The strategy of two-scale interface enrichment for constructing ultrasensitive SERS substrates based on the coffee ring effect of AgNP@β-CD

Abstract

Herein we introduced a Raman technique based on the two-scale interface enrichment for the detection of aromatic compounds. Silver nanoparticles were fabricated, β-cyclodextrins (β-CD) were physically absorbed on the surface of the silver nanoparticles as capturing layers of aromatic compounds for enriching the analytes on the interface of the silver nanoparticles in solution. After the analyte was captured, a mixture of silver nanoparticles and aromatic compounds were dropped on silicon wafer to form the coffee ring, which comprises densely packed silver nanoparticles loaded with analytes on the interface of the silicon wafer. In light of this, analytes were able to enrich twice in one process. Furthermore, densely-packed substrate produced a large number of “hot-spots” to improve the SERS effect. The combination of pre-concentration of β-CD and the SERS effect of the coffee-ring enhanced the detection ability of SERS to aromatic compounds. Due to the special structure of β-CD, this strategy can also be utilized in the SERS detection of other analytes.