A facile ratiometric electrochemical strategy for ultrasensitive monitoring HER2 using polydopamine-grafted-ferrocene/reduced graphene oxide, Au@Ag nanoshuttles and hollow Ni@PtNi yolk-shell nanocages

Human epidermal growth factor receptor 2 (HER2) is believed as a clinically important breast cancer marker, and thereby it is extremely imperative to develop a highly sensitive and effective strategy for specific recognition and assay of HER2. In this work, a facile ratiometric electrochemical immunosensor was fabricated for sensitively monitoring HER2 as a model analyte, in which reduced graphene oxide-polydopamine-grafted-ferrocene/[email protected] nanoshuttles ([email protected] NSs) performed as electrode material and hollow [email protected] yolk-shell nanocages-thionine ([email protected] HNCs) as signal tags, which provided two distinct electrochemical signals from Fc and Thi, respectively. The [email protected] NSs endowed the rGO-PDA-Fc with improved biocompatibility and dramatic magnification of the Fc signals upon sensing interface. Also, by integration of the hollow structure, enlarged specific surface area and superior catalytic ability together, the [email protected] HNCs-Thi achieved substantial amplification in the detection signals from Thi. Benefiting from the above, the as-developed immunosensor exhibited a broad linear range (0.01 ∼ 100 ng mL–1) and a low detection limit (3.3 pg mL–1) for HER2 (S/N = 3), followed by exploring its application in actual serum samples with acceptable results. It holds great potential for clinical screening of cancer biomarkers and point of-care assays.