Efficacy optimization of low frequency microbubble-mediated sonoporation as a drug delivery platform to cancer cells

Michal Eck, Ramona Aronovich, Tali Ilovitsh

Research output: Contribution to journalArticlepeer-review

13 Scopus citations


Ultrasound insonation of microbubbles can be used to form pores in cell membranes and facilitate the local trans-membrane transport of drugs and genes. An important factor in efficient delivery is the size of the delivered target compared to the generated membrane pores. Large molecule delivery remains a challenge, and can affect the resulting therapeutic outcomes. To facilitate large molecule delivery, large pores need to be formed. While ultrasound typically uses megahertz frequencies, it was recently shown that when microbubbles are excited at a frequency of 250 kHz (an order of magnitude below the resonance frequency of these agents), their oscillations are significantly enhanced as compared to the megahertz range. Here, to promote the delivery of large molecules, we suggest using this low frequency and inducing large pore formation through the high-amplitude oscillations of microbubbles. We assessed the impact of low frequency microbubble-mediated sonoporation on breast cancer cell uptake by optimizing the delivery of 4 fluorescent molecules ranging from 1.2 to 70 kDa in size. The optimal ultrasound peak negative pressure was found to be 500 kPa. Increasing the pressure did not enhance the fraction of fluorescent cells, and in fact reduced cell viability. For the smaller molecule sizes, 1.2 kDa and 4 kDa, the groups treated with an ultrasound pressure of 500 kPa and MB resulted in a fraction of 58% and 29% of fluorescent cells respectively, whereas delivery of 20 kDa and 70 kDa molecules yielded 10% and 5%, respectively. These findings suggest that low-frequency (e.g., 250 kHz) insonation of microbubbles results in high amplitude oscillation in vitro that increase the uptake of large molecules. Successful ultrasound-mediated molecule delivery requires the careful selection of insonation parameters to maximize the therapeutic effect by increasing cell uptake.

Original languageEnglish
Article number100132
JournalInternational Journal of Pharmaceutics: X
StatePublished - Dec 2022
Externally publishedYes

Bibliographical note

Publisher Copyright:
© 2022 The Authors


This work was supported by the Israel Science Foundation (grant number 3450/20 ), the Israel Ministry of Science & Technology (grant number 101716 ), a Zimin Institute grant, and was partially supported by a grant from the Nicholas and Elizabeth Slezak Super Center for Cardiac Research and biomedical engineering at Tel Aviv University .

FundersFunder number
Nicholas and Elizabeth Slezak Super Center for Cardiac Research
Israel Science Foundation3450/20
Tel Aviv University
Ministry of science and technology, Israel101716


    • Drug delivery
    • FUS
    • Low frequency
    • Microbubbles
    • Sonoporation


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