αvβ3-targeted gas vesicles for ultrasound molecular imaging of tumors

Purpose To achieve ultrasound molecular imaging (UMI) of various tumor types, this study developed a novel integrin-targeted probe, RGD-hGVs, based on gas vesicles (GVs) derived from Halobacterium salinarum NRC-1 ( Halo ) and cyclic RGDfK peptides. The application potentials of UMI were evaluated in osteosarcoma and melanoma. Materials and Methods RGD-hGV acoustic nanoprobes were constructed by conjugating Halo-derived GVs with cyclic RGD peptides. Morphology was characterized by PCM and TEM, and hydrodynamic size and zeta potential were measured. In vitro targeting to bEnd.3, K7M2, and B16-F10 cells was evaluated by flow cytometry and confocal microscopy. Ultrasound imaging was performed in osteosarcoma and melanoma models, followed by immunofluorescence staining for αvβ3 and probe distribution. Biocompatibility was assessed by hemolysis, CCK-8 assays, serum biochemistry, and H&E staining of major organs. Results RGD-hGVs (∼240 nm) demonstrated targeted binding to tumor cells (bEnd.3, K7M2, B16-F10) in vitro and in vivo . They produced stronger, longer-lasting tumor ultrasound signals than non-targeted controls, with immunofluorescence confirming localization to tumor vasculature and cells, and showed no significant toxicity. Conclusion RGD-hGVs may serve as a novel UMI probe, suitable for diagnosing multiple tumors.