Zn-CD@Eu Ratiometric Fluorescent Probe for the Detection of Dipicolinic Acid, Uric Acid, and Ex Vivo Uric Acid Imaging.

Development of reliable methods for the detection of potential biomarkers is of the utmost importance for an early diagnosis of critical diseases and disorders. In this study, a novel lanthanide-functionalized carbon dot-based fluorescent probe Zn-CD@Eu is reported for the ratiometric detection of dipicolinic acid (DPA) and uric acid (UA). The Zn-CD@Eu nanoprobe was obtained from a simple room-temperature reaction of zinc-doped carbon dots (Zn-CD) and the EDTA-Eu lanthanide complex. Under optimal conditions, a good linear response was obtained for DPA in two concentration ranges of 0-55 and 55-100 μM with a limit of detection of 0.53 and 2.2 μM respectively, which is significantly below the infectious dosage of anthrax (∼55 μM). Furthermore, the Zn-CD@Eu/DPA system was employed for the detection of UA with a detection limit of 0.36 μM in the linear range of 0-100 μM. The fluorescent probe was successfully implemented for determining DPA and UA in human blood serum, sweat, and natural water bodies with considerable recovery rates. In addition, the potential of the nanoprobe for ex vivo visualization of UA was demonstrated in fruit fly (Drosophila melanogaster) as a model organism.