BioPOW: Bioactive Dry Water Powders Enable Catalysis With Solvent‐Sensitive Enzymes in Pickering Emulsions

ABSTRACT

Bioactive PPickering emulsions (BioPEs) are useful reaction platforms for biocatalysis in organic solvents, but solvent‐sensitive enzymes often lose activity during classical emulsification. Here, we introduce BioPOW, an enzyme‐loaded dry water powder composed of buffered aqueous microdroplets stabilized by hydrophobic nanoparticles (NPs). BioPOW is rapidly prepared via mixing and forms BioPEs upon dosing into an organic solvent. Using ephedrine dehydrogenase (EDH) as a robust benchmark enzyme and carbonyl reductase (CPCR2_B16) as a solvent‐ and interface‐sensitive candidate, BioPOW‐derived BioPEs in methyl tert‐butyl ether achieved apparent reaction rates of 1.8 and 1.5 g·L ^{− 1} ·h ^{− 1} , respectively. Thus, EDH performed comparably in BioPOW‐derived and classical BioPE, while CPCR2_B16 retained measurable activity under conditions where a classical BioPE performed poorly. BioPOW formed stable emulsions with various organic solvents, including ethyl acetate, cyclopentyl methyl ether (CPME), and toluene. It could be handled and stored as a dry powder for at least 21 days, was reusable after recovery, and retained catalytic activity. These results indicate BioPOW as an easy‐to‐handle, dry precursor for generating BioPE, with particular value for enzyme systems that are difficult to operate by direct emulsification. It therefore offers potential to expand the application of BioPE in synthetic catalysis.