Self-Assembled Three-Dimensional Au Films as Highly Reproducible and "Hotspots"-Rich Substrates for Multiplex SERS...

Area of Science:

• Plasmonics
• Nanotechnology
• Analytical Chemistry

Background:

• Three-dimensional (3D) plasmonic metal nanostructures are promising for surface-enhanced Raman scattering (SERS) detection.
• Achieving uniform "hotspots" in these structures remains a significant challenge for sensitive detection.

Purpose of the Study:

• To develop a scalable and cost-effective method for preparing 3D gold (Au) films with a high density of "hotspots."
• To evaluate the SERS performance of the developed 3D Au substrate for detecting various analytes.

Main Methods:

• Utilized a deep eutectic solvent (DES)-mediated interfacial self-assembly of thermally evaporated gold nanoparticles (Au NPs).
• Controlled the size and morphology of self-assembled Au films using the hydrogen-bonded structure of DES.

Main Results:

• The 3D Au substrate demonstrated outstanding SERS detection for crystal violet (CV), rhodamine 6G (R6G), and 5,5'-dithiobis(2-nitrobenzoic acid) (DTNB) with a limit of detection (LOD) as low as 3.2 × 10^-15 M.
• Achieved high sensitivity in detecting doxorubicin (DOX) (LOD: 5.8 × 10^-12 M), heavy metal ions (As³⁺, Hg²⁺) (LODs: 5.5 × 10^-5, 4.1 × 10^-5 g/mL), and nanoplastics (PET, PMMA, PS).
• Exhibited exceptional SERS signal reproducibility.

Conclusions:

• The DES-mediated self-assembly offers a scalable and low-cost strategy for fabricating 3D Au nanostructures with abundant "hotspots."
• The developed 3D Au-SERS substrate shows great potential for sensitive and reproducible detection of diverse analytes, including environmental pollutants.