A highly selective and sensitive nanosensor for the detection of glyphosate

A turn-off fluorescence sensor synthesized by combining copper (II) oxide and multiwall carbon nanotubes (MWCNTs) were used for measuring glyphosate based on the inhibiting the catalytic activity of the CuO/MWCNTs. This sensor was synthesized by precipitating copper ions onto the acidic MWCNTs under basic conditions; the resulting material was characterized by the transmission electron microscopy, X-ray photoelectron spectroscopy, and Fourier transform infrared spectroscopy to confirm its structure. The CuO/MWCNTs nanomaterial was found to exhibit high peroxidase-like catalytic activity toward the reduction of H₂O₂ to H₂O and the oxidation of Amplex Red to resorufin, with a corresponding color change from pink to red and the fluorescence enhancement. However, this activity was inhibited and the fluorescence diminished when glyphosate was added to the system. Using this strategy, we applied this sensor to detect glyphosate. The results indicated that this sensor is not only highly sensitive, with a detection limit of 0.67 ppb and a linear range from 0.002 to 0.01ppm, but also exhibits good selectivity for glyphosate. When this sensor was assessed for detecting glyphosate in real water samples, recoveries of 96-107% were attained. This proposed material and method are a promising approach for rapid screening of glyphosate.