Programmable 2D metal‐organic framework nanosheets for enzyme‐like hydrolysis of large proteins

The development of materials that mimic the catalytic activity of natural enzymes, so called nanozymes, are of crucial importance in biochemical and biotechnological fields. A Zr-pyridine tribenzoate metal-organic framework nanosheet (MON), Zr-PTB with 6-connected Zr6O8 clusters is synthesized via a formic acid modulated solvothermal synthesis. The catalytic activity of MON, graphene-like 2D materials which possess large external surface areas and tunable properties, is reported for the first time toward peptide bond hydrolysis of various peptides and proteins. Structure-reactivity analysis and the comparison with Zr-BTB (BTB = 1,3,5-tri(4-carboxyphenylbenzene)), a structural analogue of Zr-PTB with a more hydrophobic linker, revealed a delicate interplay between coordination bonds and hydrophobic interactions with the MON's surface as the main driving forces influencing reactivity. Compared to 3D MOFs, Zr-PTB produced a larger number of peptide fragments, indicating the importance of larger external surface area with easily accessible catalytically active sites for more comprehensive hydrolysis of proteins. The advantage of 2D MONs with respect to 3D MOFs, where pore sizes and diffusion of large substrates is a limiting factor influencing their reactivity, is further reflected by the ability to hydrolyze very large proteins. The exceptional stability of Zr-PTB allowed for its recyclability for over 5 reaction cycles.