CeO2 中 pH 驱动的仿生行为的生物催化机制的密度泛函理论研究,ACS Applied Materials & Interfaces

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CeO2 中 pH 驱动的仿生行为的生物催化机制的密度泛函理论研究
ACS Applied Materials & Interfaces ( IF 8.3 ) Pub Date : 2022-03-01 , DOI: 10.1021/acsami.1c24686
Hongyang Ma ₁ , Zhao Liu ₂ , Pramod Koshy ₁ , Charles C Sorrell ₁ , Judy N Hart ₁

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氧化铈 (CeO ₂ ) 纳米粒子在生物医学中的 pH 依赖性、可切换、生物催化特性引起了相当大的兴趣，其中这些材料在碱性生理 pH 值下表现出对活性氧 (ROS) 的有益抗氧化活性，但在生理 pH 值下表现出细胞毒性促氧化活性。酸性癌细胞pH微环境。虽然氧空位作用的一般特征是已知的，但它们在不同 pH 条件下在原子尺度上的作用机制尚未阐明。目前的工作应用密度泛函理论 (DFT) 计算在原子尺度上解释 CeO _{2稳定 {111} 表面的 pH 诱导行为}含有氧空位。^{对表面吸附介质种类的分析揭示了 pH 值对 ROS（ •} O ₂^–和 H ₂ O ₂）与有缺陷的 CeO ₂ {111} 表面之间相互作用的关键作用。在碱性条件下，超氧化物歧化酶（SOD）和过氧化氢酶（CAT）的仿生反应可以循环进行，清除并分解活性氧为无害产物，使CeO ₂成为一种优良的抗氧化剂。然而，在酸性条件下，由于 Ce ³⁺ ↔ Ce ⁴⁺的有限可逆性和氧空位的形成 ↔ 湮灭，CAT 仿生反应受到阻碍。芬顿仿生反应（H₂ O ₂ + Ce ³⁺ → Ce ⁴⁺ + OH ^– + ^• OH) 预计与SOD和CAT仿生反应同时发生，导致羟基自由基的形成，使CeO ₂成为细胞毒性促氧化剂。

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Density Functional Theory Investigation of the Biocatalytic Mechanisms of pH-Driven Biomimetic Behavior in CeO2

There is considerable interest in the pH-dependent, switchable, biocatalytic properties of cerium oxide (CeO₂) nanoparticles in biomedicine, where these materials exhibit beneficial antioxidant activity against reactive oxygen species (ROS) at a basic physiological pH but cytotoxic prooxidant activity in an acidic cancer cell pH microenvironment. While the general characteristics of the role of oxygen vacancies are known, the mechanism of their action at the atomic scale under different pH conditions has yet to be elucidated. The present work applies density functional theory (DFT) calculations to interpret, at the atomic scale, the pH-induced behavior of the stable {111} surface of CeO₂ containing oxygen vacancies. Analysis of the surface-adsorbed media species reveals the critical role of pH on the interaction between ROS (^•O₂^– and H₂O₂) and the defective CeO₂ {111} surface. Under basic conditions, the superoxide dismutase (SOD) and catalase (CAT) biomimetic reactions can be performed cyclically, scavenging and decomposing ROS to harmless products, making CeO₂ an excellent antioxidant. However, under acidic conditions, the CAT biomimetic reaction is hindered owing to the limited reversibility of Ce³⁺ ↔ Ce⁴⁺ and formation ↔ annihilation of oxygen vacancies. A Fenton biomimetic reaction (H₂O₂ + Ce³⁺ → Ce⁴⁺ + OH^– + ^•OH) is predicted to occur simultaneously with the SOD and CAT biomimetic reactions, resulting in the formation of hydroxyl radicals, making CeO₂ a cytotoxic prooxidant.

更新日期：2022-03-01

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