Electrochemiluminescence Aptasensor for HER2-ECD Detection Based on Resonance Energy Transfer between AuPt@ZIF-67 and AuNPs/g-C₃N₄/PDDA Composites

The extracellular domain of the human epidermal growth factor receptor (HER2-ECD) is a breast cancer biomarker. Accurate and sensitive detection of HER2-ECD concentration in serum is crucial in the diagnosis and patient follow-up. Herein, an “off–on” type electrochemiluminescence (ECL) aptasensor based on the resonance energy transfer (RET) between AuPt@ZIF-67 and AuNPs/g-C 3 N 4 /PDDA was developed for detecting HER2-ECD. First, AuNP-modified g-C 3 N 4 (AuNPs/g-C 3 N 4 /PDDA), as a signal substrate, generates ECL signals under the co-reactant peroxodisulfate (S 2 O 8 2– ) in a specific potential range and shows significantly enhanced signal strength and stability. Then, AuPt@ZIF-67 expeditiously quenched the ECL signal of AuNPs/g-C 3 N 4 /PDDA because of ECL resonance energy transfer (ECL-RET) between AuPt@ZIF-67 and AuNPs/g-C 3 N 4 /PDDA. We designed a new aptasensor detection platform for HER2-ECD detection. After specific binding of the aptamer with HER2-ECD, the AuPt@ZIF-67 content in the system decreased, and the ECL response recovered. The biosensor demonstrated a linear range of HER2-ECD detection between 100 fg/mL and 100 ng/mL under ideal circumstances, with a low detection limit of 17.3 fg/mL. Furthermore, this biosensor was successfully tested in human serum samples. This strategy, as a novel ECL system with satisfactory stability and excellent sensitivity, can realize the detection of other biological molecules by changing the probe, which is a promising method.