A novel electrochemiluminescent cytosensor using dual-target magnetic probe recognition and nanozymes-catalyzed cascade signal amplification for precise phenotypic enumeration of CTCs

Abstract The inability of surgical biopsy to monitor the dynamic evolution of cancer cells hampers its capacity to reflect real-time tumor heterogeneity. Circulating tumor cells (CTCs), as a crucial target in liquid biopsy, offer a novel approach for accurate monitoring of tumors. However, the rarity and complex phenotype resulting from epithelial mesenchymal transition pose challenges for conventional methods such as CellSearch and immunohistochemistry, which have insufficient ability for simultaneous phenotyping and enumeration of CTCs. The enumeration of a single phenotype CTCs is insufficient for accurately assessing disease progression. Herein, we propose a strategy to address this issue by fabricating an electrochemiluminescence cytosensor via the integration of dual-target enrichment and nanozymes-catalyzed cascade signal amplification. The graphene oxide@hollow mesoporous prussian blue/Pt (GO@HMPB/Pt) complex, possessing a large specific surface area and exceptional catalytic activity, is employed for loading a substantial amount of luminol as the signal probe. Dual-target magnetic PPy@Fe3O4/Au-antibody/aptamer is utilized for the magnetic capture of both epithelial and interstitial CTCs. Glutathione (GSH) can disrupt Au-S bond on aptamer by a thiol exchange reaction and selectively release a specific subset of phenotypic CTCs, thereby facilitating the efficient capture, accurate classification, and ultrasensitive detection of CTCs in peripheral blood. Using the epithelial MCF-7 and mesenchymal Hela cells as models, the ECL cytosensor demonstrates excellent performance in identifying cells spiked into whole blood. This study presents a novel approach for early detection of metastasis, tracking tumor recurrence, and monitoring therapeutic efficacy.