Magnetically Retrievable Nanoplatelets-Armored Emulsion Microreactor Platform for Efficient and Recyclable Enzymatic Catalysis

Enzyme catalysts are highly desirable for various industrial processes, including purification, degradation, and biosensing. However, their widespread application is hindered by challenges in controlling the reaction environment and high associated costs. This study introduces an innovative amphiphilic nanoplatelet (ANPL) system that addresses these limitations by supporting enzymes as interfacial catalysts with magnetic retrievability. We synthesized iron oxide nanoplatelets (IOPLs) via reverse precipitation of ferrous ions and coated them with silica to prevent aggregation. The surface was further modified with amine groups using silane chemistry to attach bromine initiators for polymerization. Amphiphilicity was achieved by grafting hydrophilic poly(2-aminoethylmethacrylate) (pAMA) and hydrophobic poly(n-butylmethacrylate) (pBMA) on opposite sides through surface-initiated atom transfer radical polymerization. The ANPLs were then functionalized with polyethylenimine (PEI) to facilitate electrostatic immobilization of Candida Antarctica Lipase B (CALB). We demonstrated this system's efficacy by fabricating water-in-oil emulsions with ANPL_CALB for the deacetylation of 1,3,4,6-tetra-O-acetyl-β-D-mannopyranose in microdroplets. The ANPL_CALB catalysts were thoroughly characterized, and deacetylation kinetics were analyzed. We evaluated the activity, cell viability, and recyclability of the ANPL_CALB system. Notably, these interfacial catalysts could be easily retrieved using an applied magnetic field, significantly enhancing their practicality and reusability. This study presents the ANPL microreactor system as a promising platform for designing biphasic enzymatic catalysis systems with high activity and recyclability. The integration of magnetic retrievability with amphiphilic properties offers a novel approach to enzyme immobilization and catalyst recovery, potentially revolutionizing the field of biocatalysis in materials engineering applications.