Biocatalytic cascades and intercommunicated biocatalytic cascades in microcapsule systems

Biomolecule-loaded nucleic acid-functionalized carboxymethyl cellulose hydrogel-stabilized microcapsules (diameter ca. 2 mu m) are introduced as cell-like containments. The microcapsules are loaded with two DNA tetrahedra, T-1 and T-2, functionalized with guanosine-rich G-quadruplex subunits, and/or with native enzymes (glucose oxidase, GOx, and/or beta-galactosidase, beta-gal). In the presence of K+-ions and hemin, the T-1/T-2 tetrahedra constituents, loaded in the microcapsules, assemble into a hemin/G-quadruplex bridged tetrahedra dimer DNAzyme catalyzing the oxidation of Amplex Red to Resorufin by generating H2O2. In the presence of co-loaded GOx or GOx/beta-gal, the GOx//T-1/T-2 hemin/G-quadruplex cascade catalyzing the glucose-mediated oxidation of Amplex Red to Resorufin, and the three-biocatalysts cascade consisting of beta-gal//GOx//hemin/G-quadruplex bridged T-1/T-2 catalyzing the lactose-driven oxidation of Amplex Red to Resorufin proceed in the microcapsules. Enhanced biocatalytic transformations in the microcapsules, as compared to the performance of the reactions in a homogeneous phase, are observed, due to the proximity of the biocatalysts in a confined volume. As the synthetic methodology to prepare the microcapsules yields boundaries functionalized with complementary nucleic acid tethers, the dynamic association of different microcapsules, loaded selectively with biomolecular catalysts, proceeds. The dynamic dimerization of GOx-loaded microcapsules and hemin/G-quadruplex bridged T-1/T-2 DNAzyme-loaded microcapsules yields effective intercommunicated microcapsules driving the GOx//hemin/G-quadruplex bridged T-1/T-2 DNAzyme cascade. In addition, the dynamic dimerization of GOx-loaded microcapsules with beta-gal//hemin/G-quadruplex bridged T-1/T-2-loaded microcapsules enables the bi-directional intercommunicated operation of the lactose-stimulated three catalysts beta-gal//GOx//hemin/G-quadruplex bridged T-1/T-2 DNAzyme cascade. The guided separation and formation of dynamic supramolecular dimer microcapsular containments, and the dictated switchable operation of intercommunicated biocatalytic cascades are demonstrated.

Automated summary

Biomolecule-loaded microcapsules with nucleic acid-functionalized hydrogel can enhance biocatalytic reactions. By controlling the assembly and connection of microcapsules, cascaded reactions with different enzymes can be achieved.