Surfactant-assisted synthesis of colloidosomes for positional assembly of a bienzyme system

Abstract

In this study, using sorbitan monooleate (Span-80), we developed a new strategy to achieve the positional assembly of a horse radish peroxidase/glucose oxidase bienzyme system within the zeolitic imidazolate framework-8 (ZIF-8)-based colloidosomes. Span-80 with self-adsorption property, was used as an auxiliary stabilizer to endow the enzyme-loaded ZIF-8 (enzyme@ZIF-8) with proper wettability in the formation of water–in–oil Pickering emulsion templates. Benefited from this, simultaneous immobilization of the bienzymes in the lumen and shell of the colloidosomes could be achieved. Meanwhile, Span-80 was found to act as a mediator to induce and control the overgrowth of the ZIF-8 crystallites on the enzyme@ZIF-8 layers, by which a “bricklaying” solidification protocol was established for the shell preparation. The resulting colloidosomes enabled the flexible positional change of the bienzymes, its shell exhibited the monolayer structure with increased compactness and homogenized micropores. Furthermore, the multi-enzyme cascade reaction was exemplified with the oxidization of o-phenylenediamine. An in-depth investigation showed that the assembly strategies of the bienzymes significantly affected their biocatalytic efficiency by influencing the utilization efficiency of the H2O2 intermediate between the step reactions. This study provides an insight towards a facile synthetic route for constructing multi-enzyme biocatalyst.