Constructionof a Mirror-Image RNA Nanostructure forEnhanced Biostability and Drug Delivery Efficiency

The development of stable and efficient drug delivery systems is essential for advancing therapeutic applications. Here, we present an innovative approach using a mirror-image RNA (l-RNA) nanostructure to enhance the biostability and drug delivery efficiency. We engineered an l-RNA three-way junction structure conjugated with both small interfering RNA (siRNA) targeting MCL1 and the chemotherapeutic agent doxorubicin for targeted and synergistic drug delivery. This codelivery strategy leverages the combined effects of doxorubicin and MCL1 siRNA, achieving improved therapeutic outcomes. The l-RNA nanostructure demonstrates superior stability compared with natural d-RNA, resulting in reduced toxicity in healthy cells while maintaining therapeutic efficacy in cancer cells. This indicates that l-RNA nanostructures may offer enhanced biosafety when applied as therapeutic agents. The addition of folic acid (FA) to the nanostructure surface substantially increases both delivery specificity and endosomal escape efficiency, optimizing targeted delivery. Structural modeling also suggests a distinctive binding conformation of doxorubicin with l-DNA, setting it apart from native DNA interactions. This study highlights the potential of mirror-image nucleic acid nanostructures as robust and precise platforms for combinatorial drug delivery in cancer treatment.