a b s t r a c tA rapid, facile fluorescence sensing strategy was developed for dopamine (DA) detection based on polydopamine (pDA) formed on the surface of graphene quantum dots (GQDs). The prepared GQDs were strongly luminescent because of the aromatic planar structure. DA could self-polymerize to pDA and snap to the surface of GQDs to form a thin film in alkaline environment, leading to quenching of fluorescence due to fluorescence resonance energy transfer (FRET). With the optimized conditions, the analytical performance illustrated high sensitivity, selectivity in a wide linear range with a detection limit of 8 nM. In addition, the unique method was successfully applied for DA injection test with satisfactory labeled amount. Finally, the proposed strategy was applied for DA detection in serum, wherein accurate results were obtained.

This work reports a facile and effective approach for preparing graphene quantum dots co-doped with nitrogen and sulfur (N-S/GQDs). The proposed method comprised pyrolysis of citric acid with glutathione and dialysis treatment. The fabricated N-S/GQDs exhibited blue luminescence and a high fluorescence quantum yield of 36.3%. N-S/GQDs can be sensitively quenched by Fe 3+ , which was absorbed on the edge of N-S/GQDs through the coordination interaction between Fe 3+ and N, S elements. The subsequent introduction of pyrophosphate ion (PPi) resulted in the recovery of the fluorescence of Fe 3+-quenched N-S/GQDs. The stronger coordination reactivity between Fe 3+ and PPi induced changes in fluorescence. PPi concentration was facilely quantified through the recovered amplitudes of the fluorescence intensities of N-S/GQDs. Under the optimized experimental condition, increased fluorescence intensity showed a linear relationship to PPi concentration (1 μM to 1000μM) in serum samples. Additionally, the proposed method featured sensitive and selectivity for the detection of PPi in synovial fluid, suggesting the potential application for simple and accurate clinical diagnosis of arthritic diseases.

Facile, one-step strategy for selective GSH sensing in serum and in drug quality control using GQDs–MnO2 composite.

No abstract

In this present work, graphene quantum dots (GQDs) were handily prepared with citric acid by the pyrolysis method and used to fabricate an electrochemical sensor for the simultaneous determination of acetaminophen (AC) and ascorbic acid (AA) in compound preparation.