Monolayer Assembly of MultiSpiked Gold Nanoparticles for Surface-Enhanced Raman Spectroscopy-Based Trace Detection of Dyes and Explosives

Abstract

For sensitive and reproducible surface-enhanced Raman scattering (SERS)-based trace detection, a SERS platform with high concentration of homogeneously distributed hotspots is needed. Herein, we report a facile monolayer assembly of multispiked gold nanoparticles (MSGNPs) of various sizes over a large area. The assembly was achieved simply by tuning the concentration of MSGNPs in a suspension and subsequently drying it on a substrate under ambient conditions. A monolayer assembly for MSGNP sizes ranging from 150 to 640 nm has been demonstrated. The MSGNP assembly showed excellent sensitivity and uniformity of SERS-based trace detection, owing to the presence of high concentration of uniformly distributed interparticle and intraparticle hotspots. In particular, detection of 10 fM of a toxic dye, crystal violet, has been demonstrated. Moreover, ammonium nitrate, which is a commonly used material for homemade explosives, was detected at 1 μM level. The MSGNP-based SERS platforms have great potential for applications in sensitive and reliable toxin and explosive detection.

Ultrasensitive flower-like TiO2/Ag substrate for SERS detection of pigments and melamine

“…Therefore, sensitive detection of pigments and melamine is very promising for health and safety applications. 30 …”

SERS-based trace detection by size and shape controlled noble metal particles with high benefit-cost ratio

“…For reproducible SERS-based trace molecule detection, we have developed facile synthesis methods of metal nanostructures that ensure highly concentrated hotspots and uniform distribution on the substrate. Firstly, we demonstrated a size-controlled synthesis of multi-spiked gold NPs (MSGNPs) that can be assembled into monolayers over a centimeter length scale simply by drying the suspension on a substrate under ambient conditions 6 . MSGNPs were synthesized by seed-mediated synthesis and our different seed concentrations were added under vigorous stirring, then samples were labeled as from P1 to P4.…”

Reproducible fabrication of gold nanostar monolayers for surface‐enhanced Raman spectroscopy‐based trace detection

“…[37] Many studies evaluated the reproducibility of the substrate by randomly selecting several points on one substrate and collecting signals for comparison. [28,38] Actually, these evaluation results reflect only the uniformity from spot to spot, but not the reproducibility from substrate to substrate. Here, we randomly selected 20 points in substrate M and substrate N from the same batch, respectively, and found that the integral areas under the curve of the characteristic peak 1,570 cm À1 were highly consistent (Figure 3a).…”

“…In many studies, the analyte solution was dropped on the substrate and detected after drying. [14,15,28] In this case, coffee ring of the analyte will also be formed, leading to uneven distribution of analyte molecules and inaccurate determination of the concentration. [29] In this study, we employed the classic Langmuir-Blodgett (LB) technique [30] to form a SAM of gold nanostars (Au NSs) at the water oil two-phase interface and then transferred the SAM onto silicon wafers as SERS substrates (Scheme 1).…”