A ratiometric fluorescent aptasensor for detection of ACE pesticide through toehold-mediated strand displacement and...

Detection of pesticide residues is important due to their significant environmental side effects and public health concern. Herein, a facile and sensitive approach was developed based on dual emission ratiometric fluorescence signal for detection of acetamiprid (ACE) pesticide. The sensing platform was based on MWCNTs/ AuNPs nanocomposite to generate the output signals. The fluorescent FAM-functionalized aptamer with stem-loop structure was deposited on platform which resulted to fluorescence quenching during FRET process via extinction of MWCNTs/ AuNPs. Upon addition of ACE, aptamer structure was unfolded and specific sequence as the toehold was hybridized with another complementary Cy5 labeled probe. Following, FAM segment was displaced and its fluorescence signal was recovered while the fluorescence emission of Cy5 was quenched by FRET process in proximity of nanocomposite. The biosensor showed efficient detection performance in the linear range between 4 and 40 pM and the LOD was calculated at 2.8 pM. Selectivity of present strategy was confirmed among different applied targets and the real sample assay showed efficient performance in bell pepper samples. Thus, this strategy indicated sensitive and efficient performance for detection of ACE in agricultural product and food stuffs.