Green and catalyst-free preparation of triazinyl polyimide for the efficient adsorption of glycoproteins

Triazinyl polyimide is prepared via a solvent-free and catalyst-free imidization reaction by using melamine and pyromellitic dianhydride as the precursors. The characterization by means of FT-IR, X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), surface charge analysis and thermogravimetric analysis (TGA) indicates that the obtained triazinyl polyimide is highly crystalline with excellent thermal-stability. The strong hydrogen-bonding interactions between the glycan groups in the glycoproteins and the carbonyl groups in polyimide give the as-prepared triazinyl polyimide excellent adsorption selectivity and an ultra-high adsorption capacity towards glycoproteins, an adsorption capacity of 1666.7 mg g(-1) is presented for ovalbumin. This offers the possibility for the removal of glycoprotein species of high abundance from complex sample matrices by using the triazinyl polyimide as a powerful adsorbent. The practical feasibility is well demonstrated through the efficient removal of ovalbumin and conalbumin from egg white, as confirmed using an SDS-PAGE assay.