A magnetic separation-assisted signal-off fluorescence aptasensor for trace profenofos detection

A novel magnetic separation-assisted, target-induced dissociation signal-off fluorescence aptasensor is developed for the trace detection of profenofos (PFF). The sensing platform integrates a magnetic capture probe (cDNA-Fe₃O₄@PDA) and a highly luminescent signal probe (Apt-Rh6G@ZIF-8). In the absence of PFF, the two probes hybridize to form a stable, highly fluorescence complex. Upon PFF addition, specific aptamer-target binding triggers the dissociation of the signal probe. Following magnetic separation, the fluorescence intensity of the remaining complex decreases proportionally to the PFF concentration. Under optimal conditions, the aptasensor exhibits a wide linear range from 0.05 to 10 ng mL^- 1 and a remarkably low limit of detection of 0.026 ng mL^- 1. Furthermore, the sensor demonstrates favorable selectivity, anti-interference capability, and stability. Successful application in real agricultural samples yielded satisfactory recoveries of 98%-113%, indicating its practical feasibility.