Surface-enhanced Raman scattering gold nanoplatelets synthesized using extracts of the Cercis Canadensis flower

Non-spherical nanostructures such as multilayered polygons and branched Au nanoparticles demonstrate high Surface-enhanced Raman scattering (SERS) performance due to their plasmonic nature and anisotropic morphology. Unfortunately, their syntheses often involve multiple steps and complex reagents. In particular, a conventional synthesis of Au nanoplatelets (AuNPt) involves a toxic cationic surfactant that should be substituted with more ecologically friendly reagents. Herein, we demonstrate the synthesis of AuNPt utilizing organic biomolecules from the plant Cercis Canadensis. These SERS-capable AuNPt are also shown to undergo a distinctive structural modification through plasma-dependent etching of the nanoparticle. This etching allows, in high yield, the {111} facets to develop surface undulations and perforations through the entire structure that increases anisotropy. The AuNPt are demonstrated to be surfactant-free through the absence of hydrocarbons in the IR spectra and EDX measurements. The nanoplatelets displayed a 17.142 ± 1.193 × Raman to SERS peak enhancement, 4133% increase of the area under the curve, and a 1580% increase in the FWHM in the fingerprint 1341 cm⁻¹ peak of p-nitrothiophenol. Measurements were done in liquid- and solid-phase to demonstrate the versatility of the AuNPts.