A new analytical experimental setup combining quartz crystal microbalance with surface enhancement Raman spectroscopy and its application in determination of thrombin

We reported quartz crystal microbalance (QCM) and surface enhancement Raman spectroscopy (SERS) combination to detect thrombin for the first time. 1,6-hexanedithiol (HDT) monolayer was assembled on the Au electrode of crystal ship and 20 nm Au NPs were assembled on this layer with stable Au-S linkage to form a two-dimensional nanoarray interface. Aptamers modified by thiol groups were assembled on this interface for capturing thrombin in succession. In the QCM detection process, the introduction of 40 nm aptamer-functionalized Au NPs amplify the frequency signal significantly. The thrombin detection limit reduced from 1 μM to 0.1 μM, and a good linear correlation was obtained between the change of frequency and the concentration of the thrombin in a range of 0.1 to 1.0 μM. Meanwhile, with the modification of Raman reporter 4-mercaptobenzoic acid onto the surface of 40 nm Au NPs, SERS signals of thrombin were obtained simultaneously. This assay also exhibited excellent selectivity both in QCM and SERS detection of thrombin.