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 3 10 4 and 1.49 3 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.

DNA‐Origami‐Based Assembly of Au@Ag Nanostar Dimer Nanoantennas for Label‐Free Sensing of Pyocyanin

“…The obtained LOD was found to be lower than previously reported detection limit achieved using SERS and non‐SERS based pyocyanin detection platforms [39,49,51] . For example, the detection limit of electrochemical sensor designed using palladium hydride electrode by Webster et al.…”

Designing Silver Nanoparticles for Detecting Levodopa (3,4-Dihydroxyphenylalanine, L-Dopa) Using Surface-Enhanced Raman Scattering (SERS)

“…One may infer that signal enhancement for analytes can be obtained by tailoring the size and shape of the nanoparticles [12][13][14], in addition to the conformation of the analyte adsorbed as in the detection of B-complex vitamins in pharmaceutical samples [15].Such control in nanoparticle shape is afforded through various synthetic routes [16][17][18], then allowing the Localized Surface Plasmon Resonances (LSPR) to be tuned according to the region of best response (excitation) of the analyte [14,18,19]. For example, the near electromagnetic field is higher in nanoprisms (AgNPR), nanostars (AgNS) and nanorods (AgNR) than on spherical nanoparticles (AgNP) [18,19], and the LSPR may be wider to allow excitation down to the near infrared (IR) [18][19][20]. Indeed, Rycenga et al [21] reported higher SERS activity for three molecules adsorbed on Ag nanocubes (AgNC) than on AgNP due to the wider LSPR for AgNC.…”