Fig. 1

Illustrations that delineate the construct of GQDs/Cy5-miR@sEVs and their applications in the biological systems. (1) The miRNA with chemical modification of Cy5 was attached to GQDs via “π–π” stacking in “off” state, followed by the encapsulation into sEVs by sonication and further delivery into cells or animals. (2) The miRNA encapsulated into GQDs/Cy5-miR@sEVs was delivered into cells via endocytosis, released inside the cytoplasm, and hybridized with the targeted mRNA to restore the quenched fluorescence (leading to the “on” signal). (3) The GQDs/Cy5-miR@sEVs were tested in cancer cells and tumor-bearing animal models, to visualize gene therapy of the delivered miRNA both in vitro and in vivo