Potential-resolved single-nanoparticle collision electrochemistry for simultaneous quantification of MCF-7 and SK-BR-3 cells.

Compared to detecting individual target analytes by single immunoassay, multiplex immunoassays (MIAs) can simultaneously detect multiple analytes in a single experiment, saving more time and reducing sample consumption. Single-nanoparticle collision electrochemistry (SNCE), characterized by its high throughput, sensitivity, and rapid response, has been extensively employed in the field of biosensing. Herein, an innovative potential-resolved SNCE biosensor was proposed for the simultaneous and rapid detection of two types of breast cancer cells (MCF-7 and SK-BR-3 cells) based on platinum nanoparticles (Pt NPs) catalyzing hydrazine reaction and silver nanoparticles (Ag NPs) undergoing self-oxidation. By analyzing the different collision signals of two types of NPs, the MIAs for quantitatively detecting two types of cancer cells was established. By combining the stability and anti-interference capabilities of magnetic beads (MBs) with the signal amplification strategy of liposome encapsulation-release, the SNCE biosensor achieved detection of the two types of breast cancer cells as low as 5 cells/mL within 1 h. These signal-resolved MIAs could also be exerted on the detection of other biomolecules, elucidating the MIAs at the single-particle or single-molecule level and proposing new avenues for the application of SNCE in biosensing.