Streptavidin and gold nanoparticles-based dual signal amplification for sensitive magnetoelastic sensing of mercury using a specific aptamer probe

Abstract A novel wireless magnetoelastic sensor (WMS) strategy for Hg 2+ assay was proposed using a specific aptamer probe and graphene oxide (GO) as an adsorbent. The introduction of Hg 2+ results in the release of CDNA-biotin. This one can be adsorbed to the surface of GO that was immobilized on the WMS along with a decrease of the resonance frequency of the sensor. A biotin-streptavidin (SA)-gold nanoparticles (AuNPs) system designed in this work was used for amplifying response signal of the sensor. The signal intensity linearly correlated with Hg 2+ concentration ranging from 2.80 to 88.9 nM with a detection limit of 0.885 nM. This WMS has additional advantages of being less time-consuming, low cost and remote query, and can be employed for the real-time and in situ detection of Hg 2+ in real samples. The mechanism for structure switching and signal amplification was also studied by transmission electron microscopy and UV–vis spectra.