Nanocellulose is an abundant green resource that, owing to the larger surface area, length, and diameter of the fibers, can be used as a framework for loading Ag nanoparticles and serve as substrate for surface enhancement Raman scattering (SERS). These properties would cause the hydroxyl groups on the surface to adsorb the Ag ions and reduce them to Ag seed to form a load fulcrum. This paper presents a convenient and environmentally friendly method for the fabrication of silver-nanocellulose composites (NCF-Ag). A commonly used pesticide, carbendazim (CBZ), was used as a SERS probe to evaluate the properties of NCF-Ag. The results showed that NCF-Ag possesses good homogeneity, reproducibility, and stability. Additionally, CBZ was found to have a low limit of detection (LOD), i.e., 1.0 × 10−8 M, which indicates the possibility for trace analysis. Furthermore, it presents good linearity with R2 = 0.98 at 1007 and 1270 cm−1 in the range from 10−4~10−7 M CBZ.
Superhydrophobic silver films were fabricated by silver-mirror reaction and surface functionalization with thiol. The thiol-functionalization significantly improved the hydrophobic property of the Ag films (AFS), and their contact angle values slightly increased with the extension of a thiol alkyl chain, reaching about 160°. The surface-enhanced Raman scattering (SERS) detection capacity of these films were investigated, and AFS-Dodec showed the best substrate for R6G molecule detection with the concentration limit of 10 −11 M. AFS functionalized with dodecanethiol (AFS-Dodec) was applied for the SERS detection of uric acid and creatinine, it exhibited good linear dependence relationship between the Raman intensity and analyte concentration in the concentration range of 5~1000 μM.
Surface-enhanced Raman scattering (SERS) is a sensitive technique for the detection of low concentration analytes. In this study, we used cellulose fibers (CF) as the templates for the loading of silver nanoparticles (Ag NPs), and the obtained CF-Ag was applied in the detection of R6G and Malachite Green (MG) by surface-enhanced Raman scattering. The adsorption technique was employed in the sample preparation, and the optimal detecting status was identified in the dynamic range (sample status ranging from wet to dry) for different concentration of analytes. In comparison to Ag NPs, CF-Ag showed enhanced performance for adsorptive detection of Malachite Green, and the limit of detection was 5 × 10−12 M.
Heavy metal pollution has long been the focus of attention because of its serious threat to human health and the environment. Surface enhanced Raman spectroscopy (SERS) has shown great potential for metal detection owing to many advantages, including, requiring fewer samples, its minimal damage to specimen, and its high sensitivity. In this work, we proposed a simple and distinctive method, based on SERS, using facile silver film (Ag-film) combined with a DNA molecular switch, which allowed for the highly specific detection of heavy metal mercury ions (Hg2+). When in the presence of Hg2+ ions, the signals from Raman probes attach to single-stranded DNA, which will be dramatically enhanced due to the specific structural change of DNA strands—resulting from the interaction between Hg2+ ions and DNA bases. This SERS sensor could achieve an ultralow limit of detection (1.35 × 10−15 M) for Hg2+ detection. In addition, we applied this SERS sensor to detect Hg2+ in real blood samples. The results suggested that this SERS platform could be a promising alternative tool for Hg2+ detection in clinical, environmental, and food inspection.
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