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

Abstract

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.

The Translational Potential of Electrochemical DNA-Based Liquid Biopsy

“…Regarding the numerous aptasensors for cancer cells, the great performance of nanomaterials is a common feature (Sun et al, 2019) that was brought to light with multiplexing in whole blood (Dou et al, 2019). Interestingly, the release of viable CTCs for downstream analyses has been accomplished by an enzymatic digestion step of a uracil-containing aptamer sequence partially hybridized with a complementary sequence attached to the electrode.…”

Electrochemical Detection and Point-of-Care Testing for Circulating Tumor Cells: Current Techniques and Future Potentials

“…The sandwich assays add a signal probe on the basis of direct assays, that is, after CTC is bound to the capture probe on the electrode, a signal probe (another kind of nanomaterials-aptamer) is added. After the signal probe is combined with CTC, it can significantly amplify the signal, thereby increasing the sensitivity and reducing the detection limit ( Figure 2) [30,98,99]. We summarized the electrochemical-based CTC detection methods in Table 3, including the direct assay and the sandwich assay, and we listed the assay time, linear range, limit of detection, capture probe, and signal probe.…”

“…Further, the linear range is 5-500 cells mL −1 . More importantly, they also performed testing of three leukemia patients and showed obvious results ( Figure 4C) [98]. Du et al proposed a Cyclic voltammetry (CV) cytosensor based CTC electrochemical detection, and it can specifically detect the change of E-cadherin and analyze different stages of EMT.…”

“…(C) Voltammetric cytosensor for SWV detection of CCRF-CEM cells, Au nanoparticles (AuNP) array-decorated magnetic graphene nanosheet as capture probe and aptamer/electroactive species-loaded AuNP as signal probe. Reprinted with permission from ref[98]. Copyright 2019, American Chemical Society.…”

A Novel Ratiometric Electrochemical Biosensor Based on a Split Aptamer for the Detection of Dopamine with Logic Gate Operations

“…Electrochemical aptamer‐based biosensors (E‐AB) have attracted great interest due to their simplicity, robustness, reusability, and low cost, while being also highly sensitive and selective. These sensors have proven to be able to detect a variety of different analytes such as small molecules, proteins, inorganic ions, or even cells . E‐ABs traditionally utilize target‐induced conformational changes as transducer principles to generate a sensor signal.…”