On-line sensitive detection of aromatic vapor through PDMS/C3H7S-assisted SERS amplification

Abstract

Much attention has been paid to surface enhanced Raman spectroscopy (SERS) in recent years due to its capability to detect trace amounts of chemical and biological analytes with single molecule sensitivity and its rapid response. Unfortunately, sensitive SERS detection is often limited to molecules that can strongly adsorb onto the surface of plasmonic substrates. The detection of molecules without specific adsorption groups still remains a great challenge, especially for vapor molecules in a flowing system. Herein, we present a novel PDMS/C₃H₇S-assisted SERS amplification process for on-line sensitive detection of aromatic vapors. Specifically, the SERS amplification process relies on a PDMS-coated 1-propanethiol-modified Au@Ag nanoparticle monolayer film (PDMS/C₃H₇S–Au@Ag MLF) as the SERS substrate, in which the PDMS and 1-propanethiol layers are capable of capturing vapor molecules from flowing air and placing them in close proximity in plasmonic hot spots. By taking advantage of the high adsorption capability of PDMS and strong plasmonic properties of the nanoparticle film, our PDMS/C₃H₇S-assisted SERS amplification can result in about two orders of magnitude enhancement of the SERS signal in comparison with that of the naked Au@Ag MLF. We also demonstrate that our developed plasmonic nanoparticles film could be applicable for on-line SERS detection of a series of aromatic vapors in the flowing system. These results provide exciting opportunities for in situ monitoring of volatile organic pollutants in the atmospheric environment.