Functionalization of mesoporous silica surface with carboxylic groups by Meldrum’s acid and its application for sorption of proteins

A new method of silica surface functionalization with carboxyl groups is proposed based on the reaction between 2,2-dimethyl-1,3-dioxane-4,6-dione (Meldrum’s acid, MA) and the surface silanol groups. For the first time such a post-synthesis modification was successfully applied to silica materials. Although silica surface is successfully carboxylated (as evidenced by FTIR and XPS), the porosity, ordering and morphology remain practically unchanged after the proposed post-synthesis treatment (as confirmed by nitrogen sorption, XRD and electron microscopy). Adsorption study of model biomolecules (lysozyme and bovine serum albumin) shows that different surface chemistries (–OH vs. –COOH) lead to different affinities between the silica surface and sorbates.