Bio-reaction in a nano-confined space is promising in various fields but is away from being fully understood. Here, using nanochannels as a platform, we investigated enzyme catalysis-induced polymer deposition in a nano-confined space. Horseradish peroxidase (HRP) that catalyzes the polymerization of o-phenylendiamine (o-PD) was adopted as a model. The polymer precipitates blocked the channel and the ions transportation, in turn led to significant decrease of current signals. The current change was immediately triggered (within 10 s) when the polymerization occurred and the current could drop to 10% of the initial value. HRP concentration down to 5 μg/mL could cause observable signal, corresponding to three HRP molecules in each nanochannel. Enzymatic reaction kinetics in the nano-confined channel was also investigated with those in free state and surface-confined state as comparison. We found that the Michaelis constant in the nano-confinement state (63.80 mM) was obviously greater than that in free state (2.19 mM) and surface-confinement state (39.30 mM), highlighting the influence of the suppressed mass-transportation in nano-channels. And more importantly, the maximum rate (0.62) of enzyme catalysis in the nano-confinement state was much higher than that in the other two cases (9.62×10-4 and 9.40×10-3), which might be due to the activity enhancement derived from the nano-boundary effect in nanochannels. Our results may provide new information to better understand bio-reaction in a nano-confined space, and the nanochannel-based platform may be extended for development of powerful nano-effect-enhanced biosensors and their applications.

Monitoring enzyme catalysis confined in nanochannels through catalyzed polymer deposition

254th National Meeting (2017)

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.