Anticancer Drug Extraction from Plasma Samples Using Three-Dimensional Polyoxometalate-Based Supramolecular Frameworks as Sorbents

Four self-assembled inorganic–organic hybrid materials, namely, H{Na(H₂O)₃[Gd(PDA)(H₂O)₂]₃[BW₁₂O₄₀]}·4H₂O (1), H{Na(H₂O)₃[Tb(PDA)(H₂O)₂]₃[BW₁₂O₄₀]}·3H₂O (2), H{Na(H₂O)₃[Er(PDA)(H₂O)₃]₃[BW₁₂O₄₀]}·H₂O (3) (PDA = 1,10-phenanthroline-2,9-dicarboxylate), and [Pr₃(H₂O)₁₃(pydc–OH)₂][BW₁₂O₄₀]·12H₂O (4) (pydc–OH = 4-hydroxy-2,6-pyridinedicarboxylate), were hydrothermally synthesized and structurally characterized. Hybrids 1–3 are isostructural and contain a Keggin unit, which is linked to lanthanoids to produce distinct trinuclear lanthanoid building blocks. The fragments are connected by anion−π and hydrogen bonding interactions to create 3D networks. In hybrid 4, a trimeric Pr-organic species bearing a Keggin unit forms a 2D coordination polymer, and then hydrogen bonding interactions between 2D layers lead to the formation of a 3D structure. These polyoxometalate-based frameworks were used as sorbents for the dispersive microsolid-phase extraction (D-μSPE) of two anticancer drugs (doxorubicin and epirubicin) in human plasma samples. Analytes were quantified and separated using high-performance liquid chromatography with fluorescence detection (HPLC-FLD). The method’s linearity was between 0.8–500 ng mL^–1 and 1.0–500 ng mL^–1 for the antineoplastic drugs doxorubicin and epirubicin, respectively. The limits of detection (S/N = 3) were in the range of 0.2–0.3 ng mL^–1, while the precision was in the range of 3.5–4.3%. Finally, human plasma samples from patients treated with doxorubicin or epirubicin were analyzed by using the D-μSPE-HPLC-FLD method.