Protein-cell conjugates as artificial surface display for interfacial biocatalysis

Interfacial whole-cell biocatalysis has great potential for advanced chemical synthesis due to its ability to efficiently mediate complex reactions. However, the practical use of this approach is often limited by the fragility of living cells and the difficulty of maintaining enzyme activity under interfacial conditions. Here, we propose an artificial surface display strategy for interfacial biocatalysis by directly coupling sodium caseinate (NaCas) to the surface of E. coli cells. This coupling creates a robust biointerface that provides two main benefits: protecting cells from harsh interfacial environments and enabling the formation of Pickering emulsions for catalysis. The resulting protein-cell conjugates demonstrated thermal stability and strong resistance to organic solvents. Furthermore, the direct attachment of additional enzymes onto the cell surface allowed for efficient multienzyme cascade reactions, achieving an 80% yield in benzoin synthesis. The platform also showed multienzyme recyclability, retaining over 80% of enzyme activity after five reuse cycles, with emulsions that remained stable for more than 24 hours, enabling long-term catalytic applications. Therefore, these features demonstrate the significant benefits of our artificial surface display strategy, providing an environmentally friendly and versatile platform for interfacial biocatalysis applicable to synthetic chemistry and industrial biotechnology.