A Mixed-Crystal Lanthanide Zeolite-like Metal–Organic Framework as a Fluorescent Indicator for Lysophosphatidic Acid, a Cancer Biomarker

Two lanthanide zeolite-like metal–organic frameworks (Ln-ZMOFs) with rho topology, Tb-ZMOF and Eu-ZMOF, were constructed by self-assembly of a 4-connected lanthanide molecular building block and a bipyridine-dicarboxylate ligand. Varying the Tb3+ and Eu3+ ratio during synthesis afforded three mixed-crystal isostructural MZ­MOFs with variable Eu:Tb stoichiometry. Fluorescence studies revealed that a methanol suspension of one of these mixed crystals, MZ­MOF-3, exhibits selective detection of lyso­phospha­tidic acid (LPA), a biomarker for ovarian cancer and other gynecologic cancers. Linear correlation between the integrated fluor­escence intensity and the concentration of LPA was observed, enabling quantitative analysis of LPA in physiologically relevant ranges (1.4–43.3 μM). MZ­MOF-3 therefore has the potential to act as a self-referencing and self-calibrating fluor­escent indicator for LPA.