The antitumor effect of a new docetaxel-loaded microbubble combined with low-frequency ultrasound in vitro:...

To develop a novel docetaxel (DOC)-loaded lipid microbubbles (MBs) for achieving target therapy and overcoming the poor water-solubility drawback of DOC.

A novel DOC-loaded microbubble (DOC + MB) was prepared by lyophilization and the physicochemical properties including ultrasound contrast imaging of the liver were measured. The anti-tumor effect of the DOC + MBs combined with low-frequency ultrasound (LFUS; 0.8 Hz, 2.56 W/cm², 50% cycle duty) on the DLD-1 cancer cell line was examined using an MTT assay.

The physicochemical properties of the two tested formats of DOC + MBs (1.0 mg and 1.6 mg) was shown: concentration, (6.74 ± 0.02) × 10⁸ bubbles/mL and (8.27 ± 0.15) × 10⁸ bubbles/mL; mean size, 3.296 ± 0.004 μm and 3.387 ± 0.005 μm; pH value, 6.67 ± 0.11 and 6.56 ± 0.05; release rate, 3.41% and 12.50%; Zeta potential, -37.95 ± 7.84 mV and -44.35 ± 8.70 mV; and encapsulation efficiency, 54.9 ± 6.21% and 46.3 ± 5.69%, respectively. Compared with SonoVue, the DOC + MBs similarly enhanced the echo signal of the liver imaging. The anti-tumor effect of the DOC + MBs/LFUS group was significantly better than that of DOC alone and that of the normal MBs/LFUS groups.

The self-made DOC + MBs have potential as a new ultrasound contrast agent and drug-loaded microbubble, and can obviously enhance the antitumor effect of DOC under LFUS exposure.