Improving the SERS detection sensitivity of aromatic molecules by a PDMS-coated Au nanoparticle monolayer film

Abstract

Surface enhanced Raman spectroscopy (SERS) has been considered as a promising tool for detecting targets with single molecule sensitivity. However, the SERS detection on targets without a specific adsorption group has still remained a significant challenge. In this paper, we reported a facile strategy to fabricate a PDMS film-coated Au nanoparticle monolayer film (Au MLF) composite substrate for improving SERS detection of aromatic molecules in water and in the atmosphere. Toluene, benzene and nitrobenzene were used as the targets to evaluate the performance of the composite substrate. The results indicated that the PDMS film played the vital role to capture and preconcentrate these targets for improving the capability in SERS detection of these targets. The performance was critically dependent on the hydrophobicity, functional groups and the permeability of the targets. This composite substrate was more favorable for the detection of toluene and nitrobenzene than benzene. The limit of detection (LOD) for toluene and nitrobenzene was decreased by about two orders of magnitude on the PDMS-Au MLF compared to that on the naked Au MLF, and by one order of magnitude for benzene. It was estimated to be 0.5 ppm, 0.6 ppm and 78 ppm for toluene, nitrobenzene and benzene, respectively. The results demonstrated that this approach could be developed as a promising tool to detect numerous targets which were non-specifically adsorbed onto metallic nanostructures. It opened a window towards the general application of SERS for in situ monitoring of pollutants in water and in the atmosphere.