Monolithic cryopolymers with embedded nanoparticles. II. Capillary liquid chromatography of proteins using charged embedded nanoparticles

The preparation of composite monolithic cryopolymers is presented. These novel porous materials were prepared in capillary format at −70°C using poly (ethyleneglycol) diacrylate (PEGDA) M_w258 as the single monomer and a mixture of dioxane and water as the porogen. Positively (-NR₄⁺) or negatively (SO₃⁻) charged nanoparticles were incorporated within the polymeric structure by direct addition of their suspensions to the polymerisation mixture. In contrast to our previous report using neutral nanoparticles, the trapping of charged nanoparticles is mostly observed at the polymer surface. The incorporation of these nanostructures improved the chromatographic separations of standard proteins under a hydrophobic interaction chromatography (HIC) separation mode. Moreover, the presence of ionic groups on the polymer surface allowed the application of these columns under ion-exchange (IEX) conditions. The results obtained in this work show that the functionalisation of monolithic columns by direct addition of nanoparticles is a good alternative towards the modification of monolithic polymers without altering the polymeric scaffold.