro de Biotecnología, Tecnológico de Monterrey, Campus Monterrey, Avenida Eugenio Garza Sada 2501 Sur, Monterrey, NL, 64849, Mexico.
Anal Bioanal Chem. 2010 Mar;396(5):1805-16. doi: 10.1007/s00216-009-3422-4. Epub 2010 Jan 26.
Microanalytical methods offer attractive characteristics for rapid microbial detection and concentration. There is a growing interest in the development of microscale separation techniques. Dielectrophoresis (DEP), a nondestructive electrokinetic transport mechanism, is a technique with great potential for microbe manipulation, since it can achieve concentration and separation in a single step. DEP is the movement of particles due to polarization effects in nonuniform electric fields. The majority of the work on dielectrophoretic manipulation of microbes has employed alternating current fields in arrays of microelectrodes, an approach with some disadvantages. An alternative is to employ insulator-based DEP (iDEP), a dielectrophoretic mode where nonuniform fields are produced by employing arrays of insulating structures. This study presents the concentration and fractionation of a mixture of bacteria and yeast cells employing direct current-iDEP in a microchannel containing an array of cylindrical insulating structures. Negative dielectrophoretic trapping of both types of microorganisms was demonstrated, where yeast cells exhibited a stronger response, opening the possibility for dielectrophoretic differentiation. Simultaneous concentration and fractionation of a mixture of both types of cells was carried out analogous to a chromatographic separation, where a dielectropherogram was obtained in less than 2 min by applying an electric field gradient and achieving concentration factors in the order of 50 and 37 times the inlet concentration for Escherichia coli and Saccharomyces cerevisiae cells, respectively. Encouraging results were also obtained employing a sample of water taken from a pond. The findings demonstrated the great potential of iDEP as a rapid and effective technique for intact microorganism concentration and separation.
微分析方法为快速微生物检测和浓缩提供了有吸引力的特性。人们对微尺度分离技术的发展越来越感兴趣。介电泳（DEP）是一种无损电动传输机制，是一种具有很大潜力的微生物操作技术，因为它可以在一步中实现浓缩和分离。DEP 是由于非均匀电场中的极化效应而导致颗粒的运动。大多数关于微生物介电泳操作的工作都采用了微电极阵列中的交流电场，这种方法有一些缺点。另一种方法是采用基于绝缘体的介电泳（iDEP），这是一种通过采用绝缘结构阵列来产生非均匀场的介电泳模式。本研究在包含圆柱形绝缘结构阵列的微通道中采用直流-iDEP 对细菌和酵母细胞混合物进行浓缩和分级。证明了两种类型的微生物都存在负介电泳捕获，其中酵母细胞表现出更强的响应，从而为介电泳分化开辟了可能性。类似于色谱分离，同时对两种类型的细胞混合物进行浓缩和分级，通过施加电场梯度，在不到 2 分钟的时间内获得了介电泳图，大肠杆菌和酿酒酵母细胞的浓缩因子分别达到入口浓度的 50 倍和 37 倍。从池塘中采集的水样也得到了令人鼓舞的结果。研究结果表明，iDEP 作为一种快速有效的完整微生物浓缩和分离技术具有巨大的潜力。
