title: Self-assembled epoxy-modified polymer coating on a poly(dimethylsiloxane) microchip for EOF inhibition and biopolymers separation.
abstract: A straightforward approach to generate a stable and protein-resistant poly(dimethylsiloxane) (PDMS) surface using self-assembled hydrophilic polymers is demonstrated in this work. Epoxy-modified polymers were directly adsorbed from aqueous solution onto plasma oxidized PDMS based on H-bond interaction, and epoxies of polymer and silanols on oxidized PDMS surface were crosslinked by heating at 110 degrees C. The coating process could be completed within half hour. Poly(dimethylacrylamide-co-glycidyl methacrylate) (PDMA-co-GMA), poly(vinyl pyrrolidone)-g-glycidyl methacrylate (PVP-g-GMA) and poly(vinyl alcohol)-g-glycidyl methacrylate (PVA-g-GMA) (D. P. Wu, B. X. Zhao, Z. P. Dai, J. H. Qin and B. C. Lin, Lab Chip, 2006, 6, 942) were employed as examples here. Unlike PDMA, PVP, and PVA themselves, these epoxy-modified hydrophilic polymers could be directly used as static surface coatings on oxidized PDMS, and inhibited electroosmotic flow (EOF) within pH 3-11. It was also found that hard baking of PDMS at 150 degrees C for 24 hours before surface coating could greatly retard surface hydrophobicity recovery after oxygen plasma exposure, which strengthened epoxy-modified polymer coatings on oxidized PDMS surface, and resulted in EOF less than 0.2 x 10(-4) cm(2) V(-1) s(-1) (pH 9.0) within two weeks. On epoxy-modified polymer coated PDMS microchips, basic proteins, peptides and DNA fragments could be separated satisfactorily, in which more than 2 x 10(4) plates per 2 cm and less than 3% RSD (>8 runs) for migration time were obtained for lysozyme.
authors.affiliation: Dalian Institute of Chemical Physics, Dalian, 116023, China.
authors.forename: Dapeng
authors.initials: D
authors.lastname: Wu
authors.forename: Jianhua
authors.initials: J
authors.lastname: Qin
authors.forename: Bingcheng
authors.initials: B
authors.lastname: Lin
mesh_terms: D001704:Biopolymers / Q000302:isolation & purification*; D004247:DNA / Q000302:isolation & purification; D004129:Dimethylpolysiloxanes / Q000737:chemistry*; D044085:Microfluidics / Q000295:instrumentation; D009995:Osmosis; D011108:Polymers / Q000737:chemistry*; D012828:Silicones / Q000737:chemistry*; D013056:Spectrophotometry, Ultraviolet; D013499:Surface Properties
chemical_list: D001704:Biopolymers; D004129:Dimethylpolysiloxanes; D011108:Polymers; D012828:Silicones; C013830:baysilon; D004247:DNA