Electrochemical label-free immunoassay of HE4 using 3D PtNi nanocubes assemblies as biosensing interfaces

Human epididymis protein 4 (HE4) is a vital biomarker for early diagnosis of epithelial ovarian cancer (EOC). Herein, a new label-free biosensor was developed using K₃[Fe(CN)₆] as the electrochemical probe for ultrasensitive immunoassay of HE4 based on PtNi nanocubes assemblies (NCAs) as efficient biosensing interfaces. The PtNi NCAs were synthesized by a simple solvothermal approach, where N-hexadecyltrimethylammonium chloride (HTAC) and 2,2'-bis(4,5-dimethylimidazole) (BDMM) behaved as co-structuring directors. Under the optimal conditions, the obtained HE4 immunosensor displayed a wide detection range from 0.001 to 100 ng mL^-1 and a low detection limit (0.11 pg mL^-1, S/N = 3). As a result, the current sensing platform would serve as a useful reference for detecting cancer biomarkers in the clinical assay and diagnosis.