Ultra-responsive label-free electrochemical aptamer sensor based on 3D-CdCo-ONSs@AuNPs for detection of tumour marker MUC1

Mucin 1 (MUC1), a pivotal tumor biomarker overexpressed in breast cancer, is conventionally detected using laborious, costly, and technically demanding methods. To overcome these limitations, we present a novel label-free electrochemical aptasensor for rapid, sensitive, and cost-efficient MUC1 quantification. The sensor employs a nanohybrid platform composed of gold nanoparticle-decorated three-dimensional cadmium-cobalt oxide nanostructures (3D-CdCo-ONSs@AuNPs), which synergistically amplify the differential pulse voltammetry (DPV) signal. The 3D-CdCo-ONSs provide a high-surface-area scaffold for dense AuNP deposition, enabling efficient immobilization of thiolated aptamers via Au–S bonds. Comprehensive material characterization via scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS) confirmed the structural and compositional integrity of the nanocomposite. Under optimized conditions, the sensor exhibited a broad linear detection range from 10 pg/mL to 100 μg/mL (R 2  = 0.998) with an ultralow limit of detection (LOD) of 0.96 pg/mL. The assay demonstrated excellent reproducibility, stability, and selectivity in complex matrices, facilitating precise MUC1 quantification in clinical samples. This work advances the development of portable, high-performance biosensors for early cancer diagnosis and monitoring.