Modulation of electroosmotic flow in capillary electrophoresis using functional polymer coatings

► Novel polymeric coatings able to modulate capillary walls properties were synthesized. ► High stability of the film is assured by silane and chemically reactive groups. ► Functional monomers allows also electroosmotic flow modulation to desired values. ► These coatings provide very efficient protein separations in capillary electrophoresis. Capillary electrophoresis (CE) is one of the most powerful techniques for the separation of biomolecules. However, the separation efficiency of proteins in CE is often compromised by their tendency to interact with the silanol groups on the surface of the inner capillary and by an uncontrolled electroosmotic flow. Herein, we report on the synthesis of novel hydrophilic polymeric coatings that can modulate the properties of the capillary walls. The novelty of these poly(N,N-dimethylacrylamide)-based copolymers relies on the simultaneous presence of chemically reactive groups (N-acryloyloxysuccinimide and glycidyl methacrylate) and silane groups in the backbone, which results in highly stable films due to the covalent reaction between the polymer and the glass silanols. Although the functional monomers are reactive towards nucleophilic groups in proteins, they can be effectively blocked in the presence of amino modified agents. In addition, after a careful optimization of monomer concentration, it is possible to confer anti-fouling properties to the polymer coatings, and thus allow for highly efficient acidic and alkaline protein separations. Furthermore, the presence of these monomers makes it possible to modulate the electroosmotic flow from negligible to reduced values, depending on the desired application.