Effect of architecture on the activity of glucose oxidase/horseradish peroxidase/carbon nanoparticle conjugates

• The arrangement of two enzymes on nanoparticles affects the complex activity.
• Nanoparticle surfaces impair glucose oxidase more than horseradish peroxidase.
• Arrangements minimizing glucose oxidase-nanoparticle contact have higher activity.
• Carbon nanoparticles actually enhance horseradish peroxidase activity.

We investigate the activity of glucose oxidase (GOx) together with horseradish peroxidase (HRP) on carbon nanoparticles (CNPs). Because GOx activity relies on HRP, we probe how the arrangement of the enzymes on the CNPs affects enzymatic behavior. Colorimetric assays to probe activity found that the coupling strategy affects activity of the bienzyme–nanoparticle complex. GOx is more prone than HRP to denaturation on the CNP surface, where its activity is compromised, while HRP activity is enhanced when interfaced to the CNP. Thus, arrangements where HRP is directly on the surface of the CNP and GOx is not are more favorable for overall activity. Coverage also influenced activity of the bienzyme complex, but performing the conjugation in the presence of glucose did not improve GOx activity. These results show that the architecture of the assembly is an important factor in optimization of nanoparticle–protein interfaces.

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