Farkaly, T. | bioRxiv Science

bioRxiv2026

An EpCAM-Targeted Mirror-Image DNA Nanostructure for Precise Drug Delivery in Triple-Negative Breast Cancer

Triple-negative breast cancer (TNBC) remains a major therapeutic challenge due to the lack of effective molecular targets and the dose-limiting off-target toxicity of conventional chemotherapy. Here, we design and construct a mirror-image DNA (L-DNA) nanostructure functionalized with an epithelial cell adhesion molecule (EpCAM)-specific aptamer for targeted delivery of doxorubicin (DOX) to TNBC cells. The L-DNA nanostructure retains thermodynamic properties comparable to natural D-DNA while exhibiting substantially enhanced resistance to nuclease and serum-mediated degradation due to its mirror-image chirality. Thermal melting and serum stability assays confirmed superior structural stability of the L-DNA nanostructure compared to D-DNA counterparts. In vitro cytotoxicity studies demonstrated that the EpCAM-targeted L-DNA nanostructure has the potential to selectively inhibit the growth of EpCAM-positive TNBC cells while reducing cytotoxicity in normal cells. These findings demonstrate that combining aptamer targeting with mirror-image DNA nanotechnology provides a stable and selective nanoplatform for chemotherapeutic delivery, which can potentially improve the precision and therapeutic efficacy of treatment for aggressive breast cancers.

biochemistry↗

bioRxiv2026

Mirror-Image L-DNA Nanocubes for Stable and Targeted Multimodal Drug Delivery

Nucleic acid nanostructures provide programmable architectures for molecular delivery but remain limited by rapid nuclease degradation, poor in vivo persistence and inefficient intracellular cargo release. Here we report a mirror-image L-DNA nanocube as a biologically persistent and modular therapeutic delivery platform. The nanocube self-assembles from synthetic L-DNA oligonucleotides into a structurally defined architecture that exhibits substantially enhanced resistance to enzymatic degradation and prolonged stability under physiological conditions compared with the corresponding D-DNA nanostructure. Surface functionalization with folic acid enables selective tumour targeting in vitro and in vivo. The L-DNA nanocube supports the delivery of chemically distinct therapeutic cargos, including doxorubicin, a bortezomib prodrug and MCL1-targeting small interfering RNA (siRNA). In tumour-bearing mice, L-DNA nanocube-mediated delivery improves therapeutic efficacy while reducing systemic toxicity relative to free drug and D-DNA nanocube controls. For siRNA delivery, we engineer a pH-responsive release mechanism that promotes endosomal escape and cytosolic cargo localization, as visualized by cryo-electron tomography, resulting in efficient gene silencing. Together, these results establish mirror-image nucleic acid nanostructures as a class of biologically functional nanomaterials for programmable intracellular therapeutic delivery.

biochemistry↗