Herein, a novel sandwich-type electrochemical immunosensor was fabricated based on Fe₃O₄ nanoflowers (Fe₃O₄ NFs) and heterogeneous chain reaction (HCR) signal amplification strategy for the sensitive detection of hepatitis B surface antigen (HBsAg). The aldehyde-functionalized Fe₃O₄ NFs are used as a supporting matrix to immobilize the hepatitis B surface antibody 1 (HBsAb1). The biotin-modified single-strand DNA (biotin-S0) was connected onto the biotin-HBsAb2 via linkage of streptavidin (SA), followed by addition of methylene blue (MB) modified single strand DNA1 (MB-S1) and DNA2 (MB-S2) for HCR signal amplification. The designed immunosensor exhibited a detection linear range of 0.5 pg mL⁻¹-0.25 ng mL⁻¹ and a low detection limit of 0.16 pg mL⁻¹, with excellent stability, selectivity and reproducibility. Furthermore, HBsAg is detected in the serum samples with a stable and fast response, indicating that the proposed immunosensor has a promising potential application in clinical analysis.

在此，基于Fe ₃ O ₄纳米花（Fe ₃ O ₄ NFs）和异链反应（HCR）信号放大策略，制备了一种新型的夹心型电化学免疫传感器，用于灵敏地检测乙肝表面抗原（HBsAg）。醛官能化的Fe ₃ O ₄NF用作固定乙型肝炎表面抗体1（HBsAb1）的支持基质。通过链霉亲和素（SA）的连接将生物素修饰的单链DNA（biotin-S0）连接到生物素-HBsAb2，然后添加亚甲蓝（MB）修饰的单链DNA1（MB-S1）和DNA2（MB -S2）用于HCR信号放大。设计的免疫传感器显示出0.5 pg mL ^-1 -0.25 ng mL ^-1的检测线性范围和0.16 pg mL ^-1的低检测限，具有出色的稳定性，选择性和可重复性。此外，在血清样品中检测到HBsAg具有稳定和快速的响应，表明所提出的免疫传感器在临床分析中具有广阔的应用前景。