Aptamer-Functionalized and Gold Nanoparticle Array-Decorated Magnetic Graphene Nanosheets Enable Multiplexed and Sensitive Electrochemical Detection of Rare Circulating Tumor Cells in Whole Blood

The identification and monitoring of circulating tumor cells (CTCs) in human blood plays a pivotal role in the convenient diagnosis of different cancers. However, it remains a major challenge to monitor these CTCs because of their extremely low abundance in human blood. Here, we describe the synthesis of a new aptamer-functionalized and gold nanoparticle (AuNP) array-decorated magnetic graphene nanosheet recognition probe to capture and isolate rare CTCs from human whole blood. In addition, by employing the aptamer/electroactive species-loaded AuNP signal amplification probes, multiplexed electrochemical detection of these low levels of CTCs can be realized. The incubation of the probes with the sample solutions containing the target CTCs can lead to the efficient separation of the CTCs and result in the generation of two distinct voltammetric peaks on a screen-printed carbon electrode, whose potentials and current intensities, respectively, reflect the identity and number of CTCs for the multiplexed detection of the Ramos and CCRF-CEM cells with detection limits down to 4 and 3 cells mL-1. With the successful demonstration of the concept, further extension of the developed sensing strategy for the determination of various CTCs in human whole blood for the screening of different cancers can be envisioned in the near future.