Stable neutral double hydrophilic block copolymer capillary coating for capillary electrophoretic separations

Abstract

Quaternized diblock copolymer, poly(N-methyl-2-vinylpyridinium iodide-block-ethylene oxide), was successfully used as a neutral, dynamic coating to suppress the electroosmotic flow. The block copolymer consisted of two polymers that were linked covalently together. The cationic block (poly(N-methyl-2-vinylpyridinium iodide)) was bound efficiently to the negatively charged capillary wall via electrostatic interactions, and the hydrophilic block (ethylene oxide) stabilized the system and created a neutral capillary surface with ultralow electroosmotic flow (+2.0 ± 4.5 × 10(-10) m(2)/Vs). The main advantages of the coating were simple and fast preparation, easy regeneration and automation, and stable electroosmotic flow. To emphasize the potential of this type of coating its stability was measured at a wide pH range demonstrating a high stability in the pH range of 4.0-10.5 and lifetime up to 8 days. The successful studies carried out with beta-blockers, basic proteins, and lipoproteins proved the suitability of the coating for the separation of different sized analytes. Furthermore, the neutral coating developed is useful in a wide range of protein analysis and biological interaction studies under physiological condition.

Novel cationic polyelectrolyte coatings for capillary electrophoresis

“…, the separation of β‐blockers was improved in the PEC capillaries compared to bare capillaries as well as the separation selectivity and resolution of the compounds. The obtained efficiencies are comparable to the CE system with covalently bound PMOTAC polymer but better efficiencies (up to 700 000 plates/m) were reached using the block copolymer P2QVP‐ b ‐PEO . However, the presented coating process features shorter time compared to almost 3 h in and more than 48 h in case of in‐capillary polymerization and silanization in .…”

“…Cationic coatings have a certain advantage in fast adsorption to a negatively charged fused silica surface and they usually maintain a stable EOF over a wide range of pH values. Some of the very recent works with cationic coatings include applications of polymers for hindering proteins from adsorbing to the capillary wall , in protein tryptic digest separations , in lipid analysis , and in their combination with negatively charged layers to form more stable multilayered coatings . It is also important to consider the polymer charge density because a too fast EOF may prevent good identification of migrated compounds in complex mixtures .…”

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

“…This observation indicates that a complete surface coverage has been obtained without access to nonreacted surface silanol groups. In the literature, EOF below 0.06· 10 –8 m 2 V −1 s −1 has been measured for other PEG‐coated capillaries , using a pressure‐based methodology . However, small inaccuracies in the pressure control system of the CE analyzer used in the present work, led us to choose the present method.…”

Recent trends in capillary electrophoresis for complex samples analysis: A review

“…Block copolymers described in the previous section can also be applied to the formation of dynamic coatings. This way, a procedure based on the combination of the cationic poly( N ‐methyl‐2‐vinylpyridinium iodide) and the hydrophilic ethylene oxide led to the formation of a dynamic coating neutrally charged that reduced the EOF (to its practical suppression at the physiological pH 7.4) and inhibited the adsorption of cationic species in the capillary wall . This type of cationic block bind more efficiently to the silica wall (negatively charged) resulting in a more stable coating when compared to other alternatives.…”