Electrophoretic screening of ligands under suppressed EOF with an inert phospholipid coating.

The applicability of dual injection CE for affinity selection of biopolymers that contain multiple binding sites is demonstrated. The efficient analysis of biomolecules such as carbohydrates and proteins, as well as pharmaceuticals by CE requires the reduction or elimination of nonspecific interactions with the capillary surface. Phospholipids are integral components of cell membranes and aqueous phospholipid liquid crystals adopt a bilayer structure on fused-silica. This phospholipid surface does not interact significantly with the following biomolecules: serum albumin, the 96-110 heparin binding domain of amyloid precursor protein (APP), polydisperse glycosaminoglycans, and variable chain-length oligosaccharides. Pharmaceuticals including five anionic nonsteroidal anti-inflammatory drugs, three cationic analgesics, and two cationic beta-blockers, also show minimal interaction with the surface. In addition, the use of a phospholipid coating suppresses EOF, which enables reversed-polarity separations, dual opposite injection CE, affinity screening via CE by dual opposite injection, and serial target-ligand injections.