Peak Shift Measurement of Localized Surface Plasmon Resonance by a Portable Electronic System

In recent years, the characterization of surface molecular layers by localized surface plasmon resonance (LSPR) has attracted a lot of interest thanks to its ability to provide a higher spatial resolution with respect to standard SPR. LSPR can be observed as a peak in the extinction spectrum of metal nanoparticles such as gold non-connected surface patterns. A plasmon peak red shift is caused both by the presence of molecular layers on the gold surface and by molecular binding events. The current study presents a portable transmission system to observe the LSPR phenomenon that extracts the peak location employing a discrete number of light sources. The peak location extraction is performed by an algorithm that takes into account the spectral characteristics of all the components. The performance of our LSPR measurement system has been characterized on a set of Fluorinated Tin Oxide-coated slides covered with nanoislands with a diameter of approximately 30 nm. The samples have been modified with a single-stranded DNA layer and the plasmonic peak location has been determined before and after surface treatment. The samples have been characterized in parallel with a high-end spectrophotometer. The results presented demonstrated the performance of our measurement system in determining the peak location with 1 nm precision.