Electrochemical Immunosensor for Simultaneous Detection of Oral Cancer Dual Markers Based on a Functionalized Magnetic Electrode and a Photoelectric-Material-Doped Nanoalloy

Protein tumor marker (PTM) analysis is of great significance for the early diagnosis and process monitoring of tumors. However, the clinical reference value of a single PTM is restricted, and existing tests for multiple PTMs majorly suffer from complex processes and poor sensitivity. Herein, a cancerous inhibitor of protein phosphatase 2A (CIP2A) and protein c-Myc (AG(c-Myc)) with a positive feedback path in oral squamous cell carcinoma (OSCC) was chosen as a dual PTM, and a magnetic electrochemical immunosensor (MEI) for their simultaneous detection was successfully established. Fe3O4 coated with a gold nanoparticle (MAu)-functionalized magnetic electrode (f-MGE) was of benefit to immobilize two capture antibodies (C-Ab) through internal forces and external magnetic fields. By a mechanical alloying (MA) method, two photoelectric materials osmosed bimetallic-matrix nanospheres (Bi-M-PE), including luminol and Ru(bpy)(3)(2+) osmosed AuNPs-AgNPs nanoalloy (Lu@AuAg and Ru@AuAg), were prepared as innovative signal probes. Lu@AuAg and Ru@AuAg not only exhibit superior electrochemical properties than photoelectric material osmosed monometallic-matrix nanospheres but can directly label detection antibodies (D-Ab) without complex reaction conditions and additional functionalization. After immunological reactions, the distinguishable differential voltammetry pulse signals were obtained at +0.48 and +1.13 V, corresponding to AG(c-Myc) and CIP2A, respectively. The proposed assay showed a good linear response range from 5 pg L-1 to 5 ng L-1 for AG(c-Myc) and 50 pg L-1 to 50 ng L-1 for CIP2A, and a low limit of detection of 2.5 pg L-1 and 25 pg mL(-1), respectively. The MEI also exhibited satisfactory selectivity, stability, and reproducibility. Moreover, when the proposed method and the ELISA kit were simultaneously applied to saliva samples of OSCC patients, the obtained results were completely consistent, reflecting the clinical practicability of this work.