Preparation of novel targeting nanobubbles conjugated with small interfering RNA for concurrent molecular imaging and gene therapy in vivo

The aim of this study was to establish a novel targeting nanobubble (TNB) conjugated with small interfering RNA (siRNA)-cyanine 5 (Cy5) and to validate its theranostic ability in vivo. The TNB conjugated with neuroepithelial transforming gene 1 (NET-1) siRNA-Cy5 was prepared by thin-film hydration and mechanical sonication method. A hepatocellular carcinoma (HCC) xenograft model was established by subcutaneously injecting SMMC-7721 cells in BALB/c nude mice. The NET-1 siRNA-conjugated TNB was utilized for accurate contrast-enhanced ultrasound in vivo imaging, which was enabled by the target ligand GPC-3 antibody and specific gene transfection with the aid of low-frequency ultrasound (LFUS) irradiation. BALB/c nude mice bearing tumors were randomized into 5 groups and irradiated with LFUS for 5 min after TNB administration; mice were treated twice a week for a total of 60 d. The mean particle size of TNB was <500 nm. Mice treated with NET-1 siRNA-conjugated TNB showed a significant decrease in tumor growth and the highest survival rate. Our findings offer an effective and safe gene vehicle and probe for molecular imaging in vivo. It may improve the early diagnosis and treatment effects of HCC.