Preparation of Fe3O4-Ag Nanocomposites with Silver Petals for SERS Application

The formation of silver nanopetal-Fe3O4 poly-nanocrystals assemblies and the use of the resulting hetero-nanostructures as active substrates for Surface Enhanced Raman Spectroscopy (SERS) application are here reported. In practice, about 180 nm sized polyol-made Fe3O4 spheres, constituted by 10 nm sized crystals, were functionalized by (3-aminopropyl)triethoxysilane (APTES) to become positively charged, which can then electrostatically interact with negatively charged silver seeds. Silver petals were formed by seed-mediated growth in presence of Ag+ cations and self-assembly, using L-ascorbic acid (L-AA) and polyvinyl pyrrolidone (PVP) as mid-reducing and stabilizing agents, respectively. The resulting plasmonic structure provides a rough surface with plenty of hot spots able to locally enhance significantly any applied electrical field. Additionally, they exhibited a high enough saturation magnetization with M-s = 9.7 emu g(-1) to be reversibly collected by an external magnetic field, which shortened the detection time. The plasmonic property makes the engineered Fe3O4-Ag architectures particularly valuable for magnetically assisted ultra-sensitive SERS sensing. This was unambiguously established through the successful detection, in water, of traces, (down to 10(-10) M) of Rhodamine 6G (R6G), at room temperature.

Automated summary

This study reports the formation of silver nanopetal-Fe3O4 poly-nanocrystals assemblies and their application as active substrates for Surface Enhanced Raman Spectroscopy (SERS). The engineered Fe3O4-Ag architectures exhibit plasmonic properties that offer a rough surface with plenty of hot spots for enhancing electrical fields, making them valuable for ultra-sensitive SERS sensing with magnetically assisted collection. Successful detection of trace amounts of Rhodamine 6G (R6G) down to 10(-10) M in water at room temperature was achieved.