中文摘要：

在这研究，我们由指数的丰富(SELEX ) 开发了 ligands 的系统的进化用磁性的祷告固定和流动 cytometric 测量的联合的方法。作为一个例子， streptavidin 特定的 aptamers 的选择被执行。在这个协议，常规 SELEX 过程被优化，首先使用磁性的祷告让目标固定从未装订的 ssDNAs 便于有约束力的搁浅单人赛的 DNA (ssDNA ) aptamers 的高度有效的分离，并且第二使用标记监视丰富的流动 cytometry 和荧光黄。流动 cytometry 的敏感在 SELEX 过程期间为 ssDNA quantification 是足够的。当为有 biotinylated 的修改 streptavidin 的表面的占有的描述的工具指向分子，在这个工作获得的 streptavidin 特定的 aptamers 能被使用。在学习描述的方法通常也是适用的指向除 streptavidin 以外的分子。

英文摘要：

In this study, we developed a systematic evolution of ligands by exponential enrichment （SELEX） method using a combination of magnetic beads immobilization and flow cytometric measurement. As an example, the selection of streptavidin-specific aptamers was performed. In this protocol, the conventional SELEX procedure was optimized, fiirst using magnetic beads for target immobilization to facilitate highly efficient separation of the binding single-stranded DNA （ssDNA） aptamers from the unbound ssDNAs, and second using flow cytometry and fluorescein labeling to monitor the enrichment. The sensitivity of flow cytometry was adequate for ssDNA quantification during the SELEX procedures. The streptavidin-specific aptamers obtained in this work can be used as tools for characterization of the occupancy of streptavidin-modified surfaces with biotinylated target molecules. The method described in the study is also generally applicable to target molecules other than streptavidin.