Published on September 2009 | SERS, Nanotechnology

Preparation of a SERS substrate and its sample-loading method for point-of-use application

A simple approach was demonstrated to prepare a silver (Ag) nanoparticle (NP) assembly as a SERS substrate. Just by dipping a flat silicon (Si) wafer into an aqueous deposition solution of hydrogen fluoride (HF) + silver nitrate (AgNO3), a monolayer of Ag NPs was uniformly deposited onto the Si wafer surface. In order to load the to-be-detected sample onto the as-prepared SERS substrate, three methods have been individually tested, (i) by incubating the SERS substrate in the sample solution, (ii) by dropping and drying a small volume of the sample solution (1–2 µl) onto the SERS substrate surface, or (iii) by directly introducing the sample into the deposition solution. The last approach was also employed to metalize a Si nanowire (NW). Due to the NW's highly curved surface, the Ag NPs self-assembled and aggregated along the NW with a close interdistance. The aggregated Ag NPs on the NW surface can also be used as a SERS substrate. The demonstrated approach holds the promise to prepare a fresh SERS substrate at the point-of-use with the sample already loaded to promptly collect the SERS signal for the field application.