A Topology-Programmed Circular DNAzyme Enables High-Precision Diagnosis of Metastatic Triple-Negative Breast Cancer.
TL;DR
A cyclization-provoked, size-reliant topological barrier that suppresses the catalytic core folding of DNAzymes, thereby governing their catalytic activity is uncovered, enabling more accurate, spatiotemporal regulation for future therapeutic interventions.
Abstract
DNAzymes capable of RNA-cleaving are attractive, protein-independent candidates for biosensing and gene regulation. However, precise modulation of their activity remains a significant obstacle to biomedical applications. Herein, we uncovered a cyclization-provoked, size-reliant topological barrier that suppresses the catalytic core folding of DNAzymes, thereby governing their catalytic activity. Leveraging this underlying topological insight, we engineered a catalytically inert, minimal-sequence circular DNAzyme bearing a cleavable apurinic/apyrimidinic (AP) site and revealed that its substrate-cleavage potential could be restored through miRNA-10b-responsive circular-to-linear switching. The smallest circular size confers the strongest topological barrier for catalytic activity self-blocking in the circular DNAzyme, providing the most effective means for stimuli-specific activity restoration. This topology-informed strategy facilitated the design of an orthogonally activated circular DNAzyme-metal nanohybrid via Zn2+-mediated coordination self-assembly of the circular DNAzyme with its substrates. The nanohybrid allowed accurate discrimination of metastatic triple-negative breast cancer in various complex biological settings, including a heterogeneous population of cell subtypes, an in vivo subcutaneous tumor model, an in vivo sentinel lymph node metastasis model, and clinical human breast tissue samples. Our findings provide a flexible and robust framework for conditional manipulation of DNAzyme activity, enabling more accurate, spatiotemporal regulation for future therapeutic interventions.