DNAzyme-powered autocatalytic cascade MnO₂ nanodevice for ultrasensitive in situ profiling of circulating tumor cell...

Circulating tumor cells (CTCs), recognized as critical biomarkers of tumor metastasis, play a pivotal role in monitoring cancer progression and improving prognosis. However, the phenotypic and morphological heterogeneity of CTCs often leads to compromised enrichment efficiency, posing significant challenges for reliable detection and phenotypic identification. To address these limitations, we developed a MnO₂ nanoflower-loaded, DNAzyme-powered autocatalytic cascade circuit for sensitive early detection and phenotypic characterization of CTCs. In this study, a stabilized DNAzyme was incorporated with a conventional catalytic hairpin assembly (CHA) system, enabling an mRNA-triggered CHA reaction that would further initiate a self-feedback loop of DNAzyme activity. Uniform MnO₂ nanoflowers with a diameter of 120 ∼ 150 nm effectively improved cellular endocytosis and assisted stable intracellular imaging. This dual-feedback amplification mechanism significantly enhanced signal output, allowing detection of target mRNAs ranging from 10 pM to 200 nM, with a detection limit as low as 3.0 pM. Moreover, the dual-amplification circuit enables sensitive detection and typing of tumor cells before and after transforming growth factor beta 1 (TGF-β₁) induced epithelial-mesenchymal transition (EMT), as well as accurate identification and localization of CTCs in whole blood without requiring complex pre-treatment. Clinical applicability was validated through in situ imaging of clinical samples, demonstrating high concordance with CanPatrol™ method. This strategy represents a promising diagnostic tool for the early clinical detection of metastatic tumor. By enabling precise CTCs monitoring, it holds potential to improve prognostic evaluation and enhance patient survival rates, marking a significant advancement in cancer diagnostics.