Multinuclear Ce III –P III –W VI Cluster-Incorporated Phospho(III)tungstate Utilized in a Chip-Based Sensor for the Selective Detection of MicroRNA-21

Developing innovative chip-based sensors with high sensitivity for the recognition and detection of breast cancer biomarkers is of critical importance in reducing mortality rates and improving cure rates. In this research, a high-nuclear CeIII-PIII-WVI cluster-incorporated phospho(III)tungstate [H₂N(CH₃)₂]₂₂Na₈[Ce₂₄W₁₂(H₂O)₄₂(H₂ma)₆(HPO₃)₁₈O₃₀][(HP)₂W₁₄O₅₂]₆·200H₂O (1, H₃ma = malic acid) was synthesized, in which the polyanion of 1 can be conceptualized as the assembly of a CeIII-PIII-WVI [Ce₂₄W₁₂(H₂O)₄₂(HPO₃)₁₈O₃₀]⁴⁸⁺ cluster, six high-vacant Dawson-like [(HP)₂W₁₄O₅₂]¹²⁻ fragments, and malic acid ligands. Furthermore, thickness-controllable multilayered 1-PDDA films were fabricated on chips as sensing interfaces based on polydiallyldimethylammonium chloride (PDDA) and 1. The current response of the 1-PDDA chip can be modulated by the concentration of 1, which exhibits good conductivity. Accordingly, a p-DNA/1-PDDA chip-based sensor was developed, which demonstrates high sensitivity for the identification of microRNA-21 with a broad detection range (1 × 10⁻¹⁷ M - 1 × 10⁻⁹ M), a low limit of detection (1.19 × 10⁻¹⁸ M), and sensitivity. This work offers valuable insights into the synthesis of high-nuclearity poly(polyoxometalate) materials and further expands the potential applications of polyoxometalate-based materials by integrating them into chip-based sensor platforms through layer-by-layer assembly.