Ratiometric fluorescent detection of biomakers for biological warfare agents with carbon dots chelated europium-based nanoscale coordination polymers

A ratiometric fluorescent nanosensor for biological warfare agent 2,6-pyridinedicarboxylic acid (DPA) detection is developed with carbon dots (CDs)@europium-based nanoscale coordination polymers (Eu-NCPs). The abundant hydroxyl and carboxyl groups of CDs are served as starting points for the spontaneous self-assembly of europium ion (Eu3+) and 5'-guanosine monophosphate disodium (GMP) on the surface of CDs to form CDs@Eu/GMP nanocomposites. The obtained nanosensor exhibits the characteristic emission of CDs and weak emission of Eu3+. The Eu/GMP NCPs are served as the DPA recognition sites. The fluorescence of CDs remains constant as a reference, while the fluorescence of Eu/GMP NCPs is enhanced upon binding with DPA, resulting in ratiometric fluorescent response toward DPA. This ratiometric nanosensor exhibits good selectivity toward DPA detection. The ratio of F-615/F-469 linearly increases with the increasing of DPA concentration in the range of 25 nM-5.0 mu M with a detection limit as low as 5.1 nM. Additionally, the nanosensor is successfully applied for the determination of DPA in the real serum samples. (C) 2015 Elsevier B.V. All rights reserved.