(a) Diagram of GvpC genetic fusions used to engineer novel GV properties and functions. (b) Zeta potential measurements of engineered GVs having GvpC fused to LRP and wild-type GvpC (N = 4, error bars are SEM) (c) Confocal fluorescence images showing RGD-functionalized, RDG-functionalized and wild-type Alexa Fluor-488 fluorescently labeled (green) GVs after 24 hr incubation with U87 glioblastoma cells (DAPI-stained nuclei, blue). Scale bars are 50 µm (d) Mean GV fluorescence measured for each condition in (c) (N = 3, error bars are SEM). (e) Confocal fluorescence images of RAW 264.7 macrophages (DAPI-stained nuclei, blue) incubated for 30 min with fluorescently labeled GVs (green) displaying GvpC fused to mCD47, R8 or wild-type GvpC. Scale bars are 50 µm. (f) Mean GV fluorescence measured for each condition in (e) (N = 3, error bars are SEM). (g) Top panel: Ultrasound images of engineered and SpyCatcher-mNeonGreen (SC-mNG) reacted GVs at OD 2.5 in PBS, acquired using a 19 MHz transmission pulse in fundamental mode. Scale bars are 1 mm. Bottom panel: Fluorescence images of the agarose phantoms before and after acoustic collapse. (h) Mean ultrasound and fluorescence signals from the GV samples tested in (g). (N ≥ 4, error bars are SEM).