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

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.