The Synthesis of a 2D Ultra‐Large Protein Supramolecular Nanofilm by Chemoselective Thiol–Disulfide Exchange and its Emergent Functions

The design and scalable synthesis of robust 2D biological ultrathin films with a tunable structure and function and the ability to be easily transferred to a range of substrates remain key challenges in chemistry and materials science. Herein, we report the use of the thiol–disulfide exchange reaction in the synthesis of a macroscopic 2D ultrathin proteinaceous film with the potential for large‐scale fabrication and on‐demand encapsulation/release of functional molecules. The reaction between the Cys6–Cys127 disulfide bond of lysozyme and cysteine is chemo‐ and site‐selective. The partially unfolded lysozyme–cysteine monomers aggregate at the air/water or solid/liquid interface to form an ultra‐large 2D nanofilm (900 cm 2 ) with about 100 % optical transparency. This material adheres to a wide range of substrates and encapsulates and releases a range of molecules without significantly affecting activity.