Zone electrophoresis of proteins in poly(dimethylsiloxane) (PDMS) microchip coated with physically adsorbed amphiphilic phospholipid polymer

• Published in: Microfluidics and nanofluidics Vol. 14; no. 6; pp. 951 - 959
• Main Authors: Nii, Kyosuke, Sueyoshi, Kenji, Otsuka, Koji, Takai, Madoka
• Format: Journal Article
• Language: English
• Published: Berlin/Heidelberg Springer-Verlag 01.06.2013; Springer Nature B.V
• Subjects: Analytical Chemistry; Biomedical Engineering and Bioengineering; Electrophoresis; Engineering; Engineering Fluid Dynamics; Hydrophilicity; Membranes; Nanostructure; Nanotechnology and Microengineering; Phospholipids; Polymers; Proteins; Research Paper; Silicone resins; Surface chemistry; Phospholipid polymer; Surface modification; Microchip electrophoresis; PDMS
• ISSN: 1613-4982; 1613-4990
• DOI: 10.1007/s10404-012-1102-8

The zone electrophoresis of protein in poly(dimethylsiloxane) (PDMS) microchip coated with the physically adsorbed amphiphilic phospholipid polymer (PMMSi) was investigated. PMMSi was composed of 2-methacryloyloxyethyl phosphorylcholine (MPC) and 3-(methacryloyloxy) propyltris (trimethylsiloxy) silane (MPTSSi) units in a random fashion. The membrane of PMMSi can be formed on the PDMS surface by a simple and quick dip-coating method. The membrane showed high hydrophilicity and good stability in water, as determined by contact angle measurement, fourier-transformed infrared absorption by attenuated total reflection (ATR-FTIR), and X-ray photoelectron spectroscopy (XPS) analysis. High suppression of protein adsorption to the PDMS surface and reduction in electroosmotic flow (EOF) were achieved by PMMSi coating due to an increase of hydrophilicity, and a decrease of the ζ-potential on the surface of PDMS. For zone electrophoresis, the PMMSi30 containing 30 % hydrophilic MPC was the most suitable molecular design in terms of the stability of the coated membrane on PDMS surface. The average value of EOF mobility of PDMS microchip coated with PMMSi30 was 1.4 × 10 −4  cm 2  V −1  s −1 , and the RSD was 4.1 %. Zone electrophoresis of uranine was further demonstrated with high repeatability and reproducibility. Separation of two FITC-labeled proteins (BSA and insulin) was performed with high efficiency and resolution compared with non-treated PDMS microchip.