Polyelectrolyte multilayer coatings for the separation of proteins by capillary electrophoresis: Influence of polyelectrolyte nature and multilayer crosslinking.

The present work aims at studying the influence of the nature of the polyelectrolytes used in successive multiple ionic polymers on the performances of protein separation in acetic acid volatile background electrolyte. A broad library of polyelectrolyte multilayers was compared on the basis of 9 different weak/strong polyanions and 8 different weak/strong polycations. More than 20 couples of different polyelectrolytes were investigated. The separation efficiencies (expressed as the N/l ratio, where N is the plate number and l is the capillary effective length) were systematically compared for the separation of a protein test mixture. The coating stability was evaluated by the relative standard deviation of the migration times. For weak polyelectrolyte multilayers, the influence of the polymer crosslinking on the coating stability and separation efficiency has been studied. Intra-day repeatability of 100 successive runs, and capillary-to-capillary reproducibility were tested on coatings of each category (crosslinked and non crosslinked). The main (not obvious) result rising from this study is that the nature of the polyanion constituting the multilayers is of primary importance for the performance in terms of separation efficiency and stability, even when the mulilayers finish with a polycation.

Bekri S ，Leclercq L ，Cottet H 《-》

Modulation of the electroosmotic mobility using polyelectrolyte multilayer coatings for protein analysis by capillary electrophoresis.

Successive multiple ionic-polymer layers (SMIL) coatings have been often used in capillary electrophoresis due to their simplicity to implement and regenerate. However, the performances of the separation are strongly dependent on the nature of the polyelectrolyte partners used to build the SMIL coating. In this work, we investigate new couples of polyelectrolytes that were not tested before: namely, polybrene (PB), quaternized diethylaminoethyl dextran (DEAEDq) and ε-poly(lysine) (ε-PLL), as polycations, in combination with poly(acrylic acid), dextran sulfate, poly(styrenesulfonate), poly(methacrylic acid) and poly(l-lysine citramide), as polyanions. Systematic study of intra- and inter-capillaries repeatabilities/reproducibilities was performed based on the determination of migration time, separation efficiency and electroosmotic mobility. Interestingly, the electroosmotic flow was found to vary with the nature of the polycation on a broad range of electroosmotic mobility decreasing in magnitude in the order of PB>ε-PLL > DEAEDq, whatever the polyanion associated. Application of the coatings to the separation of proteins is illustrated in a 0.5 M acetic acid BGE, including CE-MS separation of ribonuclease B-glycoforms of the same mass (positional or structural isomers).

Leclercq L ，Morvan M ，Koch J ，Neusüß C ，Cottet H ... -  《-》

Influence of polyelectrolyte coating conditions on capillary coating stability and separation efficiency in capillary electrophoresis.

Nehmé R ，Perrin C ，Cottet H ，Blanchin MD ，Fabre H ... -  《ELECTROPHORESIS》

Influence of polyelectrolyte capillary coating conditions on protein analysis in CE.

Nehmé R ，Perrin C ，Cottet H ，Blanchin MD ，Fabre H ... -  《-》

Critical parameters for highly efficient and reproducible polyelectrolyte multilayer coatings for protein separation by capillary electrophoresis.

Since the introduction of polyelectrolyte multilayers to protein separation in capillary electrophoresis (CE), some progress has been made to improve separation efficiency by varying different parameters, such as buffer ionic strength and pH, polyelectrolyte nature and number of deposited layers. However, CE is often overlooked as it lacks robustness compared to other separation techniques. In this work, critical parameters for the construction of efficient and reproducible Successive multiple ionic-polymer layers (SMIL) coatings were investigated, focusing on experimental conditions, such as vial preparation and sample conservation which were shown to have a significant impact on separation performances. In addition to repeatability, intra- and inter-capillary precision were assessed, demonstrating the improved capability of poly(diallyldimethylammonium chloride) / poly(sodium styrene sulfonate) (PDADMAC / PSS) coated capillaries to separate model proteins in a 2 M acetic acid background electrolyte when all the correct precautions are put in place (with run to run%RSD(tm) < 1.8%, day to day%RSD(tm) < 3.2% and cap to cap%RSD(tm) < 4.6%). The approach recently introduced to calculate retention factors was used to quantify residual protein adsorption onto the capillary wall and to assess capillary coating performances. 5-layer PDADAMAC / PSS coatings led to average retention factors for the five model proteins of ∼4×10-2. These values suggest a relatively low residual protein adsorption leading to reasonably flat plate height vs linear velocity curves, obtained by performing electrophoretic separations at different electrical voltages (-10 to -25 kV).

Dhellemmes L ，Leclercq L ，Höchsmann A ，Neusüß C ，Biron JP ，Roca S ，Cottet H ... -  《-》