A signal-on electrochemical aptasensor for sensitive detection of human epididymis protein 4 based on functionalized metal–organic framework/ketjen black nanocomposite

Human epididymis protein 4 (HE4) is a highly sensitive and specific biomarker for diagnosing ovarian cancer. In this work, a new electrochemical aptasensor for rapid and sensitive detection of HE4 was constructed. Firstly, metal–organic framework/ketjen black (NH 2 -MIL-53(Al)/KB) composite with abundant amino groups and large specific surface area was prepared as signal amplifier to anchor gold nanoparticles (AuNPs). Subsequently, signal probe (SP) and a large amount of electroactive toluidine blue (Tb) were attached on AuNPs to form the tracer label, producing a distinct electrochemical detection signal. Moreover, Ni 3 (HITP) 2 was modified by poly(diallyldimethylammonium chloride, PDDA) to obtain PDDA/Ni 3 (HITP) 2 , and then it was covered with deposited gold nanocrystals (DpAu) to form the sensing platform, which increased the electrical conductivity, specific surface area and the loading of triple-helix assembled probes (TAP). Target HE4 was bound to its aptamer in the outer layer of the TAP, leaving a separate capture probe (CP) on the electrode surface that can bind with the tracer label. The proposed aptasensor for HE4 detection showed a wide linear range from 1 to 10 nM with a detection limit of 0.41 fM. In addition, the aptasensor has good selectivity, stability and reproducibility. More importantly, this method showed satisfactory results in clinical serum sample analysis compared with ELISA, possessing application prospects in ovarian cancer diagnosis.