Direct Cytosolic MicroRNA Detection Using Single-Layer Perfluorinated Tungsten Diselenide Nanoplatform

Intracellular miRNA detection is vitally important for diagnosing severe diseases like cancer and for resolving the ensemble of gene products that orchestrate the living state of cells. Recent advances in the design, synthesis, and application of biocompatible nanomaterials as platforms for probing miRNAs have enabled widespread efforts to mobilize new compounds in biomedical research. Two-dimensional graphene-like nanomaterials exhibit desirable physical properties such as convenient quantum size and dynamic interface functionality. Because miRNAs regulate gene expression in the cytoplasm, it is imperative that nanomaterials targeting them are properly delivered. Unloading of nanomaterials into the cytosol using the cellular endocytic transport pathway is often hindered by an inability to cross the endosomal membrane. To address this challenge, we designed a strategy to deliver functionalized WSe₂ nanosheets (FWNs) to the cytosol using perfluorinated surface functionalization. Perfluorinated compounds are both hydrophobic and lipophobic, exhibiting excellent phase-separation tendency in both polar and nonpolar environments. FWNs are ∼120 nm in diameter, feature low toxicity, and exhibit excellent stability in serum. The fluorinated nanostructure of FWNs enabled efficient cytosolic delivery from the endomembrane system. The fidelity of this approach was confirmed through intracellular delivery of two DNA probes (ssDNA-21 and ssDNA-210), which resulted in specific labeling of cytosolic miRNA and demonstrated the utility of this system for direct cytosolic biosensing.