Inspired by biological channels that occur in nature, smart biomimetic nanofluidic systems have been built to enable salinity power harvesting. However, most of these smart membranes are composites containing two incompatible components that require sophisticated fabrication techniques, thus limiting practical applications. Here, a single component polypyrrole membrane has been developed via a simple self-assembly process. The membrane provides asymmetric wettability on either side, cytocompatibility and an electrochemically tuneable ionic conductance. The ability of this membrane to capture energy arising from a salinity gradient has been demonstrated. The system can provide a stable current density over 16 h using artificial seawater and river water to provide the salinity gradient, and an energy density of 1.4 Wh/m2 was obtained. The cytocompatibility and ability to generate salinity power make this membrane a promising material for biomimetic applications.