β-CD Dimer-immobilized Ag Assembly Embedded Silica Nanoparticles for Sensitive Detection of Polycyclic Aromatic Hydrocarbons

We designed a beta-CD dimer on silver nanoparticles embedded with silica nanoparticles (Ag@SiO2 NPs) structure to detect polycyclic aromatic hydrocarbons (PAHs). Silica NPs were utilized as a template for embedding silver NPs to create hot spot structures and enhance the surface-enhanced Raman scattering (SERS) signal, and a thioether-bridged dimeric beta-CD was immobilized on Ag NPs to capture PAHs. The assembled Ag NPs on silica NPs were confirmed by TEM and the presence of beta-CD dimer on Ag@SiO2 was confirmed by UV-vis and attenuated total reflection-Fourier transform infrared spectroscopy. The beta-CD dimer@Ag@SiO2 NPs were used as SERS substrate for detecting perylene, a PAH, directly and in a wide linearity range of 10(-7) M to 10(-2) M with a low detection limit of 10(-8) M. Also, the beta-CD dimer@Ag@SiO2 NPs exhibited 1000-fold greater sensitivity than Ag@SiO2 NPs in terms of their perylene detection limit. Furthermore, we demonstrated the possibility of detecting various PAH compounds using the beta-CD dimer@Ag@SiO2 NPs as a multiplex detection tool. Various PAH compounds with the NPs exhibited their distinct SERS bands by the ratio of each PAHs. This approach of utilizing the assembled structure and the ligands to recognize target has potential for use in sensitive analytical sensors.