Electrochemical immunosensor of graphene oxide/Au/Ag and strawberry-like Au@PtPd for exosome detection

Early detection and treatment of colorectal cancer can effectively reduce the harm caused to patients. However, early symptoms are not obvious. Exosomes are extracellular vesicles that carry information between cells circulating in the human body. Despite the critical importance of tumor-derived exosomes for early cancer detection, prognosis, and treatment guidance, sensitive detection of exosomes remains challenging. We report a novel immunosensor for the detection of exosomes using graphene oxide (GO)/Au/Ag as the electrochemical sensing platform and spherical Au@PtPd porous nanoparticles to provide signal amplification. A large-surface-area GO/Au/Ag-modified screen-printed carbon electrode (SPCE) is used to immobilize CD63 aptamers. The prepared strawberry-like Au@PtPd demonstrates improved sensitivity and electrocatalytic activity with increasing aptamer load. Meanwhile, its good conductivity accelerates the electron transfer rate on the SPCE. The immunosensor exhibits a linear range (100–1.0 × 10⁶ exosomes·μl⁻¹) and a detection limit of 23 exosomes·μl⁻¹. Furthermore, its potential for the detection of exosomes provides a new clinical application for early diagnosis of colorectal tumors.