Light-controlled protein imprinted nanospheres with variable recognition specificity

This work develops a protein imprinted nanosphere with varied recognition specificity for bovine serum albumin (BSA) and lysozyme (Lyz) under different UV light through a gradient dual crosslinked imprinting strategy (i.e., covalent crosslinking and dynamic reversible crosslinking). The imprinting cavities are initially constructed using irreversible covalent crosslinking to specifically recognize BSA, and then the coumarin residues in the imprinting cavities are crosslinked under 365 nm UV light to further imprint Lyz, because Lyz has smaller size than BSA. Since the photo-crosslinking of coumarin is a reversible reaction, the imprinting cavities of Lyz can be de-crosslinked under 254 nm UV light and restore the imprinting cavities of BSA. Moreover, the N-isopropyl acrylamide (NIPAM) and pyrrolidine residues copolymerized in the polymeric surface of the nanospheres are temperature- and pH-responsive respectively. Therefore, the protein rebinding and release behaviors of the nanospheres are controlled by external temperature and pH. As a result, the materials can selectively separate BSA from real bovine whole blood and Lyz from egg white under different UV light. This study may provide a new strategy for construction of protein imprinted materials with tunable specificity for different proteins.