碳水化合物抗原19-9（CA19-9）是胰腺癌、卵巢癌等肿瘤的重要标志物，其快速、稳定的检测是早期诊断和治疗的基础。本文开发了一种用于灵敏检测 CA19-9 的无标记电化学免疫传感器。首先，采用MOF-on-MOF方法合成了两种新型核壳双金属纳米材料，即Ce-MOF-on-Fe-MOF和Fe-MOF-on-Ce-MOF。通过将聚乙烯酰亚胺 (PEI) 功能化 rGO 与 Ce-MOF-on-Fe-MOF 和 Fe-MOF-on-Ce-MOF 纳米材料相结合，解决了 MOF 材料导电性差的问题。同时，采用甲苯胺蓝（Tb）作为氧化还原探针并物理吸附到合成材料上，从而形成两种纳米材料：rGO@Ce-MOF-on-Fe-MOF@Tb 和 rGO@Fe-MOF-on -Ce-MOF@Tb。基本表征表明，基于 rGO@Ce-MOF-on-Fe-MOF@TB 的免疫传感器的传感性能优于基于 rGO@Fe-MOF-on-Ce-MOF@TB 的免疫传感器，这这是由于与 Fe-MOF-on-Ce-MOF 的层间约束结构不同，在 Ce-MOF-on-Fe-MOF 中，Ce-MOF 渗透到 Fe-MOF 中形成异质结构，这是由于Fe-MOF相对较大的孔径，更好地结合了Fe MOF优异的生物相容性和对抗体的强锚定作用，以及Ce-MOF的高电化学活性和导电性，增强了传感性能。所提出的基于rGO@Ce-MOF-on-Fe-MOF@Tb的无标记免疫传感器具有宽线性范围（1-100 000 mU mL-1）、低检测限（0.34 mU mL-1）、良好的稳定性、重现性、重复性和良好的适用性，为临床应用提供了潜在的平台。

Carbohydrate antigen 19-9 (CA19-9) is an important marker for pancreatic cancer, ovarian cancer and other tumors, and its rapid and stable detection is the basis for early diagnosis and treatment. In this paper, a label-free electrochemical immunosensor for the sensitive detection of CA19-9 has been developed. First, the synthesis of two novel core-shell bimetallic nanomaterials, namely Ce-MOF-on-Fe-MOF and Fe-MOF-on-Ce-MOF, was accomplished using the MOF-on-MOF approach. The poor electrical conductivity of MOF materials was addressed by incorporating polyethylenimide (PEI) functionalized rGO with Ce-MOF-on-Fe-MOF and Fe-MOF-on-Ce-MOF nanomaterials. Simultaneously, toluidine blue (Tb) was employed as a redox probe and physically adsorbed onto the synthesized materials, resulting in the formation of two nanomaterials: rGO@Ce-MOF-on-Fe-MOF@Tb and rGO@Fe-MOF-on-Ce-MOF@Tb. The fundamental characterization reveals that the sensing performance of the rGO@Ce-MOF-on-Fe-MOF@TB-based immune sensor surpasses that of the rGO@Fe-MOF-on-Ce-MOF@TB-based immune sensor, which is attributed to the fact that, unlike the interlayer-constrained structure of Fe-MOF-on-Ce-MOF, in Ce-MOF-on-Fe-MOF, Ce-MOF penetrates into Fe-MOF to form a heterogeneous structure due to the relatively large pore size of Fe-MOF, which better combines the excellent biocompatibility and strong anchoring effect of Fe MOFs on antibodies, as well as the high electrochemical activity and conductivity of Ce-MOF, to enhance sensing performance. The proposed label-free immunosensor based on rGO@Ce-MOF-on-Fe-MOF@Tb has a wide linear range (1-100 000 mU mL-1), a low detection limit (0.34 mU mL-1), good stability, reproducibility, and repeatability, and satisfactory applicability, which provides a potential platform for clinical applications.