Buffer effect on the ionic conductance in a pH-regulated nanochannel

• Analytical model for ionic conductance in a nanochannel with the buffer effect is derived.
• Surface chemical reactions and adsorption of metal and Tris buffer cations are considered.
• Model is verified by experimental data of conductance in silica nanochannels with Tris buffer.
• Buffer effect is significant at low salt concentration and pH.

An electrical four layer model taking into account surface chemical reactions and adsorption of the metal and Tris buffer cations is developed for the first time to investigate the buffer effect on the ionic conductance in a pH-regulated nanochannel. Predictions from the analytical model agree well with experimental data of the conductance in silica nanochannels. The buffer effect is significant at low salt concentration, and the behaviors of zeta potential, surface charge density, and conductance in a nanochannel with buffer are distinctly different from those without buffer.