Automated coating procedures to produce poly(ethylene glycol) brushes in fused‐silica capillaries

Abstract

Many bioanalytical methods rely on electrophoretic separation of structurally labile and surface active biomolecules such as proteins and peptides. Often poor separation efficiency is due to surface adsorption processes leading to protein denaturation and surface fouling in the separation channel. Flexible and reliable approaches for preventing unwanted protein adsorption in separation science are thus in high demand. We therefore present new coating approaches based on an automated in-capillary surface-initiated atom transfer radical polymerization process (covalent coating) as well as by electrostatically adsorbing a presynthesized polymer leading to functionalized molecular brushes. The electroosmotic flow was measured following each step of the covalent coating procedure providing a detailed characterization and quality control. Both approaches resulted in good fouling resistance against the four model proteins cytochrome c, myoglobin, ovalbumin, and human serum albumin in the pH range 3.4-8.4. Further, even samples containing 10% v/v plasma derived from human blood did not show signs of adsorbing to the coated capillaries. The covalent as well as the electrostatically adsorbed coating were both found to be stable and provided almost complete suppression of the electroosmotic flow in the pH range 3.4-8.4. The coating procedures may easily be integrated in fully automated capillary electrophoresis methodologies.

Number of theoretical plates achievable by a toroidal capillary electrophoresis system

“…One option is to cover the inner wall of the toroid with a hydrophilic coating (e.g., polyvinylalcohol or polyacrylamide) that mimics the relative permittivity and hydrogen bonding environment of the bulk buffer solution that fills the inner lumen of the capillary. There are many strategies to suppress the EOF in CE , and they are recommended for applications such as high precision electrophoretic mobility measurements in a wide range of temperatures, pH, and BGE compositions and concentrations.…”

Recent developments in capillary and microchip electroseparations of peptides (2015–mid 2017)

“…Automated coating procedures were developed for production of poly(ethylene glycol) brushes in FS capillaries . They are based on in‐capillary surface‐initiated atom transfer radical polymerization (covalent coating) as well as on electrostatic sorption of presynthesized polymer leading to functionalized molecular brushes.…”

Metallomic study on the metabolism of RAPTA-C and cisplatin in cell culture medium and its impact on cell accumulation

“…66 To overcome this issue, many procedures have been investigated that involve the coating of the capillary and high adsorption resistance was observed, while being even able to separate protein isoforms with high resolution. [67][68][69][70][71][72] One approach of capillary coating is based on polybrene (PB) and polyethylene glycol, 73 which creates a cationic surface requiring the use of an acidic background electrolyte (BGE). This procedure was modified and then successfully applied to binding studies of Ru compounds with serum proteins.…”

“…† The sheath liquid was supplied using the ICP-MS inbuilt peristaltic pump [0.03 revolutions per second (rps)] via the internal standard line (blue-orange tubing, 0.25 mm ID) and in conjunction with an in-built alligator clip to close the electrical circuit. The ICP-MS was tuned with 45 Sc, 72 Ge and 185 Re in the sheath liquid until a stable signal (RSD o5%) was attained. Data analysis was carried out using Origin 2017 (OriginLab Corporation, Northampton, USA).…”