2,5-Thiophenedicarboxylic Acid Bridging Hexameric Ce^III-Substituted Selenotungstate and Its Application for Detecting...

The development of polyoxometalate chemistry not only is derived from the continuous discovery of novel polyoxometalates (POMs) but also stems from the exploitation of their new functionalities. In this work, we obtained a rigid sulfur-containing heterocyclic ligand-linking aggregate [N(CH₃)₄]₁₀Na₆H₆[Ce₈(H₂O)₂₆W₈(HTDA)₂(TDA)₂O₂₀][SeW₄O₁₈]₂[SeW₉O₃₃]₄·112H₂O (1) (H₂TDA = 2,5-thiophenedicarboxylic acid). Its polyanionic unit consists of one [Ce₄(H₂O)₁₃W₄O₁₀(HTDA)(TDA)O₁₀]¹⁸⁺ cluster and two kinds of Keggin-type [SeW₄O₁₈] and [SeW₉O₃₃] segments. It is noteworthy that H₂TDA ligands not only work as connectors to link two symmetrical {[Ce₄(H₂O)₁₃W₄(HTDA)(TDA)O₁₀][SeW₄O₁₈][SeW₉O₃₃]₂}^11- units but also function as ornaments to graft to the polyanionic backbone. Furthermore, 1 and 3,4-ethylenedioxythiophene (EDOT) were deposited on the glassy carbon electrode (GCE) by the electropolymerization (EPM) method, resulting in a 1-poly(3,4-ethylenedioxythiophene) (1-PEDOT) composite film, which can provide sufficient binding sites to immobilize Au nanoparticles (Au NPs). Hereafter, the Au NPs-immobilized 1-PEDOT modified electrode (Au/1-PEDOT/GCE) was used to construct an electrochemical aptasensor to detect mucin 1, showing a low detection limit of 29.5 fM in the Tris solution. This work not only demonstrates that rigid heterocyclic ligands are beneficial for the creation of novel rare-earth-substituted selenotungstate hybrids but also provides more enlightenment for POM-based materials used for electrochemical detection of cancer markers.