Engineering Research Center of Nano-Geomaterials of Ministry of Education, China University of Geosciences, Wuhan 430074, China.
Laboratory of Advanced Mineral Materials, China University of Geosciences, Wuhan 430074, China.
Inorg Chem. 2023 May 29;62(21):8418-8427. doi: 10.1021/acs.inorgchem.3c01047. Epub 2023 May 17.
Local geometric configurations of metal cations in inorganic enzyme mimics determine their catalytic behaviors, while their optimization remains challenging. Herein, kaolinite, a naturally layered clay mineral, achieves the optimization of cationic geometric configuration in manganese ferrite. We demonstrate that the exfoliated kaolinite induces the formation of defective manganese ferrite and makes more iron cations fill into the octahedral sites, significantly enhancing the multiple enzyme-mimicking activities. The steady-state kinetic assay results show that the catalytic constant of composites toward 3,3',5,5'-tetramethylbenzidine (TMB) and HO are more than 7.4- and 5.7-fold higher than manganese ferrite, respectively. Furthermore, density functional theory (DFT) calculations reveal that the outstanding enzyme-mimicking activity of composites is attributed to the optimized iron cation geometry configuration, which has a higher affinity and activation ability toward HO and lowers the energy barrier of key intermediate formation. As a proof of concept, the novel structure with multiple enzyme-mimicking activities amplifies the colorimetric signal, realizing the ultrasensitive visual detection of disease marker acid phosphatase (ACP), with a detection limit of 0.25 mU/mL. Our findings provide a novel strategy for the rational design of enzyme mimics and an in-depth investigation of their enzyme-mimicking properties.
无机酶模拟物中金属阳离子的局部几何构型决定了其催化行为，但其优化仍然具有挑战性。本文中，高岭石作为一种天然层状粘土矿物，实现了锰铁氧体中阳离子几何构型的优化。我们证明了剥离的高岭石诱导了缺陷型锰铁氧体的形成，并使更多的铁阳离子填充到八面体位置，从而显著提高了多种酶模拟活性。稳态动力学分析结果表明，复合材料对 3,3',5,5'-四甲基联苯胺（TMB）和 HO 的催化常数分别比锰铁氧体高 7.4 倍和 5.7 倍。此外，密度泛函理论（DFT）计算表明，复合材料具有优异的酶模拟活性归因于优化的铁阳离子几何构型，其对 HO 具有更高的亲和力和激活能力，并降低了关键中间体形成的能垒。作为概念验证，具有多种酶模拟活性的新型结构放大了比色信号，实现了对疾病标志物酸性磷酸酶（ACP）的超灵敏可视化检测，检测限为 0.25 mU/mL。本研究为酶模拟物的合理设计提供了一种新策略，并深入研究了它们的酶模拟特性。
