Here we present a novel electrically switchable nanovalve array based on an intrinsic conductive polymer that has the capabilities to change its volume depending on its redox state. The polymer is created by anodic deposition of a sodium dodecylbenzenesulfonate (DBS)-doped polypyrrole (PPy). Optimization of the DBS-doped PPy layers revealed an actuatoric performance of up to 10% out of plane volume change. More interestingly, the electrochemical characterization revealed an actuatoric monostable polymer that could be used to fabricate nanovalve arrays that have a native opened state when no potential is applied and that can be closed when a reductive potential is applied. As a proof of concept, Atto488-labeled biotin (Biotin-Atto488) was used as a model compound and defined nanovalve arrays with nanopores in the range of 10 nm in diameter (opened state) were fabricated. Afterward, we were able to successfully prove the functionality of our nanovalve array by monitoring the flow-through rates of the Biotin-Atto488. More strikingly, we could demonstrate for the first time the robust and long-term stability of our nanovalve array without any performance loss for at least 72 h and retention capabilities of up to 90%. Furthermore, the demonstrated long-term stability was achieved under biocompatible conditions without the need of toxic dopant supplementation of the flow-through solution. Thus, our novel functional long-term stable nanovalve array offers the capabilities for practical applications.
Keywords: Nanovalve array; actuatoric polymer; nanoporous aluminum oxide; polypyrrole.