Nanoscopic Properties and Application of Mix-and-Match Plasmonic Surfaces for Microscopic SERS

Gold and silver nanoparticles can be immobilized on glass slides using aminosilane linkers. Here, we demonstrate that particle monolayer surfaces can also be generated by simultaneous immobilization of both gold and silver nanoparticles with the same organosilane linker. These new surfaces display surface-enhanced Raman scattering (SERS) enhancement typical for gold or silver monolayers, depending on the ratio of the two types of nanoparticles and, at the same time, have the capability to probe complex analytes composed from various molecules which adsorb at only one of the metals. The reported results from scanning electron microscopy, scanning force microscopy, and UV/vis absorbance for surfaces containing one or two types of nanoparticles indicate that an enhancement level above 10(4) is related to nanoaggregates that form in the 2D plane. High and stable enhancement factors over a wide range of analyte concentrations along with high homogeneity of the enhancement at the microscopic scale make the plasmonic nanoparticle mix-and-match surfaces ideal substrates for use in microscopic SEAS sensing.