Lightweight, Environmentally Friendly, and Underwater Superelastic 3D-Architectured Aerogels for Efficient Protein Separation

Highly purified protein adsorbents with simultaneous environmental friendliness and high performance are desirable in the biotechnological and biopharmaceutical industries. Herein, the cellulose nanofiber aerogels functionalized with sodium alginate (CNF/SA composite aerogels) featuring aligned 3D porous architecture have been developed via a freeze–drying and Ca2+ cross-linking process. The CNF/SA composite aerogels demonstrated superb underwater structural stability and shape-recovery property originating from the robust aligned porous skeletal structure. Moreover, the resultant CNF/SA composite aerogels with naturally abundant carboxyl groups exhibited unique selectivity toward positive proteins, demonstrating synchronously excellent static (1756 mg g–1) and dynamic (1146 mg g–1) lysozyme adsorption capabilities and high processing flux (21521 L m–2 h–1, gravity driven), which are superior to those of previously reported adsorbents and Sartorius Sartobind commercial membranes. Furthermore, the CNF/SA composite aerogels possessed stable recyclability, easy operation, and good environmental friendliness, demonstrating a bright practical application performance. This work sheds light on a promising direction for developing high-performance protein adsorbents and utilizing sustainable natural biomaterials in bio-separation applications.