Eu-ion doped strontium molybdate perovskite quantum dots as a turn-off-on fluorescent sensor for simultaneous detection of hypoxanthine biomarker and Fe ions.

A fluorescence "turn-off-on" nanoprobe is designed by using europium-doped strontium molybdate perovskite quantum dots (Eu:SMO PQDs) for the sequential detection of hypoxanthine (Hx) and Fe. The Eu:SMO PQDs were prepared by the sol-gel method using Sr(NO), (NH)MoO.4HO, and Eu(OCOCH) as precursors. The green fluorescence of Eu:SMO PQDs was efficiently reduced (turn-off) in the presence of Hx, then it was restored (turn-on) gradually by introducing Fe due to the competitive formation of Hx@Fe, which results to the release of Eu:SMO PQDs. In addition, the fluorescent probe exhibits excellent selectivity and sensitivity. Under the optimized experimental conditions, linear ranges and detection limits were 0.25-25 μM and 12.30 nM for Hx and 0.025-50 μM and 10.44 nM for Fe , respectively. Furthermore, the fluorescence method was successfully explored to detect Hx and Fe in plasma and urine samples.