A graphene quantum dots based fluorescent sensor for anthrax biomarker detection and its size dependence

다국어 초록 (Multilingual Abstract)

<P>Graphene quantum dots (GQDs) with two different diameters were modified with a Eu<SUP>III</SUP>-macromolecule complex and applied in dual emission fluorescent sensors for detection of <I>Bacillus anthracis</I> spores. The Eu-GQD sensors exhibited a morphology of ultrafine particles, increased surface-to-volume ratio, enhanced dispersibility, and extraordinary sensitivity. The 3 nm Eu-GQDs showed three emission bands, which are ascribed to the emission from the blue GQDs (435 nm) and the red [(Eu)-(DPA)] complex (593 nm and 616 nm). Accordingly, incorporation of the GQDs as a non-interfering internal calibration makes it possible for use as a ratiometric sensor. The time dependent fluorescence response study revealed that the reaction was complete within 8 s, thus enabling rapid detection of <I>B. anthracis</I> spores. It is noteworthy that the Eu-GQD sensors exhibited an extraordinary limit of detection (LOD) of <I>ca.</I> 10 pM towards <I>B. anthracis</I>, which is six orders of magnitude smaller than the infectious dose of the spores (60 μM). Furthermore, the selectivity study indicates that Eu-GQD sensors have an outstanding selectivity of 103-fold for DPA over competing aromatic ligands.</P>