Surface modification based on Si-O and Si-C sublayers and a series of N-substituted acrylamide top-layers for capillary electrophoresis.
Two approaches were used to prepare a series of surface-modified capillaries. In the first, a sublayer was formed by coupling gamma-methacryloxypropyltrimethoxysilane to the surface silanol groups forming an SI-O bond; a top layer was then formed by polymerizing acrylamide in the capillary, which reacted with the sublayer. In the second approach, a sublayer was formed by silanol chlorination, followed by Grignard coupling of vinylmagnesium bromide to form an Si-C bond at the surface; a top layer was formed by polymerizing either acrylamide (AA), dimethylacrylamide (DMA), N-acryloylaminoethoxyethanol (AAEE), or N-acryloylaminopropanol (AAP) onto the sublayer. The Si-Cpoly(AA) capillaries were more stable and produced an approximately 10-fold lower electroosmotic flow compared to the Si-O-poly(AA) capillaries. The Si-C sublayer was used to compare the performance of all four top layers. Electroosmotic flow decreased in the order: Si-O-poly(AA), Si-C-poly(AA), Si-Cpoly(AAEE), Si-C-poly(DMA), and Si-C-poly(AAP). Si-C-poly(AA) showed evidence of irreversible degradation at pH 9 already after 40-50 runs. Si-C-polyAAP-coated capillaries demonstrated superior efficiency and migration time reproducibility for a number of alkaline proteins and for fluorescently labeled ovalbumin. Excellent performance was maintained, in the case of poly(AAP), for a least 300 runs (of 30 min duration) at pH 9.0.
ITBA, CNR, Milano, Italy.
C
C
Gelfi
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Curcio
P G
PG
Righetti
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R
Sebastiano
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A
Citterio
H
H
Ahmadzadeh
N J
NJ
Dovichi
D020106:Acrylamide; D000327:Adsorption; D019075:Electrophoresis, Capillary / Q000379:methods*; D005782:Gels; D008689:Methacrylates; D011506:Proteins / Q000302:isolation & purification*; D012821:Silanes; D012826:Silicone Elastomers
D005782:Gels; D008689:Methacrylates; D011506:Proteins; D012821:Silanes; D012826:Silicone Elastomers; C082343:silanol; D020106:Acrylamide; C017492:methacryloxypropyltrimethoxysilane