Preparation of sodium alginate-based temperature- and pH-responsive MOF/hydrogel microspheres and their adsorption and separation of proteins

The purification of biomacromolecules, particularly proteins, plays an increasingly vital role in the fields of medicine, biopharmaceuticals, and emerging technologies. Adsorbents with excellent adsorption capacity, superior cycling performance, and environmental compatibility are crucial for protein separation and adsorption. A temperature- and pH dual-stimulus responsive hydrogel material for the adsorption and separation of protein was successfully prepared by copolymerizing sodium alginate (SA) as the matrix with N-isopropylacrylamide (NIPAM), acrylic acid (AAC), and simultaneously introducing zirconium-based metal-organic frameworks (Zr-MOF). This hydrogel material exhibits excellent adsorption and controlled release properties for protein including bovine hemoglobin (BHB) and bovine serum albumin (BSA) with maximum adsorption capacities of 617.45 mg/g and 527.06 mg/g at 45 °C, respectively. Experimental results demonstrate that the adsorption and release behavior of the hydrogel toward proteins can be effectively regulated by adjusting environmental temperature or pH value in an aqueous medium without any acidic, alkaline, high-salt, or organic solvent. Additionally, the material exhibits good cyclic stability, maintaining more than 85 % of its initial protein adsorption capacity after five adsorption-desorption cycles. This study provides new insights into the development of smart responsive biomolecular adsorption materials and has significant application potential in the fields such as drug controlled release and biological separation.