Short- and long-range sensing on gold nanostructures, deposited on glass, coated with silicon oxide films of different thicknesses

The paper reports on the possibility of short- and long-range plasmon sensing using transmission UV/vis spectroscopy. The influence of silicon oxide (SiOx) overlayers (0-310 nm), deposited on glass coated with gold nanostructures (formed by thermal evaporation and post-annealing at 500 degrees C) modified glass interfaces, on the localized surface plasmon resonance (LSPR) position and line shape was investigated. The rapid change in the LSPR spectrum for a thick overlayer suggests that it is possible to detect target molecules situated hundreds of nanometers away from the metal particle surface without loss of sensitivity. The hybridization of a covalently linked 15(mer) oligonucleotide strand on LSPR interfaces coated with 4, 35, and 151 nm thick SiOx was used to demonstrate the possibility of short- and long-range sensing. Comparable results were obtained in both cases.