Multi-praseodymium-and-tungsten bridging octameric tellurotungstate and its 2D honeycomb composite film for detecting estrogen

Abstract

Under coordination driving force of tungsten and rare-earth (RE) bridges, we synthesized a novel giant multi-tungsten-and-RE-bridging octameric tellurotungstate (TT) [H₂N(CH₃)₂]₁₆K₈Na₆H₁₀[Pr₈(H₂O)₂₀W₁₆O₄₈][B-α-TeW₉O₃₃]₈·70H₂O (1) in CH₃CN–H₂O mixed solvent. The cluster anion {[Pr₈(H₂O)₂₀W₁₆O₄₈][B-α-TeW₉O₃₃]₈}⁴⁰⁻ features sixteen W^VI bridges, eight Pr^III bridges and eight trivacant Keggin [B-α-TeW₉O₃₃]⁸⁻ fragments, which the square {W₄O₁₂} cluster can be imagined as a seed to induce the aggregation of eight [B-α-TeW₉O₃₃]⁸⁻ fragments by coordination driving force of additional twelve W^VI bridges and eight Pr^III ions. Furthermore, the 2D 1@DODA (dimethyldioctadecyl ammonium bromide = DODA·Br) honeycomb composite material was prepared. The honeycomb morphology of the 1@DODA composite material provides rich binding sites for electrodepositing Au nanoparticles to make Au/1@DODA electrodes. The aptamer of 17β-estradiol (E2) hormone can be grafted to the Au/1@DODA electrodes via Au–S bonding interaction to construct the Au/1@DODA aptamer biosensors. By virtue of the specific recognition interaction of aptamer and the electrochemical signal amplification function of methylene blue and cDNA, the Au/1@DODA aptamer biosensors can realize the electrochemical detection of E2. This finding not only offers an electrochemical biosensing platform for detecting E2, but also expands POM-based composite materials in the applications of clinical detection and biological analysis.