Biomimetic design of functional plasmonic surfaces based on polydopamine

Polydopamine is a bioinspired multifunctional material that is emerging in the last years for applications in the biomedical, energy, environmental and catalytic fields. Whereas the conformal coating of solid objects by polydopamine is a well assessed process, the development of polydopamine thin films is less explored and their potential advantages have still to be fully unveiled. Herein, we describe a green and straightforward fabrication of composite membranes based on polydopamine thin films self-assembled at the air/water interface, and two different biopolymers, bacterial cellulose and silk fibroin. Furthermore, the abundant phenolic hydroxyl groups enable the in situ Au nanoparticle decoration on the polydopamine side, providing the membrane surface with plasmonic features. The surface patterning of polydopamine layers using self-assembled templating structures is also demonstrated, opening up new perspectives for biocompatible functional membranes with tunable optical and spectroscopic properties. Lastly, we demonstrate that the obtained functional surfaces are promising tools for the fabrication of SERS substrates. By bridging dopamine chemistry with natural biopolymers and 2D photonic crystals, the results obtained within this paper establish an excellent platform for designing 2D nanoarchitectures with multiple functions.