To evaluate the ability of ultrasound contrast agent nanobubbles as carriers of siRNA combined with ultrasound targeted nanobubble destruction to improve the siRNA transfection and interference efficiency in glioma cells, so as to achieve the effect of inhibiting tumor cell growth.

Nanobubbles were fabricated using the thin-film hydration method. Nanobubbles carrying siRNA were fabricated using the biotin-avidin system. After siRNA was transfected into glioma cells, confocal laser scanning microscopy was applied to assess the transfection efficiency in three groups of cells: nanobubbles-carboxyfluorescein-scrambled siRNA-ultrasound (NB-FAM-SCR-US), NB-FAM-SCR, and normal control. NB-siRNA-US (containing siRNA specific the target gene), NB-siRNA, and NB-SCR-US were used for subsequent experiments. Real-time PCR and Western blot were used to assess interference efficiency. Cell viability and apoptosis were evaluated by CCK-8 and annexin-V analysis.

The particle size of nanobubbles fabricated by the thin film hydration method was (663.9±102.5) nm; the particle size of nanobubbles carrying siRNA was (707.0±127.6) nm. The results of laser confocal microscopy showed that the transfection efficiency of siRNA was successfully enhanced by ultrasound irradiating nanobubbles. Real-time PCR and Western blot showed that the expression of the target gene was significantly reduced in the NB-siRNA-US group (real-time PCR: t=-12.34, -20.35, P<0.01). In the CCK-8 and annexin-V experiments, the proliferation of cells in the NB-siRNA-US group decreased and apoptosis increased (CCK-8: t=-13.52, -31.55, P<0.01; annexin-V: t=8.30, 9.79, P<0.01).

SiRNA transfection and interference efficiency can be improved by ultrasound irradiating nanobubbles to achieve the aim of inhibiting the growth of glioma cells, which provides a new strategy for non-invasive treatment of gliomas.