Exosomal miRNAs play a critical role in cancer biology and could be potential biomarkers for cancer diagnosis. However, due to the low abundance of miRNAs in the exosomes, recognizing and detecting disease-associated exosomal miRNAs in an easy-to-operate way remain a challenge. Herein, we used a liposome-mediated membrane fusion strategy (MFS) to transfect CRISPR/Cas13a into exosomes, termed MFS-CRISPR, directly measuring exosomal miRNAs in plasma. Using the MFS-CRISPR platform for detection of the exosomal miR-21, we achieve a linear range spanning four orders of magnitude (104–108 particles/mL) and the method is able to detect the exosomal miR-21 in as low as 1.2 × 103 particles/mL. The liposome-mediated MFS could confine fluorescent signals in fused vesicles, which can be used for exosome heterogeneity analysis. Moreover, MFS-CRISPR assay was evaluated by measuring clinical samples, and the difference of miR-21 expression of breast cancer patients and healthy donors was significant. Because of high sensitivity and simplicity, the proposed method could have promising clinical potential for cancer diagnosis and treatment monitoring.

Activation of T-cell proliferation specifically in a tumor is crucial for reducing the autoimmune side effects of antitumor immunotherapy. Herein, we developed a pH-driven interlocked DNA nano-spring (iDNS) to stimulate T-cell activation in vivo in response to the low pH value in a tumor microenvironment. The interlocked structure of iDNS provide a more rigid scaffold in comparison to double-stranded DNA for ligand assembly, which can help to control the spatial distribution of ligands with more accuracy. We have demonstrated that the pH-driven reversible reconfiguration of iDNS provides a powerful way to regulate the nanoscale distribution of T-cell receptors (CD3) on the cell surface. The relatively low pH value (pH 6.5) in a solid tumor was able to drive the springlike shrinking of iDNS and induce significant T-cell proliferation, leading to an enhanced antitumor effect, thus providing a tool for specifically inducing an immune response in a tumor for immunotherapy.

No abstract