Responsive Emulsions Enabled by Supramolecular Polymers for Recyclable Biocatalysis

Emulsion biocatalysis harnesses liquid-liquid interfaces to facilitate mass transfer for achieving efficient biocatalysis. However, it has been a great challenge in recycling the emulsions in the downstream process. Here, we present a supramolecular approach to design a responsive emulsion for recyclable biocatalysis. Crown ether acrylate monomers are copolymerized with N-isopropylacrylamide to yield amphiphilic supramolecular polymer as emulsifiers, which further enable to form robust emulsions, accommodating both isolated enzymes and whole-cell catalysts and supporting single-step transformations as well as multi-enzymatic cascades, with performance that surpasses conventional biphasic systems. Importantly, leveraging the reversible crown-ether/secondary-ammonium recognition, the introduction of a complementary dibenzylammonium guest triggers supramolecular cross-linking, enabling straightforward recovery and reuse of both emulsifier and catalyst with minimal activity loss, and subsequent mild pH modulation de-complexes the host-guest assembly, resulting in a reversibly switching system between emulsion and two-phase states. Additionally, Escherichia coli overexpressing BAL retains 80% of its initial activity over three consecutive cycles in this responsive emulsion. Therefore, our findings establish supramolecular polymer-stabilized emulsions as a versatile, recyclable platform for biocatalysis, providing a general strategy that bridges supramolecular polymer design with green chemical synthesis and offering strong potential for sustainable industrial chemical synthesis.