Construction of a luminescent square-like Cd6Eu2 nanocluster for the quantitative detection of 2,6-dipicolinic acid as an anthrax biomarker

Abstract

Two Cd–Ln (Ln = Ho(III) and Eu(III)) complexes 1 and 2 were synthesized using two organic ligands. The square-like Cd₆Eu₂ nanocluster 2 exhibits a luminescence response to DPA through the enhancement of lanthanide emission, which can be observed directly with naked eyes. The response mechanism can be explained by the “antenna effect”, and described using a static enhancement process. The detection limit of 2 to DPA is 8.7 × 10⁻⁶ M, which is lower than the infectious dosage of anthrax spores (60 μM). The high sensitivity is not influenced by potential interferents. The test paper treated by 2 could be used to detect DPA. 2 was also used to determine DPA concentrations in tap-water and fetal calf serum (FCS). It shows potential application in the qualitative and quantitative luminescence detection of DPA.