A DNAzyme-CRISPR cascade strategy for preamplification-free detection of Mycobacterium tuberculosis.

Tuberculosis (TB) remains one of the most fatal infectious diseases worldwide, successful treatment is often limited by insufficient diagnostic capabilities. It creates a pressing need for diagnostic methods that combine high sensitivity, specificity, and operational robustness. In this work, we developed a DNAzyme-CRISPR cascade strategy (Dz-CRISPR) for the specific identification of the IS6110 sequence of Mycobacterium tuberculosis (MTB). This system integrated a thermodynamically stabilized hairpin probe, an Arch-shaped signal transduction switch, and an allosterically activated CRISPR-Cas12a cascade. The design enabled direct target recognition and subsequent signal amplification without a preamplification step, offering a simplified workflow with enhanced stability. The assay demonstrated a detection limit of 211.3 fM and exhibited high specificity by accurately discriminating the IS6110 from specific DNA sequence of non-tuberculous mycobacteria and other common respiratory pathogens. Validation using clinical bronchoalveolar lavage fluid samples further confirmed the method's reliable performance, reproducibility, and satisfactory recovery rates. Current Dz-CRISPR detection strategy provides a reliable and practical solution for tuberculosis diagnosis with high sensitivity, high specificity, and operational robustness, thus demonstrating potential for practical use in resource-constrained areas.