An electrochemical biosensor based on hemin/G-quadruplex DNAzyme and PdRu/Pt heterostructures as signal amplifier for circulating tumor cells detection

• Published in: Journal of colloid and interface science 2021-10, Vol.599, p.752-761
• Main Authors: Zhou, Xi, Pu, Qinli, Yu, Hongyan, Peng, Yang, Li, Junjie, Yang, Yujun, Chen, Huajian, Weng, Yaguang, Xie, Guoming
• Format: Article
• Language: English
• Subjects: Circulating tumor cells; Electrochemical biosensor; Hemin/G-quadruplex; PdRu/Pt heterostructures; Super P/gold nanoparticles
• ISSN: 0021-9797; 1095-7103
• DOI: 10.1016/j.jcis.2021.05.006

An enzyme-free sandwich-type electrochemical biosensor was developed for highly sensitive detection of CTCs by fabricating a novel PdRu/Pt hierarchical structures through a facile hydrothermal method and coupling with hemin/G-quadruplex as signal amplification probes. Meanwhile, high conductive Super P and gold nanoparticles (AuNPs) acted as sensing medium to improve electrical conductivity and immobilization of anti-EpCAM antibody to specifically capture model CTCs. [Display omitted] •3D hyperbranched PdRu/Pt heterostructures with excellent catalytic activity was synthesized to improve signal amplification.•PdRu/Pt integrated with hemin/G-quadruplex DNAzyme was first utilized as signal probe.•As-proposed biosensor reached a detection limit down to 2 cells mL−1. Metastasis due to circulating tumor cells (CTCs) shed from the original tumor accounts for the majority of cancer-related death. Efficient CTCs detection is pivotal to the diagnosis of early cancer metastasis. In this work, Platinum nanoparticles (PtNPs) decorated hyperbranched PdRu nanospines (PdRu/Pt) hierarchical structures were firstly synthesized to detect CTCs with the assistance of DNAzyme. Meanwhile, Super P and gold nanoparticles (AuNPs) acted as sensing medium to improve electrical conductivity and immobilization of anti-EpCAM antibody to specifically capture model CTCs. After immune-conjugation of anti-EpCAM-MCF-7-signal probes on the gold electrode, PtNPs, PdRu nanospines (PdRuNSs) and hemin/G-quadruplex co-catalyzed substrate H2O2 to realize multiplexed signal amplification, which significantly improves the analytical performance of the electrochemical biosensor. As-proposed biosensor reached a limit of detection (LOD) down to 2 cells mL−1 and showed a wide detection range of 2 to 106 cells mL−1. Application of the biosensor to detect MCF-7 cells spiked human blood samples further demonstrated the feasibility for early cancer evaluation in clinic.