Universal Fabrication of Highly Efficient Plasmonic Thin‐Films for Label‐Free SERS Detection

• Published in: Small (Weinheim an der Bergstrasse, Germany) Vol. 17; no. 33
• Main Authors: Gullace, Sara, Montes‐García, Verónica, Martín, Victor, Larios, David, Girelli Consolaro, Valentina, Obelleiro, Fernando, Calogero, Giuseppe, Casalini, Stefano, Samorì, Paolo
• Format: Journal Article
• Language: English
• Published: Weinheim Wiley Subscription Services, Inc 01-08-2021; Wiley-VCH Verlag
• Subjects: Chemical Sciences; Composition effects; core‐shell; Drinking water; Graphene; graphene oxide; Interlayers; layer‐by‐layer assembly; Material chemistry; metal nanoparticles; Nanoparticles; Nanotechnology; plasmonic thin‐films; Plasmonics; Platforms; Polyelectrolytes; Raman spectra; Substrates; surface‐enhanced Raman scattering sensing; Thin films
• ISSN: 1613-6810; 1613-6829
• DOI: 10.1002/smll.202100755

The development of novel, highly efficient, reliable, and robust surface enhanced Raman scattering (SERS) substrates containing a large number of hot spots with programmed size, geometry, and density is extremely interesting since it allows the sensing of numerous (bio‐)chemical species. Herein, an extremely reliable, easy to fabricate, and label‐free SERS sensing platform based on metal nanoparticles (NPs) thin‐film is developed by the layer‐by‐layer growth mediated by polyelectrolytes. A systematic study of the effect of NP composition and size, as well as the number of deposition steps on the substrate's performance, is accomplished by monitoring the SERS enhancement of 1‐naphtalenethiol (532 nm excitation). Distinct evidence of the key role played by the interlayer (poly(diallyldimethylammonium chloride) (PDDA) or PDDA‐functionalized graphene oxide (GO@PDDA)) on the overall SERS efficiency of the plasmonic platforms is provided, revealing in the latter the formation of more uniform hot spots by regulating the interparticle distances to 5 ± 1 nm. The SERS platform efficiency is demonstrated via its high analytical enhancement factor (≈106) and the detection of a prototypical substance(tamoxifen), both in Milli‐Q water and in a real matrix, viz. tap water, opening perspectives towards the use of plasmonic platforms for future high‐performance sensing applications.
A reliable, easy to fabricate, and label‐free surface‐enhanced Raman scattering (SERS) sensing platform is realized, via the layer‐by‐layer assembly of Au@Ag nanoparticles, with an accurate design and engineering of hot spot size and density. Graphene oxide functionalized with polyelectrolytes allows to regulate the interparticle distances to 5 ± 1 nm, leading to an increased SERS efficiency and a robust shelf‐life.