Abstract
The main objective of this thesis is to study different approaches for the modification of the electrophoresis capillary intern wall to enhance separation efficiency and reproducibility for biomolecules (model peptides and/or proteins) in acidic conditions. The first chapter (outside of bibliographic study) is dedicated to superhydrophobic coatings study. The goal is to prevent analytes adsorption by suppressing any interaction between the superhydrophobic wall and the analytes (anti-wettability). An original coating process has been developed to obtain superhydrophobic capillaries by studying the influence of layers number, coating nature, and filling and flushing pressure during layers deposition. Superhydrophobic coatings have been obtained, for the first time, with diameters from 50 µm to 180 µm. Hydrodynamic and electrokinetic characteristics have been studied, giving slipping length of 23 µm and efficiency separation increased twofold compared to fused silica capillary in the same electrophoretic conditions. The second chapter studies an air microbubbles generation process using superhydrophobic capillaries. The experimental parameters (voltage, UV ray, marker, superhydrophobic coating) needed to obtain those bubbles have been identified. Those bubbles have been characterized (diameter ~35-39 µm; length ~10 mm; zeta potential ~ -62.6 mV). The third chapter offer an experimental methodology, based on the electrochromatography theory, allowing to evaluate the residual adsorption of proteins on the capillary wall. This approach have two interesting points: (i) allowing to compare separative performances of different coatings via residual adsorption, and (ii) optimizing the experimental parameters (length, internal diameter, applied voltage) to minimize the impact of adsorption on the separation efficiencies.