Silica colloidal crystals for ultra-efficient protein separations

Nowadays, protein analysis is a vital area of interest in the field of medical research as well as clinical diagnostics. Silica colloidal nanoparticles can self-assemble into a highly ordered face centered cubic crystal. The objective of this work is to ultilize silica colloidal crystals as a separation medium for fast biomolecules separations. The particles are shown to form colloidal crystals inside the capillaries. Optical images show Bragg diffraction, which is indicative of crystallinity; SEM images show face-centered cubic crystallinity; and the porosity is 0.32, which is in agreement with that of face-centered cubic crystals. Silica colloidal crystals made of 330 nm diameter silica spheres can give extremely efficient electromigration of proteins, enabling plate heights approaching the diffusion limit at electric fields exceeding 1,000 V/cm. Silica colloidal crystals made of 470 nm nonporous silica particles form homogeneously packed capillary columns, giving plate heights that are two orders of magnitude lower than conventional materials under pressure driven flow. Dye molecules, proteins and monoclonal antibodies were all separated in less than 2 cm in less than 5 minutes. Overall, these results indicate that submicrometer particles packed in capillaries are promising for efficient separation of proteins, approaching 108 plates/m in minutes