Controllable synthesis of AgNWs@PDA@AgNPs core–shell nanocobs based on a mussel-inspired polydopamine for highly sensitive SERS detection

In this work, a series of AgNWs@PDA@AgNPs core–shell nanocobs based on a mussel-inspired polydopamine (PDA) were controllably synthesized and achieve highly sensitive SERS detection. Owing to the existence of abundant catechol and amine functional groups, PDA molecules could assemble a functional layer on the surface of silver nanowires (AgNWs) and exhibit exceptional adhesion performance. More importantly, silver nanoparticles (AgNPs) with controlled coverage and size were achieved on the surface of the PDA layer by in situ reduction of silver ions into AgNPs with catechol functional groups, forming AgNWs@PDA@AgNPs core–shell nanocobs. By regulating synergistical effect between the AgNWs and AgNPs, the AgNWs@PDA@AgNPs core–shell nanocobs demonstrated a highly sensitive and stable SERS response to Rhodamine 6G (R6G) molecules, and a low limit of detection down to 10−12 M. Furthermore, the AgNWs@PDA@AgNPs core–shell nanocobs showed an excellent reproducibility and superior stability as a SERS substrate to achieve trace detection. This strategy would have great potential to fabricate multifarious SERS-active substrates that make it possible to detect single molecules and singles cell in chemical and biological fields.