  In this study, we investigated the ionic current rectification of glass
nanopipettes modified with bovine serum albumin - glutaraldehyde (BSA-GA)
artificial membrane using solutions with various pHs. Ionic current
rectification is a phenomenon that is observed with nanopores as asymmetric I-V
curves, where the ionic currents recorded through a nanopore differ at the same
magnitude of applied electrical potentials biased with opposite polarities. The
results clearly showed that modifying the tip of a nanopipette results in a pH
dependent ionic current behavior. The proposed strategy is a facile method for
fabrication of a pH responsive nanoprobe that has a potential for intracellular
pH measurement.
