##1. Disruption of the Substrate Recognition Dogma: Expanding the Transcriptome Scope of DNA Nucleases The conventional CRISPR‑Cas12, derived from prokaryotic immune systems, has been defined as a prototypical “DNA scissor” that primarily targets and cleaves double‑stranded DNA (dsDNA). To directly manipulate intracellular RNA, separate RNA‑directed nucleases such as Cas13 or Cas14 have been required; however, these enzymes suffer from intrinsic nonspecific collateral cleavage toxicity and impose constraints on delivery vector packaging size, creating bottlenecks for clinical translation. This study demonstrates that the substrate specificity of the widely validated Cas12 platform can be inverted without any hardware modification.

##2. Molecular Trigger of Guide DNA (gDNA): Structural Control of the DNA‑RNA Hybrid Complex The investigators introduced a radical design in which the conventional guide RNA (crRNA) is replaced with a short, stable guide DNA (gDNA). Upon binding of gDNA to the Cas12 protein, the internal pocket of the complex undergoes subtle conformational adjustments that re‑optimize the cavity for single‑stranded RNA (ssRNA) target sequences rather than a DNA strand. Formation of the gDNA‑RNA hybrid duplex precisely activates the Cas12 RuvC catalytic domain, reprogramming the enzyme from a DNA‑cutting scissor into a high‑selectivity molecular executor that exclusively suppresses target RNA transcripts.

##3. Dual Diagnostic‑Therapeutic Platform: Simultaneous Variant Blocking and Delivery Stability The gDNA‑based Cas12 platform completely overcomes the intrinsic chemical fragility of crRNA, which is expensive to synthesize and rapidly degraded by RNases. gDNA exhibits markedly higher resistance to intracellular exonucleases, thereby maximizing packaging stability within conventional delivery vehicles such as lipid nanoparticles (LNPs) or adeno‑associated viruses (AAV). In pre‑clinical studies, the system suppressed off‑target gene silencing to baseline levels while rapidly capturing and degrading target viral RNA and pathogenic mRNA, demonstrating dual diagnostic and therapeutic performance.

##4. Innovation in Guide Synthesis Cost and a Reset of the Programmable RNA Therapeutics Market The pivotal significance of this work lies in its simultaneous dismantling of the economic and technical entry barriers that have constrained the RNA therapeutics and molecular diagnostics markets. By converting the guide modality from RNA to DNA, the cost of large‑scale oligonucleotide production can be reduced exponentially, potentially accelerating the commercialization timeline of patient‑specific precision medicine by several years. Moreover, the existing FDA‑cleared or clinically validated Cas12 hardware can be retained, requiring only a redesign of the guide sequence to deploy the system against RNA‑based diseases (RNA viral infections, overexpressed oncogenic transcripts), thereby offering a disruptive asset that can dramatically improve R&D efficiency across global drug pipelines.