Purification implications on SERS activity of silica coated gold nanospheres.

Silica coated gold nanospheres are purified using traditional centrifugation steps and/or anion exchange chromatography and their resulting surface-enhanced Raman activities compared. Partially silica-coated gold nanostructures are retained on the column while fully coated nanostructures elute. As a result, SERS activity becomes less erratic and follows distance dependence models. This simple chromatographic step adds a quality control measure to nanoparticle preparation which could be extended to other solution-phase nanoparticles for more predictable function in future applications.