Super-hydrophilic SERS sensor with both ultrahigh activity and exceptional 3D spatial uniformity for sensitive detection of toxic pollutants

Recently, hierarchical hybrid structures based on the combination of semiconductor micro/nanostructures and noble metal nanoparticles have become a hot research topic in the area of surface-enhanced Raman scattering (SERS). In this work, two core-satellite nanostructures of metal oxide/metal nanoparticles were successfully introduced into SERS substrates, assembling monodispersed small silver nanoparticles (Ag NPs) on large polydispersed ZnO nanospheres (p-ZnO NSs) or monodispersed ZnO nanospheres (m-ZnO NSs) core. The p-ZnO NSs and m-ZnO NSs were synthesized by the pyrolysis method without any template. The Ag NPs were prepared by the thermal evaporation method without any annealing process. An ultralow limit of detection (LOD) of 1 × 10−13 M was achieved in the two core-satellite nanostructures with Rhodamine 6G (R6G) as the probe molecule. Compared with the silicon (Si)/Ag NPs substrate, the two core-satellite nanostructures of Si/p-ZnO NSs/Ag NPs and Si/m-ZnO NSs/Ag NPs substrates have higher enhancement factors (EF) of 2.6 × 108 and 2.5 × 108 for R6G as the probe molecule due to the enhanced electromagnetic field. The two core-satellite nanostructures have great application potential in the low-cost massive production of large-area SERS substrates due to their excellent SERS effect and simple preparation process without any template.

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High-Performance Surface-Enhanced Raman Scattering Substrates Based on the ZnO/Ag Core-Satellite Nanostructures

This article presents a review of many types of SERS sensors for food safety and environmental pollution monitoring based on detecting rhodamine. It introduces the basic concepts of substrates, enhancement factors, and mechanisms, devices’ sensors integrated with the microstructure. Here, we review the state-of-the-art research in the field of rhodamine monitoring and highlight the applications of SERS sensors. The trends in the development of substrates for different applications have been mentioned with the aim of providing an overview of the development of different SERS substrates. Thus, an efficient approach for rhodamine detection has a good perspective for application in environmental monitoring.

https://www.mdpi.com/2072-666X/13/11/1840/pdf?version=1666877682

Sensors for Detection of the Synthetic Dye Rhodamine in Environmental Monitoring Based on SERS

Flexible surface-enhanced Raman spectroscopy (SERS) substrate has attracted great attention due to its convenient sampling and on-site monitoring capability. However, it is still challenging to fabricate a versatile flexible SERS substrate, which can be used for in situ detection of analytes either in water or on irregular solid surfaces. Here, we report a flexible and transparent SERS substrate based on a wrinkled polydimethylsiloxane (PDMS) film obtained by transferring corrugated structures on the aluminium/polystyrene bilayer film, onto which silver nanoparticles (Ag NPs) are deposited by thermal evaporation. The as-fabricated SERS substrate exhibits a high enhancement factor (∼1.19×105), good signal uniformity (RSD of 6.27%), and excellent batch-to-batch reproducibility (RSD of 7.3%) for rhodamine 6 G. In addition, the Ag NPs@W-PDMS film can maintain high detection sensitivity even after mechanical deformations of bending or torsion for 100 cycles. More importantly, being flexible, transparent, and light, the Ag NPs@W-PDMS film can both float on the water surface and conformally contact with the curved surface for in situ detection. The malachite green in aqueous environment and on apple peel can be easily detected down to 10-6 M with a portable Raman spectrometer. Therefore, it is expected that such a versatile flexible SERS substrate has great potential in on-site, in situ contaminant monitoring for realistic applications.

Versatile flexible SERS substrate for in situ detection of contaminants in water and fruits based on Ag NPs decorated wrinkled PDMS film.

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Chen Mengyu

Papers

High-performance flexible surface-enhanced Raman scattering substrate based on the particle-in-multiscale 3D structure