pH-modulated ion-current rectification in a cysteine-functionalized glass nanopipette.

Abstract The unique properties of nanopores depend largely on the functionalization of the pore surface, which has always been a great challenge. In this study, a facile method for functionalizing the surface of a glass nanopipette to establish thiol-based linkage without involving Au film coating was successfully developed by utilizing the thiol–maleimide click reaction which works rapidly and with high specificity. Cysteine was employed as a model molecule to functionalize the nanopipette, resulting in pH-modulated ion-current rectification behavior which showed a good reproducible response to pH. Due to the widespread existence of thiol groups in nature, this nanopipette functionalization method has the potential and versatility to be used in a wide range of applications, including mimicking biological ion channels and fabricating sensing devices. Graphical abstract Unlabelled Image Highlights • A glass nanopipette was functionalised via a thiol–maleimide click reaction without Au film coating. • pH-modulated ion-current-rectification behavior of a cysteine-functionalized glass nanopipette was achieved. • The nanopipette ion-current rectification direction was modulated by pH. [ABSTRACT FROM AUTHOR]