Song Yong-Ak, Hsu Stephanie, Stevens Anna L, Han Jongyoon
Department of Electrical Engineering and Computer Science, Biological Engineering Division, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, Massachusetts 02139, USA.
Anal Chem. 2006 Jun 1;78(11):3528-36. doi: 10.1021/ac052156t.
Efficient sample preparation tools are the key to measuring molecular signals in a complex biological system. A novel continuous-flow isoelectric point (pI)-based sorting technique has been developed for proteins and peptides in a microfluidic chip format. It can sort biomolecules at a relatively high flow rate of up to 10 microL/min and does not require carrier ampholytes, which can create molecular backgrounds for subsequent analysis. Furthermore, the electrophoretic field required to run the pI-based sorting is generated by the diffusion of buffer ions in situ, at the liquid junction between two laminar flows within the microfluidic channel. Utilizing the diffusion potential in combination with a pH difference between the buffers, we demonstrated a separation of binary mixtures of pI markers and proteins without applying any external field. The sorting resolution and its efficiency are sufficiently high for sample preparation and could be further improved by optimizing buffers or with an additional transverse electric field. Once fully developed, it can potentially be a pI-based sample fractionation tool for proteomic analysis of complex biomolecule samples.
高效的样品制备工具是在复杂生物系统中测量分子信号的关键。一种基于新型连续流等电点（pI）的分选技术已被开发出来，用于微流控芯片形式的蛋白质和肽。它能够以高达10微升/分钟的相对高流速对生物分子进行分选，并且不需要载体两性电解质，载体两性电解质会为后续分析产生分子背景。此外，基于pI分选所需的电场是由缓冲离子在微流控通道内两层层流之间的液接处原位扩散产生的。利用扩散电位与缓冲液之间的pH差异，我们在不施加任何外部电场的情况下展示了pI标记物和蛋白质二元混合物的分离。该分选分辨率及其效率对于样品制备来说足够高，并且可以通过优化缓冲液或添加额外的横向电场来进一步提高。一旦完全开发出来，它有可能成为用于复杂生物分子样品蛋白质组学分析的基于pI的样品分级工具。
