Versatile Magnetic Nanoparticles for Spatially Organized Assemblies of Enzyme Cascades: A Comprehensive Investigation of Catalytic Performance

Comprehensive Summary Inspired by nature, precise spatial organization of enzyme cascades of interest is crucial to the improvement of catalytic performance. Herein, DNA scaffolds were introduced to construct a toolkit for versatile immobilization of enzyme pairs on dextran-coated magnetic nanoparticles (MNPs). After the glucose oxidase (GOx) and horseradish peroxidase (HRP) pair was immobilized through random covalent, DNA-directed and DNA tile-directed strategies, the immobilized GOx/HRP pair on the MNP-based carrier assembled with DNA tile (TD@MNPs) exhibited the highest activity due to rational spatial organization and less conformational change of constituent enzymes. With a decrease in interenzyme distance on TD@MNPs, furthermore, the catalytic efficiency of the HRP/GOx pair increased further for both substrates, 2,2’-azinobis(3-ethyl-benzthiazoline-6-sulfonate) (ABTS) and 3,3',5,5'-tetramethyl benzidine (TMB). As the assembled HRP was closer to the carrier surface, the catalytic efficiency of the GOx/HRP pair increased by 6.2-fold for positively charged TMB and only by 62% for negatively charged ABTS compared with the free GOx/HRP pair. Moreover, a reversal of catalytic efficiency was found after the GOx/HRP pair was assembled on a positively charged carrier (TD@pMNPs). This research demonstrated that MNP-based carriers had the potential to become a versatile toolkit for shedding an insight into catalytic performance and the development of new biocatalysts.