Dynamic Coating Using Polyelectrolyte Multilayers for Chemical Control of Electroosmotic Flow in Capillary Electrophoresis Microchips

• Published in: Analytical chemistry (Washington) Vol. 72; no. 24; pp. 5939 - 5944
• Main Authors: Liu, Yan, Fanguy, Joseph C, Bledsoe, Justin M, Henry, Charles S
• Format: Journal Article
• Language: English
• Published: Washington, DC American Chemical Society 15.12.2000
• Subjects: Analytical chemistry; Chemistry; Chromatographic methods and physical methods associated with chromatography; Electrolytes; Exact sciences and technology; Other chromatographic methods; Semiconductors; Performance evaluation; Coating material; Multilayer; Capillary electrophoresis; Microminiaturization; Chip; Electrochemical detector; Polyelectrolyte; Separation method; Analysis method; Electrophoretic mobility; Fluidic devices; Physicochemical properties
• ISSN: 0003-2700; 1520-6882
• DOI: 10.1021/ac000932l

Poly(dimethylsiloxane) (PDMS) capillary electrophoresis (CE) microchips were modified by a dynamic coating method that provided stable electroosmotic flow (EOF) with respect to pH. The separation channel was coated with a polymer bilayer consisting of a cationic layer of Polybrene (PB) and an anionic layer of dextran sulfate (DS). According to the difference in charge, PB- and PB/DS-coated channels supported EOF in different directions; however, both methods of channel coating exhibited a pH-independent EOF in the pH range of 5−10 due to chemical control of the effective ζ-potential. The endurance of the PB-coated layer was determined to be 50 runs at pH 3.0, while PB/DS-coated chips had a stable EOF for more than 100 runs. The effect of substrate composition and chip-sealing methodology was also evaluated. All tested chips showed the same EOF on the PB/DS-coated channels, as compared to uncoated chips, which varied significantly. No significant variation for separation and electrochemical detection of dopamine and hydroquinone between coated and uncoated channels was observed.