Directed Assembly of Au Nanostar@Ag Satellite Nanostructures for SERS-Based Sensing of Hg 2+ Ions

• Published in: ACS applied nano materials Vol. 6; no. 12; pp. 10431 - 10440
• Main Authors: Ellis, Matthew G, Pant, Udit, Lou-Franco, Javier, Logan, Natasha, Cao, Cuong
• Format: Journal Article
• Language: English
• Published: United States 23-06-2023
• ISSN: 2574-0970; 2574-0970
• DOI: 10.1021/acsanm.3c01382

Embedding Raman reporters within nanosized gaps of metallic nanoparticles is an attractive route for surface-enhanced Raman spectroscopy (SERS) applications, although often this involves complex synthesis procedures that limit their practical use. Herein, we present the tip-selective direct growth of silver satellites surrounding gold nanostars (AuNSt@AgSAT), mediated by a dithiol Raman reporter 1,4-benzenedithiol (BDT). We propose that BDT is embedded within nanogaps which form between the AuNSt tips and the satellites, and plays a key role in mediating the satellite growth. Not only proposing a rationale for the mechanistic growth of the AuNSt@AgSAT, we also demonstrate an example for its use for the detection of Hg
ions in water. The presence of Hg
resulted in amalgamation of the AuNSt@AgSAT, which altered both its structural morphology and Raman enhancement properties. This provides a basis for the detection where the Raman intensity of BDT is inversely proportional to the Hg
concentrations. As a result, Hg
could be detected at concentrations as low as 0.1 ppb. This paper not only provides important mechanistic insight into the tip-selective direct growth of the anisotropic nanostructure but also proposes its excellent Raman enhancement capability for bioimaging as well as biological and chemical sensing applications.