Detection of Non-Diffusion-Limited Enzymatic Surface Reaction in Nanofluidic Channels

Using nanofluidic channels to detect enzymatic surface reactions can overcome diffusion-limited patterning as enzyme accelerates surface reactions without being consumed. In this paper, Trypsin proteolysis reaction is used to demonstrate this idea. Trypsin (enzyme) cleaves Poly-L-Lysine (PLL) coated on the surface of silica nanochannels, resulting in a change of surface charge density and channel height. This change is detected by monitoring the electrical conductance along the nanochannels. 50 μg/ml Trypsin has been detected in 90 nm-height nanochannels within one hour, which is 30 times faster compared to that of a diffusion-limited surface binding reaction. The effect of nanochannel height and the detection limitation are also discussed. Our results indicate that nanofluidic channels can be used for detecting enzymatic-based surface reactions.