Magnetically recyclable agar-based Pickering emulsions for green and efficient biocatalytic ester transformations

Efficient biphasic systems are important for improving enzymatic reactions involving hydrophobic substrates. In this study, a magnetically recyclable Pickering emulsion stabilized by agar-based magnetic nanoparticles (Fe₃O₄@PA) was developed to enhance lipase-catalyzed ester transformations. The Fe₃O₄@PA nanoparticles exhibited good magnetic responsiveness and effectively stabilized water-in-toluene Pickering emulsions with good emulsion stability and a large interfacial area for catalysis. Under optimal conditions (3 mg/mL stabilizer and water-to-oil ratio of 5:5), the Pickering emulsion significantly improved catalytic performance in the hydrolysis of benzyl acetate by Candida antarctica lipase B (CALB), achieving a 4-fold increase in the initial reaction rate compared with conventional biphasic and monophasic systems and reaching 98.5% conversion. The system also showed good operational stability, maintaining 71.5% conversion after 5 cycles via magnetic separation. Molecular dynamics simulations further revealed interfacial activation of CALB at the oil-water interface, providing molecular-level insight into the enhanced catalytic behavior.