Size-based characterization of dendrigraft poly(L-lysine) by free solution capillary electrophoresis using polyelectrolyte multilayer coatings

Dendrigraft poly(L-lysine) (DGL) constitutes a promising dendritic-like drug vehicle with high biocompatibility and straightforward access via ring-opening polymerization of N-carboxyanhydride in water. The characterization of the different generations of DGL is however challenging due to their heterogeneity in molar mass and branching ratio. In this work, free solution capillary electrophoresis was used to perform selective separation of the three first generations of DGL, and optimized conditions were developed to maximize inter-generation resolution. To reduce solute adsorption on the capillary wall, successive multiple ionic polymer layer coatings terminated with a polycation were deposited onto the inner wall surface. PEGylated polycation was also used as the last layer for the control of the electroosmotic flow (EOF), depending on the PEGylation degree and the methyl-polyethylene glycol (mPEG) chain length. 1 kDa mPEG chains and low grafting densities were found to be the best experimental conditions for a fine tuning of the EOF leading to high peak resolution. Molar mass polydispersity and polydispersity in effective electrophoretic mobility were successfully determined for the three first generations of DGL.

Determination of the distributions of degrees of acetylation of chitosan

Chitosan is often characterized by its average degree of acetylation. To increase chitosan's use in various industries, a more thorough characterization is necessary as the acetylation of chitosan affects properties such as dissolution and mechanical properties of chitosan films. Despite the poor solubility of chitosan, free solution capillary electrophoresis (CE) allows a robust separation of chitosan by the degree of acetylation. The distribution of degrees of acetylation of various chitosan samples was characterized through their distributions of electrophoretic mobilities. These distributions can be obtained easily and with high precision. The heterogeneity of the chitosan chains in terms of acetylation was characterized through the dispersity of the electrophoretic mobility distributions obtained. The relationship between the number-average degree of acetylation obtained by solid-state NMR spectroscopy and the weight-average electrophoretic mobilities was established. The distribution of degrees of acetylation was determined using capillary electrophoresis in the critical conditions (CE-CC).

Recent developments in capillary and microchip electroseparations of peptides (2011-2013)

The review presents a comprehensive survey of recent developments and applications of capillary and microchip electroseparation methods (zone electrophoresis, ITP, IEF, affinity electrophoresis, EKC, and electrochromatography) for analysis, isolation, purification, and physicochemical and biochemical characterization of peptides. Advances in the investigation of electromigration properties of peptides, in the methodology of their analysis, including sample preseparation, preconcentration and derivatization, adsorption suppression and EOF control, as well as in detection of peptides, are presented. New developments in particular CE and CEC modes are reported and several types of their applications to peptide analysis are described: conventional qualitative and quantitative analysis, determination in complex (bio)matrices, monitoring of chemical and enzymatical reactions and physical changes, amino acid, sequence and chiral analysis, and peptide mapping of proteins. Some micropreparative peptide separations are shown and capabilities of CE and CEC techniques to provide relevant physicochemical characteristics of peptides are demonstrated.