Ultrasensitive electrochemical cancer cells sensor based on trimetallic dendritic Au@PtPd nanoparticles for signal amplification on lab-on-paper device

A trimetallic dendritic Au@PdPt nanparticles (Au@PdPt NPs) with intrinsic peroxidase-like catalytic activity were fabricated by a facile method. Au@PdPt NPs catalyzed the reduction of H 2 O 2 with the help of the electron mediator (thionine), which produced the electrochemical signals dramatically amplified. A sandwiched sensor was designed and implemented in the paper chip device for the determination of K-562 cells. The surface of dendritic Au@PtPd NPs was linked with folic acid by click chemistry. Folic acid was attached to the folate receptor (FR) of cell surface with high affinity. So, K-562 cells could be assayed based on folic acid-functionalized Au@PtPd NPs. On the other hand, folic acid-functionalized Au-paper working electrode on origami electrochemical device was fabricated, which could be used to capture K-562 cells. The twice utilization of folic acid for the capture of K-562 cells as well as the attachment of dendritic Au@PtPd NPs nanoprobe, which enhanced the selectivity of sensor for the determination of cells. The proposed biosensor exhibited excellent analytical performance toward the cytosensing of K562 cells with a wide detection linear range from 1.0   ×   10 2 to 2.0   ×   10 7 cells   mL −1 and a detection limit of 31 cells   mL −1 . Further, the proposed electrochemical sensor was applied to monitor cells. Au@PtPd NPs nonenzymatic catalysts could be used as signal-amplifying nanoprobes for ultrasensitive electrochemical sensing.