Polyhedral-AuPd nanoparticles-based dual-mode cytosensor with turn on enable signal for highly sensitive cell...

A novel dual-mode cytosensor based on polyhedral AuPd alloy nanoparticles (PH-AuPd NPs) and three-dimentional reduced graphene oxide (3D-rGO) was constructed for highly sensitive detection of MCF-7 cells. The 3D-rGO was in situ synthesized on the paper working electrode (PWE) by a pollution-free hydrothermal method, increasing the specific surface area and further facilitating the modification of Au nanoparticles (AuNPs). After modified with AuNPs, the Au@ 3D-rGO/PWE was then functionalized by aptamer H1 to trap MCF-7 cells. To construct the cytosensor, PH-AuPd NPs was prepared as a novel catalytic material, and further modified with aptamer H2 for recognizing MCF-7 cells. With the occurrence of efficient recognition of MCF-7 cells, PH-AuPd NPs were bound onto the surface of the cells, and could catalyze H₂O₂ to generate •OH, leading to an amplified electrochemical signal. Meanwhile, as the electrolyte solution flowed, the •OH are transferred outward to the colorimetric detection zone, and catalyzed a chromogenic substrate TMB forms a colored product. The electrical signal measurement and colorimetric detection were carried out on a compatibly designed lab-on-paper device (LPD), realizing a dual-mode signal readout. This paper-based dual-mode cytosensor provided a relatively low detection limit of 20 cells mL^-1 and a sensitive detection from 50 cells mL^-1 to 10⁷ cells mL^-1 for MCF-7 cells, providing a reliable pathway of sensitively detecting cancer cells in clinical applications.