Optimization of ultrasound parameters for microbubble-nanoliposome complex-mediated delivery.

Purpose: The aim of this study was to identify the optimal ultrasound (US) parameters for gene and drug delivery.

Methods: In order to target SkBr3, which is a breast cancer cell overexpressing the Her2 receptor, trastuzumab (Herceptin) was used. Micobubble-nanoliposome complex (MLC) was mixed with trastuzumab and stored overnight. Finally, MLC was combined with Her2Ab. A US device equipped with a 1-MHz probe was used for delivery to the cell. Several parameters, including intensity (w/cm(2)), time (minutes), and duty cycle (%), were varied within a range from 1 w/cm(2), 1 minute, and 20% to 2 w/cm(2), 2 minutes, and 60%, respectively. A confocal laser scanning microscope (CLSM) was used to confirm the delivery of MLC to the cells after US treatment.

Results: MLC with fluorescent dyes and trastuzumab was synthesized successfully. By delivering MLC with Her2Ab to cells, the targeting effect of trastuzumab with MLC was confirmed by CLSM. The cell membranes showed green (fluorescein isothiocyanate) and red (Texas red) fluorescence but treatments with MLC without Her2Ab did not show any fluorescence. Optimal conditions for US-mediated delivery were 1 or 2 w/cm(2), 2 minutes, and 60% (uptake ratio, 95.9% for 1 w/cm(2) and 95.7% for 2 w/cm(2)) for hydrophobic materials and 2 w/cm(2), 2 minutes, and 60% (uptake ratio, 95.0%) for hydrophilic materials.

Conclusion: The greater the strength, duty cycle, and period of US application within the tested range, the more efficiently the fluorescent contents were conveyed.