Reduced graphene oxide nanosheets and gold nanoparticles covalently linked to ferrocene-terminated dendrimer to construct electrochemical sensor with dual signal amplification strategy for ultra-sensitive detection of pesticide in vegetable

We report herein a novel electrochemical signal amplification strategy for ultra-sensitive detection of pesticide by covalently linking nanoparticles (AuNPs) and reduced graphene oxide (rGO) nanosheets to ferrocene units of ply (amine) ester based ferrocene dendrimer(FcDr). The FcDr dendrimers with the native redox signaling center (Fe3+/Fe2+) provide a large number of active terminal carboxyl groups as well as a compact matrix for the covalent linking of rGO nanosheets and AuNPs. AuNPs has superior electrical conductivity and catalytic activity, while rGO nanosheets have a larger surface area that allow more deposition of AuNPs. In this way, AuNPs and rGO nanosheets can synergistically accelerate the electron transfer from FcDr to glassy carbon electrode (GCE), which will amplify the electrochemical signal of AuNPs/FcDr/rGO/GCE sensor and then improve the sensing performance. The fabricated electrode demonstrates an admirable electrochemical sensing performance towards dichlorvos in terms of low detection limit (0.21 mu M), wide concentration range (0.43-218.4 mu M) and rapid response time (1.8 s). The practical applicability of the sensor was successfully evaluated in real vegetable sample and achieved satisfactory accuracy. This designed approach provides a facile, efficient strategy for timely detection of dichlorvos.