Membrane protein and endogenous GSH co-gated cascade DNA sensor for accurate and sensitive mRNA imaging

Accurate and sensitive imaging of tumor-associated mRNA remains a major challenge due to low target abundance and non-specific signal leakage. Herein, we reported a multifunctional DNA triangular sensor (TSDz) that integrates aptamer-mediated targeting and glutathione (GSH) co-gated activation for precise imaging of Egr-1 mRNA in cancer cells. The DNA sensor was constructed by multiple functionalized DNA sequences, including the aptamer sequence for specific membrane protein, the GSH activation sequence, and the target recognition sequence. The presence of GSH cleaved the disulfide bond in TSDz, releasing the site that could bind Egr-1 mRNA. This sensor showed a strong fluorescent signal for Egr-1 mRNA with a detection limit of 81.3 pM in buffer. The aptamer in TSDz that was for the membrane protein of MCF-7 cells could enhance the cellular uptake efficiency and the specific target recognition. Therefore, the DNA sensor exhibited precise imaging of Egr-1 mRNA in MCF-7 cells through specific targeting and stimulus response co-gating activation, opening up innovative avenues for disease diagnosis and intelligent cancer treatment.