Ultra-sensitive detection of ATP in serum and lysates based on nitrogen-doped carbon dots.

In this work, novel types of nitrogen-doped carbon dots (N-CDs) were prepared from citric acid and glycine (GLY) as precursors through a simple pyrolysis method. The GLY-CDs showed strong fluorescence with a fluorescence quantum yield as high as 33.34% and good water solubility. The fluorescence of GLY-CDs could be selectively quenched by iron(III) ion (Fe3+ ) resulting in the non-fluorescent complex. Due to the high affinity of Fe3+ to adenosine-5'-triphosphate (ATP), the fluorescence of the GLY-CDs in GLY-CDs-Fe3+ could be recovered by ATP. Thereby, quantitatively fluorescent turn-on detection of ATP could be achieved. The fluorescence recovery ratio was linearly proportional to the concentration of ATP with a detection limit as low as 15.0 nM, indicating the CDs have high sensitivity. The GLY-CDs were successfully employed in the detection of ATP in serum and cell lysates.

A glycine-functionalized graphene quantum dots synthesized by a facile post-modification strategy for a sensitive and selective fluorescence sensor of mercury ions.

In this work, we have developed a facile method for the synthesis of glycine-functionalized graphene quantum dots (Gly-GQDs) through post-modification of graphene quantum dots with Gly under alkaline conditions. The as-synthesized Gly-GQDs exhibit an excellent blue emission at 444 nm, independent of excitation, as well as a high quantum yield (QY) of 35.7%. The Gly-GQDs have a narrow size distribution with an average size of 5.9 nm. Moreover, the as-prepared Gly-GQDs showed a better selective and sensitive recognition capability towards mercury ion (Hg2+) in aqueous solutions with a low detection limit of 8.3 nM, compared with GQDs and other nitrogen-doped GQDs synthesized through the one-step solvent thermal method. Gly-GQDs are successfully applied for the determination of Hg2+ in real water samples. This work shows a new promising approach for the design and synthesis of desirable GQDs with a given function.

Novel two-tiered approach of ecological risk assessment for pesticide mixtures based on joint effects.

Ecological risk assessments for mixtures have attracted considerable attention. In this study, 38 pesticides in the real environment were taken as objects and their toxicities to different organisms from three trophic levels were employed to assess the ecological risk of the mixture. The first tier assessment was based on the CA effect and the obtained sum of risk quotients (SRQspecies-CA) were 3.06-9.22. The second tier assessment was based on non-CA effects and the calculated SRQspecies-TU are 5.37-9.29 using joint effects (TUsum) as modified coefficients, which is higher than SRQspecies-CA and indicates that ignoring joint effects might run the risk of underestimating the actual impact of pesticide mixtures. Due to the influences of synergistic and antagonistic effects, risk contribution of components to mixture risks based on non-CA effects are different from those based on the CA effect. Moreover, it was found that the top 8 dominating components explained 95.5%-99.8% of mixture risks in this study. The dominating components are similar in the two tiers for a given species. Accordingly, a novel two-tiered approach was proposed to assess the ecological risks of mixtures based on joint effects. This study provides new insights for ecological risk assessments with the consideration of joint effects of components in the pesticide mixtures.