A wireless and sensitive detection of octachlorostyrene using modified AuNPs as signal-amplifying tags

• It is the first time to use the magnetoelastic sensor immunoassay method to test octachlorostyrene.
• AuNPs here was used to amplify responses, increasing the sensitivity.
• The limit of detection (LOD) of this proposal is 1.6 nM and the linear range is from 7.4 μM to 9 nM.

A wireless, remote query octachlorostyrene (OCS) biosensor was fabricated by coating a mass-sensitive magnetoelastic ribbon with anti-OCS antibody. In response to a time-varying magnetic field, the magnetoelastic sensor mechanically vibrates at a characteristic resonance frequency which inversely depends on the sensor mass loading. As the magnetoelastic film is magnetostrictive itself, the vibrations launch magnetic flux that can be remotely detected using a pickup coil. Au nanoparticles (NPs) were used to amplify the mass loading. In a sample solution containing OCS target and OCS-modified AuNPs (OCS–AuNPs), both OCS and OCS–AuNPs react with the anti-OCS antibody immobilized on the sensor surface in a competition mode. The bound OCS–AuNPs amount is inversely proportional to the OCS target concentration. The reduction of bound OCS–AuNPs induced by free OCS results in significant change in mass loading, which amplifies the responses. The biosensor demonstrates a linear shift in resonance frequency with OCS concentration between 7.4 μM and 9 nM, with a detection limit of 2.8 nM.