Surface-enhanced Raman Scattering Substrate For Detection Research Articles

Template-assisted fabrication of Ag-nanoparticles@ZnO-nanorods array as recyclable 3D surface enhanced Raman scattering substrate for rapid detection of trace pesticides

We present a template-assisted fabrication method for a large-scale ordered arrays of ZnO nanorods (ZnO-NRs) modified with Ag nanoparticles (Ag-NPs), which possess high-density three-dimensional (3D) hot spots uniformly dispersed all over the substrate, being beneficial to ultrahigh sensitivity of surface enhanced Raman scattering (SERS) detection. These achieved Ag-NPs@ZnO-NRs arrays show high sensitivity, good spectral uniformity and reproducibility as substrates for SERS detection. Using the arrays, both dye molecules (rhodamine 6G, R6G) and organic pollutants like toxic pesticides (thiram and methyl parathion) are detected, with the detection limits of thiram and methyl parathion being 0.79 × 10−9 M and 1.51 × 10−8 M, respectively. In addition, the Ag-NPs@ZnO-NRs arrays have a self-cleaning function because the analyte molecules can be photocatalytic degraded using ultraviolet irradiation, showing that the 3D recyclable arrays have promising opportunities to be applied in rapid SERS-based detection of toxic organic pesticides.

Gold loaded textile fibres as substrates for SERS detection

Spectroscopic methods based on surface-enhanced Raman scattering (SERS) are among the analytical tools most exploited in recent years for the detection of vestigial amounts of compounds with environmental and health relevance. In the last decades, SERS methods have been largely improved with the unprecedented progress in instrumentation and materials development in the scope of nanoscale science. The current developments in Raman instruments, in particular for Raman imaging, brought a new look on composites and its applications. The use of confocal microscopes allows high resolution Raman mapping with short measurement times, creating strongly improved Raman images in two and three dimensions. In this manuscript, we will present an overview of our own research on the development of malleable and easy-handled SERS substrates based on textile fibres for analytical detection. The strategies employed for the coating of the textile fibres with gold nanoparticles (NPs) will be described in detail. A final section will focus on the combination of Raman imaging and SERS for the development of substrates based on textile fibres and their application on the detection of water pollutants and biomolecules. A case study on the development of cotton swab fibres coated with Au NPs for SERS detection of l-lactate will be illustrated in more detail.

Cicada wing decorated by silver nanoparticles as low-cost and active/sensitive substrates for surface-enhanced Raman scattering

A green, low-cost and highly efficient surface-enhanced Raman scattering (SERS) substrate was achieved by a chemical deposition of silver nanoparticles on a cicada wing, which has the large-scale nanosized protrusions on its surface. Employing the already-formed Ag/cicada wing as substrate for SERS detection, the detection limit for rhodamine 6G could reach 10−7M, the Raman enhancement factor of the substrate was as large as 106 and the relative standard deviation remains lower than 7%. The three-dimensional finite-difference time-domain simulation results showed that two types of inter-Ag-nanoparticle nanogaps in the formed geometry created a huge number of SERS “hot spots” where the electromagnetic field is substantially amplified and contributes to the higher SERS sensitivity. Meanwhile, the water contact angle of the SERS substrate is roughly 150°, which indicates the super-hydrophobic surface of the substrate. This feature may be conducive to the gathering of target molecules during the SERS detection, which in turn further improves the detection limit of target molecules. In order to improve the application of the substrate, thiram was used as the probe molecule, and the detection limit also reached 10−7 M. Meanwhile, the calibration of the Raman peak intensities of Rhodamine 6G and thiram allowed their quantitative detection. Therefore, the green and low-cost SERS substrates could be used for fast and quantitative detection of trace organic molecules. Our findings may contribute to the development of the green and low-cost SERS substrates and will allow the fast and quantitative detection of trace organic molecules.