Acoustically-active microbubbles conjugated to liposomes: Characterization of a proposed drug delivery vehicle

Azadeh Kheirolomoom, Paul A. Dayton, Aaron F H Lum, Erika Little, Eric E. Paoli, Hairong Zheng, Katherine W. Ferrara

Research output: Contribution to journalArticlepeer-review

189 Scopus citations


A new acoustically-active delivery vehicle was developed by conjugating liposomes and microbubbles, using the high affinity interaction between avidin and biotin. Binding between microbubbles and liposomes, each containing 5% DSPE-PEG2kBiotin, was highly dependent on avidin concentration and observed above an avidin concentration of 10 nM. With an optimized avidin and liposome concentration, we measured and calculated as high as 1000 to 10,000 liposomes with average diameters of 200 and 100 nm, respectively, attached to each microbubble. Replacing avidin with neutravidin resulted in 3-fold higher binding, approaching the calculated saturation level. High-speed photography of this new drug delivery vehicle demonstrated that the liposome-bearing microbubbles oscillate in response to an acoustic pulse in a manner similar to microbubble contrast agents. Additionally, microbubbles carrying liposomes could be spatially concentrated on a monolayer of PC-3 cells at the focal point of ultrasound beam. As a result of cell-vehicle contact, the liposomes fused with the cells and internalization of NBD-cholesterol occurred shortly after incubation at 37 °C, with internalization of NBD-cholesterol substantially enhanced in the acoustic focus.

Original languageEnglish (US)
Pages (from-to)275-284
Number of pages10
JournalJournal of Controlled Release
Issue number3
StatePublished - Apr 23 2007


  • Delivery vehicle
  • Liposome
  • Microbubble
  • Ultrasound radiation forces

ASJC Scopus subject areas

  • Pharmaceutical Science


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