Covalent organic frameworks as crystalline sponges for enzyme extraction and production from natural biosystems

Biomacromolecules, as represented by enzymes have played critical parts in various fields, especially in biomanufacture and biomedicinal applications. However, their purification from complex biological systems is of great significance but very challenging. Herein, we develop an approach using high-performance covalent organic frameworks (COFs) as crystalline sponges to extract and produce enzymes directly from the complex natural biosystem. For instance, lysozyme with high purity and activity is successfully extracted from chicken egg white through a simple adsorption and elution process. Attributed to the well-tuned pore microenvironment of COFs, both high uptake and selectivity can be realized by this high-performance crystalline sponges. Notably, the encapsulated lysozyme can be smartly and conveniently released by pH adjustment of the eluent. The harvested lysozyme demonstrates ultrahigh purity and improved activity, surpassing the commercial lysozyme (activity boosted up to 344%). The mild operation condition and good protection effect of COFs contribute to the high activity of the obtained enzyme. Moreover, compared with conventional separation media, COFs sponges demonstrate superior selectivity, efficiency, and reusability. One gram of COFs can produce ∼ 0.69 g of enzyme product per batch, and the COFs can be reused for at least 5 times. This study opens up a new avenue to extract enzymes and provides valuable guidance for the design of crystalline sponges for highly efficient bioseperation.