A wireless and sensitive sensing detection of polycyclic aromatic hydrocarbons using humic acid-coated magnetic Fe3O4 nanoparticles as signal-amplifying tags

A wireless magnetoelastic-sensing device for the detection of polycyclic aromatic hydrocarbons (PAHs) with anthracene as the model target is reported using humic acid-modified magnetic Fe3O4 nanoparticles (HMNPs) as signal-amplifying tags. A sandwich-type detection strategy involves the humic acid (HA)/chitosan composite self-assembled on the polyurethane-protected sensor surface and HMNPs, both of which flank the anthracene target in sequence. As the HMNPs-combined anthracene absorbs to the sensor surface, there is an increase in the mass load on the sensor, and consequently a decrease in resonance frequency. Under optimal conditions, the sensor shows a linear response to polycyclic aromatic hydrocarbons with sensitivity depending on the benzene rings. The sensor shows the largest sensitivity to benzo[a]pyrene due to its 5 ring with a detection limit of 3 nM. Tap water, river water and spring water were analyzed with this sensor.