Development of a pressure-driven nanofluidic control system and its application to an enzymatic reaction

A novel air-pressure-based nanofluidic control system was developed and its performance was examined. We found that the flow in a 100 nm scale nanochannel on a chip (called an extended nanospace channel) could be controlled within the pressure range of 0.003-0.4 MPa, flow rate range of 0.16-21.2 pL/min, and residence time range of 24 ms-32.4 s by using the developed nanofluidic control system. Furthermore, we successfully demonstrated an enzyme reaction in which the fluorogenic substrate TokyoGreen-beta-galactoside (TG-beta-gal) was hydrolyzed to the fluorescein derivative TokyoGreen (TG) and beta-galactose by the action of beta-galactosidase enzyme as a calalyst in a Y-shaped extended nanospace channel. The parameters for the reaction kinetics, such as K(m), V(max) and k(cat), were estimated for the nanofluidic reaction, and these values were compared with the results of bulk and microfluidic reactions. A comparison showed that the enzyme reaction rate in the Y-shaped extended nanospace channel increased by a factor of about two compared with the rates in the bulk and micro spaces. We thought that this nanospatial property resulted from the activated protons of water molecules in the extended nanospace. This assumption was supported by the result that the pH dependence of the maximum enzyme activity in the Y-shaped extended nanospace channel was slightly different from that in the bulk and micro spaces.