Tunable Donnan Potential and Electrokinetic Flow in a Biomimetic Gated Nanochannel with pH-Regulated Polyelectrolyte Brushes

Learning from nature, many experimental results have revealed that biomimetic nanofluidics functionalized by pH-regulated polyelectrolyte (PE) brushes have significant potential for next-generation biosensing devices. The present study theoretically investigates for the first time the field effect on the Donnan potential and electrokinetic flow (EKF) in a biomimetic PE-modified nanochannel. The results obtained show that, in addition to the thickness and softness of the PE brush layer, the EKF velocity is tunable by modulating the Donnan potential of PE-modified nanochannels with a nanofluidic field effect transistor under various solution properties including pH and background salt concentration. The electrostatic gating effect on the Donnan potential depends significantly on the solution properties, but insignificantly on the thickness of the PE brush layer.