Terbium-Doped Graphene Quantum Dots: A Highly Efficient and Selective Fluorescent Nanoprobe for Vanillin Detection

Abstract Vanillin, an extensively used flavoring compound in our daily life, may lead to health problems when overused, adulterated, or poorly controlled in commercial settings, necessitating the development of sensitive and rapid detection techniques. In this work, terbium-doped graphene quantum dots (Tb-GQD) were synthesized using carbonization and chemical conjugation methods for developing an efficient fluorescent probe for vanillin detection. The structural and optical characteristics of Tb-GQD confirm that terbium is doped in GQDs, without disturbing the sp2 graphitic core of GQD, and efficient energy transfer from GQD to Tb3+ was observed from the photoluminescence emission studies. Upon addition of vanillin to Tb-GQD, a decrease in fluorescence emission intensity and a change in lifetime were observed, suggesting a dynamic, photoinduced electron transfer mechanism. The Tb-GQD shows a linear detection range of 0.2–85 μM with a detection limit of 13.2 nM. The synthesized fluorescent probe shows excellent selectivity, and was implemented in real-sample analysis with a good recovery range of 96.4–100.06% and an RSD below 3.6%. These findings show that Tb-GQD will serve as an efficient platform for detecting vanillin.