Covalent Organic Framework As an Ion Exchange Material for Adsorptive Separation of Biomolecules

In this work, the use of covalent organic frameworks (COFs) in biomolecule separation has been explored. We examined the ionic COF Py-BPy²⁺-COF as an ion exchange material for protein and amino acid separation. After characterizing the physical and chemical properties of the synthesized COF with a variety of techniques such as Fourier transform infrared analysis, powder X-ray diffraction, X-ray photoelectron spectroscopy, and transmission electron microscopy, binding experiments with both large and small biomolecules were performed. High adsorption capacities of amino acids with different hydrophobicity and charge, as well as proteins of different isoelectric points and molecular weights were determined in batch equilibrium experiments. Desorption experiments with model proteins mixture demonstrated an ability to successfully separate one protein from another with selectivity hypothesized to be a combination of isoelectric point, hydrophobicity, and ability to penetrate the crystalline material. The results demonstrated that Py-BPy²⁺-COF can be exploited as a robust crystalline anion exchange biomolecule separation material.