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 cm2 ) 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.