Co-immobilization of enzymes with the help of a dendronized polymer and mesoporous silica nanoparticles
Artikel i vetenskaplig tidskrift, 2015

The two enzymes Aspergillus sp. glucose oxidase (GOD) and horseradish peroxidase (HRP) were co-immobilized on solid silica supports in a spatially controlled way by using mesoporous silica nanoparticles (Hiroshima Mesoporous Materials, HMM) and a polycationic dendronized polymer (denpol). The silica support was first coated with the denpol, followed by the deposition of the mesoporous silica nanoparticles into which-in a next step-GOD was adsorbed. Finally, the GOD-loaded silica nanoparticles were coated with a denpol-HRP conjugate constituting of several HRP molecules which were covalently bound to the denpol via bis-aryl hydrazone (BAH) bonds. The entire immobilization process was followed in real time with quartz crystal microbalance with dissipation monitoring (QCM-D). The activities and storage stabilities of the co-immobilized enzymes were determined by analyzing a two-step cascade reaction involving the two immobilized enzymes GOD and HRP. d-glucose and o-phenylenediamine (OPD) were used as substrates for GOD and HRP, respectively. The cascade reaction-in which intermediate hydrogen peroxide was formed from d-glucose and dissolved O 2 with GOD-was shown to take place. The immobilized enzymes remained fairly stable for at least 2 weeks if stored in contact with an aqueous solution of pH = 7 at 4°C. If, however, denpol-BAH-GOD coated HRP-loaded mesoporous silica nanoparticles were used (the reversed situation), the cascade reaction was not effective. This was probably due to slow diffusion of hydrogen peroxide from the surface-exposed GOD to the particle-trapped HRP, and/or due to an inefficient loading of active HRP inside the particles. Overall, the combination of two enzyme immobilization methodologies-enzymes adsorbed within mesoporous silica nanoparticles and enzymes adsorbed as denpol-BAH-enzyme conjugates-allows the spatially controlled localization of different types of enzymes in a simple way. Possible applications of the concept are in the field of bioelectrode fabrication.


Hanna Gustafsson

Chalmers, Kemi och kemiteknik, Tillämpad kemi

A. Küchler

Eidgenössische Technische Hochschule Zürich (ETH)

Krister Holmberg

Chalmers, Kemi och kemiteknik, Tillämpad kemi

P. Walde

Eidgenössische Technische Hochschule Zürich (ETH)

Journal of Materials Chemistry B

2050750x (ISSN) 20507518 (eISSN)

Vol. 3 30 6174-6184





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