CAS Engineering Laboratory for Nanozyme, Key Laboratory of Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing 100101, China.
Nanozyme Medical Center, School of Basic Medical Sciences, Zhengzhou University, Zhengzhou 450001, China.
ACS Appl Mater Interfaces. 2024 Jun 19;16(24):30958-30966. doi: 10.1021/acsami.4c06024. Epub 2024 Jun 4.
Iron sulfide nanomaterials represented by FeS and FeS nanozymes have attracted increasing attention due to their biocompatibility and peroxidase-like (POD-like) catalytic activity in disease diagnosis and treatments. However, the mechanism responsible for their POD-like activities remains unclear. Herein, taking the oxidation of 3,3,5,5-tetramethylbenzidine (TMB) by HO on FeS(100) and FeS(001) surfaces, the catalytic mechanism was investigated in detail using density functional theory (DFT) calculations and experimental characterizations. Our experimental results showed that the catalytic activity of FeS nanozymes was significantly higher than that of FeS nanozymes. Our DFT calculations indicated that the surface iron ions of iron sulfide nanozymes could effectively catalyze the production of HO• radicals via the interactions between Fe 3d electrons and the frontier orbitals of HO in the range of -10 to 5 eV. However, FeS nanozymes exhibited higher POD-like activity due to the surface Fe(II) binding to HO, forming inner-orbital complexes, which results in a larger binding energy and a smaller energy barrier for the base-like decomposition of HO. In contrast, the surface iron ions of FeS nanozymes bind to HO, forming outer-orbital complexes, which results in a smaller binding energy and a larger energy barrier for the base-like decomposition of HO. The charge transfer analysis showed that FeS nanozymes transferred 0.12 e and FeS nanozymes transferred 0.05 e from their surface iron ions to HO, respectively. The simulations were consistent with the experimental observations that the FeS nanozymes had a greater affinity for HO compared to that of FeS nanozymes. This work provides a theoretical foundation for the rational design and accurate preparation of iron sulfide functional nanozymes.
硫化亚铁纳米材料（如 FeS 和 FeS 纳米酶）因其在疾病诊断和治疗中的生物相容性和过氧化物酶样（POD-like）催化活性而受到越来越多的关注。然而，其 POD-like 活性的机制尚不清楚。在此，我们以 3,3,5,5-四甲基联苯胺（TMB）在 FeS(100)和 FeS(001)表面上被 HO 氧化为例，使用密度泛函理论（DFT）计算和实验表征详细研究了其催化机制。我们的实验结果表明，FeS 纳米酶的催化活性明显高于 FeS 纳米酶。我们的 DFT 计算表明，硫化亚铁纳米酶表面的铁离子可以通过 Fe 3d 电子与 HO 的前线轨道之间的相互作用，有效地催化 HO•自由基的产生，其作用范围在-10 到 5 eV 之间。然而，FeS 纳米酶由于表面 Fe(II)与 HO 结合形成内轨络合物，具有更高的 POD-like 活性，这导致 HO 碱基分解的结合能更大，能垒更小。相比之下，FeS 纳米酶表面的铁离子与 HO 形成外轨络合物，导致 HO 碱基分解的结合能更小，能垒更大。电荷转移分析表明，FeS 纳米酶将 0.12 e 和 FeS 纳米酶分别从其表面铁离子转移到 HO。模拟结果与实验观察一致，即 FeS 纳米酶对 HO 的亲和力大于 FeS 纳米酶。这项工作为合理设计和精确制备硫化亚铁功能纳米酶提供了理论基础。
