Long Spiky Au-Ag Nanostar Based Fiber Probe for Surface Enhanced Raman Spectroscopy

Abstract

The detection performances of noble metal-based surface enhanced Raman spectroscopy (SERS) devices are determined by the compositions and geometries of the metal nanostructures, as well as the substrates. In the current study, long spiky Au-Ag alloy nanostars were synthesized, and both core diameters and spike lengths were controlled by Lauryl sulfobetaine concentrations (as the nanostructure growth skeleton). The long spiky star geometries were confirmed by transmission electron micrograph images. Elements energy dispersive spectrometer mapping confirmed that Au and Ag elements were inhomogeneously distributed in the nanostructures and demonstrated a higher Ag content at surface for potential better SERS performance. Selected synthesized spiky nanostars were uniformly assembled on multi-mode silica fiber for probe fabrication by silanization. The SERS performance were characterized using crystal violet (CV) and rhodamine 6G (R6G) as analyte molecules. The lowest detection limit could reach as low as 10−8 M, with a 6.23 × 106 enhancement factor, and the relationship between analyte concentrations and Raman intensities was linear for both CV and R6G, which indicated the potential qualitative and quantitative molecule detection applications. Moreover, the fiber probes also showed good reproducibility and stability in the ambient atmosphere.

A review of recent advances in the use of complex metal nanostructures for biomedical applications from diagnosis to treatment

“…He et al synthesized long, spiky Au–Ag alloy nanostars using one‐pot seedless green synthetic method and explored their potential as a surface enhanced Raman spectroscopy probe. Figure 8 shows the TEM of these Au–Ag nanostars along with their optical properties in NIR (He et al, 2022). Biosynthesis of nanostars using a strain of Saccaropolyspora hirsute has also been investigated by Eslam et al In this report, the biosynthesized silver nanostars demonstrated antimicrobial characteristics using agar diffusion method against various pathogens such as Staphylococcus aureus ( S. aureus ), Candida albicans , and Streptococcus pyogenes (Sholkamy et al, 2019).…”

“…Insert images represents singular nanostar morphology, and (e) extinction spectra of the nanostructures. Figure reproduced with permission from reference He et al (2022).…”

Electrochemical Self-Assembled Gold Nanoparticle SERS Substrate Coupled with Diazotization for Sensitive Detection of Nitrite

“…Surface-enhanced Raman scattering (SERS) technology has been widely used in the detection of trace amounts of substances in recent decades due to its competitive merits such as high sensitivity and rapid detection of low concentration analytes, high specificity due to rich vibration fingerprint information with narrow Raman peaks, and simplicity and practicability with portable instrument [24][25][26]. For the better application of SERS technique, an important requirement is to fabricate highly stable, reliable, and reproducible metallic nanostructures substrates, which can generate intensively localized electromagnetic fields at gaps between plasmonic nanostructures [27][28][29].…”