A sensitive electrochemical aptasensing platform based on exonuclease recycling amplification and host-guest recognition for detection of breast cancer biomarker HER2

In this study, a novel and sensitive electrochemical aptasensing platform was fabricated for the detection of the breast cancer biomarker HER2. HER2 aptamer was firstly hybridized with ferrocene-labeled DNA/Au nanospheres (FcNS), and then bound with the target HER2. The released FcNS homogeneously hybridized with horseradish peroxidase-labeled DNA/Au nanospheres (HRPNS). Benefiting from the introduction of RecJ_f exonuclease, HER2 was recycled as the degradation of aptamer and bound another aptamer connected on FcNS. Thus, FcNS/HRPNS in large amounts was generated and captured by the modified Au electrode through the host-guest recognition between beta-cyclodextrin (β-CD) and ferrocene (Fc). Horseradish peroxidase (HRP) catalyzed o-PD in presence of H₂O₂, producing a significantly amplified signal. Under the optimal conditions, the fabricated aptasensing platform showed an excellent sensitivity with a low detection limit of 4.9 ng ml⁻¹ (S/N = 3), and high specificity towards HER2. Furthermore, this proposed strategy presented the good reliability and applicability in the analysis of human serum samples, showing great potential for applications in early diagnosis of breast cancer.