SERS-Based Flavonoid Detection Using Ethylenediamine-ß-Cyclodextrin as a Capturing Ligand.

ABSTRACT

Ethylenediamine-modified ß-cyclodextrin (Et-ß-CD) was immobilized on aggregated silver nanoparticle (NP)-embedded silica NPs (SiO2@Ag@Et-ß-CD NPs) for the effective detection of flavonoids. Silica NPs were used as the template for embedding silver NPs to create hot spots and enhance surface-enhanced Raman scattering (SERS) signals. Et-ß-CD was immobilized on Ag NPs to capture flavonoids via host-guest inclusion complex formation, as indicated by enhanced ultraviolet absorption spectra. The resulting SiO2@Ag@Et-ß-CD NPs were used as the SERS substrate for detecting flavonoids, such as hesperetin, naringenin, quercetin, and luteolin. In particular, luteolin was detected more strongly in the linear range 10-7 to 10-3 M than various organic molecules, namely ethylene glycol, ß-estradiol, isopropyl alcohol, naphthalene, and toluene. In addition, the SERS signal for luteolin captured by the SiO2@Ag@Et-ß-CD NPs remained even after repeated washing. These results indicated that the SiO2@Ag@Et-ß-CD NPs can be used as a rapid, sensitive, and selective sensor for flavonoids.