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Surface-enhanced Raman spectroscopy (SERS) can provide a fingerprint of molecules with ultrahigh sensitivity, down to the single-molecule level. However, accurate quantitative detection in practical samples using SERS is still a great challenge. Herein, a highly uniform shell-isolated Ag@SiO2 nanoparticle (Ag SHIN) monolayer film was prepared and employed as a substrate for the quantitative determination of melamine in milk samples through shell-isolated nanoparticle-enhanced Raman spectroscopy. The Ag SHIN film exhibits excellent reproducibility, high stability, as well as ultrahigh sensitivity with a limit of detection of 0.03 ppm. A linear relationship between the Raman intensity and the melamine concentration in a wide range (1 ppb to 5 ppm) was obtained. These results demonstrate that the Ag SHIN monolayer film is a promising and reliable substrate for the quantitative SERS analysis of practical samples. Copyright © 2017 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

Shell-isolated nanoparticle-enhanced Raman spectroscopy (SHINERS) as a new member of Raman technique garnered great atten- tion among scientific community. In this work, we used an improved experimental setup to float the bare silver nanoparticles in air with the help of extraneous airflow, and used atomic layer deposition (ALD) method to coat ultra-thin inert shell without pinholes. Under optimal conditions, we successfully prepared three kinds of SHINERS NPs (Ag@Al2O3, Ag@SiO2 and Ag@TiO2) in large quantity without pinholes. The ultra-thin inert shell maintains the SERS activity of silver nanoparticles for long period of time. Transmission electron microscopy (TEM) images confirm the uniform coating of shell material on silver nanoparticles. Finally, the as-prepared SHINs have been applied to detect various samples to demonstrate the applications. The presented ALD method offers a unique way to coat ultrathin shell (1-10 nm) on metal nanoparticles in large quantity (1-10 g) for practical applications. [ABSTRACT FROM AUTHOR]

[Display omitted] • A flexible and cost-effective SERS sensor is created utilizing fish scales as a template. • The resulting SERS substrate exhibits notable porosity and wettability, promoting the formation of densely packed hotspots. • An impressive SERS enhancement factor of 1.3 × 106 is achieved, with a relative standard deviation of 6.4 %. • Demonstrations of fish scale substrates in detecting harmful environmental pollutant perfluorooctane sulfonamide in lake water, soil, and human urine samples are presented. Biological materials with unique surface properties provide a new avenue for fabricating green and sensitive SERS-active substrates. Herein, we present a simple but efficient method to prepare surface-enhanced Raman scattering (SERS) substrates by depositing silver nanoparticles (AgNPs) on fish scale substrates using an evaporation-induced self-assembly method (EISA). Characterization of the formed flexible Ag-impregnated substrate proved outstanding SERS sensitivity, uniformity, and reproducibility properties, with a Raman enhancement factor of 1.3 × 106 and a relative standard deviation of 6.4 %. Using this powerful fish scale substrate, a toxic environmental pollutant perfluorooctane sulfonamide (PFOSA) was indirectly detected in lake water, soil, and human urine samples. Due to its chemical structure, it is difficult to detect low concentrations of PFOSA in real samples. Interestingly, malachite green (MG) was smartly used as the Raman label for PFOSA detection in real samples. One of the main appeals is that the concentration of PFOSA can be correlated with a decrease in the SERS signal of MG in real samples. In conclusion, the strategy employed and reproducible SERS substrates may have diverse applications in clinical and environmental analyses. [ABSTRACT FROM AUTHOR]