Citrate/Tb Lanthanide Coordination Polymer Nanoparticles: Preparation and Sensing of Guanosine-5-Monophosphate

Abstract Metal-organic coordination polymers have emerged as attractive functional materials due to their tunable structures and unique properties. In this work, by the self-assembly of citrate (Cit) and lanthanide ions, we developed lanthanide coordination polymer nanoparticles (LCPNPs), Cit/Tb, for fluorescence sensing of guanosine-5-monophosphate (GMP). The LCPNP-based Cit/Tb sensor alone displayed weak luminescence, however, the addition of GMP to Cit/Tb led to the formation of a ternary LCPNP, Cit/Tb-GMP, with a significantly enhanced luminescence (15-fold) owing to the intramolecular energy transfer from GMP to Cit/Tb and the hydrophobic environment in the polymer interior. This luminescence turn-on assay exhibited excellent selectivity and high sensitivity for GMP with detection limit of 100 nmol·L-1. Furthermore, the Cit/Tb LCPNP possesses a long luminescence lifetime of up to a millisecond, which is important for detecting GMP in complicated samples of infant formula and ham by time-resolved fluorimetry. We believe that the presented Cit-based nanosensor would inspire the development of various new LCPNP-based fluorescent assays by utilizing Cit or other water-soluble, non-toxic organic ligands for a variety of applications in fluorescence sensing, bio-imaging, drug delivery and so on.