Biosynthesis of Green-Emissive Copper Nanoclusters from Plectranthus scutellarioides Extract for the Detection of Terbufos in Carrot and Water Samples

Abstract

The development of superior sensors that can detect terbufos insecticide in the fields of agriculture and human health is of utmost importance. Herein, green emissive copper nanoclusters (Cu NCs) were fabricated using the extract of Plectranthus scutellarioides (P. scutellarioides) leaves as biological ligands. The synthesized Plectranthus scutellarioides-Cu NCs (P. scutellarioides-Cu NCs) possess green fluorescence (FL) under UV-light and depict excitation-dependent emission behavior at 450 nm showing maximum emission intensity at 510 nm. The dispersive nature and size of the P. scutellarioides-Cu NCs were calculated to be 2.1 ± 0.6 nm using high-resolution transmission electron microscopy (HR-TEM). The as-synthesized P. scutellarioides-Cu NCs are waterdispersive and show good stability. The introduction of terbufos quenched the FL intensity of P. scutellarioides-Cu NCs via a static quenching mechanism. With terbufos concentrations ranging from 0.1 to 4.0 μM, the ratio of I 0 /I of P. scutellarioides-Cu NCs showed a clear linear relationship with a corresponding low detection limit (LOD) of 0.029 μM. The as-synthesized detection methodology was successfully used to analyze terbufos in vegetable (carrot) and water samples with good recovery and relative standard deviation (RSD) values of less than 2. The real-time study was also performed using a paper-strip-based detection method.