Ultrasensitive Electrochemical Aptasensor Based on Ag-Cu2O/rGO and CeO2/AuPt Nanocomposites for PCB77 Detection

In this study, based on the specific binding of nucleic acid aptamers (Apts) to 3,3′,4,4′-tetrachlorobiphenyl (PCB77), an ultrasensitive electrochemical aptasensor was constructed for the detection of PCB77. The Apts were captured by hairpin (HP) deoxyribonucleic acid capture probes through complementary base pairing. The large surface area of reduced graphene oxide (rGO) combined with Ag-Cu 2 O significantly improved the efficiency of electron transfer on the electrode surface and provided a large number of binding sites for HP capture probes. Streptavidin (SA)-modified CeO 2 /AuPt was used as signal-generating material to amplify electrical signals cooperatively with Ag-Cu 2 O/rGO, and it was also combined with biotin-modified nucleic acid Apts via the SA-biotin system to form signal labels, which significantly improved the sensitivity of the aptasensor. The morphology and size of the synthesized materials were characterized by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The internal structure and composition of the materials were further analyzed by x-ray photoelectron spectroscopy (XPS), x-ray diffraction (XRD), and Fourier transform infrared (FT-IR) spectroscopy. The sensor assembly process was confirmed by electrochemical impedance spectroscopy (EIS) and cyclic voltammetry (CV). Differential pulse voltammetry (DPV) was used to optimize the experimental conditions and evaluate the performance of the sensor. Under optimal conditions, the detection limit of the aptasensor was 0.069 ng/L, and the dynamic range was 0.1–10 3 ng/L, providing a high-quality platform for PCB77 detection. Graphical Abstract