Surface-enhanced Raman scattering on a hierarchical structural Ag nano-crown array in different detection ways

Abstract

A highly ordered Ag nano-crown array with a hierarchical pattern is designed as a three-dimensional (3D) surface-enhanced Raman scattering (SERS) substrate. It was achieved by depositing Ag on a patterned polymethyl methacrylate (PMMA) film which precisely replicates the patterns of a honeycomb-like anodic aluminum oxide (AAO) template. We made a detailed analysis on the structure of Ag nano-crowns and place emphasis on the detection mode to optimize the excitation and collection of the SERS signals. Finite-different time-domain (FDTD) simulation was performed to confirm and compare electric field enhancement in the gaps between nano-crowns in two different detection ways. All the results exposed and confirmed that the unique detection way of the Ag nano-crown substrate which is different from the traditional mode is optimal. This hierarchical structural Ag nano-crown not only has satisfactory repeatability, but also provides high sensitivity which was supported by the high electric field enhancement in the proper detection way. As a practical application, the detection of pesticide thiram was achieved with a limit of detection down to 1.0 × 10(-14) M. This hierarchical structural Ag nano-crown array on a polymer film is a promising candidate as a portable SERS chip.

Fabrication of transparent SERS platform via interface self-assembly of gold nanorods and gel trapping technique for on-site real time detection

“…Recently, due to the high elasticity, high swelling and adsorption capability and excellent optical transparency of polydimethylsiloxane (PDMS), several novel metal nanoparticle-PDMS nanocomposites have been developed for various applications. [37][38][39] Singh et al took advantage of the high elasticity of PDMS to fabricate buckled PDMS silver nanorod arrays as active 3D SERS cages for trapping and enhancing the Raman signal of P. aeruginosa bacteria. 40 Based on the high swelling and adsorption capabilities of PDMS, Yao et al coated a PDMS film on a Au nanoparticle monolayer to fabricate a novel metal-organic frameworks (MOFs) SERS platform for improving SERS detection of aromatic molecules in water and in the atmosphere.…”

“…The thickness, shape or size of PDMS can be easily tuned, and SERS signals can be measured through backside irradiation and SERS collection. 37,38 We hypothesize that transparent SERS substrates with flat morphology are able to address the aforementioned limitations of solid SERS substrates by confining sample droplets into a regular shape. Thereby real-time quantitative determination can be achieved.…”

Insight into SERS Chemical Enhancement Mechanism of Fungicide Thiram Adsorbed on Silver Nanoparticles

“…Liu et al also propose AgNPs prepared on flexible film to detect THR in commercial grape juice with LOD of as low as 0.1 lm (0.03 ppm) [26]. Wang et al achieve a very low LOD of 10 -14 M in detecting THR using Ag nano-crown array with a hierarchical pattern [27]. Recently, hybrid Au-Ag NPs have widely been used as SERS substrates.…”

Gold‐patterned microarray chips for ultrasensitive surface‐enhanced Raman scattering detection of ultratrace samples

“…Metal film is one kind of commercially used SERS substrate, with good reproducibility and long‐term stability, which are easily to be fabricated into chip form, given the capability for fast and in situ detection . But the intrinsic low enhancement capability still hinders its practical application, like Klarite and Q‐SERS substrates, although it could be further increased by building some nanostructures on the surface of the film . A practical detection application requires the SERS substrate not only has high enhancement, long‐term stability, and good reproducibility but also satisfies fast and easily‐operated analytical method with only trace samples.…”