Pillar[5]arene‐stabilized Plasmonic Nanoparticles as Selective SERS Sensors

Abstract We present here a simple procedure for the surface modification of plasmonic nanoparticles (NPs) with a cationic water‐soluble ammonium pillar[5]arene (AP[5]A) in order to create selective surface‐enhanced Raman scattering (SERS) spectroscopy based sensors. The strategy is based on a ligand exchange reaction between the AP[5]A and the stabilizing agent of the as‐prepared plasmonic NPs. The approach could be applied to plasmonic nanoparticles either negatively charged, stabilized by citrate ions (Au spheres) or positively charged, stabilized by cetyltrimethylammonium bromide (Au and Au@Ag nanorods). The SERS performance of all systems was studied as a function of NP size and excitation laser line by using an analyte with no affinity towards the metal surface such as pyrene. The analytical enhancement factor (AEF) for the different systems was estimated between 0.55×10 4 and 1.49×10 5 . Finally the synergistic effect of combining supramolecular chemistry and plasmonic NPs is demonstrated through SERS‐based detection, in aqueous media, of molecules with no affinity towards a bare plasmonic substrate such as the contaminant pyrene or the biomolecule pyocyanin with nanomolar limit of detection.