Oxidized multiwalled carbon nanotubes decorated with silver nanoparticles for fluorometric detection of dimethoate

- The nanomaterial (AgNPs/OxMWCNTs) was synthesized and found to have peroxidase-like activity.
- AgNPs/OxMWCNTs based on fluorometric assay for dimethoate was developed.
- This sensor can detect dimethoate without any enzyme.
- This sensor can be applied to the determination of dimethoate in real samples.

A novel method for the detection of dimethoate based on the peroxidase-like activity of silver-nanoparticles-modified oxidized multiwalled carbon nanotubes (AgNPs/oxMWCNTs) has been developed. The synthesized AgNPs/oxMWCNTs showed excellent peroxidease-like catalytic activity in hydrogen peroxide-Amplex red (AR) system (AR is oxidized to resorufinat, with the resorufin fluorescence at 584 nm being used to monitor the catalytic activity). After dimethoate was added to AgNPs/oxMWCNTs, the interaction between dimethoate and the AgNPs inhibited the catalytic activity of AgNPs/oxMWCNTs. The decrease in fluorescence was used for the detection of dimethoate in the range of 0.01-0.35 μg mL−1 (R2 = 0.998) with a detection limit of 0.003 μg mL−1 (signal/noise = 3). This method exhibited good selectivity for the detection of dimethoate even in the presence of high concentration of other pesticides. Consequently, the method was applied to measure the concentration of dimethoate residue in lake water and fruit, thus obtaining satisfactory results.