Sandwich-Type Electrochemical Sensor for Mucin-1 Detection Based on a Cysteine–Histidine–Cu@Cuprous Oxide Nanozyme
Zhi Li, Hui Li, Xing Geng, Ge Dai, Zhaohui Chu, Feifei Luo, Fan Zhang, Qingjiang Wang
Abstract
The sensitive detection of biomarkers is crucial for the early identification and treatment of cancer. In this study, a cysteine–histidine–Cu-modified jujube-like Cu2O (CH-Cu@J-Cu2O) nanozyme was synthesized and used to fabricate an electrochemical sensor for mucin-1 (MUC1) sensitive detection. Gold-modified reduced graphene oxide and CH-Cu@J-Cu2O for the sensor were prepared and also characterized by transmission electron microscopy (TEM), scanning electron microscopy (SEM), high-resolution transmission electron microscopy (HRTEM), X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS). The CH-Cu@J-Cu2O nanozyme was used as a signal probe, containing two catalytic units of cysteine–histidine–Cu and jujube-like Cu2O. The CH-Cu@J-Cu2O nanozyme can potently catalyze the H2O2-driven oxidation of dopamine to aminochrome, leading to a high-level electrochemical signal. This electrochemical sensor was used to detect MUC1 with a linear range from 0.5 to 5000 pg·mL–1, and the limit of detection was 0.085 pg·mL–1, owing to the excellent catalytic activity of CH-Cu@J-Cu2O. The expression of MUC1 on the surface of MCF-7 cells was further analyzed, and the results indicate that the proposed strategy is practical for the detection of biomarkers.