Highly efficient dynamic modification of plastic microfluidic devices using proteins in microchip capillary electrophoresis - Analytical Methods & Tools for Lyophilization

Highly efficient dynamic modification of plastic microfluidic devices using proteins in microchip capillary electrophoresis
Available online 24 July 2006.
Nahoko Naruishia, Yoshihide Tanaka, a, , Tetsuji Higashia and Shin-ichi Wakidaa
Journal of Chromatography A
Volume 1130, Issue 2 , 20 October 2006
ScienceDirect
Copyright ? 2006 Elsevier B.V. All rights reserved.
aHuman Stress Signal Research Center (HSS), National Institute of Advanced Industrial Science and Technology (AIST), 1-8-31 Midorigaoka, Ikeda, Osaka 563-8577, Japan
Abstract
New dynamic coating agents were investigated for the manipulation of electroosmotic flow (EOF) in poly(methylmethacrylate) (PMMA) microchips. Blocking proteins designed for enzyme-linked immunosorbent assay (ELISA) applications (e.g. Block Ace and UltraBlock), and egg-white lysozyme were proposed in this study. The EOF could be enhanced, suppressed or its direction could be reversed, depending on the buffer pH and the charge on the proteins. The coating procedure is simple, requiring only filling of the microchannels with a coating solution, followed by a rinse with a running buffer solution prior to analysis. One major advantage of this method is that it is not necessary to add the coating agent to the running buffer solution. Block Ace and UltraBlock coatings were stable for at least five runs in a given microchannel without the need to condition the coating between runs other than replenishing the buffer solution after each run, i.e. the RSD values of EOF (n = 5) were less than 4.3%, and there was no significant change in the EOF after 5 runs. The reproducibility of the coating procedures was found from the channel-to-channel RSD values of the EOF, and were less than 5.0% when using HEPES-Na buffer (pH 7.4) as the running buffer. Several examples of electrophoretic separations of amino acids and biogenic amines derivatized with 4-fluoro-7-nitro-2,1,3-benzoxadiazole (NBD-F) are demonstrated in this paper. The dynamic coating method has the potential for a broad range of applications in microchip capillary electrophoresis (microchip CE) separations.
Keywords: Microchip capillary electrophoresis; Poly(metheylmethacrylate) chip; Dynamic coating; Protein; EOF control
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