Fabricating a novel label-free aptasensor for acetamiprid by fluorescence resonance energy transfer between NH2-NaYF4: Yb, Ho@SiO2 and Au nanoparticles.

Rare earth-doped upconversion nanoparticles have promising potential in the field of pesticide detection because of their unique frequency upconverting capability and high detection sensitivity. This paper reports a novel aptamer-based nanosensor for acetamiprid detection using fluorescence resonance energy transfer (FRET) between NH2-NaYF4: Yb, Ho@SiO2 (UCNPs) and gold nanoparticles (GNPs). Herein, GNPs as acceptors efficiently quench the fluorescence of UCNPs and acetamiprid specifically interacts with acetamiprid binding aptamer (ABA), causing the conformation changes of ABA from random coil to hairpin structure. Accordingly, ABA no longer stabilizes the GNPs in salt solution, leading to the varying aggregation extent of GNPs. Thus, the fluorescence of UCNPs are proportionally recovered. Under the optimized conditions, the enhancement efficiency was observed to increase linearly with the concentration of acetamiprid from 50 nM to 1000 nM, resulting in a relatively low limit of 3.2 nM. Additionally, the aptasensor demonstrated high selectivity to similar structure pesticides such as imidacloprid and chlorpyrifos, and further confirmed its application capacity in adulterated tea samples.