Separations of proteins and peptides in capillary zone electrophoresis suffer from non-specific adsorption of the analytes to the capillary surface. Semi-permanent phospholipid bilayers have been used to minimize adsorption, but must be regenerated regularly to ensure reproducibility. We present the formation, characterization, and use of hybrid phospholipid bilayers (HPBs) as capillary coatings for protein separations. HPBs are formed by covalently modifying a support with a hydrophobic monolayer onto which a lipid monolayer self-assembles. Capillaries were modified with 3-cyanopropyldimethylchlorosilane or n-octyldimethylchlorosilane to yield hydrophobic surfaces with lowered surface free energies, 6.0 ± 0.3 or 0.2 ± 0.1 mJ / m2 for cyano- or octyl-modified capillaries, respectively, compared to 17 ± 1 mJ / m2 for bare capillaries. HPBs were formed by fusing vesicles of 1,2-dilauroyl-sn-glycero-3-phosphocholine or 1,2-dioleoyl-sn-glycero-3-phosphocholine with cyano- and octyl-modified capillaries, generating HPB-coated capillaries with shielded surfaces and reduced electroosmotic mobilities (1.3 1.9 × 10-4 cm2 / Vs) compared to bare capillaries (6.0 ± 0.2 × 10-4 cm2 / Vs). Finally, in all HPB-coated capillaries, peaks for cytochrome c and ribonuclease had reproducible migration times (less than 1.6 % RSD) with separation efficiencies as high as 109,000 plates / m.
Pub Type: Journals