Nanoporous Gold Membranes as Robust Constructs for Selectively Tunable Chemical Transport

Nanopores are promising structures for small-volume separations, but they often require complex top-down fabrication and are not easily (re)configurable to allow for dynamically tuned separations. Herein we report the first use of nanoporous gold (NPG) membranes as tunable, charge-based separation elements. NPG is fabricated into a robust network of interconnecting pores via simple solution de-alloying. We demonstrate that control over the selective permeation of small-molecule analytes can be controlled via three different methods: (1) anion adsorption at the Au surface; (2) pH-tuning of self-assembled monolayer (SAM) charge; and (3) electrochemical oxidation of a redox-active SAM. This simple and versatile membrane system is promising as a dynamically tunable element for small-volume separations.