Single-Particle SERS Enhancement with Optimized Gold-Nanostar Morphologies

The field of plasmonic nano-additives is expanding beyond the targeted synthesis of energy-tuned absorption materials toward the development of additive structures that efficiently translate the absorbed energy into a material response. In this work, the methodology to create gold nanostars with tailored extrusion features is optimized through a detailed investigation on the impact of each reaction chemical on the resulting structure morphology. Key elements including silver nitrate, ascorbic acid, and chloroauric acid concentrations are isolated to control nanostar tip length, symmetry, and quantity. Utilizing the optimized gold nanostar structure, a Raman tag sensitive to the plasmon field is integrated into nanostar structure at defined locations to isolate the regions of maximal plasm on intensity. The reporter molecule demonstrated an 18-fold enhancement in Raman signal intensity when adhered to the nanostar protrusions over other locations on the particle, isolating the area of highest Plasmon intensity at the nanostar tips.