Hybrid Surface-Enhanced Raman Scattering Substrates for the Trace Detection of Ammonium Nitrate, Thiram, and Nile Blue

Abstract

We report the fabrication and performance evaluation of hybrid surface-enhanced Raman scattering (SERS) substrates involving laser ablation and chemical routes for the trace-level detection of various analyte molecules. Initially, picosecond laser ablation experiments under ambient conditions were performed on pure silver (Ag) and gold (Au) substrates to achieve distinct nanosized features on the surface. The properties of the generated surface features on laser-processed portions of Ag/Au targets were systematically analyzed using UV–visible reflection and field emission scanning electron microscopy studies. Later, hybrid-SERS substrates were achieved by grafting the chemically synthesized Au nanostars on the plain and laser-processed plasmonic targets. Subsequently, we employed these as SERS platforms for the detection of a pesticide (thiram), a molecule used in explosive compositions [ammonium nitrate (AN)], and a dye molecule [Nile blue (NB)]. A comparative SERS study between the Au nanostar-decorated bare glass, silicon, Ag, Au, and laser-processed Ag and Au targets has been established. Our studies and the obtained data have unambiguously determined that laser-processed Ag structures have demonstrated reasonably good enhancements in the Raman signal intensities for distinct analytes among other substrates. Importantly, the fabricated hybrid SERS substrate of “Au nanostar-decorated laser-processed Ag” exhibited up to eight times enhancement in the SERS intensity compared to laser-processed Ag (without nanostars), as well as up to three times enhancement than the Au nanostar-loaded plain Ag substrates. Additionally, the achieved detection limits from the Au nanostar-decorated laser-processed Ag SERS substrate were ∼50 pM, ∼5 nM, and ∼5 μM for NB, thiram, and AN, respectively. The estimated enhancement factors accomplished from the Au nanostar-decorated laser-processed Ag substrate were ∼10 6 , ∼10 6 , and ∼10 4 for NB, thiram, and AN, respectively.

Femtosecond laser patterned silicon embedded with gold nanostars as a hybrid SERS substrate for pesticide detection

“…The intense Raman peak of thiram at 1370 cm −1 can be associated with the CH 3 symmetric in-plane deformation and C-N stretching. 40 The Raman spectra of thiram is shown in Fig. S1 (ESI †) and observed vibrational peaks with their corresponding mode assignments are tabulated in Table T2 (ESI †).…”

Wafer-scale silver nanodendrites with homogeneous distribution of gold nanoparticles for biomolecules detection

“…Hence, with the rapid developments in the modern world, chemical, environmental, and microbiological contaminants are significant pollutants that should be moderated and detected easily. The rapid growth and involvement of molecular sensing encouraged numerous researchers to explore various technologies toward the fabrication of economical, reproducible, and highly sensitive SERS-active substrates for label-free molecular detection (Vendamani et al, 2018a, 2018b, Ravi Kumar et al, 2021Moram et al, 2018;Bharati et al, 2018;Beeram et al, 2022;Rathod et al, 2022;Banerjee et al, 2022). The plasmonic nanostructures (NSs) with different dimensions on rough surfaces attracted researcher's interests owing to the exploration of SERS by Fleischmann et al in the seventies, witnessed through Raman enhancement of pyridine in the order of $10 6 on a rough metal silver electrode (Fleischmann et al, 1974).…”

Picosecond laser-ablated metal nanostructures and nanoparticles for SERS-based sensing applications

“…In the case of Ag NPs in DIW, a broader absorption spectrum was noticed compared to alkali metal hydroxide, possibly due to the ablation medium's ionic (Na + and K + ) species and the variation in the size distribution [16]. In the case of Au nanostars, the peak in the visible region (582 nm) corresponds to the core, and in the NIR region (763 nm) is owing to the sharp tips of Au nanostars, Fig 1(d) [17,18]. FESEM images revealed that the Au nanostars were decorated randomly throughout the area on plain and laser-processed Au substrate.…”