Abstract
We revealed that, in nanochannels with increased surface-to-volute ratio, surface electrostatic interactions restrict motion of solute molecules, and they significantly affect injection of solute molecules from micro to nanochannel by pressure-driven flow. 100% solute injection to the nanochannel was achieved in case of the solute without electric charge. The results indicate that uniform sampling from micro to nanochannel is prevented by the electrostatic interactions, and this can lead to significant bias of analytical results in nanofluidic devices. Accordingly, this study provides important knowledge for conceptual design of nanofluidic devices for analysis and ultra-high efficient separation.