先前的研究已经提出乳腺癌发展和血清中miRNA-21浓度之间的潜在相关性。理论上，多价金属离子掺杂在WS2中可以带来更高的电子转移能力，但这还没有得到证明。为了填补这一研究空白，我们通过一锅法制备了七种不同金属离子（Co2+、Ni2+、Mn2+、Zn2+、Fe3+、Cr3+、La3+）修饰的纳米复合结构。表征结果显示，水热尿素产生的氨气使多层石墨烯氧化物（MGO）剥离并提供了氮源，用于掺杂还原形成具有高比表面积的三维花状结构（NrGOF）。同时，经Fe3+修饰的WS2不仅增强了其电化学导电性，还赋予了材料额外的过氧化物酶活性中心。在复合物Fe3+-WS2/NrGOF-AgNPs中，NrGOF被用作WS2的导电负载界面，而Fe3+则用作电催化和电子转移中心，用于电化学信号的二次放大。实验结果表明，该传感平台在10-17 -10-12 M的浓度范围内具有1.18 aM的低检测限（LOD），并已成功应用于真实血清样本的检测。Copyright © 2023 Elsevier B.V. All rights reserved.

Previous researches have suggested the potential correlation between the development of breast cancer and the concentration of miRNA-21 in serum. Theoretically the doping of multivalent metal ions in WS2 could bring higher electron transfer capacity, but this hasn't been proven. To fill this research gap, through one-pot method we prepared seven nanocomposite structures modified with different metal ions (Co2+, Ni2+, Mn2+, Zn2+, Fe3+, Cr3+, La3+). Characterization revealed that ammonia produced by hydrothermal urea exfoliated the multilayer graphene oxide (MGO) and provided a nitrogen source for doping reduction to form a 3D flower-like structure (NrGOF) with high specific surface area. Meanwhile, the modification of WS2 by Fe3+ not only enhanced its electrochemical conductivity but also gave the material an additional peroxidase activity centre. In the composite Fe3+-WS2/NrGOF-AgNPs, NrGOF is used as a conductive loading interface for WS2, while Fe3+ served as the catalytic and electron transfer centre for secondary amplification of the electrochemical signal. The experimental results showed that the sensing platform has a low limit of detection (LOD) of 1.18 aM for miRNA-21 in the concentration range of 10-17-10-12 M and has been successfully applied to the detection of real serum samples.Copyright © 2023 Elsevier B.V. All rights reserved.